ABSTRACT
The chapter on identity and diversity added to the second edition, apparently at the instigation of Molyneux, stands in some respects as a natural culmination of Locke's system, if in others as an awkward afterthought. Like very many seventeenth-century discussions of the principium individuationis, its real concern is with the possibility of immortality. Yet it constitutes one of the most philosophically interesting chapters of the Essay for the modern reader, as well as, historically speaking, one of the most controversial and influential. Locke's antidogmatic programme, combined with his 'reasonable' Christianity, required him to demonstrate that scepticism about the essence of that which thinks in us is compatible with a belief in immortality: 'All the great Ends of Morality and Religion, are well enough secured, without philosophical Proofs of the Soul's Immateriality.'1 In effect he argued that consciousness of oneself as a thinking thing is not, as the Cartesians, Leibniz and others supposed, immediate awareness of the simple essence of an immaterial substance. For the perceived unity of the thinking thing (including its continuity over time) just is the given unity of consciousness essentially involved in the reflexivity of thought. This passage (in particular, II.xxvii.9) was no doubt a crucial source of Kant's conception of the unity of apperception as a necessary condition of experience, but all Locke meant to say was that the perceived unity of consciousness is no more than a unity at the phenomenal level, and that (as Kant agreed) no conclusions can be drawn from it as to the ultimate unity or simplicity of the underlying substance. As such, he held, it is both necessary and sufficient for the purposes of a satisfactory account of moral obligation as obligation to a divine lawgiver with the power of eternal reward and punishment.
