Hilary Putnam was one of the most influential analytical philosophers of the late 20th century, making major contributions to philosophy of language, mind, science, and mathematics. His work is characterised by a willingness to revise or abandon previously held positions, earning him a reputation for intellectual restlessness and honesty.
Semantic externalism
Putnam’s most famous contribution is his argument for semantic externalism in “The Meaning of ‘Meaning’” (1975). Through the Twin Earth thought experiment, he demonstrated that meaning cannot be reduced to mental states—that “meanings ain’t in the head.” This revolutionised philosophy of language and influenced debates about mental content, self-knowledge, and the nature of reference.
Philosophy of mind
In philosophy of mind, Putnam developed functionalism—the view that mental states are defined by their functional roles rather than their physical realisation. However, he later became one of functionalism’s most sophisticated critics, arguing against computational theories of mind and challenging the idea that the brain is simply a biological computer.
Realism and anti-realism
Putnam’s views on metaphysical realism evolved throughout his career. He moved from scientific realism to what he called “internal realism” or “pragmatic realism,” rejecting both metaphysical realism (the “God’s eye view”) and radical relativism. His later work sought a middle path that respects the role of conceptual schemes whilst avoiding the pitfalls of both realism and anti-realism.
Influence and legacy
Putnam’s Twin Earth argument, along with Kripke’s work on rigid designators, fundamentally reshaped analytical philosophy’s approach to language and reference. His willingness to critically examine and revise his own positions set a standard for philosophical integrity, even as it complicated attempts to pin down a single “Putnamian” doctrine.