Putnam, Hilary (1926–2016)

Putnam’s work spans a broad spectrum of philosophical interests, yet nonetheless reflects thematic unity in its concern over the question of realism. A critic of logical positivism, Putnam opposed verificationism and conventionalism, arguing for a realist understanding of scientific theories. He rejected the traditional conception of meaning according to which speakers’ mental states determine meaning and consequently, reference, and put forward a conception of meaning on which external reality, for example, what one talks about, contributes essentially to meaning. Further, citing what he called the division of linguistic labour, Putnam saw the conferring of meaning as a social rather than an individual enterprise. In response to the relativistic challenge that the incommensurability of different theories precludes any possibility of intertheoretical dialogue, Putnam invoked a causal theory of reference construing reference as relatively insensitive to theoretical variation, so that the continuity and rationality of science and communication are upheld. The Copenhagen interpretation of quantum mechanics posed yet another difficulty for realism. Putnam saw quantum logic as an alternative which was compatible with realism, and argued that logic, like geometry, can be revised on the basis of empirical considerations. In the philosophy of mind, Putnam proposed functionalism, the view that mental states are characterized by function rather than material constitution. Putnam also made a substantial contribution to mathematics through his work on the insolvability of Hilbert’s tenth problem.

In 1976, Putnam launched an attack on the coherence of the view he termed ‘metaphysical realism’. Arguing that relativism and scepticism are disguised forms of metaphysical realism, and likewise incoherent, he suggested an alternative, referred to as ’internal realism’. Clarification of this position and its viability as a third way between realism and relativism is the focus of Putnam’s later writings, and of much of the criticism they have incurred.