1 In writing earlier versions of this paper, I have been helped by conversations with Chris Gray, Nollaig MacKenzie, John Heintz, John Baker, and Ali Kazmi, and by suggestions made by Bernie Linsky and Doug Walton. More recent versions have been helped along by discussions with members of the philosophy departments at Auckland, Palmerston North, Brisbane, and Dalhousie. Despite all this help the mistakes remain my own.

2 Though, as we shall see, these may be more complex than they initially appear to be.

3 This may be a bit misleading. Locke made his point in the context of a nominalistic argument against natural kinds. His is a two-sided point: first, that we shouldn't be as hasty as we are (or were) to call physically deformed fetuses or new-born children monsters when we don't have any adequate notion of what it is to be human to serve as a standard; and second, that if we do speak of such fetuses and new-born children as monsters, then we should be as unwilling, indeed more unwilling, to allow the congenitally mentally deficient ('changelings') into the fold of humanity. This is a straightforward ad hominem against what he saw as the contemporary willingness to tolerate the one while finding the other unacceptable. See Locke, Essay Concerning Human Understanding, Peter H. Nidditch, ed. (Oxford: Clarendon Press 1975), 4.4 passim, but esp. 4.4.13-18.

4 Locke, for example, makes this point for 'Finite Spirits' and particles of matter in the Essay at 2.27.2.

5 In what follows, I give the various proofs concerning identity claims in terms of proper names a, b, c, etc.; the extension to the general case is straightforward in each instance. I take it that it is by now a commonplace, thanks to Prior and Kripke, that the introduction of definite descriptions in such contexts can give rise to scope fallacies if we maneuver carelessly.

6 is read: ’a is the same F as b.’ Note that

It is worth noting, also, that although predicate letters occur in two contexts, Fa, and , the first (as Geach has pointed out) may be defined in terms of the second:

Why choose Leibniz's Law in this form rather than in its more familiar absolute form? Because· in this paper I want to deal with the wholly understandable temptation, in certain cases, to decide that we have a case of 'same s1, but different s2,' for example: 'same human being, but different person.' This notation allows us to symbolize such claims. But in fact this version of LL does neither more nor less than the Law in its more usual dress, as may be seen by trying to find counter-examples to it (and see further n.7). For a thorough discussion of apparent counter-examples see David Wiggins, Sameness and Substance (Oxford: Basil Blackwell1980), ch. 1, 'The Absoluteness of Sameness.'

7 A baby is not an adult, and an adult is not a baby, so baby a is not the same adult as adult b, it seems, and not the same baby either. But baby a will become adult b, and adult b was baby a. (On this topic see Wiggins, Sameness and Substance, esp. ch. 1, §3.) The proof of the claim that if a and b are the same under one sortal, they are the same under every applicable sortal is straightforward:

Of course we can generalize this to get

which shows that with these versions of Reflex and LL we can get everything we could get with 'absolute' identity. (Which is to say, given these versions of Reflex and LL, relativizing is unnecessary save for notational convenience in making some points.) In what follows I shall on occasion, when the relativizing of identity is unimportant, write simply 'a = b.'

8 The combination of reflex and LL as stated entails the falsity of the relative identity thesis, R: , which certainly gives a supporter of relative identity one reason for rejecting the form of LL I have offered.

9 P.T. Geach, 'Identity,' Review of Metaphysics 21 (1967-68) 3-12; 'Ontological Relativity and Relative Identity,' in M.K. Munitz, ed., logic and Ontology (New York: New York University Press 1973) 287-302

10 Macintosh, J.J. 'A Problem About Identity,' Dialogue 13 (1974) 455-74.CrossRefGoogle Scholar For a retraction, see Macintosh, J.J. 'Reincarnation and Relative Identity,' Religious Studies 25 (1989) 153-65CrossRefGoogle Scholar

11 Griffin, N. Relative Identity (Oxford: Oxford University Press 1977)Google Scholar

12 If persons are rational agents, it seems as if one is a human being before one is a person. Locke notes that ' ... we are born Free, as we are born Rational; not that we have actually the Exercise of either: Age that brings one, brings with it the other too' (Two Treatises of Government [2nd ed., London 1694], Second Treatise, ch. 6, § 61, 209), and reminds us of the 'judicious Hooker' who remarked: 'But at what time a man may be sayde to haue attayned so farre foorth the vse of reason, as sufficeth to make him capable of those lawes, whereby he is then bound to guide his actions; this is a great deale more easie for common sense to discerne, then for any man by skill and learning to determine ...' (Richard Hooker, Of the Lawes of Ecclesiasticall Politie [London 1594; reprinted Amsterdam: Da Capo Press 1971], bk 1, § 6). This is, however, probably just a terminological matter, as Hobbes points out: 'Children therefore are not endued with Reason at all, till they have attained the use of Speech: but are called Reasonable Creatures, for the possibility apparent of having the use of Reason in time to come' (Hobbes, Leviathan [London, 1651; reprinted Menston: The Scholar Press 1969], 1.5, 21). Paley, 'An Irrevocable Diameter,' in The Little Disturbances of Man (New York: Viking For an important recent paper casting doubt on the singleness of the concept of a person see Amélie 0. Rorty, 'Persons and Personae,' in Gill, C. ed., The Person and The Human Mind (Oxford: Clarendon Press 1990).Google Scholar

13 Day Lewis, C. Collected Poems (London: Chatto & Windus 1970), 9Google Scholar

14 Graham, Greene Ways of Escape (Harmondsworth: Penguin 1980), 63Google Scholar

15 Grace Press 1968), 117

16 Ogden, Nash 'Time Marches On,' in The Face is Familiar (Garden City, NY: Garden City Publishing 1941) 323Google Scholar

17 This is presumably true for all the whales, but most of the experiments have been carried out on dolphins.

18 Cf. Peter Geach's brisk dismissal of this option: 'It is a savage superstition to suppose that a man consists of two pieces, body and soul, which come apart at death; the superstition is not mended but rather aggravated by conceptual confusion, if the soul-piece is supposed to be immaterial. The genius of Plato and Descartes has given this superstition an undeservedly long lease of life...' (God and the Soul [London: Routledge & Kegan Paul1969], 38).

19 Someone who holds that we have in the case of, say, statues, two physical objects: both the statue and the piece of material which constitutes it might, I suppose, want to suggest that so here we have both persons and the animals which are constitutive of them. My problem with this is that it seems impossible to deny to the human animals not only such shared predicates as weight and bipedality, but also such things as genetic structure (and hence genetically determined ranges of possibilities) and brain states. But once we've got this much duplication, we've clearly got too much for anyone with physicalist leanings not to want to hold that the animal simply is a person. But see Denis, Robinson 'Can Amoebae Divide Without Multiplying?' Australian Journal of Philosophy 63 (1985), 299-319, for a subtly argued view to the contrary.Google Scholar

20 Of the many more recent studies and popularizations, Daniel Keyes's The Minds of Billy Milligan might be mentioned particularly as being philosophically one of the more interesting.

21 Morton, Prince The Dissociation of a Personality 2nd ed. (New York: Longman, Green 1913 [1905]), 1Google Scholar

22 Actually, in the case described by Prince there are between three and five candidates for personhood: I simplify here for expository convenience.

23 Indeed, to make any sense of it, I am interpreting it as 'a is the same Fa as b,' which may be a mistake, but if it is, it is a plausible one.

24 Now that we have seen what is involved I shall, in what follows, ignore the complications which are introduced by attaching adverbial names to relativized identity.

25 Jean-Paul, Sartre Words (Harmondsworth: Penguin 1967), 17Google Scholar

26 On this point see Erving, Goffmann The Presentation of Self in Everyday Life (New York: Doubleday Anchor 1959).Google Scholar

27 Donald, Davidson 'Truth and Meaning,' Synthese 17 (1967), 304-23Google Scholar; 'Semantics for Natural Languages,' in Bruno Visentini, et al., eds., Linguaggi nella societa e nella technica (Edizioni di Communita 1970), 177-88; and 'The Logical Form of Action Sentences,' in Nicholas, Rescher ed., The logic of Decision and Action (Pittsburgh: Pittsburgh University Press 1974), 188-221Google Scholar. See also John, McDowell 'Truth Conditions, Bivalence and Verificationism,' in Gareth, Evans and John, McDowell eds., Truth and Meaning (Oxford: Oxford University Press 1976), 42-66Google Scholar; and 'On the Sense and Reference of a Proper Name,' Mind 86 (1977), 159-85; Martin Davies, Meaning, Quantification, Necessity: Themes in Philosophicall.logic (London: Routledge & Kegan Paul 1981); Barry Taylor, Modes of Occurrence, Aristotelian Society Series Vol. 2 (Oxford: Basil Blackwell1985).

28 Taylor, Modes of Occurrence, 16

29 Davidson, The Logical Form of Action Sentences,' 82

30 Taylor, Modes of Occurrence, ch. 1

31 A similar point is made later on the same page for phrase adverbs.

32 Modes of Occurrence, 97-105

33 The question of the way in which adverbs modify, and indeed what they modify, is a difficult and complicated one. The best treatment of this topic that I know is to be found in Romane Clark's 'Deeds, Doings and What is Done: the Non-Extensionality of Modifiers' (Nous 23 (1989) 199-210). This is not the place to discuss Clark's treatment in detail, but I should perhaps mention that, unlike Davidson's, his treatment allows us to treat 'as Sally' as a straightforward adverb.

34 Phillipa, Foot 'Morality and Art,' Proceedings of the British Academy 56 (1970), 5Google Scholar

35 Wilkes, K. Real People (Oxford: Clarendon Press 1988), 130Google Scholar

36 The terminology is Prince's: "'Carthage must be destroyed." Sally must die that Miss Beauchamp might live' (Dissociation, 489).