Hilary Putnam

Lore & Background

Putnam was born in Chicago to a secular Jewish family and spent his early childhood in France, where his first language was French. He studied philosophy at the University of Pennsylvania and earned his Ph.D. at UCLA under Hans Reichenbach. He taught at Northwestern, Princeton, MIT, and Harvard, where he became Cogan University Professor. He married fellow philosopher Ruth Anna Jacobs in 1962, and together they embraced Judaism later in life.

In the 1960s and early 1970s, Putnam was politically active, supporting the Civil Rights Movement, opposing the Vietnam War, and joining the Progressive Labor Party. He later called his involvement with the PLP a mistake. He was elected president of the American Philosophical Association in 1976. Throughout his career, he developed the Davis–Putnam algorithm, argued for functionalism and multiple realizability in philosophy of mind, and formulated semantic externalism via the Twin Earth thought experiment.

Putnam also contributed to philosophy of mathematics with the Quine–Putnam indispensability argument, and criticized the 'brain in a vat' skeptical argument. He moved from metaphysical realism to internal realism, which he later abandoned, while remaining committed to scientific realism. In later years, he engaged with American pragmatism, Jewish philosophy, ethics, and metaphilosophy.

Reader's Guide

Putnam's significance lies in his wide-ranging and often self-revising contributions to multiple fields of philosophy and computer science. In philosophy of mind, his hypothesis of multiple realizability undermined the type-identity theory and helped establish functionalism as a dominant approach to the mind–body problem. He also originated the computational theory of mind. In philosophy of language, his causal theory of reference and Twin Earth thought experiment introduced semantic externalism, reshaping debates about meaning and reference. His work with Martin Davis on the Davis–Putnam algorithm advanced automated theorem proving, and his collaboration with Quine on the indispensability argument provided a major justification for mathematical realism. Putnam's willingness to abandon his own earlier positions—from metaphysical realism to internal realism and beyond—exemplified his commitment to rigorous philosophical inquiry. His later turn to pragmatism and ethics broadened his legacy, and his political activism, though controversial, reflected his belief in academics' social responsibility. Overall, Putnam's career illustrates a philosopher who constantly challenged both his peers and himself, leaving a lasting impact on analytic philosophy and related disciplines.

Did You Know?

• Putnam's first language was French, as he spent his early childhood in France.
• He co-developed the Davis–Putnam algorithm for the Boolean satisfiability problem.
• He was a member of the Progressive Labor Party from 1968 to 1972, later calling that involvement a mistake.
• Putnam celebrated a belated bar mitzvah in 1994.

Notable Quotes (Wikiquote)

"[Oddly enough, Putnam believes part of the attraction of some of these formalisms is their obscurity]. "I think part of the appeal of mathematical logic is that the formulas look mysterious - you write backward Es!" — Hilary Putnam "It was Rudolf Carnap’s dream for the last three decades of his life to show that science proceeds by a formal syntactic method; today no one to my knowledge holds out any hope for that project." — Hilary Putnam "Introduction: Science as approximation to truth" — Hilary Putnam "Introduction: Science as approximation to truth" — Hilary Putnam