Locke’s account of personal identity has been highly influential because of its emphasis on a psychological criterion. The same consciousness is required for being the same person. It is not so clear, however, exactly what Locke meant by ‘consciousness’ or by ‘having the same consciousness’. Interpretations vary: consciousness is seen as identical to memory, as identical to a first personal appropriation of mental states, and as identical to a first personal distinctive experience of the qualitative features of one’s own thinking. (...) There is wide agreement, however, that Locke’s theory of personal identity is meant to complement his moral and theological commitments to a system of divine punishment and reward in an afterlife. But these commitments seem to require also a metaphysical criterion, and Locke is insistent that it cannot be substance. The difficulty reconciling the psychological and metaphysical requirements of the theory has led, at worst, to charges of incoherence and, at best, to a slew of interpretations, none of which is widely accepted. (shrink)

Criticism of Locke's account of personal identity has proceeded cumulatively. Three years after the publication of the chapter “Of Identity and Diversity”, John Sergeant raised an objection which, in Bishop Butler's hands, was to become famous as the dictum that “one should really think it self-evident that consciousness of personal identity presupposes, and therefore cannot constitute, personal identity: any more than knowledge, in any other case, can constitute truth, which it presupposes”. Berkeley added, in effect, that when consciousness is taken (...) to be the criterion of personal identity, one must admit that a man conscious of segments of his life at some times and not at others both is — because “conscious of” states a transitive relation — and is not — because of lack of consciousness—the same person. (shrink)

Locke's contribution to the discussion was fourfold: First , he saw the importance of the problem; Second , he realized that the puzzle cases, the “strange suppositions,” were relevant; Third , he maintained “same” had a different meaning when applied to “person” from its meaning in other contexts; and, Fourth , he offered his much criticized solution of the problem.

Ralph Cudworth (1617–1688) is a member of the group of philosophers and theologians commonly called ‘the Cambridge Platonists’. Although not part of the canon of great early modern philosophers, Cudworth’s work is of more than merely passing interest. Cudworth was an influential philosopher in the early modern period both for his criticisms of contemporaries like Hobbes, Descartes, and Spinoza, and for his own distinctive philosophical views. This entry focusses on Cudworth’s views on mind and body, considering both his criticisms of (...) contemporaries’ theories of mind and body, and outlining his alternative form of dualism in which plastic nature plays a central role. (shrink)