View source for Hilary Putnam

{{short description|American mathematician and philosopher (1926–2016)}}
{{Use mdy dates|date=November 2023}}
{{Infobox philosopher
 | region          = [[Western philosophy]]
 | era             = [[20th-century philosophy]]
 | image           = Hilary Putnam.jpg
 | caption         = Putnam in 2006
 | birth_name      = Hilary Whitehall Putnam
 | birth_date       = {{Birth date|1926|7|31}}
 | death_date       = {{Death date and age|2016|3|13|1926|7|31}}
 | birth_place      = [[Chicago]], [[Illinois]], U.S.
 | death_place      = [[Arlington, Massachusetts|Arlington]], [[Massachusetts]], U.S.
 | spouse           = [[Ruth Anna Putnam]]
 | alma_mater       = [[University of Pennsylvania]] ([[B. A.|BA]])<br />[[Harvard University]]<br />[[University of California, Los Angeles]] ([[PhD]])
 | institutions     = [[Northwestern University]]<br />[[Princeton University]]<br />[[Massachusetts Institute of Technology]]<br />[[Harvard University]]
 | school_tradition = [[Analytic philosophy|Analytic]]<br />[[Neopragmatism]]<ref>{{cite web|url=https://www.iep.utm.edu/pragmati/ |title=Pragmatism |website=[[Internet Encyclopedia of Philosophy]]|access-date=August 18, 2022|archive-url=https://web.archive.org/web/20220812023316/https://iep.utm.edu/pragmati/|archive-date=August 12, 2022}}</ref><br />[[Postanalytic philosophy]]<br />[[Mathematical quasi-empiricism]]<br />[[Metaphysical realism]] (1983)<br />[[Internal realism]] (1987, 1990)<br />[[Direct realism]] (1994)<br />[[Transactionalism]] (2012)
 | main_interests   = [[Philosophy of mind]], [[Philosophy of language|of language]], [[Philosophy of science|of science]], and [[Philosophy of mathematics|of mathematics]]<br />[[Metaphilosophy]]<br />[[Epistemology]]<br />[[Jewish philosophy]]
 | notable_ideas    = [[Multiple realizability]] of [[Mental event|the mental]]<br />[[Functionalism (philosophy of mind)|Functionalism]]<br />[[Causal theory of reference]]<br />[[Semantic externalism]] ([[reference theory of meaning]])<br />[[Brain in a vat]]{{·}} [[Twin Earth thought experiment|Twin Earth]]<br />Putnam's [[Model theory|model-theoretical]] argument against [[metaphysical realism]] (Putnam's paradox)<ref>{{cite book|first=Hilary |last=Putnam |chapter="Realism and reason", Presidential Address to the Eastern Division of the American Philosophical Association, December 1976 |title=Meaning and the Moral Sciences |publisher=Routledge and Kegan Paul |year=1978 |pages=123–140 |isbn=978-0-710-08754-6 |oclc=318417931}}</ref><ref>{{cite journal|author-link=Bas van Fraassen |first=Bas |last=van Fraassen |url=https://www.princeton.edu/~fraassen/abstract/PutnamParadox-published.pdf |title=Putnam's Paradox: Metaphysical Realism Revamped and Evaded |journal=Philosophical Perspectives |volume=11 |pages=17–42 |year=1997 |jstor=2216123}}</ref><br />[[Internal realism]]<br />[[Quine–Putnam indispensability thesis]]<br />[[Davis–Putnam algorithm]]<br />Criticism of the [[innateness hypothesis]]
 | awards           = [[Rolf Schock Prizes|Rolf Schock Prize in Logic and Philosophy]] (2011), [[Nicholas Rescher Prize for Systematic Philosophy]] (2015)
 | doctoral_advisor  = [[Hans Reichenbach]]<ref name="mathgeo">{{MathGenealogy | 13387 }}</ref>
 | thesis_title      = The Meaning of the Concept of Probability in Application to Finite Sequences<ref name="mathgeo"/>
 | thesis_url        =
 | thesis_year       = 1951
 | website = https://putnamphil.blogspot.com/
| module             = {{Infobox scientist
|embed= yes
|fields             = [[Computer science]]<br>[[Mathematics]]
}}
}}
'''Hilary Whitehall Putnam''' ({{IPAc-en|ˈ|p|ʌ|t|n|əm}}; July 31, 1926 – March 13, 2016) was an American philosopher, mathematician, computer scientist, and figure in [[analytic philosophy]] in the second half of the 20th century. He contributed to the studies of [[philosophy of mind]], [[philosophy of language]], [[philosophy of mathematics]], and [[philosophy of science]].<ref name="CR">{{cite book|last=Casati |first=R. |authorlink=:it:Roberto Casati|chapter=Hillary Putnam |title=Enciclopedia Garzanti della Filosofia |editor-first=Gianni |editor-last=Vattimo |editor-link=Gianni Vattimo |year=2004 |publisher=Garzanti Editori |location=Milan |isbn=88-11-50515-1}}</ref> Outside philosophy, Putnam contributed to [[mathematics]] and [[computer science]]. Together with [[Martin Davis (mathematician)|Martin Davis]] he developed the [[Davis–Putnam algorithm]] for the [[Boolean satisfiability problem]]<ref name="DandP">{{cite journal|last1=Davis |first1=M. |last2=Putnam |first2=H |title=A computing procedure for quantification theory |journal=[[Journal of the ACM]] |volume=7 |pages=201–215 |year=1960 |issue=3 |doi=10.1145/321033.321034|s2cid=31888376 |doi-access=free }}</ref> and he helped demonstrate the unsolvability of [[Hilbert's tenth problem]].<ref name="Mat">{{cite book|title=Hilbert's Tenth Problem|last=Matiyesavic |first=Yuri|publisher=MIT|year=1993|isbn=0-262-13295-8|location=Cambridge}}</ref>

Putnam applied equal scrutiny to his own philosophical positions as to those of others, subjecting each position to rigorous analysis until he exposed its flaws.<ref name=King170>{{cite book|last=King |first=P. J. |title=One Hundred Philosophers: The Life and Work of the World's Greatest Thinkers |publisher=Barron's |year=2004 |page=170 |isbn=978-0-764-12791-5 |oclc=56593946}}</ref> As a result, he acquired a reputation for frequently changing his positions.<ref>{{cite web|first=Jack |last=Ritchie|title=TPM: Philosopher of the Month|url=https://www.philosophers.co.uk/|date=June 2002|archive-date=July 9, 2011|archive-url=https://web.archive.org/web/20110709060653/http://www.philosophers.co.uk/cafe/phil_jun2002.htm}}</ref> In philosophy of mind, Putnam argued against the [[type physicalism|type-identity]] of mental and physical states based on his hypothesis of the [[multiple realizability]] of [[Mental event|the mental]], and for the concept of [[functionalism (philosophy of mind)|functionalism]], an influential theory regarding the [[mind–body problem]].<ref name="CR" /><ref>{{cite book|last=LeDoux |first=J. |title=The Synaptic Self: How Our Brains Become Who We Are| publisher=Viking Penguin|location=New York|year=2002|isbn=88-7078-795-8}}</ref> Putnam also originated the [[computational theory of mind]].<ref>{{Cite journal |last=Horst |first=Steven |date=1999 |title=Symbols and Computation A Critique of the Computational Theory of Mind |url=https://link.springer.com/article/10.1023/A:1008351818306 |journal=Minds and Machines |volume=9 |issue=3 |pages=347–381 |doi=10.1023/A:1008351818306}}</ref> 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 [[externalism|semantic externalism]] based on a [[thought experiment]] called [[Twin Earth thought experiment|Twin Earth]].<ref name="CH">{{cite book|editor-first1=Peter |editor-last1=Clark |editor-first2=Bob |editor-last2=Hale |title=Reading Putnam |publisher=Blackwell |location=Cambridge (Massachusetts), Oxford |year=1995 |isbn=978-0-631-19995-3 |oclc=35303308}}</ref>

In [[philosophy of mathematics]], Putnam and [[Willard Van Orman Quine|W. V. O. Quine]] developed the [[Quine–Putnam indispensability argument]], an argument for the reality of mathematical entities,<ref name="SEP-Colyvan">{{cite SEP|author-last=Colyvan |author-first=Mark |author-link=Mark Colyvan |url-id=mathphil-indis |title=Indispensability Arguments in the Philosophy of Mathematics |date=Spring 2019}}</ref> later espousing the view that mathematics is not purely logical, but "[[quasi-empiricism in mathematics|quasi-empirical]]".<ref name="PutBen">{{cite book|last=Putnam |first=H. |title=Philosophy of Mathematics: Selected Readings |editor-first=Paul |editor-last=Benacerraf |editor-link=Paul Benacerraf |location=Englewood Cliffs, N.J. |publisher=Prentice-Hall |year=1964 |oclc=1277244158}} 2nd ed., Cambridge: Cambridge University Press, 1983.</ref> In [[epistemology]], Putnam criticized the "[[brain in a vat]]" thought experiment, which appears to provide a powerful argument for [[skepticism|epistemological skepticism]], by challenging its coherence.<ref name="BIV">{{Cite book|last=Putnam|first=H.|year=1981|chapter=Brains in a vat|title=Reason, Truth, and History|publisher=Cambridge University Press|archive-url=https://web.archive.org/web/20211006131612/https://philosophy.as.uky.edu/sites/default/files/Brains%20in%20a%20Vat%20-%20Hilary%20Putnam.pdf|archive-date=October 6, 2021|chapter-url=https://philosophy.as.uky.edu/sites/default/files/Brains%20in%20a%20Vat%20-%20Hilary%20Putnam.pdf |isbn=978-0-521-23035-3 |oclc=442822274}} reprinted in {{Cite book|editor-last1=DeRose |editor-first1=K. |editor-last2=Warfield |editor-first2=T. A. |year=1999|title=Skepticism: A Contemporary Reader|publisher=Oxford University Press |isbn=978-0-195-11826-1 |oclc=1100897197}}</ref> 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]]",<ref name="Human">{{cite book|last=Putnam |first=H. |title=Realism with a Human Face |editor-first=J. F. |editor-last=Conant |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=1990 |isbn=978-0-674-74945-0 |oclc=1014989000}}</ref> which he later abandoned. Despite these changes of view, throughout his career Putnam remained committed to [[scientific realism]], roughly the view that mature scientific theories are approximately true descriptions of ways things are.<ref>{{cite book|last=Putnam |first=H. |year=2012 |chapter=From Quantum Mechanics to Ethics and Back Again |editor-last1=De Caro |editor-first1=M. |editor1-link=Mario De Caro|editor-last2=Macarthur |editor-first2=D. |editor2-link=David Macarthur|title=Philosophy in an Age of Science |location=Cambridge, Massachusetts |publisher=Harvard University Press |isbn=978-0-674-05013-6 |oclc=913024858}}</ref>

In his later work, Putnam became increasingly interested in [[Pragmatism|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.<ref name="Auxier">{{cite book|first=Hilary |last=Putnam |editor-link1=Randall Auxier |editor-last1=Auxier |editor-first1=R. E. |editor-last2=Anderson |editor-first2=D. R. |editor-last3=Hahn |editor-first3=L. E. |title=The Philosophy of Hilary Putnam |location=Chicago |publisher=[[Open Court Publishing Company|Open Court]] |year=2015 |url=https://books.google.com/books?id=adoKCQAAQBAJ |isbn=978-0-8126-9898-5 |oclc=921843436}}</ref> He was at times a politically controversial figure, especially for his involvement with the [[Progressive Labor Party (United States)|Progressive Labor Party]] in the late 1960s and early 1970s.<ref name="Auxier"{{Rp|81–82}}</<ref name="Foley">{{cite book|title=Confronting the War Machine: Draft Resistance during the Vietnam War|url=https://books.google.com/books?id=WdRGDgAAQBAJ|last=Foley |first=M.|publisher=North Carolina Press|year=2003|isbn=0-8078-2767-3|location=Chapel Hill, North Carolina}}</ref>

== Life ==
Hilary Whitehall Putnam was born on July 31, 1926, in [[Chicago]], [[Illinois]].<ref name=":0">{{Cite book |last=Baghramian |first=Maria |author-link=Maria Baghramian |oclc=809409617 |title=Reading Putnam |date=2012 |publisher=Routledge |isbn=978-0-415-53007-1 |editor-last=Baghramian |editor-first=M. |location=New York |pages=1–16 |chapter=Introduction: A life in philosophy |chapter-url=https://books.google.com/books?id=DWXBB_g41ngC&pg=PA1}}</ref> His father, [[Samuel Putnam]], was a scholar of Romance languages, columnist, and translator who wrote for the ''[[Daily Worker]]'', a publication of the [[Communist Party USA|American Communist Party]], from 1936 to 1946.<ref>{{cite book|last=Wolfe |first=Bertram David |author-link=Bertram Wolfe |title=Strange Communists I Have Known |publisher=Stein and Day |year=1965 |page=79 |oclc=233981919}}</ref> Because of his father's commitment to communism, Putnam had a secular upbringing, although his mother, Riva, was [[Judaism|Jewish]].<ref name=King170/> In early 1927, six months after Hilary's birth, the family moved to France, where Samuel was under contract to translate the surviving works of [[François Rabelais]].<ref name="Auxier"/><ref name=":0" /> In a 2015 autobiographical essay, Putnam said that his first childhood memories were from his life in France, and his first language was [[French language|French]].<ref name="Auxier" />

Putnam completed the first two years of his [[primary education]] in France before he and his parents returned to the U.S. in 1933, settling in [[Philadelphia]].<ref name=":0" /> There, he attended [[Central High School of Philadelphia|Central High School]], where he met [[Noam Chomsky]], who was a year behind him.<ref name="Auxier"/>{{Rp|8}} The two remained friends—and often intellectual opponents—for the rest of Putnam's life.<ref>{{cite book|first=Robert F. |last=Barsky |author-link=Robert F. Barsky |title=Noam Chomsky: A Life of Dissent |chapter-url=https://direct.mit.edu/pages/cognet|chapter=2: Undergraduate Years. A Very Powerful Personality |publisher=[[MIT Press]]|year=1997 |isbn=978-0-262-02418-1 |oclc=760607694|archive-url=https://web.archive.org/web/20031106040709/http://cognet.mit.edu/library/books/chomsky/chomsky/2/7.html |archive-date=November 6, 2003 }}</ref> Putnam studied philosophy at the [[University of Pennsylvania]], receiving his [[Bachelor of Arts|B.A.]] degree and becoming a member of the [[Philomathean Society]], the country's oldest continually existing collegiate literary society.<ref name="King170" /><ref name="Hick">{{cite book|last=Hickey |first=L. P. |url=https://books.google.com/books?id=kxUdCgAAQBAJ |title=Hilary Putnam |location=London, New York |publisher=[[Continuum International Publishing Group|Continuum]] |year=2009 |isbn=978-1-847-06076-1 |oclc=1001716818}}</ref> He did graduate work in philosophy at [[Harvard University]]<ref name="King170" /> and later at [[University of California, Los Angeles|UCLA]]'s philosophy department, where he received his [[Doctor of Philosophy|Ph.D.]] in 1951 for his dissertation, ''The Meaning of the Concept of Probability in Application to Finite Sequences''.<ref name="mathgeo"/><ref>{{cite book|last=Putnam |first=H. |url=https://books.google.com/books?id=P-KTnW55h9QC |title=The Meaning of the Concept of Probability in Application to Finite Sequences |location=New York |publisher=[[Garland Science|Garland]] |year=1990 |isbn=978-0-824-03209-8 |oclc=463716809}}</ref> 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 was his rejection of logical positivism as [[Self-refuting idea|self-defeating]].<ref name="Hick" /> Over the course of his life, Putnam was his own philosophical adversary, changing his positions on philosophical questions and critiquing his previous views.<ref name="CH" />

After obtaining his PhD, Putnam taught at [[Northwestern University]] (1951–52), [[Princeton University]] (1953–61), and [[Massachusetts Institute of Technology|MIT]] (1961–65). For the rest of his career, Putnam taught at [[Harvard University|Harvard]]'s [[Harvard University Department of Philosophy|philosophy department]], becoming Cogan University Professor. In 1962, he married fellow philosopher [[Ruth Anna Putnam]] (born Ruth Anna Jacobs), who took a teaching position in philosophy at [[Wellesley College]].<ref name="Hick"/><ref name=":2">{{Cite web |last=O'Grady |first=Jane |date=March 14, 2016 |title=Hilary Putnam obituary |url=https://www.theguardian.com/books/2016/mar/14/hilary-putnam-obituary |access-date=July 29, 2022 |website=The Guardian |language=en}}</ref><ref>{{Cite web |last=Marquard |first=Bryan |date=May 20, 2019 |title=Ruth Anna Putnam, Wellesley College philosophy professor, dies at 91 |url=https://www.bostonglobe.com/metro/obituaries/2019/05/20/ruth-anna-putnam-wellesley-college-philosophy-professor-dies/diL1ksbY9iYovu2EHQYomM/story.html |access-date=July 21, 2022 |website=Boston Globe |language=en-US}}</ref> Rebelling against the [[antisemitism]] they experienced during their youth, the Putnams decided to establish a traditional Jewish home for their children.<ref name="Globe">{{cite news|url=http://www.boston.com/news/globe/magazine/articles/2006/07/30/finding_my_religion/?page=3|title=Finding My Religion|author=Wertheimer, L. K.|authorlink=Linda Wertheimer|date=July 30, 2006|work=[[The Boston Globe]]}}</ref> Since they had no experience with the rituals of Judaism, they sought out invitations to other Jewish homes for [[Passover Seder|Seder]]. They began to study Jewish rituals and [[Hebrew language|Hebrew]], became more interested in Judaism, self-identified as Jews, and actively practiced Judaism. In 1994, Hilary celebrated a belated [[Bar and Bat Mitzvah|bar mitzvah]] service; Ruth Anna's bat mitzvah was celebrated four years later.<ref name="Globe"/>

In the 1960s and early 1970s, Putnam was an active supporter of the [[Civil rights movement|American Civil Rights Movement]] and he was also [[opposition to the Vietnam War|an active opponent of the Vietnam War]].<ref name="Foley"/> In 1963, he organized one of MIT's first faculty and student anti-war committees.<ref name="Hick"/><ref name=":2" /> 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 (1960 organization)|Students for a Democratic Society]] and in 1968 a member of the [[Progressive Labor Party (United States)|Progressive Labor Party]] (PLP).<ref name="Hick"/><ref name=":2" /> He was elected a Fellow of the [[American Academy of Arts and Sciences]] in 1965.<ref name=AAAS>{{cite web|title=Book of Members, 1780–2010: Chapter P|url=http://www.amacad.org/publications/BookofMembers/ChapterP.pdf|publisher=American Academy of Arts and Sciences|access-date=April 19, 2011}}</ref> After 1968, his political activities centered on the PLP.<ref name="Foley"/> The Harvard administration considered these activities disruptive and attempted to censure Putnam.<ref>{{cite news|last=Epps |first=G. |author-link=Garrett Epps |url=https://www.thecrimson.com/article/1971/4/14/faculty-will-vote-on-new-procedures/ |title=Faculty Will Vote on New Procedures for Discipline |work=[[The Harvard Crimson]] |date=April 14, 1971}}</ref><ref>{{cite news|last=Thomas |first=E. W. |author-link=Evan Thomas |url=https://www.thecrimson.com/article/1971/5/28/putnam-says-dunlop-threatens-radicals-philary/ |title=Putnam Says Dunlop Threatens Radicals |work=The Harvard Crimson |date=May 28, 1971}}</ref> Putnam permanently severed his relationship with the PLP in 1972.<ref>{{cite news|title=''NYT'' correction, March 6, 2005|url=https://query.nytimes.com/gst/fullpage.html?res=940DE1DE1E3DF935A35750C0A9639C8B63&n=Top%2fReference%2fTimes%20Topics%2fOrganizations%2fH%2fHarvard%20University%20|access-date=August 1, 2006 | work=[[The New York Times]] | date=March 6, 2005}}</ref> In 1997, at a meeting of former draft resistance activists at Boston's [[Arlington Street Church (Boston)|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.<ref name="Foley"/>

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. 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).<ref name="Hick"/>

Putnam was a Corresponding Fellow of the [[British Academy]]. He was elected to the [[American Philosophical Society]] in 1999.<ref>{{Cite web|title=APS Member History|url=https://search.amphilsoc.org/memhist/search?creator=Hilary+Putnam&title=&subject=&subdiv=&mem=&year=&year-max=&dead=&keyword=&smode=advanced|access-date=December 2, 2021|website=search.amphilsoc.org}}</ref> He retired from teaching in June 2000, becoming Cogan University Professor Emeritus, 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.<ref>{{cite web|url=https://www.uva.nl/en/discipline/philosophy/spinoza-chair/spinoza-chair.html |title=The Spinoza Chair |website=Department of Philosophy |publisher=University of Amsterdam |access-date=July 27, 2022 |year=2022}}</ref> 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.<ref name="chosenness">{{cite magazine|url=http://new.bostonreview.net/BR29.1/putnam.html|title=Hilary Putnam: The Chosen People|magazine=[[Boston Review]]|access-date=December 14, 2010|url-status=dead|archive-url=https://web.archive.org/web/20131224095541/http://new.bostonreview.net/BR29.1/putnam.html|archive-date=December 24, 2013}}</ref> With his wife, he co-authored several essays and a book on the late-19th-century American [[pragmatism|pragmatist]] movement.<ref name="Hick"/>

For his contributions in philosophy and logic, Putnam was awarded the [[Rolf Schock Prize]] in 2011<ref>{{cite web|url=https://thephilosopherseye.com/2011/04/12/hilary-putnam-awarded-the-rolf-schock-prize-in-logic-and-philosophy/|title=Hilary Putnam awarded The Rolf Schock Prize in Logic and Philosophy|work=The Philosopher's Eye|date=April 12, 2011|url-status=dead|archive-url=https://web.archive.org/web/20160315120644/https://thephilosopherseye.com/2011/04/12/hilary-putnam-awarded-the-rolf-schock-prize-in-logic-and-philosophy/|archive-date=March 15, 2016}}</ref> and the [[Nicholas Rescher Prize for Systematic Philosophy]] in 2015.<ref>{{Cite web |last=Fike |first=Katie |date=October 5, 2015 |title=Harvard's Hilary Putnam Awarded Pitt's Nicholas Rescher Prize |url=https://www.news.pitt.edu/news/harvard-s-hilary-putnam-awarded-pitt-s-nicholas-rescher-prize |access-date=August 18, 2022 |publisher=[[University of Pittsburgh]]}}</ref> Putnam died at his home in [[Arlington, Massachusetts|Arlington]], [[Massachusetts]], on March 13, 2016.<ref>{{cite news|last=Weber |first=B. |url=https://www.nytimes.com/2016/03/18/arts/hilary-putnam-giant-of-modern-philosophy-dies-at-89.html |title=Hilary Putnam, Giant of Modern Philosophy, Dies at 89 |work=The New York Times |date=March 17, 2016}}</ref> At the time of his death, Putnam was Cogan University Professor Emeritus at Harvard University.

== Philosophy of mind ==
=== Multiple realizability ===
[[File:Reduktionismus.png|thumb|right|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]].<ref name="Bick">{{cite SEP|author-last=Bickle |author-first=John |url-id=multiple-realizability |title=Multiple Realizability |date=Fall 2006}}</ref> In these papers, Putnam argues that, contrary to the famous claim of the [[type-identity theory]], 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".<ref name="Bick"/> 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 [[animal cognition|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 [[artificial intelligence|intelligent robots]] and other [[silicon-based life form]]s. 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. This is sometimes called the "likelihood argument", as it focuses on the claim that multiple realizability is more likely than type-identity theory.<ref name="MLR">{{cite book|last=Putnam |first=H. |title=Mind, Language and Reality. Philosophical Papers, vol. 2 |location=Cambridge |publisher=Cambridge University Press |year=1975 |isbn=88-459-0257-9}}</ref><ref name=":3" />{{Rp|page=640}}

Putnam also formulated an ''[[a priori]]'' argument in favor of multiple realizability 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.<ref name="MLR"/><ref name=":3">{{Cite journal |last=Shapiro |first=Lawrence A. |author-link=Lawrence Shapiro|date=2000 |title=Multiple Realizations |url=https://www.jstor.org/stable/2678460 |journal=[[The Journal of Philosophy]] |volume=97 |issue=12 |pages=635–654 |doi=10.2307/2678460 |jstor=2678460 |issn=0022-362X}}</ref>{{Rp|page=637}}

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. [[Functionalism (philosophy of mind)|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, including mousetraps and eyes, that are multiply realized at the physical level.<ref name="MLR"/><ref>{{cite journal|last=Fodor |first=J. |year=1974 |title=Special Sciences |journal=Synthese |volume=28 |pages=97–115 |doi=10.1007/BF00485230 |jstor=20114958|s2cid=46979938 |url=https://philarchive.org/rec/FODSSO-2 }}</ref><ref name=":3" />{{Rp|pages=648–649}}<ref>{{Cite book |last=Shapiro |first=Lawrence A. |title=The Mind Incarnate |date=2004 |publisher=MIT Press |isbn=9780262693301 |location=Cambridge, MA |pages=1–33 |chapter=The Multiple Realizability Thesis: Significance, Scope, and Support}}</ref>{{Rp|page=6}}

Multiple realizability has been criticized on the grounds that, if it were true, research and experimentation in the neurosciences would be impossible.<ref name="BandM">{{cite journal |last1=Bechtel |first1=William |last2=Mundale |first2=Jennifer |title=Multiple Realizability Revisited |journal=Philosophy of Science |volume=66 |pages=175–207 |doi=10.1086/392683 |jstor=188642 |number=2 |s2cid=122093404}}</ref> 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 (biology)|homology]]) of brain structures that allows us to generalize across species.<ref name="BandM" /> 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).<ref>{{cite journal |last=Kim |first=Sungsu |year=2002 |title=Testing Multiple Realizability: A Discussion of Bechtel and Mundale |journal=Philosophy of Science |volume=69 |issue=4 |pages=606–610 |doi=10.1086/344623 |s2cid=120615475}}</ref> [[Jaegwon Kim]], [[David Kellogg Lewis|David Lewis]], Robert Richardson and [[Patricia Churchland]] have also criticized metaphysical realism.<ref>{{cite journal |last=Kim |first=Jaegwon |title=Multiple Realizability and the Metaphysics of Reduction |journal=Philosophy and Phenomenological Research |volume=52 |pages=1–26 |date=March 1992| doi=10.2307/2107741 |jstor=2107741}}</ref><ref>{{cite journal |last=Lewis |first=David |year=1969 |title=Review of Art, Mind, and Religion |journal=Journal of Philosophy |volume=66 |pages=23–35 |doi=10.2307/2024154 |jstor=2024154}}</ref><ref>{{cite journal |last=Richardson |first=Robert |year=1979 |title=Functionalism and Reductionism |journal=Philosophy of Science |volume=46 |issue=4 |pages=533–558 |doi=10.1086/288895 |jstor=187248 |s2cid=171075636}}</ref><ref>{{cite book |last=Churchland |first=Patricia |title=Neurophilosophy: Toward a unified science of the mind-brain |publisher=MIT Press |year=1986 |isbn=978-0-262-03116-5 |location=Cambridge, Massachusetts |oclc=299398803}}</ref>

=== 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 machine]]s.<ref>{{cite book|last=Davis |first=J. B. |title=The Theory of the Individual in Economics: Identity and Value |location=Oxford|publisher=[[Routledge]] |year=2003 |url=https://books.google.com/books?id=DpZKxHzGlC4C&pg=PA87 |page=87 |isbn=978-0-415-20219-0 |oclc=779084377}}</ref> 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.<ref>{{cite book|last=Block |first=Ned |chapter=What is Functionalism | chapter-url=https://www.nedblock.us/papers/functionalism.encyc.pdf|title=Consciousness, Function, and Representation |publisher=MIT Press |year=2007 |isbn=978-0-262-02603-1 |oclc=494256364 |pages=27–44}}</ref>

=== Rejection of functionalism ===
[[Ian Hacking]] called ''Representation and Reality'' (1988) a book that "will mostly be read as Putnam's denunciation of his former philosophical psychology, to which he gave the name 'functionalism'."<ref>{{Cite news |last=Hacking |first=Ian |author-link=Ian Hacking |date=1989-05-04 |title=Putnam's Change of Mind |url=https://www.lrb.co.uk/the-paper/v11/n09/ian-hacking/putnam-s-change-of-mind |access-date=2024-06-05 |work=[[London Review of Books]] |language=en |volume=11 |issue=9 |issn=0260-9592}}</ref> Writing in ''[[Noûs]]'', Barbara Hannon described "the inventor of functionalism" as arguing "against his own former computationalist views".<ref>{{Cite journal |last=Hannon |first=Barbara |date=1993 |title=Review of Representation and Reality. |url=https://www.jstor.org/stable/2215905 |journal=Noûs |volume=27 |issue=1 |pages=102–106 |doi=10.2307/2215905 |jstor=2215905 |issn=0029-4624}}</ref>

Putnam's change of mind was primarily due to the difficulties computational theories have in explaining certain intuitions with respect to the [[Internalism and externalism|externalism]] of mental content.<ref name="Three">{{cite book |last=Putnam |first=H. |title=The Threefold Cord: Mind, Body, and World |publisher=Columbia University Press |year=1999 |isbn=978-0-231-10286-5 |location=New York |oclc=868429895}}</ref> This is illustrated by his [[Twin Earth thought experiment]].<ref>Rescorla, M., "The Computational Theory of Mind", esp. [https://plato.stanford.edu/entries/computational-mind/#ExtAboMenCon 5.2 Externalism about mental content], ''[[Stanford Encyclopedia of Philosophy]]'', December 18, 2024.</ref>

In 1988 Putnam 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 of mind|identity theory]] in which mental kinds are identified with functional kinds, he 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]].<ref>{{cite book|last=Putnam |first=Hilary |year=1988 |title=Representation and Reality |location=Cambridge, Massachusetts |publisher=MIT Press |isbn=978-0-262-66074-7 |oclc=951364040}}</ref>{{Primary source inline|date=October 2022}}

Despite Putnam's rejection of functionalism, it has continued to flourish and been developed into numerous versions by Fodor, [[David Marr (psychologist)|David Marr]], [[Daniel Dennett]], and [[David Lewis (philosopher)|David Lewis]], among others.<ref name="Mar">{{cite book|last=Marhaba |first=S. |year=2004 |chapter=Funzionalismo |title=Enciclopedia Garzanti della Filosofia |editor-link1=Gianni Vattimo |editor-first1=G. |editor-last1=Vattimo |editor-first2=G. |editor-last2=Chiurazzi |location=Milan |publisher=[[Aldo Garzanti|Garzanti Editore]] |isbn=88-11-50515-1}}</ref> Functionalism helped lay the foundations for modern [[cognitive science]]<ref name="Mar"/> and was the dominant theory of mind in philosophy in the last part of the 20th century.<ref>{{cite SEP|last=Levin |first=Janet |url-id=functionalism |title=Functionalism |date=Fall 2004}}</ref>

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".<ref name="blog">{{cite web |last=Putnam |first=Hilary |date=October 30, 2015 |title=What Wiki Doesn't Know About Me |url=https://putnamphil.blogspot.com/2014/10/what-wiki-doesnt-know-about-me-in-1976.html |access-date=March 15, 2016 |work=Sardonic comment}}</ref> 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.<ref name="blog"/>

Putnam himself formulated one of the main arguments against functionalism, the [[Twin Earth thought experiment]], though there have been additional 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. It 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. People outside the room instruct the person inside 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.<ref>{{cite journal |last=Searle |first=John |year=1980 |title=Minds, Brains and Programs |url=https://www.cambridge.org/core/journals/behavioral-and-brain-sciences |journal=Behavioral and Brain Sciences |volume=3 |pages=417–424 |doi=10.1017/S0140525X00005756 |archive-url=https://web.archive.org/web/20010221025515/http://www.bbsonline.org/Preprints/OldArchive/bbs.searle2.html |archive-date=February 21, 2001 |number=3 |s2cid=55303721}}</ref> [[Ned Block]] has advanced several other arguments against functionalism.<ref>{{cite book |last=Block |first=Ned |title=Perception and Cognition: Issues in the Foundations of Psychology, Minnesota Studies in the Philosophy of Science |publisher=University of Minnesota Press |year=1978 |isbn=978-0-816-60841-6 |editor-last=Savage |editor-first=C. W. |chapter=Troubles With Functionalism |oclc=1123818208}}</ref>

== Philosophy of language ==
=== Semantic externalism ===
One of Putnam's contributions to [[philosophy of language]] is his [[semantic externalism]], the claim that terms' meanings are determined by factors outside the mind, encapsulated in his slogan 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 defend this thesis.<ref>{{Cite book |last=Aranyosi |first=István |title=The Peripheral Mind: Philosophy of Mind and the Peripheral Nervous System |date=2013 |publisher=Oxford University Press |isbn=978-0-19-998960-7 |pages=77–101 |chapter=Semantic Externalism |doi=10.1093/acprof:oso/9780199989607.003.0005}}</ref><ref>{{Cite encyclopedia |title=Externalism About the Mind |encyclopedia=[[Stanford Encyclopedia of Philosophy]] |publisher=Metaphysics Research Lab, [[Stanford University]] |url=https://plato.stanford.edu/archives/win2020/entries/content-externalism/ |last1=Rowlands |first1=Mark |editor-last=Zalta |editor-first=E. N. |edition=Winter 2020 |last2=Lau |first2=Joe |last3=Deutsch |first3=Max|date=December 10, 2020 }}</ref>

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 H<sub>2</sub>O. 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.<ref>{{Cite journal |last=Stalnaker |first=Robert |date=1993 |title=Twin Earth Revisited |jstor=4545179 |journal=Proceedings of the Aristotelian Society |volume=93 |pages=297–311 |doi=10.1093/aristotelian/93.1.297 |issn=0066-7374}}</ref> This led Putnam to adopt a version of [[semantic externalism]] with regard to meaning and mental content.<ref name="BIV"/><ref name="MLR" /> The philosopher of mind and language [[Donald Davidson (philosopher)|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.<ref>{{cite book|last=Davidson |first=D. |year=2001 |title=Subjective, Intersubjective, Objective |location=Oxford |publisher=Oxford University Press |url=https://books.google.com/books?id=5XPnCwAAQBAJ&pg=PA177 |pages=177–192 |isbn=88-7078-832-6}}</ref>

=== Theory of meaning ===
Along with Kripke, [[Keith Donnellan]], and others, Putnam contributed to what is known as the [[causal theory of reference]].<ref name="CR"/> 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 designator]]s in the Kripkean sense and are disseminated outward to the linguistic community.<ref name="MLR"/><ref>Zelinsky-Wibbelt, C., ''Discourse and the Continuity of Reference: Representing Mental Categorization'' ([[Berlin]]: [[De Gruyter]], 2011) [https://books.google.com/books?id=34a9pz1XyTUC&pg=PA33 p. 33].</ref>{{rp|33}}

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:
# the object to which the term refers, e.g., the object individuated by the chemical formula H<sub>2</sub>O;
# a set of typical descriptions of the term, referred to as "the stereotype", e.g., "transparent", "colorless", and "hydrating";
# the semantic indicators that place the object into a general category, e.g., "natural kind" and "liquid";
# 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.<ref name="Auxier"/>{{rp|339–340}} 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.<ref name="MLR"/>{{Primary source inline|date=October 2022}} Since there is no limit to the number of such expressions to be considered, Putnam embraced a form of [[semantic holism]].<ref>{{cite book|title=Olismo |editor-first=Massimo |editor-last=Dell'Utri |publisher=Quodlibet |location=Macerata |year=2002 |isbn=88-86570-85-6}}</ref>

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 one accepts the truth of a sentence and then rejects it later on, the meaning of what one rejected and what one accepted are completely different and therefore one cannot change opinions with regard to the same sentences.<ref>{{cite book |last1=Fodor |first1=J. |title=Holism: A Shopper's Guide |last2=Lepore |first2=E. |publisher=Blackwell |year=1992 |isbn=978-0-631-18192-7 |location=Oxford |oclc=644785316}}</ref>{{page needed|date=January 2023}}<ref>{{cite book |last=Dummett |first=Michael |title=The Logical Basis of Metaphysics |publisher=Harvard University Press |year=1991 |isbn=978-0-674-53785-9 |location=Cambridge, Massachusetts |oclc=21907992}}</ref>{{page needed|date=January 2023}}<ref>{{cite book |last=Penco |first=Carlo |title=Olismo |publisher=Quodlibet |year=2002 |isbn=88-86570-85-6 |editor-last=Dell'Utri |editor-first=Massimo |location=Macerata |chapter=Olismo e Molecularismo}}</ref>{{page needed|date=January 2023}}

== Philosophy of mathematics ==
In the [[philosophy of mathematics]], Putnam has utilized [[indispensability argument]]s to argue for a [[Mathematical realism|realist]] interpretation of mathematics. In his 1971 book ''Philosophy of Logic'', he presented what has since been called the [[wikt:locus classicus|''locus classicus'']] of the Quine–Putnam indispensability argument.<ref name="SEP-Colyvan" /> The argument, which he attributed to [[Willard Van Orman Quine]], is presented in the book as "quantification over mathematical entities is indispensable for science, both formal and physical; therefore we should accept such quantification; but this commits us to accepting the existence of the mathematical entities in question."<ref>{{Cite book |last=Putnam |first=Hilary |title=Philosophy of Logic |date=1971 |publisher=[[Harper & Row]] |isbn=9780061360428 |author-link=Hilary Putnam}}</ref> According to [[Charles Parsons (philosopher)|Charles Parsons]], Putnam "very likely" endorsed this version of the argument in his early work, but later came to deny some of the views present in it.<ref name="Hill2">{{cite book |title=The Philosophy of Hilary Putnam |publisher=[[University of Arkansas Press]] |year=1992 |editor-last=Hill |editor-first=C. S.|editor-link=Christopher S. Hill |location=Fayetteville, Arkansas |oclc=60085231}}</ref>{{Rp|128}}

In 1975, Putnam formulated his own indispensability argument based on the [[no miracles argument]] in the [[philosophy of science]], saying, "I believe that the positive argument for realism [in science] has an analogue in the case of mathematical realism. Here too, I believe, realism is the only philosophy that doesn't make the success of the science a miracle".<ref name=":4">{{Cite IEP|last=Marcus|first=Russell|author-link=Russell Marcus|url-id=indimath|title=The Indispensability Argument in the Philosophy of Mathematics|access-date=August 23, 2022}}</ref> According to Putnam, Quine's version of the argument was an argument for the existence of [[Abstract and concrete|abstract]] mathematical objects, while Putnam's own argument was simply for a realist interpretation of mathematics, which he believed could be provided by a "mathematics as [[modal logic]]" interpretation that need not imply the existence of abstract objects.<ref name="Hill2" />{{Rp|61–62}}

Putnam also held the view that mathematics, like physics and other empirical sciences, uses both strict logical proofs and "[[quasi-empirical]]" methods.<ref>{{Cite book |last1=Hellman |first1=Geoffrey |author1-link=Geoffrey Hellman|title=Hilary Putnam on Logic and Mathematics |last2=Cook |first2=Roy T. |date=2018 |publisher=Springer |isbn=978-3-319-96273-3 |oclc=1040620232}}</ref>{{Rp|page=150}} For example, [[Fermat's Last Theorem]] states that for no [[integer]] <math>n>2</math> are there positive integer values of ''x'', ''y'', and ''z'' such that <math>x^n+y^n=z^n</math>. Before [[Andrew Wiles]] proved this for all <math>n>2</math> in 1995,<ref>{{MacTutor|id=Wiles|title=Andrew Wiles}}</ref> 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.<ref name="PutBen" />

The Quine–Putnam indispensability argument has been extremely influential in the philosophy of mathematics, inspiring continued debate and development of the argument in [[contemporary philosophy]] of mathematics. According to the ''[[Stanford Encyclopedia of Philosophy]]'', many in the field consider it the best argument for mathematical realism.<ref name="SEP-Colyvan" /> Prominent counterarguments come from [[Hartry Field]], who argues that mathematics is not indispensable to science, and [[Penelope Maddy]] and [[Elliott Sober]], who dispute whether we are committed to mathematical realism even if it is indispensable to science.<ref name="SEP-Colyvan" />

== Mathematics and computer science ==
Putnam has contributed to scientific fields not directly related to his work in philosophy.<ref name="CR"/> 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 (mathematician)|Martin Davis]].<ref>{{cite book|author-link=S. Barry Cooper |first=S. Barry |last=Cooper |title=Computability Theory |pages=97–98 |publisher=Chapman and Hall/CRC Press |year=2004 |isbn=978-1-584-88237-4 |oclc=318382229}}</ref>

In [[computability theory]], Putnam investigated the structure of the ramified [[analytical hierarchy]]<!-- link is not quite appropriate: the ''ramified'' analytical hierarchy is not the same as the analytical hierarchy; but Wikipedia has nothing more specific, so I think it is better to link here than to yet-to-be-written article -->, its connection with the [[Constructible universe|constructible hierarchy]] and its [[Turing degree]]s. He showed that there are many levels of the constructible hierarchy that add no subsets of the integers.<ref>{{cite journal |last=Putnam |first=Hilary |year=1963 |title=A note on constructible sets of integers |journal=Notre Dame J. Formal Logic |volume=4 |pages=270–273 |doi=10.1305/ndjfl/1093957652 |issue=4 |doi-access=free }}</ref> Later, with his student [[George Boolos]], he showed that the first such "non-index" is the [[Large countable ordinal|ordinal]] <math>\beta_0</math> of ramified analysis<ref>{{cite journal |last1=Boolos |first1=George |last2=Putnam |first2=Hilary |year=1968 |title=Degrees of unsolvability of constructible sets of integers |journal=Journal of Symbolic Logic |volume=33 |pages=497–513 |doi=10.2307/2271357 |issue=4 |publisher=The Journal of Symbolic Logic|jstor=2271357 |s2cid=28883741 }}</ref> (this is the smallest <math>\beta</math> such that <math>L_\beta</math> is a model of full [[Second-order arithmetic|second-order comprehension]]). Also, together with a separate paper with his student [[Richard Boyd]] and Gustav Hensel, he demonstrated how the Davis–[[Andrzej Mostowski|Mostowski]]–[[Stephen Cole Kleene|Kleene]] [[Hyperarithmetical theory|hyperarithmetical]] hierarchy of arithmetical degrees can be naturally extended up to <math>\beta_0</math>.<ref>{{cite journal |last1=Boyd |first1=Richard |last2=Hensel |first2=Gustav |last3=Putnam |first3=Hilary |year=1969 |title=A recursion-theoretic characterization of the ramified analytical hierarchy |journal=Trans. Amer. Math. Soc. |publisher=Transactions of the American Mathematical Society, Vol. 141 |volume=141 |pages=37–62 |doi=10.2307/1995087 |jstor=1995087 |doi-access=free}}</ref>

In [[computer science]], Putnam is known for the [[Davis–Putnam algorithm]] for the [[Boolean satisfiability problem]] (SAT), developed with Martin Davis in 1960.<ref name="CR"/> 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.<ref name="DandP"/>

== Epistemology ==
[[File:Brainvat.png|thumb|right|A "brain in a vat"—Putnam uses this thought experiment to argue that skeptical scenarios are impossible.]]

In [[epistemology]], Putnam is known for his argument against skeptical scenarios based on the "[[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]]".<ref name="BIV"/><ref name=":5">{{cite SEP|author-last=McKinsey|author-first=Michael|url-id=skepticism-content-externalism|title=Skepticism and Content Externalism|date=Summer 2018}}</ref>

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.<ref name=BIV/><ref name=":5" />

Putnam has clarified that his real target in this argument was never skepticism, but [[metaphysical realism]], which he thought implied such skeptical scenarios were possible.<ref>{{cite book|last=Putnam |first=H. |title=Realism and Reason. Philosophical Papers, vol. 3 |location=Cambridge |publisher=Cambridge University Press |year=1983 |isbn=978-0-521-24672-9 |oclc=490070776}}</ref><ref name="Wright">{{cite journal|last=Wright |first=C. |year=1992 |title=On Putnam's Proof That We Are Not Brains-in-a-Vat |journal=Proceedings of the Aristotelian Society |volume=92 |number=1 |pages=67–94 |doi=10.1093/aristotelian/92.1.67 |jstor=4545146}}</ref> 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.<ref>{{cite journal|last=Dell'Utri |first=M. |year=1990 |title=Choosing Conceptions of Realism: the Case of the Brains in a Vat |journal=[[Mind (journal)|Mind]] |volume=99 |number=393 |pages=79–90 |jstor=2254892 |doi=10.1093/mind/XCIX.393.79}}</ref><ref name=":6">{{cite SEP|author-last=Khlentzos|author-first=Drew|url-id=realism-sem-challenge|title=Challenges to Metaphysical Realism|edition=Spring 2021}}</ref>

Putnam's [[brain in a vat]] argument has been criticized.<ref name="Stein">{{cite journal |last=Steinitz |first=Yuval |author-link=Yuval Steinitz |year=1994 |title=Brains in a Vat: Different Perspectives |url=https://philosophy.as.uky.edu/sites/default/files/Brains%20in%20a%20Vat%20-%20Different%20Perspectives%20-%20Yuval%20Steinitz.pdf |journal=[[The Philosophical Quarterly]] |volume=44 |pages=213–222 |doi=10.2307/2219742 |jstor=2219742 |number=175}}</ref> [[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 their entire life outside the vat—speaking the English language and interacting normally with the outside world—before "envatment" by a mad scientist, when they wake up inside the vat, their words and thoughts (e.g., "tree" and "grass") will still refer to the objects or events in the external world they had referred to before envatment.<ref name="Wright" />

== Metaphilosophy and ontology <!--'Internal realism' and 'pragmatic realism' redirect here--> ==
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 defense 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—and adopted a rather different view, which he called "'''internal realism'''<!--boldface per WP:R#PLA-->" or "'''pragmatic realism'''<!--boldface per WP:R#PLA-->".<ref name=":7">{{Cite book |last=Künne |first=Wolfgang |title=Conceptions of Truth |date=2009 |publisher=Clarendon Press |isbn=978-0-19-928019-3}}</ref>{{Rp|page=404}}<ref>{{cite journal|first=Ernest |last=Sosa |author-link=Ernest Sosa |title=Putnam's Pragmatic Realism |journal=The Journal of Philosophy |volume=90 |number=12 |date=December 1993 |pages=605–626 |doi=10.2307/2940814 |jstor=2940814 |quote=Putnam argues against 'metaphysical realism' and in favor of his own 'internal (or pragmatic) realism.'}}</ref><ref>{{cite book|last=Putnam |first=H. |title=The Many Faces of Realism |location=La Salle, Ill. |publisher=Open Court |year=1987 |isbn=0-8126-9043-5}}</ref> 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 [[Category (Kant)|categories of thought]].<ref name="Brown">{{cite journal| author=Curtis Brown |title=Internal Realism: Transcendental Idealism?|url=https://core.ac.uk/download/pdf/216385012.pdf|journal=[[Midwest Studies in Philosophy]]|issue=12|year=1988|volume=12 |pages=145–55 |doi=10.5840/msp19881238}}</ref>

According to Putnam, the problem with metaphysical realism is that it fails to explain the possibility of reference and truth.<ref>{{cite book|first=Michael |last=Devitt |author-link=Michael Devitt |title=Realism and Truth |location=Princeton, New Jersey |publisher=[[Princeton University Press]] |year=1984 |url=https://books.google.com/books?id=UXDODkIs2DYC&pg=PA331 |page=331 |isbn=978-0-691-07290-6 |oclc=10559172}}</ref> 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.<ref name=":6" /> In ''Reason, Truth, and History'', Putnam identified truth with what he termed "idealized rational acceptability." The theory is that a belief is true if it would be accepted by anyone under ideal epistemic conditions.<ref name="Human"/><ref name=":7" />{{Rp|location=§7.1}}

[[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.<ref>{{cite book|last=Goodman |first=N. |title=Fact, Fiction, and Forecast |location=Cambridge, Massachusetts & London |publisher=[[Harvard University Press]] |year=1983 |url=https://books.google.com/books?id=i97_LdPXwrAC&pg=PA57 |page=57 |isbn=978-0-674-29071-6 |oclc=1090329720}}</ref> 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. He thus accepted "conceptual relativity"—the view that it may be a matter of choice or convention, e.g., whether [[wikt:mereological|mereologic]]al sums exist, or whether spacetime points are individuals or mere limits.<ref name="Half">{{cite journal|author=Putnam, H.|title=A Half Century of Philosophy, Viewed from Within|journal=Daedalus|year=1997|volume=126|issue=1|pages=175–208|jstor=20027414}}</ref>{{Primary source inline|date=October 2022}}

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.<ref name="Brown" /> In his reply to [[Simon Blackburn]] in the volume ''Reading Putnam'', Putnam renounced internal realism<ref name="CH" /> because it assumed a "cognitive interface" model of the relation between the mind and the world. Under the increasing influence of [[William James]] and the [[pragmatism|pragmatists]], he adopted a [[Naïve realism|direct realist]] view of this relation.<ref>{{cite journal |last=Putnam |first=Hilary |date=September 1994 |title=The Dewey Lectures 1994: Sense, Nonsense, and the Senses: An Inquiry into the Powers of the Human Mind |journal=The Journal of Philosophy |volume=91 |pages=445–518 |doi=10.2307/2940978 |jstor=2940978 |number=9}}</ref><ref>{{Cite book |last=Pihlström |first=Sami |title=Encyclopedia of Sciences and Religions |publisher=Springer |year=2013 |isbn=978-1-4020-8264-1 |editor-last=Runehov |editor-first=Anne L. C. |pages=1455–1465 |chapter=Neopragmatism |doi=10.1007/978-1-4020-8265-8_1538 |editor-last2=Oviedo |editor-first2=Lluis}}</ref><ref>{{Cite book |last=Reed |first=Edward |author-link=Edward S. Reed|title=The Necessity of Experience |date=1996 |publisher=[[Yale University Press]] |isbn=0-300-06668-6 |location=New Haven }}</ref>{{Rp|pages=23–24}} 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 came to accept metaphysical realism in a broader sense, rejecting all forms of [[verificationism]] and all talk of our "making" the world.<ref>{{cite web | title = Wiki Catches Up a Bit | last = Putnam | first = Hilary | work = Sardonic comment | date = November 9, 2015 | access-date = March 15, 2016 | url = https://putnamphil.blogspot.com/2014/11/wiki-catches-up-bit-in-1976-when-i.html }}</ref>

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 between the mind and the world.<ref name="Three" /> 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]].<ref name="blog" /><ref>{{cite book |last=Putnam |first=H. |title=Philosophy in an Age of Science |publisher=Harvard University Press |year=2012 |isbn=978-0-674-05013-6 |editor-last1=De Caro |editor-first1=M. |location=Cambridge, Massachusetts |chapter=How to Be a Sophisticated "Naive Realist" |oclc=913024858 |editor-last2=Macarthur |editor-first2=D.}}</ref>

== Quantum mechanics ==
During his career, Putnam espoused various positions on the [[interpretation of quantum mechanics]].<ref name=":1">{{Cite journal |last=Putnam |first=Hilary |date=December 1, 2005 |title=A Philosopher Looks at Quantum Mechanics (Again) |url=https://www.journals.uchicago.edu/doi/10.1093/bjps/axi135 |journal=The British Journal for the Philosophy of Science |language=en |volume=56 |issue=4 |pages=615–634 |doi=10.1093/bjps/axi135 |issn=0007-0882}}</ref> In the 1960s and 1970s, he contributed to the [[quantum logic]] tradition, holding that the way to resolve quantum theory's apparent paradoxes is to modify the logical rules by which propositions' truth values are deduced.<ref>{{Cite journal |last=Gardner |first=Michael R. |date=1971 |title=Is Quantum Logic Really Logic? |url=https://www.jstor.org/stable/186692 |journal=Philosophy of Science |volume=38 |issue=4 |pages=508–529 |doi=10.1086/288393 |jstor=186692 |s2cid=120329154 |issn=0031-8248}}</ref><ref>{{Cite journal |last=Bub |first=Jeffrey |author-link=Jeffrey Bub |date=1982 |title=Quantum Logic, Conditional Probability, and Interference |url=https://www.jstor.org/stable/187282 |journal=Philosophy of Science |volume=49 |issue=3 |pages=402–421 |doi=10.1086/289068 |jstor=187282 |s2cid=120818704 |issn=0031-8248}}</ref> Putnam's first foray into this topic was "A Philosopher Looks at Quantum Mechanics" in 1965, followed by his 1969 essay "[[Is Logic Empirical?]]". He advanced different versions of quantum logic over the years,<ref>{{Cite journal |last=Demopoulos |first=William |date=April 2010 |title=Effects and Propositions |url=https://link.springer.com/article/10.1007/s10701-009-9321-x |journal=Foundations of Physics |language=en |volume=40 |issue=4 |pages=368–389 |arxiv=0809.0659 |doi=10.1007/s10701-009-9321-x |bibcode=2010FoPh...40..368D |s2cid=119273606 |issn=0015-9018}}</ref> and eventually turned away from it in the 1990s, due to critiques by [[Nancy Cartwright (philosopher)|Nancy Cartwright]], [[Michael Redhead]], and others.<ref name="CH" />{{Rp|pages=265–280}} In 2005, he wrote that he rejected the [[many-worlds interpretation]] because he could see no way for it to yield meaningful probabilities.<ref>{{Cite journal |last1=Hemmo |first1=Meir |last2=Pitowsky |first2=Itamar |date=June 2007 |title=Quantum probability and many worlds |url=https://linkinghub.elsevier.com/retrieve/pii/S135521980700024X |journal=Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics |language=en |volume=38 |issue=2 |pages=333–350 |doi=10.1016/j.shpsb.2006.04.005|bibcode=2007SHPMP..38..333H }}</ref> He found both [[de Broglie–Bohm theory]] and the [[Ghirardi–Rimini–Weber theory|spontaneous collapse theory of Ghirardi, Rimini, and Weber]] to be promising, yet also dissatisfying, since it was not clear that either could be made fully consistent with [[special relativity]]'s symmetry requirements.<ref name=":1" />

== Neopragmatism and Wittgenstein ==
In the mid-1970s, Putnam became increasingly disillusioned with what he perceived as modern [[analytic philosophy]]'s "[[scientism]]" and focus on metaphysics over ethics and everyday concerns.<ref>{{cite book |last=Gaynesford |first=R. M. de| author-link=Maximilian de Gaynesford|title=Hilary Putnam |publisher=[[McGill–Queen's University Press]] / Acumen |year=2006 |isbn=978-1-844-65040-8 |oclc=224793821}}</ref>{{Rp|pages=186–190}} He also became convinced by his readings of James and [[John Dewey]] that there is no [[Fact–value distinction|fact–value dichotomy]]; that is, [[normative]] (e.g., ethical and aesthetic) judgments often have a factual basis, while scientific judgments have a normative element.<ref name="Half" /><ref name="CH" />{{Rp|page=240}} For a time, under [[Ludwig Wittgenstein]]'s influence, Putnam adopted a pluralist view of philosophy itself and came to view most philosophical problems as no more than conceptual or linguistic confusions philosophers created by using ordinary language out of context.<ref name="Half"/>{{Primary source inline|date=October 2022}} 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'', edited by [[David Macarthur]], was published in 2017.<ref>{{cite web|last=Bartlett |first=T. |url=https://www.chronicle.com/article/A-Marriage-of-Minds/241103 |title=A Marriage of Minds: Hilary Putnam's most surprising philosophical shift began at home |website=[[The Chronicle of Higher Education]] |date=September 10, 2017}}</ref>

Many of Putnam's last works addressed the concerns of ordinary people, particularly social problems.<ref>{{cite journal|last=Reed |first=Edward |year=1997 |url=https://www.piaget.org/Piaget/GE/1997/GE-25-3.html |title=Defending Experience: A Philosophy For The Post-Modern World |journal=The Genetic Epistemologist: The Journal of the Jean Piaget Society |volume=25 |number=3}}</ref> 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]].<ref name="Hick"/>

== Works ==

=== Books authored ===
* {{cite book|last=Putnam |first=H. |url=https://books.google.com/books?id=QxpIAwAAQBAJ |title=Philosophy of Logic |location=New York |publisher=[[Harper (publisher)|Harper & Row]] |year=1971 |isbn=0-04-160009-6}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/mathematicsmatte0001putn |title=Mathematics, Matter and Method. Philosophical Papers, vol. 1 |location=Cambridge |publisher=Cambridge University Press |year=1975 |isbn=978-0-521-20665-5 |oclc=59168146 |url-access=registration}} 2nd. ed., 1985 paperback: {{ISBN|0-521-29550-5}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/mindlanguagereal0000putn |title=Mind, Language and Reality. Philosophical Papers, vol. 2 |location=Cambridge |url-access=registration |publisher=Cambridge University Press |year=1975 |isbn=88-459-0257-9}} 2003 paperback: {{ISBN|0-521-29551-3}}
* {{cite book|first=H. |last=Putnam |title=Meaning and the Moral Sciences |publisher=Routledge and Kegan Paul |year=1978 |pages=123–140 |isbn=978-0-710-08754-6 |oclc=318417931}}
* {{Cite book |last=Putnam |first=H. |year=1981 |url=https://archive.org/details/reasontruthhisto0000putn |title=Reason, Truth, and History |publisher=Cambridge University Press |isbn=978-0-521-23035-3 |oclc=442822274 |url-access=registration}} 2004 paperback: {{ISBN|0-521-29776-1}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/philosophicalpap0000putn |title=Realism and Reason. Philosophical Papers, vol. 3 |location=Cambridge |publisher=Cambridge University Press |year=1983 |isbn=978-0-521-24672-9 |oclc=490070776 |url-access=registration}} 2002 paperback: {{ISBN|0-521-31394-5}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/isbn_2900812690438 |title=The Many Faces of Realism |location=La Salle, Ill. |url-access=registration |publisher=Open Court |year=1987 |isbn=0-8126-9043-5}}
* {{cite book |last=Putnam |first=H. |year=1988 |url=https://archive.org/details/representationre0000putn_r1j9 |title=Representation and Reality |location=Cambridge, Massachusetts |publisher=MIT Press |isbn=978-0-262-66074-7 |oclc=951364040 |url-access=registration}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/realismwithhuman0000putn |title=Realism with a Human Face |editor-first=J. F. |editor-last=Conant |editor-link=James F. Conant |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=1990 |isbn=978-0-674-74945-0 |oclc=1014989000 |url-access=registration}}
* {{cite book|last=Putnam |first=H. |title=Renewing Philosophy |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=1992 |isbn=0-674-76094-8}}
* {{cite book|title=Pursuits of Reason: Essays in Honor of Stanley Cavell |editor-first1=H. |editor-last1=Putnam |editor-first2=Ted |editor-last2=Cohen |editor-first3=Paul |editor-last3=Guyer |editor-link3=Paul Guyer |location=Lubbock |publisher=Texas Tech University Press |year=1993 |isbn=0-89672-266-X}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/wordslife0000putn_u9b1 |title=Words and Life |editor-first=J. F. |editor-last=Conant |location=Cambridge, Massachusetts |url-access=registration |publisher=Harvard University Press |year=1994 |isbn=0-674-95607-9}}
* {{cite book|last=Putnam |first=H. |title=Pragmatism: An Open Question |location=Oxford |publisher=Blackwell |year=1995 |isbn=0-631-19343-X}} Based on the [[Gifford Lectures]] that Putnam delivered at the [[University of St Andrews]] in 1990 and 1991.<ref>{{Cite web |date=August 18, 2014 |title=Hilary Putnam |url=https://www.giffordlectures.org/lecturers/hilary-putnam |access-date=July 30, 2022 |website=The Gifford Lectures |language=en}}</ref>
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/threefoldcordmin0000putn/page/n7/mode/2up |title=The Threefold Cord: Mind, Body, and World |location=New York |publisher=Columbia University Press |year=1999 |isbn=978-0-231-10286-5 |oclc=868429895 |url-access=registration}}
* {{cite book|last=Putnam |first=H. |title=Enlightenment and Pragmatism |location=Assen |publisher=Koninklijke Van Gorcum |year=2001 |isbn=978-9-023-23739-6 |oclc=248668591}}
* {{cite book|last=Putnam |first=H. |title=The Collapse of the Fact/Value Dichotomy and Other Essays |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=2002 |isbn=0-674-01380-8}}
* {{cite book|last=Putnam |first=H. |title=Ethics Without Ontology |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=2002 |isbn=0-674-01851-6}}
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/jewishphilosophy0000putn |title=Jewish Philosophy as a Guide to Life: Rosenzweig, Buber, Levinas, Wittgenstein |location=Bloomington |publisher=Indiana University Press |year=2008 |isbn=978-0-253-35133-3 |oclc=819172227 |url-access=registration}}
* {{cite book|last=Putnam |first=H. |year=2012 |editor-last1=De Caro |editor-first1=M. |editor-last2=Macarthur |editor-first2=D. |title=Philosophy in an Age of Science |location=Cambridge, Massachusetts |publisher=Harvard University Press |isbn=978-0-674-05013-6 |oclc=913024858}}
* {{cite book|last=Putnam |first=H. |title=Naturalism, Realism, and Normativity |editor-first=Mario |editor-last=De Caro |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=2016 |isbn=978-0-674-65969-8}}
* {{cite book|last1=Putnam |first1=H. |last2=Putnam |first2=R. A. |url=https://books.google.com/books?id=jDfFDgAAQBAJ |title=Pragmatism as a Way of Life: The Lasting Legacy of William James and John Dewey |editor-first=David |editor-last=Macarthur |location=Cambridge, Massachusetts |publisher=Harvard University Press |year=2017 |isbn=978-0-674-96750-2}}

=== Books edited ===
* {{cite book |last=Putnam |first=H. |url=https://archive.org/details/philosophyofmath0000bena |title=Philosophy of Mathematics: Selected Readings |editor-first=Paul |editor-last=Benacerraf |editor-link=Paul Benacerraf |location=Englewood Cliffs, N.J. |publisher=Prentice-Hall |year=1964 |oclc=1277244158 |url-access=registration}} 2nd ed., Cambridge: Cambridge University Press, 1983. {{ISBN|0-521-29648-X}}
* {{cite book|title=Methodology, Epistemology, and Philosophy of Science: Essays in Honour of Wolfgang Stegmüller |editor-first2=H. |editor-last2=Putnam |editor-first3=Wilhelm K. |editor-last3=Essler |editor-first1=Carl G. |editor-last1=Hempel |editor-link1=Carl G. Hempel |editor-link3=:de:Wilhelm K. Essler|location=Dordrecht |publisher=D. Reidel |year=1983 |isbn=978-9-027-71646-0 |oclc=299388752}}
* {{cite book|title=Epistemology, Methodology, and Philosophy of Science: Essays in Honour of Carl G. Hempel |editor-first2=H. |editor-last2=Putnam |editor-first1=Wilhelm K. |editor-last1=Essler |editor-first3=Wolfgang |editor-last3=Stegmüller |editor-link3=Wolfgang Stegmüller |location=Dordrecht |publisher=D. Reidel |year=1985 |oclc=793401994}}

=== Select papers, book chapters and essays ===
* .{{cite journal|last=Putnam |first=H. |title=The 'Innateness Hypothesis' and Explanatory Models in Linguistics |journal=Synthese |volume=17 |number=1 |date=March 1967 |pages=12–22 |doi=10.1007/BF00485014 |jstor=20114532|s2cid=17124615 }}

An exhaustive bibliography of Putnam's writings, compiled by John R. Shook, can be found in ''The Philosophy Of Hilary Putnam'' (2015).<ref>{{Cite book |last=Shook |first=John R. |url=https://books.google.com/books?id=adoKCQAAQBAJ |title=The Philosophy of Hilary Putnam |date=2015-05-18 |publisher=Open Court |isbn=978-0-8126-9898-5 |editor-last=Auxier |editor-first=Randall E. |editor-link=Randall Auxier |language=en |chapter=Bibliography of the Writings of Hilary Putnam |editor-last2=Anderson |editor-first2=Douglas R. |editor-last3=Hahn |editor-first3=Lewis Edwin |chapter-url=http://pragmatism.org/putnam/putnam_bibliography.pdf|archive-url=https://web.archive.org/web/20160214163844/http://pragmatism.org/putnam/putnam_bibliography.pdf |archive-date=February 14, 2016 }}</ref><ref>{{Cite journal |last=Chang |first=Hasok |date=2018 |title=Review of The Philosophy of Hilary Putnam |url=https://www.jstor.org/stable/27130985 |journal=[[The Philosophical Review]] |volume=127 |issue=2 |pages=240–247 |doi=10.1215/00318108-4326677 |jstor=27130985 |issn=0031-8108 |url-access=subscription}}</ref>

== See also ==
{{Portal|Biography|Philosophy}}
* [[American philosophy]]
* [[List of American philosophers]]

== References ==
{{Reflist|30em}}

== Further reading ==
* {{cite book|editor-first1=James |editor-last1=Conant |editor-first2=Sanjit |editor-last2=Chakraborty |title=Engaging Putnam |publisher=De Gruyter |year=2022 |isbn=978-3-110-76916-6 |oclc=1302581520}}
* {{cite book |editor-first=Y. |editor-last=Ben-Menahem |url=https://archive.org/details/HilaryPutnam-ContemporaryPhilosophyInFocus |title=Hilary Putnam |series=Contemporary Philosophy in Focus |publisher=Cambridge University Press |location=Cambridge |year=2005 |isbn=978-0-521-81311-2 |oclc=912352048}}

== External links ==
* {{wikiquote-inline}}
* Hilary Putnam's blog, [https://putnamphil.blogspot.com/ Sardonic comment], as stated by Putnam in "Hookway and Quine", ''Transactions of the Charles S. Peirce Society'', vol. 51, no. 4, 2015, pp.&nbsp;495–507. {{doi|10.2979/trancharpeirsoc.51.4.07}}
* {{PhilPapers|search|Hilary%20Putnam}}
* {{IMDb name|2687666}}
* {{InPho|thinker|3762}}
* [https://www.lrb.co.uk/contributors/hilary-putnam ''London Review of Books'' contributor page]
* [https://www.hcs.harvard.edu/~hrp/issues/1992/Putnam.pdf Hilary Putnam: On Mind, Meaning and Reality] {{Webarchive|url=https://web.archive.org/web/20160303205306/http://www.hcs.harvard.edu/~hrp/issues/1992/Putnam.pdf |date=March 3, 2016 }}, Interview by Josh Harlan, ''[[The Harvard Review of Philosophy]]'', Spring 1992.
* [https://www.hcs.harvard.edu/~hrp/issues/2000/Putnam.pdf "To Think with Integrity"] {{Webarchive|url=https://web.archive.org/web/20160303220435/http://www.hcs.harvard.edu/~hrp/issues/2000/Putnam.pdf |date=March 3, 2016 }}, Hilary Putnam's Farewell Lecture, ''The Harvard Review of Philosophy'', Spring 2000.
* {{YouTube|GlrEbffVVjM|A short film about the Putnam-Rorty debate and its influence on the pragmatist revival}}

{{Analytic philosophy}}
{{Metaphysics}}
{{Epistemology}}
{{Philosophy of language}}
{{Philosophy of mind}}
{{Schock Prize laureates}}
{{Authority control}}

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