Haecceitistic

Probably, most of us are Haecceitists with respect to most things through time, but the very inaccessibility of other possible worlds seems to have produced a goodly number of Anti-Haecceitists with respect to trans-world identifications. Even when their quantified modal logics look Haecceitistic, their pre-systematic remarks may explain the so-called identities as a manner of speaking.

Source: wiktionary

[T]here are no clear actual cases of individual substances discernible only with respect to relational and haecceitistic properties. On the other hand, there do seem to be pairs of possible individuals which differ only with respect to such properties. Max Black has argued that there is a possible universe containing only two qualitatively indiscernible brass spheres. These spheres will have the same mass, shape, color; be made of the same kind of stuff; and so on. But they will differ with respect to spatial relational properties involving the haecceity of what they're made of, such as being made of this matter, as well as differing with respect to purely haecceitistic properties like being this and impurely haecceitistic properties like being this brass sphere. If, as seems plausible, there are possible universes of the sort Black envisions, then there are individuals that cannot be distinguished save relationally or haecceitistically.

Source: wiktionary

Well, the existence of spacetime points is closely tied up with questions of counting of possibilities – so they are vulnerable to elimination in the transition from a haecceitistic means of counting to an anti-haecceitistic one. But in the case of particles we have much more to hang on to.

Source: wiktionary

[…] One might wonder whether if x and y share every 'non-haecceitistic property', then x and y are identical (where haecceitistic properties — such as being identical to John or being the daughter of Jim — are those which, in some intuitive way, make direct references to a particular individual(s)). One may be so interested because one thinks that there are not, strictly speaking, haecceitistic properties in reality […]; but even if one tolerates haecceitistic properties, one might think it an interesting metaphysical question whether the restricted thesis is true.

Source: wiktionary