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Hilary Putnam

Hilary Whitehall Putnam (born July 31, 1926) is a key figure in the philosophy of mind during the 20th century. After receiving his BA at the University of Pennsylvania and PhD at UCLA (under Hans Reichenbach), he taught at Princeton, MIT, and Harvard, where he is now Cogan University Professor emeritus.

Putnam has earned a reputation for changing his mind frequently during the course of his career, and he has written on so many diverse topics that it is often difficult to sort out his views.


Philosophy of mind

Putnam is probably most famous for his contributions to the philosophy of mind. He was an early and influential advocate of functionalism (roughly, the view that the human mind is analogous to a digital computer) but in "Representation and Reality" he recanted his earlier views and set out to explain why functionalism, in his revised view, would not work.

Philosophy of language

One of Putnam's most significant contributions to the philosophy of language is his doctrine that "meaning just ain't in the head", which is most famously illustrated by his Twin Earth thought experiment. Concisely, he argues that if you see a liquid and call it "water" and some alien twin of yours (identical down to the last detail) on an alien planet sees what appears to be an identical liquid and calls it water AND if it turns out it was really XYZ and not H2O, then you and your double actually mean something different by water even though water has the same function for both of you (note that this relates to his abandoning functionalism as a feasible philosophy of mind).

Putnam and Saul Kripke both made important contributions to what is known as the causal theory of reference.

Putnam has also made an argument that is regarded by some as a refutation of skepticism known as the Brain in a Vat argument. He argues that you cannot coherently state that you are a Brain in a Vat placed there by a Mad Scientist (an old science fiction cliche, as seen in The Matrix, and also an allusion to Descartes' Dieu trompeur). This is because, as in the Twin Earth case, if you are indeed a Brain in a Vat, whose every experience is received through wiring and other gadgetry created by the Mad Scientist, then your idea of a "Brain" would not refer to a "Real" Brain, since you never saw one - you only, perhaps, saw something that looks like a Brain, but it was only fed to you through the wiring. Similarly, your idea of a "Vat" would not refer to a "Real" Vat. So, if, as a Brain in a Vat, you say "I'm a Brain in a Vat", you actually mean to say "I'm a vat-Brain in a vat-Vat", which is incoherent. If, on the other hand, you are not a Brain in a Vat, then saying you are is still incoherent, but this time because you actually mean the opposite. This is a form of Externalism: where the meaning of a word or concept resides outside of it, and is not inherent in the word/concept (as in Internalism).

Philosophy of mathematics

Putnam and Benacerraf are co-editors of Philosophy of Mathematics: Collected Essays, which contains a useful introduction to the subject.

Putnam also contributed to the resolution of Hilbert's tenth problem in mathematics.

Putnam also held the view that in mathematics, as in physics and other empirical sciences, we don't use only strict logical proofs, but rather, while not doing this explicitly, we use "quasi-empirical" methods. That is, methods like verifying by many calculations that for no integer n > 2 do there exist integer values of x, y, and z (except the trivial cases of 0,0,0; 0,1,1; 1,0,1) such that xn + yn = zn (what was proved not long ago by Andrew Wiles, and is known as Fermat's last theorem). Even if we treat such knowledge as more conjectural than a strictly proven theorem, we still make use of it in developing mathematical ideas that are based on it.


Putnam, while not quite as famous as Richard Rorty, has nevertheless contributed to metaphilosophical questions, while attempting to avoid the charges of relativism that have been levelled at Rorty and other neo-pragmatists.

(more needs to be added on)

  • pragmatism
  • metaphysical realism
  • internal realism

Political ideology

Although Putnam has not written as extensively on politics as on other matters, he has been involved in political movements in the United States. In the late 1960s and early 1970s, he was a very active opponent of American military intervention in Vietnam as well as a supporter of civil rights causes. Nevertheless, after 1968 most of these efforts were directed through the Progressive Labor Party (PLP) a small, left wing political organization which described itself as Marxist-Leninist. At one point, Harvard University attempted to censure Putnam for his political activities which the university administration considered disruptive, but he succeeded in rallying large numbers of friends and supporters to defeat this attempt. It is not known exactly when or why Putnam severed his ties with the PLP, but by 1975 he had broken off contact with that organization. In 1997, at a meeting of former draft resistance activists at Arlington Street Church in Boston, Putnam admitted making a mistake in joining PLP. He said he had at first been impressed with PLP's commitment to alliance-building and its willingness to attempt to organize from within the armed forces.

Last updated: 05-13-2005 07:56:04