Some philosophers find it important or at least expedient puro frame the issue durante terms of the case of a statue \(s\) and piece of clay \(c\) that coincide throughout their entire existence. We bring both \(c\) and \(s\) into existence by joining two other pieces of clay together, or we do something else that guarantees total coincidence. It seems that total coincidence is supposed sicuro lend plausibility to the claim that, in such per case at least, constitution is identity (and hence NI is false – Gibbard 1975). For example, \(s\) may be admired for its aesthetic traits, even long after it ceases preciso exist, but this need not be true of \(c\). And \(s\) has the property, which \(c\) lacks, of being destroyed if squeezed into a ball. Those who defend the thesis that constitution is identity need esatto defend it durante the general case of partial coincidence; and those who attack the thesis do so with arguments that sistema equal well against both total and partial coincidence. The assumption that \(s\) and \(c\) are totally coincident is therefore inessential.
The doctrine of temporal parts offers only limited help. The statement that \(c\) is identical puro \(s_1\)on day 1 but identical onesto \(s_2\) on day 2 can be construed esatto mean that \(c\) is per temporally extended object whose day 1 tirocinio is identical sicuro \(s_1\) and whose day 2 stage is identical puro \(s_2\). Similarly, we can regard \(s_2\) as per temporally extended object that overlaps \(c\) on day 2 and \(c’\) on day 3. But unless temporal parts theorists are prepared sicuro defend per doctrine of modally extended objects – objects extended through possible worlds analogous onesto objects extended mediante time, there remains verso problem. \(s_2\) might have been made of a different piece of clay, as is sopra fact the case on day 3. That is, it is logically possible for \(s_2\) onesto fail preciso coincide with the day 2 tirocinio of \(c\). But it is not logically possible for the day 2 tirocinio of \(c\) preciso fail to coincide with itself.
Since the two stages are not identical, NI does not apply
Lewis recognizes this difficulty and proposes to deal with it by appealing puro his counterpart theory (Lewis 1971, 1986, and 1993). Different concepts, ed.g., statue and piece of clay are associated with different counterpart relations and hence with different criteria of trans-world identity. The property determined by per modal predicate may be affected by the subject term of verso sentence containing the predicate. The subject term denotes an object belonging sicuro this or that kind or sort. But different kinds or sorts may determine different properties (or different counterpart relations). Durante particular, the properties determined by the predicate ‘might not have coincided with \(c_2\)’ (where \(c_2\) names the day 2 tirocinio of \(c)\) con the following sentences,
This has the effect of rendering modal predicates “Abelardian” (Noonan 1991, 1993)
- \(s_2\) might not have coincided with \(c_2\),
- \(c_2\) might not have coincided with \(c_2\),
are different, and hence (a) and (b) are compatible, even assuming that \(s_2\) and \(c_2\) are identical. (It should be emphasized that counterpart theory is not the only means of obtaining Abelardian predicates. See Noonan 1991.)
The upshot seems sicuro be that that the advocate of the norma account Ricerca bbwdesire of identity must maintain either that constitution is not identity or that modal predicates are Abelardian. The latter option may be the fruitful one, since for one thing it seems esatto have applications that go beyond the issue of constitution.