Author’s Introduction (Sections 1 & 2)
- In "Wiggins (David) - Identity & Spatio-temporal Continuity" (1967) and its successor "Wiggins (David) - Sameness and Substance" (1980a) David Wiggins defends an absolute, or Leibnizian, concept of identity against relative identity theorists.
- The books contain much more, of course. In particular, there is Wiggins's examination of the concept of personal identity which (in its version in (1980a)) contains the radical suggestion that the debate over personal identity is misconceived so long as we do not appreciate that the concept of a person is parasitic on that of a man and cannot involve a distinct, non-coinciding, criterion of identity.
- But it remains true that the attack on relative identity is at the heart of Wiggins's position. In what follows I attempt an assessment of the debate.
- In both (1967) and (1980a) Wiggins begins by asking 'Can a be the same f as but not the same g as b? Can this happen even when a or b is itself a g?' Here 'f and 'g' range over sortal concepts and hence to give an affirmative answer to the question is to endorse Geach's famous thesis of the sortal relativity of identity (see for example "Geach (Peter) - Ontological Relativity and Relative Identity" (1973)), which Wiggins refers to as 'thesis R'. Wiggins rejects thesis R and presents a case for its rejection comprising both general arguments and detailed examinations of particular cases which, at first sight, seem to support it. It is in the course of his discussion of these cases that Wiggins introduces his famous 'is' of constitution, which has since become a standard weapon employed by defenders of absolute identity against their relativist opponents.
- I begin my discussion of thesis R, in the next section, with an analysis of what is going on in these cases. (I do not have space to discuss Wiggins's general arguments against thesis R, but I should say, to make my position clear, that I do not find them convincing) With respect to putative diachronic case of relative identity I argue that their logical form disqualifies them from illustrating thesis R - and hence that no appeal to the 'is' of constitution is needed by an opponent of relative identity to deal with them. With respect to putative synchronic cases of relative identity, the most well-known of which is the example of the cat on the mat1, I argue that whilst their logical form is not inappropriate, an opponent of thesis R can nevertheless still reject them as illustrations of that thesis without appeal to the 'is' of constitution. Appeal to the 'is' of constitution is required, it emerges, only if not only Geach's relative identity thesis, but also his thesis of the irreducibility of restricted (sortal) qualification to unrestricted quantification is rejected. But I suggest that the linguistic facts in such a case as that of the cat on the mat do not enable a decision to be made either for or against the irreducibility thesis.
- However, the fundamental point at issue between absolutists and relativists, I believe, is not to be found here. Rather, the crucial notion to be examined is that of a criterion of identity (this is implicit, of course, in the fact that thesis R is a thesis about identity under a sortal concept, for sortal concepts are precisely those with which a criterion of identity is associated2). Absolute identity theorists like Wiggins maintain that absolute equivalence relations (i.e. equivalence relations which ensure the indiscernibility of their terms) can constitute criteria of identity but that relative equivalence relations (i.e. ones which do not ensure indiscernibility) cannot; relative identity theorists, like Geach, maintain that relative equivalence relations can constitute criteria of identity.
- I argue, in the last two sections of the paper, that when the expression 'a criterion of identity' is used in one sense that can be given to it, the absolutist is right; when it is used in another sense that can be given to it the relativist is right, but when it is used in the sense which is its most common in the philosophical literature, neither is right. I suggest, however, that the sense which can be given to the expression by the absolutist is of doubtful legitimacy and hence that only relativists have anything useful to offer.
- Thus, I suggest, though neither the position of the relativist nor that of thee absolutist is wholly correct, the relativist position is nearer to being so.
- The main emphasis of Geach's work on identity has always been on the uselessness of the notion of absolute identity, and on its inability to provide any usable criterion of identity. If the arguments given in this paper are correct, this point is vindicated.
- Oh dear! I thought I’d not heard of this one!
- But it’s just Tib / Tibbles, with and without a tail.
- In a well-known passage, referred to by Wiggins, Strawson draws the distinction between sortal and non-sortal concepts in the following terms; 'A sortal universal provides a principle for distinguishing and counting the particulars it collects. It presupposes no antecedent principle or method of individuating the particulars it collects. Characterizing universals . . . whilst they supply principles of grouping, even of counting particulars, supply such principles only for particulars already distinguished, or distinguishable, in accordance with some antecedent principle or method' ("Strawson (Peter) - Individuals: An Essay in Descriptive Metaphysics" (1959), p. 168).
- Wiggins rightly criticises the suggestion here that countability is a necessary condition of a concept's qualifying as a sortal concept, but it seems plausible if taken as a sufficient condition. However, if so, resistance to the relative identity thesis must be unmotivated. For, as Geach has made plain, and is now generally accepted, we can count by relations weaker than absolute identity.
- Moreover, as Wiggins has made plain, a relation may be such that it cannot hold between two objects which are simultaneously spatially distinct without being an absolute identity relation. The thesis that a sortal concept supplies a principle for counting particulars thus does not require that identity under a sortal concept be Leibnizian. It is only when the notion of a criterion of identity is included in the account of a sortal concept that opposition to thesis R becomes comprehensible.
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