Natural kinds and a posteriori necessities: Putnam pro Kripke, Putnam versus Kripke

LOGIC, METHODOLOGY AND PHILOSOPHY OF SCIENCE

Abstract

Most contemporary analytic philosophers of language and mind accept the view that there is a wide class of terms, “natural kind terms”, which includes names of substances (the most common example is “water”), of species of animals, and of many other kinds of things in nature, whose meaning and reference is determined in the way explained by the theory developed in the 1970s by Saul Kripke and Hilary Putnam. The theory is often referred to as “the Kripke-Putnam theory” and is supposed to have such achievements as the overthrow of the earlier dominant Fregean theory of word-meanings (dubbed “descriptivism” by Kripke) as determined by the concepts in our minds, providing support for the “externalist” approach to linguistic meanings (in line with Putnam’s claim that “"Meanings" just ain’t in the head”), and the discovery that there is a wide class of truths (such as that water is H₂0) that are both a posteriori and necessary. Although the priority in the development of this theory belongs to Kripke, it could hardly gain such a wide acceptance without contributions by Putnam, which turned out to be very influential. However, the habitual idea of “the Kripke-Putnam theory”, as one theory, tends to play down the differences between Putnam’s and Kripke’s approaches and to hush up the fact that in his late works, of 1983 and 1990, Putnam revised and abandoned pretty much of his “Kripkean” views of 1970-ies; in particular, repudiated the pride of Kripke’s theory, the idea of necessary a posteriori truths. This article makes critical analysis and evaluation of Putnam’s ideas and arguments usually credited as important contributions to “the Kripke-Putnam theory”, and highlights the main points of the revision in late Putnam’s works. The case is made that Putnam's famous argument for externalism about meanings, the Twin-Earth thought experiment, is question-begging, fails to do justice to likely changes in the meanings of words with the development of knowledge, and conflicts with the linguistic practice in the relevantly similar case of “jade”. Putnam's argument for externalism from the division of linguistic labour is not cogent too, because “semantic deference” is itself a matter of what is there in “heads” - of some (non-expert) heads deferring to other (recognised as expert) heads. Eventually, on close inspection and in the light of Putnam's later reexplanation and revision, his account of meaning and reference turns out to be a sophisticated variety of conceptualism/internalism.