Wednesday, May 5, 2021

Hilary Putnam, American Philosopher


American Philosopher Hilary Putnam
Born July 31, 1926, Chicago, Illinois
Died March 13, 2016 (aged 89)
Subjects of Study: Realism




Hilary Putnam, American Philosopher

by Yemima Ben-Menahem

Barbara Druss Dibner Professor of the History of Science Emeritus,
The Hebrew University of Jerusalem. Author of Conventionalism and others.

Last Updated: Mar 10, 2021

Hilary Putnam, (born July 31, 1926, Chicago, Illinois, U.S.—died March 13, 2016), leading American philosopher who made major contributions to metaphysics, epistemology, the philosophy of mind, the philosophy of language, the philosophy of science, the philosophy of mathematics, and the philosophy of logic. He is best known for his semantic externalism, according to which linguistic meanings are not purely mental entities but reach out to external reality; his antireductionist philosophy of mind; and his persistent defense of realism, the view that truth and knowledge are objective. In his later years he became increasingly sensitive to the moral aspects of epistemology and metaphysics and, more generally, to philosophy’s moral calling.

Early Life And Career

Putnam was the only child of Samuel and Riva Putnam. His father was a writer and translator, an active communist, and a columnist for the Daily Worker, the newspaper of the Communist Party of the United States of America (CPUSA). Putnam studied mathematics and philosophy at the University of Pennsylvania and attended graduate school in philosophy at Harvard University and the University of California at Los Angeles (UCLA). At UCLA he wrote a dissertation, under Hans Reichenbach, on the concept of probability, obtaining a Ph.D. in 1951. He taught philosophy at Northwestern University, Princeton University, and the Massachusetts Institute of Technology (MIT) until 1976, when he joined the philosophy department at Harvard. He retired as Cogan University Professor Emeritus at Harvard in 2000.

At Princeton, where he became acquainted with the logical positivist Rudolf Carnap and the mathematical logician Georg Kreisel, Putnam immersed himself in mathematical logic. Among other projects, he worked on one of the 23 unsolved problems in mathematics identified by David Hilbert in 1900: that of finding a general algorithm for solving Diophantine equations (polynomial equations, named after Diophantus of Alexandria, involving only integer constants and allowing only integer solutions). The basis for a proof that the problem is unsolvable was provided by Putnam, Martin Davis, and Julia Robinson in 1961 and completed by Yuri Matiyasevich in 1970.

During the 1960s Putnam was deeply involved in the antiwar movement that opposed U.S. participation in the Vietnam War. He was active in Students for a Democratic Society (SDS) and in the Progressive Labor Party, a Maoist group, but by the early 1970s he had become disillusioned with far-left political ideology. At about the same time, he developed a sustained interest, both personal and professional, in his Jewish heritage.

Realism And Meaning

The unifying theme of Putnam’s philosophy is his defense of realism, the view that, ordinarily, assertions (including theories, beliefs, and so on) are objectively true or false. Putnam, like most realists, also upheld the possibility of knowledge, distinguishing between knowledge and mere belief, convention, dogma, and superstition. Always self-reflective and self-critical, Putnam frequently revisited and revised his earlier positions. The most-pronounced change occurred in 1976, when he launched an attack on the view he called “metaphysical realism,” recommending that “internal realism” be adopted in its stead (see below Varieties of realism). Internal realism, in turn, was also modified. Over the years, however, it became exceedingly clear that Putnam’s commitment to realism overrode the nuanced differences between the various versions of realism he espoused. The clearest indication of this core stability is the centrality of his theory of meaning to all his versions of realism.

Questions about the nature of truth and objectivity have always occupied a central place in philosophy. Following the “linguistic turn” in Anglo-American (analytic) philosophy in the early 20th century, these questions came to be inseparable from questions about linguistic meaning and representation. An account of the word-world relation (the relation between words and the things in the world they refer to or represent) is thus considered fundamental to contemporary philosophy. For instance, it is crucial for philosophers to take a position on the question of whether there is a uniquely correct representation of the world in language or whether multiple languages represent the world in diverse and possibly incompatible ways, all equally legitimate. Moreover, truth and meaning are closely linked. To determine whether a certain sentence is true, one must be able to understand the sentence, to know what it means. On the other hand, it stands to reason that understanding a sentence involves knowing under what conditions it should be considered true (or false). Theories of truth and meaning are thus inherently interconnected. This connection is manifest in Putnam’s conception of meaning, first proposed in his classic paper “The Meaning of ‘Meaning’ ” (1975), which construes meanings not as purely mental entities (e.g., mental images) or as purely conceptual constructs but as being anchored in external reality. This conception, known as semantic externalism, can therefore serve as a basis for an objective account of truth and knowledge. Consequently, it can also support realism—and was indeed employed by Putnam (and many others after him) to that end.

Putnam’s early defense of realism was primarily directed against the logical positivists, who held a verificationist theory of meaning. According to this theory, synthetic statements—statements that are not true, or false, merely by virtue of the meanings of their terms (“All bachelors are unmarried”)—are cognitively meaningful only if they are empirically verifiable, at least in principle. Logical positivists claimed that value judgments, inasmuch as they express emotional attitudes that are, by their very nature, subjective, have no truth value (i.e., are neither true nor false) and are devoid of cognitive meaning. They further claimed that the theoretical (as opposed to the observational) claims of science are also unverifiable and in fact function as predictive instruments (predictors of observations) rather than as descriptions of an independently existing reality. Against the logical positivists, Putnam argued that the verificationist view of scientific theories rendered the overwhelming success of science a miracle. In other words, if successful scientific theories are not understood as describing an independently existing reality, their success is impossible to explain. This argument for realism came to be known as the “no-miracle” argument for realism. Putnam was equally critical of conventionalism, the view that logic, mathematics, and extensive portions of science do not express truths but are based on human stipulations—i.e., convention.

It soon became apparent, however, that the most serious threat to realism was not verificationism or conventionalism but metaphysical relativism, a clear model of which was provided by the American philosopher of science Thomas S. Kuhn in his influential work The Structure of Scientific Revolutions (1962). According to Kuhn, different stages in the history of scientific thought are characterized by different scientific paradigms, or worldviews, each consisting of a body of formal theories, classic experiments, and trusted methodologies. Because the theories of a given paradigm will refer to entities that have no exact, if any, parallel in other paradigms, theories falling under different paradigms refer—literally—to different worlds and are therefore “incommensurable”: they can be neither compared with each other nor tested against some putative objective reality. In essence, the notion of reality is discarded.

The theory of meaning underlying this relativist picture is that meanings are constituted “internally” within each paradigm. Theoretical changes generate changes in the meanings of scientific terms (i.e., the terms are associated with different definitions or descriptions), which in turn lead to changes in reference (i.e., the terms are taken to refer to different entities). In short, meaning is relative to a theory, paradigm, or conceptual scheme. Moreover, truth is also relative in this sense, in virtue of the close connection between truth and meaning: if the meaning of a theoretical statement is relative to a theory, paradigm, or conceptual scheme, then its truth value will be relative in the same way and to the same extent.

If this theory of meaning is accepted—i.e., if typical scientific terms have different meanings, and thus different referents, in different paradigms—then theories grounded in different paradigms are indeed incommensurable. Even worse, they lose contact with reality. From the realist point of view, these conclusions are totally unacceptable. Yet as long as the theory of meaning from which they follow is accepted, they cannot simply be dismissed. To defend realism against this kind of relativism, therefore, an alternative theory of meaning is required.

Putnam rose to this challenge, proposing a theory that, among other things, rejected the common assumption that meanings are mental entities (e.g., beliefs or mental images). “Meanings just ain’t in the head!” as he put it in “The Meaning of ‘Meaning.’ ” Nor are meanings constituted by definitions or descriptions. Rather, it is reference (or extension)—the entity one points to when introducing or explaining a term—that is paramount in fixing meaning and determining whether words vary in meaning from speaker to speaker or from theory to theory. Although reference does not exhaust meaning, it constitutes its essential core. The same referent may thus be characterized in different ways in different theories, so that the theories may vary while their referents remain fixed. This move enabled Putnam to put forward two claims that, taken together, defeat the relativist argument:

1. Theories grounded in different paradigms can refer to the same entities. The connection between a scientific term and the entity to which it refers is established by causal chains of prior uses of the term and by social practices such as pointing, moving, and weighing, rather than by definitions, descriptions, or mental images. This claim rebuts the incommensurability argument.

2. Different speakers can associate a word with identical beliefs and mental images, or even with the same definition, and yet diverge in the meanings they ascribe to it. Putnam devised his “Twin Earth” thought experiment to demonstrate this claim. Twin Earth replicates Earth in almost every detail, including its inhabitants, who are exact duplicates of the inhabitants of Earth, speaking the same languages and having the same mental lives (e.g., the same beliefs and mental images). On Twin Earth, however, the stuff that looks, feels, and functions like water on Earth is not H2O but a different chemical compound, abbreviated XYZ. (Because the year is 1750—about 50 years before the molecular structure of water was discovered—the inhabitants of Earth and Twin Earth do not know that the substances they call “water” are H2O and XYZ, respectively.) Although the beliefs and images associated with the word water on Twin Earth are identical to those associated with water on Earth (e.g., the inhabitants of both planets believe that “water is the clear liquid that fills the oceans, lakes, and rivers and falls as rain”), the term differs in meaning on the two planets because the substance it refers to on Earth differs from the substance it refers to on Twin Earth. The word water, Putnam argues, always refers to the stuff “out there” in the external world that a speaker, uttering “water,” might point to when identifying or referring to a certain liquid as water. From an Earthly perspective, the word water always refers to the stuff that an Earthling might point to, whereas on Twin Earth it refers to the stuff that a Twin Earthling might point to. This conclusion is a manifestation of the externalism that is at the heart of Putnam’s conception of meaning.

Another aspect of Putnam’s theory of meaning is what he called “the division of linguistic labor”—namely, the fact that lay users of a language need not have the detailed knowledge of it that experts have. For example, as long as there are, in the community of speakers, experts who know how to tell gold from other materials, lay speakers can successfully use the term gold to refer to that substance even though they lack the knowledge in question. This view, originally articulated in “The Meaning of ‘Meaning,’ ” was later elaborated on to highlight further features of linguistic practice, the most important being context-dependence, or the variation of meaning with speaker background and conversational context. Thus, words such as honour and justice may have very dissimilar meanings in different cultures, and even scientific terms such as atom and heat can vary with time and context.

Varieties Of Realism

Beginning in the mid-1970s, Putnam sought to distinguish his understanding of realism from what he now called “metaphysical realism.” According to Putnam (“Why There Isn’t a Ready-Made World” [1983]),

What the metaphysical realist holds is that we can think and talk about things as they are, independently of our minds, and that we can do this by virtue of a “correspondence” relation between the terms in our language and some sorts of mind-independent entities.

For Putnam, this picture of word-world correspondence is absurd, pointing to a realism gone wild. Putnam considered metaphysical realism to be blind to the autonomy and complexity of human language. In particular, it is blind to the fact that the same reality can be described in multiple ways.

Whether Putnam’s early realism was ever “metaphysical” in this sense is questionable, but it is clear that his explicit critique of metaphysical realism gives Putnam’s philosophy a Kantian bent; this is particularly salient in the papers collected in Reason, Truth and History (1981). Much like Kant’s denial of the knowability of the “thing in itself,” the modest realism Putnam endorsed there eschewed the notion of reality “in itself,” with its built-in representation. After initially calling his position “internal realism,” Putnam later referred to it as “commonsense realism” or simply “realism,” as opposed to “Realism.” The essential point is that none of these changes impelled Putnam to deny objective truth. Truth under a description, he maintained, is all the truth one needs to avoid subjectivism and relativism. He emphasized, for example, the prevalence in science and mathematics of the phenomenon of equivalence between different theories or descriptions. Such equivalent theories can differ in their respective ontologies (e.g., one adducing forces, the other fields) and still predict and explain the very same phenomena.

Not surprisingly, this middle ground soon came under fire. Critics considered Putnam’s realism unstable and at risk of collapsing into either metaphysical realism or relativism. The latter option was particularly repugnant to Putnam: in its thoroughgoing denial of objective truth, relativism is but a form of radical skepticism and is clearly at odds with Putnam’s realism.

One of Putnam’s striking insights at that time was that the two polar positions—metaphysical realism on the one hand and skepticism on the other—are equally vulnerable, and for the same reason. Both positions construe truth as radically non-epistemic, and, thus, both countenance the possibility that the best scientific theory of the world—a theory that satisfies every epistemic desideratum and is perfect in every methodological and aesthetic respect—could still turn out to be false. But this possibility, Putnam argued, is meaningless, and so are the metaphysical views that countenance it.

Putnam devoted considerable effort to the rebuttal of skepticism. In particular, he addressed the oft-touted skeptical claim that, for all one knows, one might be a brain in a vat. As Putnam described it in “Brains in a Vat” (1981), this thought experiment contemplates the following scenario:

A human being (you can imagine this to be yourself) has been subjected to an operation by an evil scientist. The person’s brain (your brain) has been removed from the body and placed in a vat of nutrients which keeps the brain alive. The nerve endings have been connected to a super-scientific computer which causes the person whose brain it is to have the illusion that everything is perfectly normal.

The purpose of the thought experiment, Putnam noted, is “to raise the classical problem of scepticism with respect to the external world in a modern way. (How do you know you aren’t in this predicament?)” Here too, Putnam’s argument follows directly from his theory of meaning. On the externalist conception of meaning, words in the vat brain language do not have the same referents as “normal” words in “normal” human languages because they are not causally connected in the normal way to the referents of normal words. In particular, for brains in a vat, the word tree would refer not to real trees but at best to images of trees produced by a supercomputer and experienced by envatted brains. Likewise, the word vat in the vat brain language would refer not to real vats but at best to images of vats so produced and experienced. “In short,” Putnam concluded, “if we are brains in a vat, then ‘We are brains in a vat’ is false.” The brains-in-a-vat hypothesis is thus paradoxical and self-defeating. Skepticism is, it turns out, fundamentally flawed: the skeptic’s concerns cannot even be expressed in a meaningful way.

Putnam’s realism also led him to pursue a realist interpretation of quantum mechanics, a theory generally considered to pose insurmountable difficulties for the realist. Many physicists believe, for example, that quantum mechanics, unlike classical mechanics, does not represent the actual physical state of a system. Rather, it is an algorithm for calculating the probabilities of the results of measurements. Putnam’s first attempt to provide a more realist understanding of quantum mechanics invoked the radical claim that logic is empirical. He argued that quantum mechanics does, in fact, represent real physical states, but the logical rules used for quantum calculations diverge from those used in classical physics. Putnam later renounced that approach, adopting a less radical version of quantum mechanics put forward by David Bohm and further developed by G.C. Girardi, A. Rimini, and T. Weber.

Putnam’s realism also extended to mathematics. Together with the American philosopher W.V.O. Quine, he proposed the indispensability thesis: given that mathematical objects such as numbers, sets, and groups play an indispensable role in the best theories of the world, their reality must be granted (see also philosophy of mathematics: The Fregean argument for Platonism).

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Hilary Whitehall Putnam (/ˈpʌtnəm/; July 31, 1926 – March 13, 2016) was an American philosopher, mathematician, and computer scientist, and a major figure in analytic philosophy in the second half of the 20th century. He made significant contributions to philosophy of mind, philosophy of language, philosophy of mathematics, and philosophy of science.[8] Outside philosophy, Putnam contributed to mathematics and computer science. Together with Martin Davis he developed the Davis–Putnam algorithm for the Boolean satisfiability problem[9] and he helped demonstrate the unsolvability of Hilbert's tenth problem.[10]

Putnam was known for his willingness to apply equal scrutiny to his own philosophical positions as to those of others, subjecting each position to rigorous analysis until he exposed its flaws.[11] As a result, he acquired a reputation for frequently changing his positions.[12] In philosophy of mind, Putnam is known for his argument against the type-identity of mental and physical states based on his hypothesis of the multiple realizability of the mental, and for the concept of functionalism, an influential theory regarding the mind–body problem.[8][13] In philosophy of language, along with Saul Kripke and others, he developed the causal theory of reference, and formulated an original theory of meaning, introducing the notion of semantic externalism based on a thought experiment called Twin Earth.[14]

In philosophy of mathematics, he and his mentor W. V. O. Quine developed the "Quine–Putnam indispensability thesis", an argument for the reality of mathematical entities,[15] later espousing the view that mathematics is not purely logical, but "quasi-empirical".[16] In epistemology, he is known for his critique of the well-known "brain in a vat" thought experiment. This thought experiment appears to provide a powerful argument for epistemological skepticism, but Putnam challenges its coherence.[17] In metaphysics, he originally espoused a position called metaphysical realism, but eventually became one of its most outspoken critics, first adopting a view he called "internal realism",[18] which he later abandoned. Despite these changes of view, throughout his career he remained committed to scientific realism, roughly the view that mature scientific theories are approximately true descriptions of ways things are.[19]

In the philosophy of perception, Putnam came to endorse direct realism, according to which perceptual experiences directly present one with the external world. He once further held that there are no mental representations, sense data, or other intermediaries that stand between the mind and the world.[20] By 2012, however, he rejected this commitment in favor of "transactionalism", a view that accepts both that perceptual experiences are world-involving transactions, and that these transactions are functionally describable (provided that worldly items and intentional states may be referred to in the specification of the function). Such transactions can further involve qualia.[21][22] In his later work, Putnam became increasingly interested in American pragmatism, Jewish philosophy, and ethics, engaging with a wider array of philosophical traditions. He also displayed an interest in metaphilosophy, seeking to "renew philosophy" from what he identified as narrow and inflated concerns.[23] He was at times a politically controversial figure, especially for his involvement with the Progressive Labor Party in the late 1960s and early 1970s.[24][25] At the time of his death, Putnam was Cogan University Professor Emeritus at Harvard University.

Life

Putnam was born in Chicago, Illinois, in 1926. His father, Samuel Putnam, was a scholar of Romance languages, columnist, and translator who wrote for the Daily Worker, a publication of the American Communist Party, from 1936 to 1946 (when he became disillusioned with communism).[26] As a result of his father's commitment to communism, Putnam had a secular upbringing, although his mother, Riva, was Jewish.[11] The family lived in France until 1934, when they returned to the United States, settling in Philadelphia.[11] Putnam attended Central High School; there he met Noam Chomsky, who was a year behind him. The two remained friends—and often intellectual opponents—for the rest of Putnam's life.[27] Putnam studied philosophy at the University of Pennsylvania, receiving his B.A. degree and becoming a member of the Philomathean Society, the country's oldest continually existing collegiate literary society.[11][28] He did graduate work in philosophy at Harvard University[11] and later at UCLA'S philosophy department, where he received his Ph.D. in 1951 for his dissertation, The Meaning of the Concept of Probability in Application to Finite Sequences.[29] Putnam's dissertation supervisor Hans Reichenbach was a leading figure in logical positivism, the dominant school of philosophy of the day; one of Putnam's most consistent positions has been his rejection of logical positivism as self-defeating.[28]

After teaching at Northwestern University (1951–52), Princeton University (1953–61), and MIT (1961–65), Putnam moved to Harvard in 1965. His wife, the philosopher Ruth Anna Putnam, took a teaching position in philosophy at Wellesley College.[28] Hilary and Ruth Anna were married on August 11, 1962.[30] Ruth Anna, descendant of a family with a long scholarly tradition in Gotha (her ancestor was the German classical scholar Christian Friedrich Wilhelm Jacobs),[31] was born in Berlin, Germany,[32] in 1927 to anti-Nazi activist parents and, like Putnam, was raised atheist (her mother was Jewish and her father from a Christian background).[33][34][35][36] The Putnams, rebelling against the antisemitism they experienced during their youth, decided to establish a traditional Jewish home for their children.[33] Since they had no experience with the rituals of Judaism, they sought out invitations to other Jews' homes for Seder. They had "no idea how to do it [themselves]", in Ruth Anna's words. They began to study Jewish ritual and Hebrew, and became more Jewishly interested, identified, and active. In 1994, Hilary Putnam celebrated a belated Bar Mitzvah service. His wife had a Bat Mitzvah service four years later.[33]

Putnam was a popular teacher at Harvard. In keeping with his family tradition, he was politically active.[28] In the 1960s and early 1970s, he was an active supporter of the American Civil Rights Movement and opposition to the Vietnam War.[25] In 1963, he organized one of MIT's first faculty and student committees against the war. Putnam was disturbed when he learned from David Halberstam's reports that the U.S. was "defending" South Vietnamese peasants from the Vietcong by poisoning their rice crops.[28] After moving to Harvard in 1965, he organized campus protests and began teaching courses on Marxism. Putnam became an official faculty advisor to the Students for a Democratic Society and in 1968 a member of the Progressive Labor Party (PLP).[28] He was elected a Fellow of the American Academy of Arts and Sciences in 1965.[37] After 1968, his political activities centered on the PLP.[25] The Harvard administration considered these activities disruptive and attempted to censure Putnam, but two other faculty members criticized the procedures.[38][39] Putnam permanently severed his ties with the PLP in 1972.[40] In 1997, at a meeting of former draft resistance activists at Boston's Arlington Street Church, he called his involvement with the PLP a mistake. He said he had been impressed at first with the PLP's commitment to alliance-building and its willingness to attempt to organize from within the armed forces.[25]

In 1976, Putnam was elected president of the American Philosophical Association. The next year, he was selected as Walter Beverly Pearson Professor of Mathematical Logic in recognition of his contributions to the philosophy of logic and mathematics.[28] While breaking with his radical past, Putnam never abandoned his belief that academics have a particular social and ethical responsibility toward society. He continued to be forthright and progressive in his political views, as expressed in the articles "How Not to Solve Ethical Problems" (1983) and "Education for Democracy" (1993).[28]

Putnam was a Corresponding Fellow of the British Academy. He retired from teaching in June 2000, but as of 2009 continued to give a seminar almost yearly at Tel Aviv University. He also held the Spinoza Chair of Philosophy at the University of Amsterdam in 2001.[41] He was the Cogan University Professor Emeritus at Harvard University and a founding patron of the small liberal arts college Ralston College. His corpus includes five volumes of collected works, seven books, and more than 200 articles. Putnam's renewed interest in Judaism inspired him to publish several books and essays on the topic.[42] With his wife, he co-authored several books and essays on the late-19th-century American pragmatist movement.[28]

For his contributions in philosophy and logic, Putnam was awarded the Rolf Schock Prize in 2011[43] and the Nicholas Rescher Prize for Systematic Philosophy in 2015.[44] He delivered his last Skype talk, "Thought and Language," at an international conference on "The Philosophy of Hilary Putnam" held at the Indian Institute of Technology, Bombay, on October 3, 2015, organized by his student Sanjit Chakraborty.[45][46] Putnam died at his home in Arlington, Massachusetts, on March 13, 2016.[47]

Philosophy of mind

Multiple realizability

An illustration of multiple realizability. M stands for mental and P stands for physical. It can be seen that more than one P can instantiate one M, but not vice versa. Causal relations between states are represented by the arrows (M1 goes to M2, etc.).

Putnam's best-known work concerns philosophy of mind. His most noted original contributions to that field came in several key papers published in the late 1960s that set out the hypothesis of multiple realizability.[48] In these papers, Putnam argues that, contrary to the famous claim of the type-identity theory, it is not necessarily true that "Pain is identical to C-fibre firing." According to Putnam's papers, pain may correspond to utterly different physical states of the nervous system in different organisms even if they all experience the same mental state of "being in pain".

Putnam cited examples from the animal kingdom to illustrate his thesis. He asked whether it was likely that the brain structures of diverse types of animals realize pain, or other mental states, the same way. If they do not share the same brain structures, they cannot share the same mental states and properties, in which case mental states must be realized by different physical states in different species. Putnam then took his argument a step further, asking about such things as the nervous systems of alien beings, artificially intelligent robots and other silicon-based life forms. These hypothetical entities, he contended, should not be considered incapable of experiencing pain just because they lack human neurochemistry. Putnam concluded that type-identity theorists had been making an "ambitious" and "highly implausible" conjecture that could be disproved by one example of multiple realizability.[49] This is sometimes called the "likelihood argument".[48]

Putnam formulated a complementary argument based on what he called "functional isomorphism". He defined the concept in these terms: "Two systems are functionally isomorphic if 'there is a correspondence between the states of one and the states of the other that preserves functional relations'." In the case of computers, two machines are functionally isomorphic if and only if the sequential relations among states in the first exactly mirror the sequential relations among states in the other. Therefore, a computer made of silicon chips and one made of cogs and wheels can be functionally isomorphic but constitutionally diverse. Functional isomorphism implies multiple realizability.[49] This is sometimes called an "a priori argument".[48]

Putnam, Jerry Fodor, and others argued that, along with being an effective argument against type-identity theories, multiple realizability implies that any low-level explanation of higher-level mental phenomena is insufficiently abstract and general.[49][50][51] Functionalism, which identifies mental kinds with functional kinds that are characterized exclusively in terms of causes and effects, abstracts from the level of microphysics, and therefore seemed to be a better explanation of the relation between mind and body. In fact, there are many functional kinds, such as mousetraps, software and bookshelves, that are multiply realized at the physical level.[49]

Machine state functionalism

Putnam himself put forth the first formulation of such a functionalist theory. This formulation, now called "machine-state functionalism", was inspired by analogies Putnam and others made between the mind and Turing machines. The point for functionalism is the nature of the states of the Turing machine. Each state can be defined in terms of its relations to the other states and to the inputs and outputs, and the details of how it accomplishes what it accomplishes and of its material constitution are completely irrelevant. According to machine-state functionalism, the nature of a mental state is just like the nature of a Turing machine state. Just as "state one" simply is the state in which, given a particular input, such-and-such happens, so being in pain is the state which disposes one to cry "ouch", become distracted, wonder what the cause is, and so forth.[52]

Rejection of functionalism

In the late 1980s, Putnam abandoned his adherence to functionalism and other computational theories of mind. His change of mind was primarily due to the difficulties computational theories have in explaining certain intuitions with respect to the externalism of mental content. This is illustrated by Putnam's own Twin Earth thought experiment (see Philosophy of language).[20] In 1988 he also developed a separate argument against functionalism based on Fodor's generalized version of multiple realizability. Asserting that functionalism is really a watered-down identity theory in which mental kinds are identified with functional kinds, Putnam argued that mental kinds may be multiply realizable over functional kinds. The argument for functionalism is that the same mental state could be implemented by the different states of a universal Turing machine.[53]

Despite Putnam's rejection of functionalism, it has continued to flourish and been developed into numerous versions by Fodor, David Marr, Daniel Dennett, and David Lewis, among others.[54] Functionalism helped lay the foundations for modern cognitive science[54] and is the dominant theory of mind in philosophy today.[55]

By 2012 Putnam accepted a modification of functionalism called "liberal functionalism". The view holds that "what matters for consciousness and for mental properties generally is the right sort of functional capacities and not the particular matter that subserves those capacities".[21] The specification of these capacities may refer to what goes on outside the organism's "brain", may include intentional idioms, and need not describe a capacity to compute something or other.[21]

Philosophy of language

Semantic externalism

One of Putnam's contributions to philosophy of language is his claim that "meaning just ain't in the head". His views on meaning, first laid out in Meaning and Reference (1973), then in The Meaning of "Meaning" (1975), use his "Twin Earth" thought experiment to illustrate that terms' meanings are determined by factors outside the mind.

Twin Earth shows this, according to Putnam, since on Twin Earth everything is identical to Earth, except that its lakes, rivers and oceans are filled with XYZ rather than H2O. Consequently, when an earthling, Fredrick, uses the Earth-English word "water", it has a different meaning from the Twin Earth-English word "water" when used by his physically identical twin, Frodrick, on Twin Earth. Since Fredrick and Frodrick are physically indistinguishable when they utter their respective words, and since their words have different meanings, meaning cannot be determined solely by what is in their heads.[56]:70–75 This led Putnam to adopt a version of semantic externalism with regard to meaning and mental content.[17][49] The philosopher of mind and language Donald Davidson, despite his many differences of opinion with Putnam, wrote that semantic externalism constituted an "anti-subjectivist revolution" in philosophers' way of seeing the world. Since Descartes's time, philosophers had been concerned with proving knowledge from the basis of subjective experience. Thanks to Putnam, Saul Kripke, Tyler Burge and others, Davidson said, philosophy could now take the objective realm for granted and start questioning the alleged "truths" of subjective experience.[57]

Theory of meaning

Along with Kripke, Keith Donnellan, and others, Putnam contributed to what is known as the causal theory of reference.[8] In particular, he maintained in The Meaning of "Meaning" that the objects referred to by natural kind terms—such as "tiger", "water", and "tree"—are the principal elements of the meaning of such terms. There is a linguistic division of labor, analogous to Adam Smith's economic division of labor, according to which such terms have their references fixed by the "experts" in the particular field of science to which the terms belong. So, for example, the reference of the term "lion" is fixed by the community of zoologists, the reference of the term "elm tree" is fixed by the community of botanists, and chemists fix the reference of the term "table salt" as sodium chloride. These referents are considered rigid designators in the Kripkean sense and are disseminated outward to the linguistic community.[49]

Putnam specifies a finite sequence of elements (a vector) for the description of the meaning of every term in the language. Such a vector consists of four components:

  1. the object to which the term refers, e.g., the object individuated by the chemical formula H2O;
  2. a set of typical descriptions of the term, referred to as "the stereotype", e.g., "transparent", "colorless", and "hydrating";
  3. the semantic indicators that place the object into a general category, e.g., "natural kind" and "liquid";
  4. the syntactic indicators, e.g., "concrete noun" and "mass noun".

Such a "meaning-vector" provides a description of the reference and use of an expression within a particular linguistic community. It provides the conditions for its correct usage and makes it possible to judge whether a single speaker attributes the appropriate meaning to it or whether its use has changed enough to cause a difference in its meaning. According to Putnam, it is legitimate to speak of a change in the meaning of an expression only if the reference of the term, and not its stereotype, has changed. But since no possible algorithm can determine which aspect—the stereotype or the reference—has changed in a particular case, it is necessary to consider the usage of other expressions of the language.[49] Since there is no limit to the number of such expressions to be considered, Putnam embraced a form of semantic holism.[58]

Philosophy of mathematics

Putnam made a significant contribution to philosophy of mathematics in the Quine–Putnam "indispensability argument" for mathematical realism.[59] Stephen Yablo considers this argument one of the most challenging in favor of the existence of abstract mathematical entities, such as numbers and sets.[60] The form of the argument is as follows.

  1. One must have ontological commitments to all entities that are indispensable to the best scientific theories, and to those entities only (commonly referred to as "all and only").
  2. Mathematical entities are indispensable to the best scientific theories. Therefore,
  3. One must have ontological commitments to mathematical entities.[61]

The justification for the first premise is the most controversial. Both Putnam and Quine invoke naturalism to justify the exclusion of all non-scientific entities, and hence to defend the "only" part of "all and only". The assertion that "all" entities postulated in scientific theories, including numbers, should be accepted as real is justified by confirmation holism. Since theories are not confirmed in a piecemeal fashion, but as a whole, there is no justification for excluding any of the entities referred to in well-confirmed theories. This puts the nominalist who wishes to exclude the existence of sets and non-Euclidean geometry but include the existence of quarks and other undetectable entities of physics, for example, in a difficult position.[61]

Putnam holds the view that mathematics, like physics and other empirical sciences, uses both strict logical proofs and "quasi-empirical" methods. For example, Fermat's last theorem states that for no integer  are there positive integer values of x, y, and z such that . Before Andrew Wiles proved this for all  in 1995,[62] it had been proved for many values of n. These proofs inspired further research in the area, and formed a quasi-empirical consensus for the theorem. Even though such knowledge is more conjectural than a strictly proved theorem, it was still used in developing other mathematical ideas.[16]

Mathematics and computer science

Putnam has contributed to scientific fields not directly related to his work in philosophy.[8] As a mathematician, he contributed to the resolution of Hilbert's tenth problem in mathematics. This problem (now known as Matiyasevich's theorem or the MRDP theorem) was settled by Yuri Matiyasevich in 1970, with a proof that relied heavily on previous research by Putnam, Julia Robinson and Martin Davis.[63]

In computability theory, Putnam investigated the structure of the ramified analytical hierarchy, its connection with the constructible hierarchy and its Turing degrees. He showed that there are many levels of the constructible hierarchy that add no subsets of the integers[64] and later, with his student George Boolos, that the first such "non-index" is the ordinal  of ramified analysis[65] (this is the smallest  such that  is a model of full second-order comprehension), and also, together with a separate paper with Richard Boyd (another of Putnam's students) and Gustav Hensel,[66] how the Davis–Mostowski–Kleene hyperarithmetical hierarchy of arithmetical degrees can be naturally extended up to .

In computer science, Putnam is known for the Davis–Putnam algorithm for the Boolean satisfiability problem (SAT), developed with Martin Davis in 1960.[8] The algorithm finds whether there is a set of true or false values that satisfies a given Boolean expression so that the entire expression becomes true. In 1962, they further refined the algorithm with the help of George Logemann and Donald W. Loveland. It became known as the DPLL algorithm. It is efficient and still forms the basis of most complete SAT solvers.[9]

Epistemology

A "brain in a vat"—Putnam uses this thought experiment to argue that skeptical scenarios are impossible.

In epistemology, Putnam is known for his "brain in a vat" thought experiment (a modernized version of Descartes's evil demon hypothesis). The argument is that one cannot coherently suspect that one is a disembodied "brain in a vat" placed there by some "mad scientist".[17]

This follows from the causal theory of reference. Words always refer to the kinds of things they were coined to refer to, the kinds of things their user, or the user's ancestors, experienced. So, if some person, Mary, is a "brain in a vat", whose every experience is received through wiring and other gadgetry created by the mad scientist, then Mary's idea of a brain does not refer to a real brain, since she and her linguistic community have never encountered such a thing. To her a brain is actually an image fed to her through the wiring. Nor does her idea of a vat refer to a real vat. So if, as a brain in a vat, she says, "I'm a brain in a vat", she is actually saying, "I'm a brain-image in a vat-image", which is incoherent. On the other hand, if she is not a brain in a vat, then saying that she is a brain in a vat is still incoherent, because she actually means the opposite. This is a form of epistemological externalism: knowledge or justification depends on factors outside the mind and is not solely determined internally.[17]

Putnam has clarified that his real target in this argument was never skepticism, but metaphysical realism.[67][68] Since realism of this kind assumes the existence of a gap between how one conceives the world and the way the world really is, skeptical scenarios such as this one (or Descartes's evil demon) present a formidable challenge. By arguing that such a scenario is impossible, Putnam attempts to show that this notion of a gap between one's concept of the world and the way it is is absurd. One cannot have a "God's-eye" view of reality. One is limited to one's conceptual schemes, and metaphysical realism is therefore false.[69]

Metaphilosophy and ontology

In the late 1970s and the 1980s, stimulated by results from mathematical logic and by some of Quine's ideas, Putnam abandoned his long-standing defence of metaphysical realism—the view that the categories and structures of the external world are both causally and ontologically independent of the conceptualizations of the human mind. He adopted a rather different view, which he called "internal realism"[70][18] or "pragmatic realism".[71]

Internal realism is the view that, although the world may be causally independent of the human mind, the world's structure—its division into kinds, individuals and categories—is a function of the human mind, and hence the world is not ontologically independent. The general idea is influenced by Immanuel Kant's idea of the dependence of our knowledge of the world on the categories of thought.[72]

The problem with metaphysical realism, according to Putnam, is that it fails to explain the possibility of reference and truth.[73]:331 According to the metaphysical realist, our concepts and categories refer because they match up in some mysterious manner with the categories, kinds and individuals inherent in the external world. But how is it possible that the world "carves up" into certain structures and categories, the mind carves up the world into its own categories and structures, and the two carvings perfectly coincide? The answer must be that the world does not come pre-structured but that the human mind and its conceptual schemes impose structure on it. In Reason, Truth, and History, Putnam identified truth with what he termed "idealized rational acceptability." The theory, which owes something to C. S. Peirce, is that a belief is true if it would be accepted by anyone under ideal epistemic conditions.[18]

Nelson Goodman formulated a similar notion in Fact, Fiction and Forecast (1956). "We have come to think of the actual as one among many possible worlds. We need to repaint that picture. All possible worlds lie within the actual one", Goodman wrote.[74]:57 Putnam rejected this form of social constructivism, but retained the idea that there can be many correct descriptions of reality. None of these descriptions can be scientifically proven to be the "one, true" description of the world. For Putnam, this does not imply relativism, because not all descriptions are equally correct and correctness is not determined subjectively.[75]

Putnam renounced internal realism in his reply to Simon Blackburn in the volume Reading Putnam.[76] The reasons he gave up his "antirealism" are stated in the first three of his replies in "The Philosophy of Hilary Putnam", an issue of the journal Philosophical Topics, where he gives a history of his use(s) of the term "internal realism", and, at more length, in his The Threefold Cord: Mind, Body and World (1999).[77]

Although he abandoned internal realism, Putnam still resisted the idea that any given thing or system of things can be described in exactly one complete and correct way. He thus accepts "conceptual relativity"—the view that it may be a matter of choice or convention, e.g., whether mereological sums exist, or whether spacetime points are individuals or mere limits. In other words, having abandoned internal realism, Putnam came to accept metaphysical realism in the broad sense of rejecting all forms of verificationism and all talk of our "making" the world.[78]

Under the influence of Peirce and William James, Putnam also became convinced that there is no fact–value dichotomy; that is, normative (e.g., ethical and aesthetic) judgments often have a factual basis, while scientific judgments have a normative element.[75]

Neopragmatism and Wittgenstein

At the end of the 1980s, Putnam became increasingly disillusioned with what he perceived as the "scientism" and the rejection of history that characterize modern analytic philosophy. He rejected internal realism because it assumed a "cognitive interface" model of the relation between the mind and the world. Putnam claimed that the very notion of truth would have to be abandoned by a consistent eliminative materialist.[79] Under the increasing influence of James and the pragmatists, he adopted a direct realist view of this relation.[80] For a time, under the influence of Ludwig Wittgenstein, he adopted a pluralist view of philosophy itself and came to view most philosophical problems as nothing more than conceptual or linguistic confusions created by philosophers by using ordinary language out of context.[75] A book of articles on pragmatism by Ruth Anna Putnam and Hilary Putnam, Pragmatism as a Way of Life: The Lasting Legacy of William James and John Dewey (Harvard UP, ISBN 9780674967502), edited by David Macarthur, was published in 2017.[81]

Many of Putnam's last works addressed the concerns of ordinary people, particularly social problems.[82] For example, he wrote about the nature of democracy, social justice and religion. He also discussed Jürgen Habermas's ideas, and wrote articles influenced by continental philosophy.[28]

Criticism

Putnam himself may be his own most formidable philosophical adversary:[14] his frequent changes of mind have led him to attack his previous positions. But many significant criticisms of his views have come from other philosophers and scientists. For example, multiple realizability has been criticized on the grounds that, if it were true, research and experimentation in the neurosciences would be impossible.[83] According to William Bechtel and Jennifer Mundale, to be able to conduct such research in the neurosciences, universal consistencies must either exist or be assumed to exist in brain structures. It is the similarity (or homology) of brain structures that allows us to generalize across species.[83] If multiple realizability were an empirical fact, results from experiments conducted on one species of animal (or one organism) would not be meaningful when generalized to explain the behavior of another species (or organism of the same species).[84] Jaegwon Kim, David Lewis, Robert Richardson and Patricia Churchland have also criticized metaphysical realism.[85][86][87][88]

Putnam himself formulated one of the main arguments against functionalism: the Twin Earth thought experiment. But there have been other criticisms. John Searle's Chinese room argument (1980) is a direct attack on the claim that thought can be represented as a set of functions. The thought experiment is designed to show that it is possible to mimic intelligent action with a purely functional system, without any interpretation or understanding. Searle describes a situation in which a person who speaks only English is locked in a room with Chinese symbols in baskets and a rule book in English for moving the symbols around. The person is instructed, by people outside the room, to follow the rule book for sending certain symbols out of the room when given certain symbols. The people outside the room speak Chinese and are communicating with the person inside via the Chinese symbols. According to Searle, it would be absurd to claim that the English speaker inside "knows" Chinese based on these syntactic processes alone. This argument attempts to show that systems that operate merely on syntactic processes cannot realize any semantics (meaning) or intentionality (aboutness). Searle thus attacks the idea that thought can be equated with following a set of syntactic rules and concludes that functionalism is an inadequate theory of the mind.[89] Ned Block has advanced several other arguments against functionalism.[90]

Despite the many changes in his other positions, Putnam consistently adhered to semantic holism. Michael Dummett, Jerry Fodor, Ernest Lepore, and others have identified problems with this position. In the first place, they suggest that, if semantic holism is true, it is impossible to understand how a speaker of a language can learn the meaning of an expression in the language. Given the limits of our cognitive abilities, we will never be able to master the whole of the English (or any other) language, even based on the (false) assumption that languages are static and immutable entities. Thus, if one must understand all of a natural language to understand a single word or expression, language learning is simply impossible. Semantic holism also fails to explain how two speakers can mean the same thing when using the same expression, and therefore how any communication is possible between them. Given a sentence P, since Fred and Mary have each mastered different parts of the English language and P is related in different ways to the sentences in each part, P means one thing to Fred and something else to Mary. Moreover, if P derives its meaning from its relations with all the sentences of a language, as soon as the vocabulary of an individual changes by the addition or elimination of a sentence, the totality of relations changes, and therefore also the meaning of P. As this is a common phenomenon, the result is that P has two different meanings in two different moments in the life of the same person. Consequently, if I accept the truth of a sentence and then reject it later on, the meaning of what I rejected and what I accepted are completely different and therefore I cannot change my opinions with regard to the same sentences.[91][92][93]

Putnam's brain in a vat argument has also been criticized.[94] Crispin Wright argues that Putnam's formulation of the brain-in-a-vat scenario is too narrow to refute global skepticism. The possibility that one is a recently disembodied brain in a vat is not undermined by semantic externalism. If a person has lived her entire life outside the vat—speaking the English language and interacting normally with the outside world—prior to her "envatment" by a mad scientist, when she wakes up inside the vat, her words and thoughts (e.g., "tree" and "grass") will still refer to the objects or events in the external world that they referred to before her envatment.[68] In another scenario, a brain in a vat may be hooked up to a supercomputer that randomly generates perceptual experiences. In that case, one's words and thoughts would not refer to anything: semantics would no longer exist and the argument would be meaningless.[95]

In philosophy of mathematics, Stephen Yablo has argued that the Quine–Putnam indispensability thesis does not demonstrate that mathematical entities are truly indispensable. The argumentation is sophisticated, but the upshot is that one can achieve the same logical results by simply adding to any statement about an abstract object the assumption "so-and-so is assumed (or hypothesized) to exist". For example, one can take the argument for indispensability described above and adjust it as follows:

1*. One must have ontological commitments to all and only the [abstract] entities for which, under the assumption that they exist, their existence is indispensable to the best scientific theories.
2*. Under the assumption that they exist, the existence of mathematical entities is indispensable to the best scientific theories. Therefore,
3*. Under the assumption that mathematical entities exist, one must have ontological commitments to the existence of mathematical entities.[60]

Finally, Curtis Brown has criticized Putnam's internal realism as a disguised form of subjective idealism, in which case it is subject to the traditional arguments against that position. In particular, it falls into the trap of solipsism. That is, if existence depends on experience, as subjective idealism maintains, and if one's consciousness ceased to exist, then the rest of the universe would also cease to exist.[72]

Major works and bibliography

Vincent C. Müller compiled a detailed bibliography of Putnam's writings, citing 16 books and 198 articles, published in 1993 in PhilPapers.[96]

See also

Notes

  1. ^ Pragmatism – Internet Encyclopedia of Philosophy
  2. ^ Hilary Putnam, "Realism and reason", Presidential Address to the Eastern Division of the American Philosophical Association, December 1976; reprinted in his Meaning and the Moral Sciences, Routledge and Kegan Paul, 1978, pp. 123–140.
  3. ^ Bas van Fraassen, "Putnam's Paradox: Metaphysical Realism Revamped and Evaded", Philosophical Perspectives 11:17–42 (1997).
  4. ^ David Marshall Miller, Representing Space in the Scientific Revolution, Cambridge University Press, 2014, p. 4 n. 2.
  5. ^ Hilary Putnam. Realism with a Human Face. Edited by James F. Conant. Harvard University Press. 1992. p. xlv.
  6. ^ Borradori, G. et al. The American Philosopher, 1994, p. 58
  7. ^ J. Worrall, "Structural Realism: the Best of Both Worlds" in D. Papineau(ed.), The Philosophy of Science (Oxford 1996).
  8. ^ Jump up to:a b c d e Casati R., "Hillary Putnam" in Enciclopedia Garzanti della Filosofia, ed. Gianni Vattimo. 2004. Garzanti Editori. Milan. ISBN 88-11-50515-1
  9. ^ Jump up to:a b Davis, M. and Putnam, H. "A computing procedure for quantification theory" in Journal of the ACM, 7:201–215, 1960.
  10. ^ Matiyesavic, Yuri (1993). Hilbert's Tenth Problem. Cambridge: MIT. ISBN 0-262-13295-8.
  11. ^ Jump up to:a b c d e King, P.J. One Hundred Philosophers: The Life and Work of the World's Greatest Thinkers. Barron's 2004, p. 170.
  12. ^ Jack Ritchie (June 2002). "TPM: Philosopher of the Month". Archived from the original on 2011-07-09.
  13. ^ LeDoux, J. (2002). The Synaptic Self; How Our Brains Become Who We Are. New York: Viking Penguin. ISBN 88-7078-795-8.
  14. ^ Jump up to:a b P. Clark-B. Hale (eds.), "Reading Putnam", Blackwell, Cambridge (Massachusetts): Oxford 1995.
  15. ^ Colyvan, Mark, "Indispensability Arguments in the Philosophy of Mathematics", The Stanford Encyclopedia of Philosophy (Fall 2004 Edition), Edward N. Zalta (ed.)
  16. ^ Jump up to:a b Putnam, H. Philosophy of Mathematics: Selected Readings. Edited with Paul Benacerraf. Englewood Cliffs, N.J.: Prentice-Hall, 1964. 2nd ed., Cambridge: Cambridge University Press, 1983.
  17. ^ Jump up to:a b c d Putnam, H. (1981): "Brains in a vat" in Reason, Truth, and History, Cambridge University Press; reprinted in DeRose and Warfield, editors (1999): Skepticism: A Contemporary Reader, Oxford UP.
  18. ^ Jump up to:a b c Putnam, H. Realism with a Human Face. Edited by J. F. Conant. Cambridge, Massachusetts: Harvard University Press, 1990.
  19. ^ Putnam, H. 2012. From Quantum Mechanics to Ethics and Back Again. In his (Au.), De Caro, M. and Macarthur D. (Eds.) "Philosophy in an Age of Science". Cambridge, Massachusetts: Harvard University Press.
  20. ^ Jump up to:a b Putnam, H.. The Threefold Cord: Mind, Body, and World. New York: Columbia University Press, 1999.
  21. ^ Jump up to:a b c Putnam, Hilary (October 30, 2015). "What Wiki Doesn't Know About Me". Sardonic comment. Retrieved March 15, 2016.
  22. ^ Putnam, H. 2012. How to Be a Sophisticated "Naive Realist". In his (Au.), De Caro, M. and Macarthur D. (Eds.) "Philosophy in an Age of Science". Cambridge, Massachusetts: Harvard University Press.
  23. ^ Auxier, R. E., Anderson, D. R., & Hahn, L. E., eds., The Philosophy of Hilary Putnam (Chicago: Open Court, 2015), pp. 93–94.
  24. ^ Auxier, R. E., Anderson, D. R., & Hahn, L. E., eds., The Philosophy of Hilary Putnam (Chicago: Open Court, 2015), pp. 81–82.
  25. ^ Jump up to:a b c d Foley, M. (1983). Confronting the War Machine: Draft Resistance during the Vietnam War. North Carolina: North Carolina Press. ISBN 0-8078-2767-3.
  26. ^ Wolfe, Bertram David. "Strange Communists I Have Known", Stein and Day, 1965, p. 79.
  27. ^ Robert F. Barsky, Noam Chomsky: A Life of Dissent, Ch. 2: Undergraduate Years. "A Very Powerful Personality", MIT Press, 1997
  28. ^ Jump up to:a b c d e f g h i j Hickey, L. P., Hilary Putnam (London / New York: Continuum, 2009).
  29. ^ Putnam, The Meaning of the Concept of Probability in Application to Finite Sequences (New York: Garland Publishing, 1990).
  30. ^ "Putnam, Hilary 1926- - Dictionary definition of Putnam, Hilary 1926- | Encyclopedia.com: FREE online dictionary". www.encyclopedia.com. Retrieved 2018-01-18.
  31. ^ Deutsches Geschlechterbuch, vol. 214, Limburg 2002, p. 267-946
  32. ^ Hortsch, Michael. "Dr. Hans Nathan Kohn – ein Berliner Jüdischer Arzt und Forscher am Vorabend des Nationalsozialismus." Berlin Medical, Vol. 4:26–28 August 2007
  33. ^ Jump up to:a b c Linda Wertheimer (July 30, 2006). "Finding My Religion". The Boston Globe.
  34. ^ "Ruth Anna Putnam, Wellesley College philosophy professor, dies at 91 - The Boston Globe". BostonGlobe.com. Retrieved 2019-10-01.
  35. ^ http://www.haaretz.com/jewish/news/1.709318
  36. ^ http://www.firstthings.com/article/2008/10/004-wrestling-with-an-angel
  37. ^ "Book of Members, 1780–2010: Chapter P" (PDF). American Academy of Arts and Sciences. Retrieved 19 April 2011.
  38. ^ Epps, G., "Faculty Will Vote on New Procedures for Discipline", The Harvard Crimson, April 14, 1971.
  39. ^ Thomas, E. W., "Putnam Says Dunlop Threatens Radicals", The Harvard Crimson, May 28, 1971.
  40. ^ "NYT correction, March 6, 2005". The New York Times. March 6, 2005. Retrieved 2006-08-01.
  41. ^ The Spinoza Chair – Philosophy – University of Amsterdam
  42. ^ "Hilary Putnam: The Chosen People". Boston Review. Archived from the original on 2013-12-24. Retrieved 2010-12-14.
  43. ^ "Hilary Putnam awarded The Rolf Schock Prize in Logic and Philosophy". The Philosopher's Eye. 12 April 2011. Archived from the original on 15 March 2016.
  44. ^ "Hilary Putnam Wins the Rescher Prize for 2015!". University of Pittsburgh.
  45. ^ Chakraborty, Sanjit. "Dr". PhilPapers.
  46. ^ "International Conference on THE PHILOSOPHY OF HILARY PUTNAM".
  47. ^ Weber, B., "Hilary Putnam, Giant of Modern Philosophy, Dies at 89", The New York Times, March 17, 2016.
  48. ^ Jump up to:a b c Bickle, John "Multiple Realizability", The Stanford Encyclopedia of Philosophy (Fall 2006 Edition), Edward N. Zalta (ed.)
  49. ^ Jump up to:a b c d e f g Putnam, H. (1975) Mind, Language and Reality. Philosophical Papers, vol. 2. Cambridge: Cambridge University Press, 1975. ISBN 88-459-0257-9
  50. ^ Fodor, J. (1974) "Special Sciences" in Synthese, 28, pp. 97–115
  51. ^ Fodor, J. (1980) "The Mind-Body Problem", Scientific American, 244, pp. 124–132
  52. ^ Block, Ned (August 1983). "What is Functionalism".
  53. ^ Putnam, Hilary (1988). Representation and Reality. Cambridge, Massachusetts: MIT Press.
  54. ^ Jump up to:a b Marhaba, Sadi. (2004) Funzionalismoin "Enciclopedia Garzantina della Filosofia" (ed.) Gianni Vattimo. Milan: Garzanti Editori. ISBN 88-11-50515-1
  55. ^ Levin, Janet, "Functionalism", The Stanford Encyclopedia of Philosophy (Fall 2004 Edition), Edward N. Zalta (ed.)
  56. ^ Marvan, T., ed., What Determines Content? The Internalism/Externalism Dispute (Newcastle: Cambridge Scholars Publishing, 2006), pp. 70–75.
  57. ^ Davidson, D. (2001) Subjective, Intersubjective, Objective. Oxford: Oxford University Press. ISBN 88-7078-832-6
  58. ^ Dell'Utri, Massimo. (2002) Olismo. Quodlibet. Macerata. ISBN 88-86570-85-6
  59. ^ C. S. Hill (ed.), "The Philosophy of Hilary Putnam", Fayetteville, Arkansas 1992.
  60. ^ Jump up to:a b Yablo, S. (November 8, 1998). "A Paradox of Existence".
  61. ^ Jump up to:a b Putnam, H. Mathematics, Matter and Method. Philosophical Papers, vol. 1. Cambridge: Cambridge University Press, 1975. 2nd. ed., 1985.
  62. ^ J J O'Connor and E F Robertson (April 1997). "Andrew Wiles summary".
  63. ^ S. Barry Cooper, Computability theory, p. 98
  64. ^ Putnam, Hilary (1963). "A note on constructible sets of integers". Notre Dame J. Formal Logic. 4 (4): 270–273. doi:10.1305/ndjfl/1093957652.
  65. ^ Boolos, George; Putnam, Hilary (1968). "Degrees of unsolvability of constructible sets of integers". Journal of Symbolic Logic. The Journal of Symbolic Logic, Vol. 33, No. 4. 33 (4): 497–513. doi:10.2307/2271357. JSTOR 2271357.
  66. ^ Boyd, Richard; Hensel, Gustav; Putnam, Hilary (1969). "A recursion-theoretic characterization of the ramified analytical hierarchy". Trans. Amer. Math. Soc. Transactions of the American Mathematical Society, Vol. 141. 141: 37–62. doi:10.2307/1995087. JSTOR 1995087.
  67. ^ Putnam, H., Realism and Reason. Philosophical Papers, vol. 3.Cambridge: Cambridge University Press, 1983.
  68. ^ Jump up to:a b Wright, C. (1992), "On Putnam's Proof That We Are Not Brains-in-a-Vat", Proceedings of the Aristotelian Society 92.
  69. ^ Dell'Utri, M. (1990), "Choosing Conceptions of Realism: the Case of the Brains in a Vat", Mind 99.
  70. ^ Putnam, H. The Many Faces of Realism. La Salle, Ill.: Open Court, 1987.
  71. ^ Ernest Sosa, Putnam's Pragmatic Realism", The Journal of Philosophy, 90(12), Dec. 1993, pp. 605–626, esp. 605: "Putnam argues against 'metaphysical realism' and in favor of his own 'internal (or pragmatic) realism.'"
  72. ^ Jump up to:a b Curtis Brown (1988). "Internal Realism: Transcendental Idealism?". Midwest Studies in Philosophy (12): 145–55.
  73. ^ Devitt, M., Realism and Truth (Princeton: Princeton University Press, 1984), p. 331.
  74. ^ Goodman, N., Fact, Fiction, and Forecast (Cambridge & London: Harvard University Press, 1979), p. 57.
  75. ^ Jump up to:a b c Putnam, H. (1997). "A Half Century of Philosophy, Viewed from Within". Daedalus. 126 (1): 175–208. JSTOR 20027414.
  76. ^ Peter Clark and Bob Hale, eds., Reading Putnam. Oxford: Blackwell, 1994.
  77. ^ See also Philosophical Topics (vol. 20, Number 1, Spring 1992). And Hilary Putnam, "When 'Evidence Transcendence' is Not Malign", Journal of Philosophy, XCVIII, 11 (Nov. 2001), 594–600.
  78. ^ Putnam, Hilary (November 9, 2015). "Wiki Catches Up a Bit". Sardonic comment. Retrieved March 15, 2016.
  79. ^ Feser, E., The Last Superstition: A Refutation of the New Atheism (South Bend, IN: St. Augustine Press, 2008), p. 234.
  80. ^ Putnam, Hilary. Sep. 1994. "The Dewey Lectures 1994: Sense, Nonsense, and the Senses: An Inquiry into the Powers of the Human Mind." The Journal of Philosophy 91(9):445–518.
  81. ^ Bartlett, T., "A Marriage of Minds: Hilary Putnam’s most surprising philosophical shift began at home", The Chronicle of Higher Education, September 10, 2017.
  82. ^ Reed, Edward (1997). "Defending Experience: A Philosophy For The Post-Modern World" in The Genetic Epistemologist: The Journal of the Jean Piaget Society, Volume 25, Number 3.
  83. ^ Jump up to:a b Bechtel, William and Mundale, Jennifer. Multiple Realizability Revisitedin Philosophy of Science 66: 175–207.
  84. ^ Kim, Sungsu. Testing Multiple Realizability: A Discussion of Bechtel and Mundale in Philosophy of Science. 69: 606–610.
  85. ^ Kim, Jaegwon. Multiple Realizability and the Metaphysics of Reduction on Philosophy and Phenomenological Research. 52: 1–26.
  86. ^ Lewis, David (1969). "Review of Art, Mind, and Religion." Journal of Philosophy, 66: 23–35.
  87. ^ Richardson, Robert (1979). "Functionalism and Reductionism." Philosophy of Science, 46: 533–558.
  88. ^ Churchland, Patricia (1986). Neurophilosophy. Cambridge, Massachusetts: MIT Press.
  89. ^ Searle, John. (1980). "Minds, Brains and Programs", Behavioral and Brain Sciences, vol.3. (online)
  90. ^ Block, Ned. (1980b). "Troubles With Functionalism", in Block (1980a).
  91. ^ Fodor, J. and Lepore, E. Holism: A Shopper's Guide. Blackwell. Oxford. 1992.
  92. ^ Dummett, Michael. The Logical Basis of Metaphysics. Harvard University Press. Cambridge (MA). 1978.
  93. ^ Penco, Carlo. Olismo e Molecularismo in Olismo ed. Massimo Dell'Utri. Quodlibet. Macerata. 2002.
  94. ^ Steinitz, Y. (1994), "Brains in a Vat: Different Perspectives", Philosophical Quarterly 44.
  95. ^ Brueckner, A. (1986), "Brains in a Vat", Journal of Philosophy 83.
  96. ^ Müller, V. C., "Bibliography of Hilary Putnam's Writings", PhilPapers, 1993.

References

  • Bechtel, W. & Mundale, J. "Multiple Realizability Revisited" in Philosophy of Science 66: pp. 175–207.
  • Bickle, J. "Multiple Realizability" in The Stanford Encyclopedia of Philosophy(Fall 2006 Edition), Edward N. Zalta (ed.), (online).
  • Brown, C. "Internal Realism: Transcendental Idealism?" Midwest Studies in Philosophy 12 (1988): pp. 145–155.
  • Casati R. "Hilary Putnam" in Enciclopedia Garzanti della Filosofia. Gianni Vattimo (ed). Milan: Garzanti Editori, 2004. ISBN 88-11-50515-1.
  • Churchland, P. Neurophilosophy. Cambridge, Massachusetts: MIT Press, 1986.
  • Clark, P. & Hale, B. (eds.) Reading Putnam. Oxford: Blackwell, 1995.
  • Dummett, M. The Logical Basis of Metaphysics. Harvard University Press. Cambridge (MA) 1972.
  • Fodor, J. & Lepore, E. Holism: A Shopper's Guide. Oxford: Blackwell, 1992.
  • Foley, M. Confronting the War Machine. North Carolina: North Carolina Press. 1983. ISBN 0-8078-2767-3.
  • Gaynesford, M. de Hilary Putnam, Acumen, 2006. (See Robert Maximilian de Gaynesford)
  • Hickey, L. P., Hilary Putnam (London / New York: Continuum, 2009).
  • Hill, C. S. (ed.) The Philosophy of Hilary Putnam, Fayetteville, Arkansas. 1992.
  • Kim, J. "Multiple Realizability and the Metaphysics of Reduction." Philosophy and Phenomenological Research 52: 1–26.
  • King, P. J. One Hundred Philosophers: The Life and Work of the World's Greatest Thinkers. Barron's 2004, p. 170.
  • Lewis, D. "Review of Art, Mind, and Religion." Journal of Philosophy 66 (1969): 23–35.
  • Matiyesavic, Y. 'Hilbert's Tenth Problem. Cambridge: MIT Press, 1993. ISBN 0-262-13295-8.
  • Penco, C. Olismo e Molecularismo in Olismo, ed. Massimo Dell'Utri. Quodlibet. Macerata. 2002.
  • Putnam. Philosophy of Mathematics: Selected Readings. Edited with P. Benacerraf. Englewood Cliffs, N.J.: Prentice-Hall, (1964). 2nd ed., Cambridge: Cambridge University Press, 1983.
  • ———. Mind, Language and Reality. Philosophical Papers, vol. 2. Cambridge: Cambridge University Press, (1975).
  • ———. "Brains in a Vat" in Reason, Truth, and History, Cambridge University Press (1981); reprinted in DeRose and Warfield, editors (1999): Skepticism: A Contemporary Reader, Oxford University Press.
  • ———. Realism with a Human Face. Cambridge, Massachusetts: Harvard University Press, 1990.
  • ———. The Threefold Cord: Mind, Body, and World. New York: Columbia University Press, 1999.
  • ___. "Mind, Body and World in the Philosophy of Hilary Putnam". Interview wit Léo Peruzzo Júnior. In: Transformação Journal - UNESP, v.38, n.2, 2015.
  • Richardson, R. "Functionalism and Reductionism." Philosophy of Science 46 (1979): 533–558.
  • Searle, J. "Minds, Brains and Programs." Behavioral and Brain Sciences 3 (1980).
  • Wertheimer, L. ""Finding My Religion." Boston Globe, July 30, 2006.
  • Yablo, S. "A Paradox of Existence", June 8, 1998.

Further reading

  • Y. Ben-Menahem (ed.), Hilary Putnam, Contemporary Philosophy in Focus, Cambridge University Press, Cambridge, 2005.
  • P. Clark-B. Hale (eds.), Reading Putnam, Blackwell, Cambridge (Massachusetts)-Oxford 1995.
  • C. S. Hill (ed.), The Philosophy of Hilary Putnam, Fayetteville, Arkansas 1992.
  • M. Rüdel, Erkenntnistheorie und Pragmatik: Untersuchungen zu Richard Rorty und Hilary Putnam (dissertation), Hamburg 1987.
  • Maximilian de Gaynesford, Hilary Putnam, McGill-Queens University Press / Acumen, 2006.
  • Auxier, R. E., Anderson, D. R., & Hahn, L. E., eds., The Philosophy of Hilary Putnam, The Library of Living Philosophers, Open Court, Chicago, Illinois, 2015.
  • Sanjit Chakraborty, Understanding Meaning and World: A Relook on Semantic Externalism, Cambridge Scholars Publishing, London, 2016.

External links




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Hilary Putnam: Pragmatism and realism, Routledge
https://ndpr.nd.edu/reviews/hilary-putnam-pragmatism-and-realism-routledge/

Conant, James and Zeglen, Urszula M. (eds.),
Hilary Putnam: Pragmatism and Realism, Routledge, 2002,
256pp,  $80.00 (hbk), ISBN 0-415-25605-4.

Reviewed by Gabor Forrai, University of Miskolc
2002.07.11

The book is an outgrowth of a 1998 conference held at the Nicholas Copernicus University in Toru (Poland), for which Hilary Putnam was the keynote speaker. It contains eleven papers with responses by Putnam, and is divided into two parts, one on pragmatism and one on realism. Each part is prefaced by a short and well-focused introduction by Urszula M. Zeglen, which may be useful for those who did not keep up with the development of Putnam’s thought since the late seventies. Some papers are directly addressed to Putnam, seeking to challenge or support him on particular points, but more of them aim at developing themes on which Putnam has a view. I will discuss only some of the papers; the others will be listed at the end of this review.

Ruth Anna Putnam’s “Taking pragmatism seriously” and Hilary Putnam’s own “Pragmatism and nonscientific knowledge” survey the issues with respect to which the latter claims to be an heir to classical pragmatism. The most important of these are as follows:

(1) Philosophy should not lose contact with general human concerns. What this means is that the common man’s views which are integral to human practices should not be brushed aside as if they were necessarily inferior to the sophisticated technical doctrines of professional philosophers. Even though the commonly held views may not be right as they stand, the philosophical views which are opposed to them – such as skepticism about the external world, indirect realist theories of perception, denial of the cognitive status of ethics – are more suspect. It follows then that one important task for a philosopher who takes pragmatism seriously is to expose the fallacies underlying those philosophical doctrines, which seem incredible for the layman. No wonder that Wittgenstein and Austin are just as much philosophical heroes for Putnam as Peirce, James and Dewey.

(2) Rejection of the sharp separation of theoretical and practical concerns and the fact/value dichotomy. Many philosophers tend to exalt science and regard it as pure inquiry, completely detached from rather than continuous with nonscientific knowledge. As a part of this picture they maintain that science is unaffected by value considerations. Scientific knowledge is supposed to be the product of experience and certain methods, which, as a matter of fact, lead to truth or high probability. Putnam rejects this attitude. He maintains that scientific methods cannot be applied in a blind, mechanical fashion. Their application presupposes judgments about coherence and simplicity, which are value judgments, just like the judgments in ethics. As result, knowledge of facts depends on knowledge of values. The dependence goes in the other direction as well: knowledge of values presupposes knowledge of facts.

(3) Value judgments can be objective. This is a straightforward consequence of the previous point. Since factual claims are infected by values, the subjectivity of values would entail the subjectivity of facts. But what does objectivity mean here? For Putnam a claim is objective if it is free of personal idiosyncrasies, and the way to weed out idiosyncrasies is rational argumentation. In the final analysis, objectivity is what rational argumentation delivers. However, rational argumentation should not be equated with a particular set of practices, for two reasons. First, rationality is manifold. Different issues call for different ways of argumentation. Second, rationality is not static. We may develop new ways of arguing and we may also revise our previous practices. (This is another point where Putnam is indebted to Wittgenstein.)

This picture of objectivity brings us to the second main theme of the book, realism and truth. Putnam is famous for rejecting metaphysical realism, the view that the character of reality is wholly independent of human practices, and truth means capturing what is out there independently of how anyone would regard it. He has recommended two pictures for its replacement, first ‘internal realism’, best summarized in Reason, Truth and History (Cambridge, Mass.: Cambridge University Press, 1981), then ‘natural realism’, which was first spelled out in his Dewey lectures (“Sense, Nonsense, and the Senses: An Inquiry into the Powers of the Human Mind”, Journal of Philosophy 91 (1994): 445-517, reprinted as Part I The Threefold Chord: Mind, Body and the World, New York: Columbia University Press, 1999).

Internal realism is a modest version of verificationism, maintaining that the truth conditions of statements are not independent of their verification conditions, as a result of which truth is epistemically constrained. It is discussed in two papers, Nicholas Rescher’s “Knowledge of the truth in pragmatic perspective” and Wolfgang Künne’s “From alethic anti-realism to alethic realism”. Rescher takes Putnam to be tempted to identify truth with verification and claims that the identification will not work. For actual verification may not give us the truth, and ideal verification is so far from where we are now that truth becomes as elusive as it is according to the correspondence theory, which he, like Putnam, rejects. It seems to him that Putnam has no better solution for closing the gap between verification and truth than suggesting that we ignore it and seek refuge in the democratic consideration that we are all in the same boat. Rescher’s own approach is to keep truth conceptually independent of verification and close the gap in the following way. We should estimate truth relying on our methods of verification and then assess these methods themselves by asking whether the views these methods favor ‘provide materials for successful prediction and effective applicative control’ (73). In his response Putnam explains where Rescher got him wrong, which is useful because he is often understood in Rescher’s way, i. e. as if he were proposing to reduce truth to verification rather than emphasizing the mutual dependence of the two. But misunderstandings of this kind are excusable for it is not easy to follow how Putnam has struggled with the concept of truth. Künne’s paper does a very nice job of clarifying that. It also contains a new version of Fitch’s argument against the idea that truth is epistemically constrained. What makes this version interesting is that it makes relatively weak assumptions. It talks of ‘justified belief’ rather than ‘knowledge’, does not use logical principles which the intuitionists would reject and does not involve substitution into modal contexts.

Putnam’s more recent natural realism differs from internal realism in two respects. First, verificationism becomes even more modest. He used to hold that truth and verification are conceptually linked. Now he does not believe this is true for all statements. There are indeed many statements whose truth conditions we cannot understand without knowing what would verify them, but not all statements are of this kind. The second and more important difference is that Putnam has become a direct realist about perception. The picture he rejects is this. The process of perception divides into a causal and a cognitive part. The things affecting our senses bring about mental or physical items in the mind or the brain (sense data, qualia, or representations, which are outputs of sensory modules), and it is to these items that we have cognitive access to. In Putnam’s opinion, however, cognition does not end within the mind or the brain but extends all the way to the object. This is not a call for a change in terminology; what Putnam wants is not to reclassify the causal part as cognitive. He rejects that there are two parts. Perception is a direct transaction between the mind and the thing, and there is no interface between the two. This view is challenged from different directions by John Haldane and Tadeusz Szubka. Haldane’s “Realism with a metaphysical skull” initiates a new round in his ongoing exchange with Putnam. They agree that metaphysical realism creates an unbridgeable gap between the mind and the world, but they disagree about the way of closing it. Haldane suggests we go back to Aristotle: in perception the mind takes on the form of the thing perceived. Since the very same form is present in the mind and in the thing, there is just no gap. He welcomes Putnam’s new position as a step in the right direction, but he believes that the sort of Aristotelian epistemological realism Putnam has adopted cannot be sustained without the support of Aristotelian metaphysics. The mind cannot touch reality unless there is something the mind and reality have in common, and that item must have all the important characteristics of Aristotelian forms. Putnam, not surprisingly, would have no truck with forms, which he finds completely unintelligible. What he particularly dislikes about Haldane’s suggestion is its essentialism, the idea that things can be individuated and ordered into kinds only in one specific way.

In his “The causal theory of perception and direct realism” Szubka argues that, contrary to what Putnam says, the causal theory of perception is compatible with direct realism. Putnam is right only about the reductive versions of the causal theory, which hold that we can give an exhaustive account of perception in causal terms and can safely dispense with unreduced intentional notions. Non-reductive causal theories, like Strawson’s, escape Putnam’s arguments and are fully compatible with direct realism. Even though Szubka makes a number of good points, I am not sure that he gets right what is at issue between Strawson and Putnam. Occasionally, he seems to take Putnam to maintain that there are perceptual experiences within our minds (112, 113), but these resist reduction. Strawson would probably accept this, but Putnam would not because it is the very idea of intermediary entities which he regards as flawed. Szubka seems to favor a non-reductionist, causal, direct realist view, which, however, I cannot clearly distinguish from the purely terminological version of direct realism, albeit he appears to accept that direct realism should not be bought for cheap by means of a simple linguistic reform (112).

Charles Travis’s “What laws of logic say” is one of the highlights of the book. It takes up an issue Putnam has grappled with throughout his career, the nature of logical necessity. Relying on Wittgenstein’s remarks in the Investigations (§§96-131) he sketches an account the consequences of which agree very well with what Putnam says on this subject. His central ideas are as follows. A system of formal logic is an idealized system of inferential relations between linguistic forms. It is defined by strict rules, and it is these rules, which make the inferential relations described in the system necessary. So, necessity is intrinsic to the system. The reason why systems of logic do not seem to admit refutations is that they do not say much. In particular, they do not say that natural language as a whole or even a particular segment of a natural language agrees with the system. If the logical connectives as used in a particular stretch of discourse fail to behave as the connectives of a system of logic (i.e. if we refuse to draw the conclusions we should draw if we were to apply the system to this stretch of discourse), then all that follows is that the system is not applicable to that particular stretch of discourse. It does not follow that the system is wrong. The crucial idea is that logical form is not inherent in language, but rather it is imposed on language if we choose to view it through a particular system. A particular system makes no commitment with regard to other systems: it does not say that it is the only possible system. Nor does it say what other systems must be like. And it does not even say that other systems must attribute the same logical form to a particular statement as the system in question. This shows that the connection between the meaning of the logical connectives of ordinary language and logical systems is looser than it is usually assumed. For example, a particular way of using the ordinary ‘or’ can be viewed through different logical systems, so the meaning of the ordinary ‘or’ cannot be associated with one particular logic. However, this kind of distance between ordinary speech and systems of logic does not imply that logical systems can never prove to be false. A system imposes several different constraints on the items, which figure in logical forms. And it might happen that under the pressure the world puts on our discourse we have to adopt ways of speaking so that the different constraints cannot be jointly satisfied. On the other hand, we cannot now envisage what a situation of this sort would be like.

Apart from the ones mentioned so far there are four more papers in the volume. Richard Warner describes how pragmatist themes emerge in the discussion about legal reasoning. Robert Brandom seeks to entangle the relationship between various kinds of pragmatism. John Heil argues that we should not assume that for every predicate which holds of an object there must be a specific property which the predicate designates. Giving up this assumption, which was basic to the functionalist philosophy of mind, means getting rid of the idea that there are higher and lower level properties. Gary Ebbs sharpens Putnam’s argument against deflationism and develops a version of deflationism which can escape it.

Putnam is an important thinker, and this collection devoted to his work is welcome, especially because his views have changed considerably since the last collection of this kind was published (Reading Putnam, edited by P. Clark and B. Hale, Oxford: Basil Blackwell, 1994.) This is a rich book, which covers the most important themes from Putnam’s work in the last 25 years. Those who work on Putnam should definitely read it. But some of the papers will also be valuable to those who are interested in the same issues as Putnam, even if they are not specifically interested in his work.



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PHILOSOPHY: REALISM

WRITTEN BY

Professor of Philosophy, University of Sheffield. Author (with Crispin Wright) of The Reason's
Proper Study: Essays Towards a Neo-Fregean Philosophy of Mathematics and others.


Realism, in philosophy, the viewpoint which accords to things which are known or perceived an existence or nature which is independent of whether anyone is thinking about or perceiving them.

Varieties Of Philosophical Realism

The history of Western philosophy is checkered with disputes between those who have defended forms of realism and those who have opposed them. While there are certainly significant similarities linking the variety of positions commonly described as realist, there are also important differences which obstruct any straightforward general characterization of realism. Many, if not all, of these disputes may be seen as concerned in one way or another with the relations between, on the one hand, human beings as thinkers and subjects of experience and, on the other hand, the objects of their knowledge, belief, and experience. Do sense perception and other forms of cognition, and the scientific theorizing which attempts to make sense of their deliverances, provide knowledge of things which exist and are as they are independently of people’s cognitive or investigative activities? It is at least roughly true to say that philosophical realists are those who defend an affirmative answer to the question, either across the board or with respect to certain areas of knowledge or belief—e.g., the external world, scientific theories, mathematics, or morality.

The affirmative answer may seem no more than the merest common sense, because the vast majority of one’s beliefs are certainly most naturally taken to concern mind-independent objects whose existence is an entirely objective matter. And this seems to be so whether the beliefs in question are about mundane matters such as one’s immediate surroundings or about theoretical scientific entities such as subatomic particles, fundamental forces, and so on. Nevertheless, much argument and clarification of the issues and concepts involved (e.g., objectivity and mind-independence) is required if the realism favoured by common sense is to be sustained as a philosophical position.

Any general statement of realism, however, inevitably obscures the great variation in focus in controversies between realists and antirealists from antiquity to the present day. In some controversies, what is primarily at issue is a question of ontology, concerning the existence of entities of some problematic kind. In others, the opposition, while still broadly ontological in character, concerns rather the ultimate nature of reality as a whole, a historically important example being the controversies generated by various forms of idealism. In yet others the dispute, while not entirely divorced from questions of ontology, is primarily concerned with the notion of truth, either in general or in application to statements of some particular type, such as moral judgments or theoretical scientific claims about unobservable entities.

Realism In Ontology

In application to matters of ontology, realism is standardly applied to doctrines which assert the existence of entities of some problematic or controversial kind. Even under this more restricted heading, however, realism and opposition to it have taken significantly different forms, as illustrated in the following three examples.


One of the earliest and most famous realist doctrines is Plato’s theory of Forms, which asserts that things such as “the Beautiful” (or “Beauty”) and “the Just” (or “Justice”) exist over and above the particular beautiful objects and just acts in which they are instantiated and more or less imperfectly exemplified; the Forms themselves are thought of as located neither in space nor in time. Although Plato’s usual term for them (eido) is often translated in English as Idea, it is clear that he did not think of them as mental but rather as abstract, existing independently both of mental activity and of sensible particulars. As such, they lie beyond the reach of sense perception, which Plato regarded as providing only beliefs about appearances as opposed to knowledge of what is truly real. Indeed, the Forms are knowable only by the philosophically schooled intellect.

Plato, marble portrait bust, from an original of the 4th century BCE; in the
Capitoline Museums, Rome.G. Dagli Orti—DeA Picture Library/Learning Pictures


Although the interpretation of Plato’s theory remains a matter of scholarly controversy, there is no doubt that his promulgation of it initiated an enduring dispute about the existence of universals—often conceived, in opposition to particulars, as entities, such as general properties, which may be wholly present at different times and places or instantiated by many distinct particular objects. Plato’s pupil Aristotle reacted against the extreme realism which he took Plato to be endorsing: the thesis of universalia ante res (Latin: “universals before things”), according to which universals exist in their own right, prior to and independently of their instantiation by sensible particulars. He advocated instead a more moderate realism of universalia in rebus (“universals in things”): While there are universals, they can have no freestanding, independent existence. They exist only in the particulars that instantiate them.

Aristotle, marble portrait bust, Roman copy (2nd century BCE) of a Greek original (c. 325 BCE);
in the Museo Nazionale Romano, Rome.A. Dagli Orti/©De Agostini Editore/age fotostock

In the medieval period, defenders of a broadly Aristotelian realism, including William of Shyreswood and Peter of Spain, were opposed by both nominalists and conceptualists. Nominalists, notably William of Ockham, insisted that everything in the nonlinguistic world is particular. They argued that universals are merely words which have a general application—an application which is sufficiently explained by reference to the similarities among the various particulars to which the words are applied. Conceptualists agreed with the nominalists that everything is particular but held that words which have general application do so by virtue of standing for mental intermediaries, usually called general ideas or concepts.

Although medieval in origin, the latter view found its best-known implementation in the English philosopher John Locke’s theory of abstract ideas, so called because they are supposed to be formed from the wholly particular ideas supplied in experience by “abstracting” from their differences to leave only what is common to all of them. Locke’s doctrine was vigorously criticized in the 18th century by his empiricist successors, George Berkeley and David Hume, who argued that ideas corresponding to general words are fully determinate and particular and that their generality of application is achieved by making one particular idea stand indifferently as a representative of many.

The problem of universals remains an important focus of metaphysical discussion. Although Plato’s extreme realism has found few advocates, in the later 20th century there was a revival of interest in Aristotle’s moderate realism, a version of which was defended—with important modifications—by the Australian philosopher David Armstrong.

Abstract entities and modern nominalism

In the second half of the 20th century the term nominalism took on a somewhat broader sense than the one it had in the medieval dispute about universals. It is now used as a name for any position which denies the existence of abstract entities of any sort, including not only universals but also numbers, sets, and other abstracta which form the apparent subject matter of mathematical theories. In their classic nominalist manifesto, “Steps Toward a Constructive Nominalism” (1947), the American philosophers Nelson Goodman and W.V.O. Quine declared:

We do not believe in abstract entities. No one supposes that abstract entities—classes, relations, properties, etc.—exist in space-time; but we mean more than this. We renounce them altogether.…Any system that countenances abstract entities we deem unsatisfactory as a final philosophy.

The term “Platonism” has often been used, especially in the philosophy of mathematics, as an alternative to the correspondingly wider use of “realism” to denote ontological views to which such nominalism stands opposed. Nominalists have often recommended their rejection of abstracta on grounds of ontological economy, invoking the methodological maxim known as Ockham’s razor—Entia non sunt multiplicanda praeter necessitatem (“Entities are not to be multiplied beyond necessity”). The maxim is problematic, however, for at least two reasons. First, it gives a clear directive only when accompanied by some answer to the obvious question, “Necessary for what?” Although the answer—“Necessary to account for all the (agreed upon) facts”—is equally obvious, it is doubtful that there is sufficient agreement between the nominalist and the realist to enable the former to cut away abstracta as unnecessary. The realist is likely to suppose that the relevant facts include the facts of mathematics, which, taken at face value, do require the existence of numbers, sets, and so on.

But second, even if the facts could be restricted, without begging the question, to facts about what is concrete, it is still unclear that nominalists will be in a position to wield the razor to their advantage, because it may be argued that such facts admit of no satisfactory explanation without the aid of scientific (and especially physical) theories which make indispensable use of mathematics. Indispensability arguments of this kind were advanced by the American philosopher Hilary Putnam and (having relinquished his earlier nominalism) by Quine.

Hilary Putnam. Photo courtesy of Harvard University

Other, perhaps weightier, arguments for nominalism appeal to the broadly epistemological problems confronting realism. Given that numbers, sets, and other abstracta could, by their very nature, stand in no spatiotemporal (and therefore no causal) relation to human beings, there can be no satisfactory explanation of how humans are able to think about and refer to abstracta or come to know truths about them.

Whether or not these problems are insuperable, it is clear that, because theories (especially mathematical theories) ostensibly involving reference to abstracta appear to play an indispensable role in the human intellectual economy, nominalists can scarcely afford simply to reject them outright; they must explain how such theories may be justifiably retained, consistently with nominalistic scruples.

Attempts by orthodox nominalists to reinterpret or reconstruct mathematical theories in ways which avoid reference to abstracta have not met with conspicuous success. Following a more radical course, the American philosopher Hartry Field has argued that nominalists can accept mathematical theories under certain conditions while denying that they are true. They can be accepted provided that they are conservative—i.e., provided that their conjunction with nonmathematical (scientific and especially physical) theories entails no claims about nonmathematical entities which are not logical consequences of the nonmathematical theories themselves. Conservativeness is thus a strong form of logical consistency. Because consistency in general does not require truth, a mathematical theory can be conservative without being true.

Possible worlds

One kind of modal realism holds that there is a distinctive class of truths essentially involving the modal notions of necessity and possibility. Since the mid-20th century, however, advances in modal logic—in particular the development of possible-world semantics—have given rise to a further, distinctively ontological dispute concerning whether that semantics gives a literally correct account of the “truth-conditions” of modal propositions. According to possible-world semantics, (1) a proposition is necessarily true if (and only if) it is true not only in the actual world but in all possible worlds; and (2) a proposition is possibly true if and only if it is true in at least one possible world, perhaps distinct from the actual world. If statements 1 and 2 are literally correct descriptions of the truth-conditions of modal propositions, then, if any truths are nontrivially necessary or correctly assert unrealized possibilities, there must exist, in addition to the actual world, many other merely possible worlds. Modal realism, in the uncompromising form defended by the American philosopher David Lewis, is the view that there exists a (very large) plurality of worlds, each of which is a spatiotemporally (and therefore causally) closed system, disjoint from all others and comprising its own distinctive collection of concrete particulars, replete with all their properties and relations to each other.

David Kellogg Lewis
Image: Courtesy of Princeton University, Princeton, New Jersey

Although Lewis’s worlds are not, as he conceived them, abstract entities, it is clear that his realism faces epistemological objections similar to those mentioned in connection with abstracta. These, along with other considerations, led some philosophers to propose alternatives designed to secure the benefits of possible-world semantics without the costs of full-blooded realism. The alternatives included a more moderate realism propounded by the American philosopher Robert Stalnaker which denies Lewis’s homogeneity thesis (the claim that merely possible worlds are entities of the same kind as the actual world), as well as fictionalism, the view that possible-world theory is literally false but useful.

Realism And Idealism

The opposition between idealism and realism, although undeniably ontological in a broad sense, is distinct both from general disputes about realism in ontology and from disputes which turn upon the notion of truth or its applicability to statements of some specified type (see below Realism and truth). In its most straightforward and, arguably, basic sense, idealism not only asserts the existence of “ideas” (and perhaps other mental entities) but also advances a restrictive claim about the nature or composition of reality as whole: there is nothing in reality other than ideas and the minds whose ideas they are. So understood, idealism is a form of monism, which is opposed both to other forms of monism (e.g., materialism) and to pluralism, which posits two or more irreducibly distinct kinds of stuff or things (e.g., mental and physical, as in various versions of dualism).

A paradigmatic example of an idealist position is Berkeley’s rejection of “brute matter” as unintelligible and his accompanying doctrine that reality consists exclusively of “ideas”—for which esse est percipi (“to be is to be perceived”)—and “spirits,” including finite spirits corresponding to individual human beings and at least one infinite spirit, or God. If idealism in this sense is to be viewed as a kind of antirealism, the realism it opposes must be one which maintains the existence of material things independently of their being perceived or otherwise related to any mind, finite or otherwise.

The 18th-century German philosopher Immanuel Kant recognized that Berkeley’s “dogmatic idealism” involved denying the independent reality of space. Berkeley’s arguments, he thought, were effective against metaphysical positions which assumed that space is a property of “things in themselves,” as opposed to their representations, or “appearances,” in the mind. Kant argued to the contrary that space as well as time are forms of “sensible intuition,” or the mode in which the mind is affected by sensible objects. Thus, the reality of objects external to the mind (objects in space) is guaranteed, because being in space and time is a condition of being an object of sensible experience at all. Kant’s combination of transcendental idealism—the doctrine that what is given in experience are only appearances—with empirical realism—the view that there are objects external to the mind—allowed him to reject the conception of external objects as “lying behind” appearances and as knowable only (if at all) by a problematic and ultimately indefensible inference from what is given in experience to its hidden causes.

Immanuel Kant, print published in London, 1812. Image: Photos.com/Getty Images

The views of G.E. Moore (1873–1958) were appreciably closer to commonsense realism about the external world than were Kant’s. Although reacting, especially in his early papers, primarily against the prevailing tradition of 19th-century British idealism, Moore criticized Berkeley’s esse est percipi doctrine while at the same time rejecting Kant’s transcendental idealism.

Realism And Truth

As suggested by the prevalence in philosophical discussion of composite labels such as scientific realism, moral realism, and modal realism, realism need not be a global thesis. A realist attitude with regard to one area of thought or discourse (e.g., science) is at least prima facie consistent with an antirealist view with regard to others (e.g., morality or mathematics). Such eclecticism is sometimes motivated by underlying beliefs about what kinds of objects should be accepted as genuinely existing, or as part of the ultimate “furniture of the universe.” But sometimes it is not. At least some realist-antirealist disagreements, including several contemporary ones, are better understood as primarily concerned with whether statements belonging to a certain area of discourse really are, as their surface grammar may indicate, capable of objective truth and so capable of recording genuine, mind-independent facts. It is a further question whether, if statements of a given kind are true or false as a matter of objective, mind-independent fact, those statements record facts of some special irreducible type, distinctive of that discourse. Satisfaction of the first of these conditions (objective and mind-independent truth) is generally accepted as essential to any position worth describing as a form of realism. Realism is widely, but not invariably, taken to require also satisfaction of the second (irreducibility) condition.

Reductionism, error theories, and projectivism

If fulfillment of both of the conditions stated above is taken to be necessary for realism, reductionism in its various guises qualifies as an antirealist position. The reductionist about a given area of discourse (“A-discourse”) maintains that its characteristic statements (“A-statements”) are reducible to—analyzable or translatable without loss of content into—statements of some other type (“B-statements”), which are usually thought to be philosophically less problematic. The reductionist accepts that there are objective facts stated by A-statements but denies that such statements report any facts over and above those stated in B-statements. A-facts are just B-facts in disguise. An example of this approach is logical behaviourism, which maintains that statements about mental events and states are logically equivalent to statements which, while typically much more complicated, are wholly about observable behaviour in varying kinds of circumstances. Thus, there are no mental facts over and above physical facts. In this sense, logical behaviourism is a form of antirealism about psychological discourse.

Phenomenalism, the view that statements about material objects such as tables and chairs can be reduced to statements about sense experiences, amounts to a form of antirealism about the external world. The doctrine that all scientific language must acquire meaning via “operational definitions” in terms of measurement procedures and the like constitutes a reductionist form of scientific antirealism. Nominalist attempts to paraphrase or reinterpret mathematical statements so as to eliminate all apparent commitment to numbers, sets, or other abstracta may likewise be viewed as a species of reductive antirealism. Finally, ethical naturalism, which identifies the rightness or goodness of actions with, say, their tendency to promote happiness, thereby reduces moral facts to natural (e.g., psychological) ones. (It should be noted, however, that some contemporary ethical naturalists count their position as a form of realism—as indeed it is, at least in the weaker sense that it maintains the objective truth of ethical judgments.)

In each of these cases, as already noted in relation to traditional nominalism, it is at best questionable that the requisite reductions can be carried through. But antirealists need not nail their colours to the reductionist mast. Somewhat more radically, they may reject the assumption, which reductionists do not question, that statements belonging to the area in dispute are ever objectively true at all. This may be done in either of two quite distinct ways.

First, antirealists may agree with realists about the kind of meaning possessed by statements belonging to the problematic discourse—in particular, about the conditions required for their truth—but decline to accept that those conditions are ever met. If antirealists go so far as to deny that the requisite conditions are ever met, their position amounts to an “error theory,” according to which statements of the problematic kind are systematically false. If the claim is, rather, that one can never be justified in taking such statements to be true, the resultant antirealism is better described as a form of agnosticism.

Second, antirealists may claim that the surface appearance of the problematic statements—their apparent recording of objective facts which obtain independently of human beings and their responses and attitudes to external reality—is misleading; properly understood, those statements discharge some quite different, nondescriptive role, such as expressing (typically noncognitive) attitudes, enjoining courses of action, or, perhaps, endorsing conventions or rules of language. Often, and especially when underpinned by an expressivist account of the problematic statements, antirealism of this second kind amounts to a version of “projectivism,” according to which, in making such statements, one is not seeking to correctly describe features of a mind-independent world but is merely projecting one’s own responses and attitudes onto it.

Such nonreductive forms of antirealism have been opposed to both moral realism and scientific realism and have been defended in several other areas besides. The nominalism of Hartry Field involves an error-theoretic treatment of pure mathematical discourse, as may other fictionalist approaches—e.g., to possible worlds. Hume’s treatment of the idea of “necessary connection” in causality as deriving from the habitual expectation of the effect upon the observation of its cause is a classic example of projectivism, which some of his successors sought to extend to modality in general, including logical necessity. The German mathematician David Hilbert’s differential treatment of the “real” or “contentful” statements of finitary arithmetic, in contrast to the “ideal” statements of transfinite mathematics, has been interpreted as a form of instrumentalism about the latter, broadly akin to that recommended by many thinkers in relation to the theoretical parts of science (see below Scientific realism and instrumentalism). And Ludwig Wittgenstein, in his Remarks on the Foundations of Mathematics (1956), can be seen as recommending a noncognitivist approach to logical and mathematical statements, according to which they do not record truths of some special kind but rather express rules which regulate the use of more ordinary or empirical statements.

Moral realism

According to moral realists, statements about what actions are morally required or permissible and statements about what dispositions or character traits are morally virtuous or vicious (and so on) are not mere expressions of subjective preferences but are objectively true or false according as they correspond with the facts of morality—just as historical or geographic statements are true or false according as they fit the historical or geographic facts. As with realism in other areas, moral realism faces challenges on two fronts. On the metaphysical front, there is obvious scope for skepticism about whether there is, or even could be, a realm of distinctively moral facts, irreducible to and apparently inexplicable in terms of the facts of nature. On the epistemological front, it has seemed to be an insuperable obstacle to moral realism to explain how, if there really were such a realm of moral facts, human beings could possibly gain access to it. Although reason alone may seem to deliver knowledge of some kinds of nonempirical truths—e.g., of logic and mathematics—it does not seem to deliver the truths of morality, and there appears to be no other special faculty by which such truths may be detected. Talk of “moral sense” or “moral intuition,” though once popular, now seems merely to rename rather than to solve the problem.

On the antirealist side, attempts to reduce moral properties to natural ones (by identifying right actions with, say, those which promote happiness) have found support, but they face difficulties of their own. Indeed, they seem particularly vulnerable to Moore’s celebrated “open question” argument, which points out that, because it is always a substantive and not a tautological question whether some naturalistically specified property is morally good—one can always ask, for example, “Is happiness good?”—the meanings of moral terms like “good” cannot simply be identified with the property in question. Appealing to the intrinsic “queerness” of moral properties as contrasted with natural ones, some theorists, notably the Australian-born philosopher J.L. Mackie, have denied their existence altogether, propounding an error theory of moral discourse.

Other antirealists have sought to rescue moral discourse by reinterpreting it along expressivist or projectivist lines. This approach, which may also be traced back to Hume, is exemplified in the theory of ethical emotivism, which was favoured by (among others) the logical positivists in the first half of the 20th century. According to emotivism, moral statements such as “Lying is wrong” do not record (or misrecord) facts but serve other, nondescriptive purposes, such as expressing a feeling of disapproval of the behaviour or discouraging others from engaging in it. A sophisticated contemporary development of expressivism and projectivism, defended by the English philosopher Simon Blackburn and others under the title “quasi-realism,” seeks to explain how one can properly treat ethical propositions as true or false without presupposing a special domain of nonnatural facts.

Scientific realism and instrumentalism

The dispute between scientific realists and antirealists, though often associated with conflicting ontological attitudes toward the unobserved (and perhaps unobservable) entities ostensibly postulated by some scientific theories, primarily concerns the status of the theories themselves and what scientists should be seen as trying to accomplish in propounding them. Both sides are agreed that, to be acceptable, a scientific theory should “save the phenomena”—that is, it should at least be consistent with, and ideally facilitate correct prediction of, such matters of observable fact as may be recorded in reports of relevant observations and, where appropriate, experiments. The issue concerns whether theories can and should be seen as attempting more than this. Realists, notably including Karl Popper, J.J.C. Smart, Ian Hacking, and Hilary Putnam, along with many others, have claimed that they should be so viewed: Science aims, in its theories, at a literally true account of what the world is like, and accepting those theories involves accepting their ingredient theoretical claims as true descriptions of aspects of reality—perhaps themselves not open to observation—additional to and underlying the phenomena.

Karl Popper, 1991. Image: Graziano Arici/age fotostock

Against this, the doctrine of instrumentalism claims that scientific theories are no more than devices, or “instruments” (in effect, sets of inference rules) for generating predictions about observable phenomena from evidence about such phenomena. This claim can be understood in two ways. It could be that theoretical scientific statements are not, despite appearances, genuine statements at all but rules of inference in disguise, so that the question of their truth (or falsehood) simply does not arise. In this case, instrumentalism is akin to expressivism about ethical statements. Alternatively, it could be that, as far as the aims of science go, what matters when evaluating a scientific theory—given that it meets other desiderata such as simplicity, economy, generality of application, and so on—is only its inferential (or instrumental) reliability; its truth or falsehood is of no scientific concern. A notable development of the latter approach is the constructive empiricism of Bas van Fraassen, according to which science aims not at true theories but at theories which are “empirically adequate,” in the sense that they capture or predict relevant truths about observable matters.

Antirealism about science, both in its earlier instrumentalist form and in van Fraassen’s version, clearly relies upon a fundamental distinction between statements which are, and those which are not, wholly about observable entities or states of affairs. Realists frequently deny the tenability of this distinction, arguing that there is no “theory-neutral” language in which observations may be reported, or at any rate that there is no sharp, principled division between what is observable and what is not. Antirealists may acknowledge that a great deal of language, perhaps even all of it, is theory-laden but claim that this does not require acceptance of the theories with which it is infected; nor does it entail that statements involving theory-infected terms (e.g., “The Geiger counter is reading 7.3”) cannot be true solely in virtue of observable matters. Against the claim that there is no difference in principle between, say, detecting a passing jet airplane by seeing its vapour trail and detecting a subatomic particle by seeing its trace in a cloud chamber, they may reply that indeed there is. While the plane is an observable object—even though, in this case, only its effect is observed—there is no observing the particle itself, as distinct from its supposed effects.

A further argument commonly advanced in support of realism is that it provides the best, or the only credible, explanation for the success of scientific theories. From an instrumentalist perspective, it is claimed, it must be quite mysterious or even miraculous that the world should behave as if the best scientific theories about it were true. Surely, realists argue, the obvious and best explanation is that the world behaves in this way because the theories about it are in fact true (or at least approximately true). Although this argument certainly presents antirealists with a serious challenge, it is not clear that they cannot meet it. In particular, van Fraassen argued that, in so far as the demand for an explanation of science’s success is legitimate, that success can be explained in terms of the idea that scientists aim to construct theories which are empirically adequate.

Metaphysical Realism And Objective Truth

Although several realist disputes seem to turn on whether statements of a certain kind are capable of being objectively true, it is far from obvious what being objectively true amounts to. The question of what it is for a statement to be objectively true has itself been a focus of realist-antirealist disagreement.

Objective truth uncontroversially requires mind-independence, at least in the sense of being true independently of what anyone knows or believes. That is, if a proposition is to be “objectively” true, then it must be possible for it to be true without anyone knowing or believing that it is; conversely, believing the proposition should not be sufficient for its truth (except in a few very special cases, such as believing that one believes something). This notion of objectivity is clearly quite weak, and it falls well short of the kind of objectivity attributed to true statements in some strongly realist theories of truth.

Metaphysical realism and antirealism

One such theory is metaphysical (or “external”) realism, as characterized (but not professed) by Putnam. According to this view, even an ideal scientific theory—one which is judged to be true by the best operational criteria for assessing scientific theories—may nevertheless in reality be false. The metaphysical realist’s truth is, as Putnam also put it, “radically nonepistemic,” potentially outstripping not only what scientists actually believe but also what they would believe were they to form their beliefs perfectly rationally under evidentially ideal conditions. In a similar vein, the realist as characterized by the English philosopher Michael Dummett holds that statements may be true (or false) independently of any possibility, even in principle, of their being recognized as such.

Putnam and Dummett both rejected the realist positions they characterized. Putnam argued that metaphysical realism faces insuperable problems in explaining how words and sentences can determinately refer or correspond to the world in the way apparently required if it is to be possible for even an ideal theory to be false. Dummett, for his part, pressed two main challenges to realism: (1) to explain how humans could come to understand statements which are unrecognizably true, given that human linguistic training necessarily proceeds in terms of publicly accessible and recognizable aspects of use, and (2) to explain how such an alleged understanding could be manifested or displayed.

Although neither Putnam nor Dummett was prepared to endorse verificationism (the view that a statement is cognitively meaningful only if it is possible in principle to verify it), both argued for positions which connect truth more closely than the realist does with evidence or with grounds for belief. In opposition to metaphysical or external realism, Putnam defended an “internal” realism which identifies truth with ideal rational acceptability; his view, as he pointed out, has significant affinities with Kant’s transcendental idealism. Dummett argued that the meanings of statements must be explicated not in terms of potentially evidence-transcendent truth-conditions but by reference to conditions—such as those under which a statement counts as proved or justified—which can be recognized to obtain whenever they do.

As Dummett emphasized, the adoption of such an antirealist view of truth carries significant implications outside the theory of meaning, especially for logic and hence mathematics. In particular, logical principles such as the law of excluded middle (for every proposition p, either p or its negation, not-p, is true, there being no “middle” true proposition between them) can no longer be justified if a strongly realist conception of truth is replaced by an antirealist one which restricts what is true to what can in principle be known. There is no guarantee, for example, that for an arbitrary mathematical proposition p, either p or not-p can be proved. Because many important theorems in classical mathematics depend for their proof upon the principles affected, large parts of classical mathematics are called into question. In this way, Dummett’s antirealism about truth and meaning lends support to revisionary constructivist approaches to mathematics, such as intuitionism (see also mathematics, philosophy of: Logicism, intuitionism, and formalism.

“Modest” objective truth

Although some realist-antirealist disputes may, as illustrated, turn on the applicability of a strongly realist notion of truth to statements of a certain kind, it does not seem that this can be what is at issue in all cases in which realists assert, and their opponents deny, that statements of the problematic sort are capable of objective truth. Even in mathematics, there can be realist-antirealist disagreements over very elementary statements, such as 172 = 289, which cannot be true in a way which transcends all evidence, because they are effectively decidable by a routine computation. Again, whatever precisely is at issue between moral realists and their opponents, it is not plausible that they disagree about whether ethical statements can be true in a way which in principle eludes detection.

The apparent implication of these examples is that there is some other, more modest notion of objective truth in play in such disputes. There is in fact a notion of truth—the minimal notion defined by the equivalence schema It is true that p if and only if p—which is guaranteed to apply to statements of any kind for which there are standards of proper or correct assertion (see semantics: Meaning and truth).

Because such standards undoubtedly exist for mathematical and ethical discourse, some assertions complying with them will be true in at least this minimal sense. If this is right, therefore, the disagreement between realists and antirealists, in at least some areas, must concern the truth or objectivity of the problematic statements in a more substantial sense, but one which is still less exacting than that of the metaphysical realist characterized by Putnam and Dummett.

Whether there is any such notion of truth is controversial. Defenders of the “deflationary” or “redundancy” theory of truth—e.g., Frank P. Ramsey, A.J. Ayer, and more recently Paul Horwich—have denied that truth can be a substantial property, arguing that all there is to the notion of truth is captured by instances of the equivalence schema. Even if this is accepted, however, it does not follow that there cannot be a more substantial notion of objectivity. An improved understanding of issues about realism may thus depend on clarifying further the respects in which statements which are capable of minimal truth may differ—such as whether there is scope for persistent but faultless disagreement about them (as with matters of taste or humour) and whether the facts they record may play a significant role in explaining facts of other kinds. These and related questions have been pursued in work since the 1990s, especially by the English philosopher Crispin Wright.

Bob Hale


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