Routledge Encyclopedia of Philosophy entry.
As ‘particulars’ we count objects like computers, mountains, bicycles, and scissors, as well as individuals like Plato, Socrates, and Aristotle. These are all reasonably well-understood entities (at least, that is how they appear at first glance), which might lead one to conclude that so too is their particularity. It is, however, doubtful whether studying the items just mentioned (from the point of view of their being particulars) informs us about the nature of particularity. This is because all these things, apart from being particular, are also concrete (in the sense that they are spatiotemporally located), complex (in the sense that they have other – particular – entities as parts), and natured (in the sense that they have – and hence are not – properties). Whatever ‘being particular’ amounts to, it is most likely not restricted in this way. To see this, consider an alternative list of items, which most would categorise as ‘particulars’ or – at least – as ‘particular’: the Number Two; God; the state of affairs that Socrates is wise; the event that Plato is running; the redness of this apple; and Socrates’ frown. At least the first item on this new list is abstract not concrete; the fifth and sixth are plausibly understood as properties, not objects (so-called tropes); and the third and fourth are neither objects nor properties. Add to this the idea that there are ‘thin’ particulars or ‘non-qualitative properties’ (sometimes called substrates, sometimes haecceities), and what ‘being a particular’ amounts to becomes even further removed from what typically characterises the ordinary objects and individuals on our first list.
In other words, various distinctions must be kept apart. To be a particular is to be a non-universal. But to be a non-universal should not be equated with being a non-property (so as not to rule out particular properties, or tropes (see Properties); it should not be equated with being necessarily spatiotemporally located (so as not to rule out abstract particulars – see Abstract objects); it should not be equated with being or having a nature (so as not to rule out thin particulars – see Substance, and Haecceity and thisness); and it is highly unlikely that it should be equated with being either an object or a trope (so as not to rule out states of affairs, for example – see Facts), events (see Events), or even Platonic Forms (see Forms, Platonic). Indeed, one of the interesting things about particularity – one that makes it reasonable to think that it captures something very fundamental about (some of) reality’s inhabitants – is precisely that it cuts across all of these distinctions.
In the literature, the distinction between particular and universal (see Universals) has been understood in various ways: in terms of exemplification (particulars exemplify, but are not exemplified); in terms of the functioning of terms with the help of which particulars and universals are picked out (particulars are picked out by terms in subject position); in terms of completeness (particulars, unlike universals, are ‘complete’ entities); in terms of their relation to space-time (particulars cannot exist in more than one position in space at each moment in time); and in terms of similarity (particulars do not obey the identity of indiscernibles, and so can be distinct yet exactly similar (see Identity of indiscernibles). Adopting any one of these accounts of the distinction (with the possible exception of the last one) means having to understand one or more of the items on our second list as non-particulars. For this and related reasons, there is no real consensus on what makes something a particular.
Link to entry here. Link to final draft below.