Putnam, Hilary (1926–2016)

3. The meaning of meaning

Putnam faults traditional theories of meaning that associate meanings with particular definitions or particular mental images for being individualistic rather than social, and for neglecting the contribution of external reality to meaning. He construes the standard theory as based on two assumptions: First, to know a term’s intension is to be in a particular psychological state and second, intension determines extension. Hence, it is argued, speakers who are in the same mental state when uttering a word share both its intension and its extension. Putnam uses the twin earth (TE) thought experiment to attack this theory. TE resembles earth down to the smallest detail except that the liquid functioning as water, and called ’water’, on TE is not H2O,but a different chemical compound. There is no reason to ascribe different mental states to a person using ’water’ on earth, and their counterpart on TE, or, at least, there was no such difference prior to the emergence of chemistry as a science. We therefore have an example of people using the same word when in identical mental states, but ascribing different meanings to it: one refers to water, the other to its TE equivalent. One need not, however, travel as far as TE to find examples of similar mental states differing in extension. Putnam testified that he was unable to tell a beech from an elm: his mental image of the two was the same, yet the extensions, and the meanings, of ’elm’ and ’beech’ were quite different in his idiolect. Could Putnam refer to an elm though being unable to identify one? His answer introduces the concept of the division of linguistic labour: it is sufficient that experts can distinguish an elm from a beech, and unnecessary that each member of the linguistic community be able to do so.

The assumption underlying the TE example is that words like ’water’ always refer to the stuff we call ‘water’ in the actual world. Though it is neither analytic nor even irrevisable that water is H2O, the extensions of ’water’ on TE and on earth cannot be identical. To complete the account of meaning, one has to address the question of how extension is actually fixed. Putnam is often considered a proponent of a causal theory of reference on which reference is fixed by causal chains between speakers and the entities they refer to rather than by the theoretical descriptions of these entities. In fact, due to the difficulties generated by the notion of cause, Putnam espouses a more general conception of reference that emphasizes not only causal relations, but also contextual, social and pragmatic factors (see Content: wide and narrow).

These aspects of Putnam’s conception are related to Kripke’s work on reference and rigid designation (see Kripke, S.A.; Proper names; Reference §2), but while Kripke was thinking primarily of proper names, Putnam’s main concern is the meaning of scientific terms, natural kinds in particular. If the extensions of these terms were fixed by the theories in which they figure, then extensions would be liable to change with theoretical change. This conclusion encapsulates Kuhn’s relativism: different theories, or paradigms, refer to different entities, and are therefore incommensurable (see Incommensurability); they cannot be compared with one another let alone with reality. The testability of science and the rationality of the scientific process are thereby seriously threatened. Putnam views incommensurability as a reductio ad absurdum of the theory of meaning on which it rests. By contrast, the externalist conception of meaning outlined in The Meaning of 'Meaning'' (and further developed in later writings) provides a perfect meaning-theoretic grounding for a realist philosophy of science.