One might reasonably wonder, ‘why difference?’ Why does difference matter so much? Or does it matter so much? If this question is of such vital philosophical importance, why does it appear primarily within the continental tradition of the late twentieth century, without so much as a whisper elsewhere in Western philosophy's two-and-a-half-millennia-long history? In his work, Reconsidering Difference, Todd May speaks of the problem of difference as a ‘pattern … in the French philosophy of this generation, of the generation running roughly from the mid to late sixties up to the present’, claiming that ‘For philosophers outside the French tradition, there may be some puzzlement as to why one should be so concerned about difference.’ Indeed, in the previous chapter, I myself referred to it as the defining problem of twentieth-century continental philosophy. So, why should anyone besides a continental philosopher care?

Moreover, we might reasonably wonder: is a philosophy of difference, as a philosophy, even possible? Given that philosophy has traditionally attempted to think the universal, and given that, as we noted in Chapter 1, difference necessarily eludes the stasis of representational thinking, which attempts to freeze borders around conceptual content, will attempting to formulate a concept of difference not simply result in obscurity, paradox, contradiction, in a word, non-philosophy?

By way of introduction, we can say that the question of difference matters in so far as the question of identity matters. Prima facie, to characterise the identity of a thing means to be able to say things about that thing, to characterise that thing in ways that augment our understanding of it. This requires predicating of the thing qualities, characteristics, or attributes that are not essential to that thing, but are different from it in some senses. To say that A is A – the sky is the sky, or blue is blue, for instance – requires no thought at all. Each proposition is a simple expression of the principle of identity, and as such, each is tautologically, but trivially, true. But to say that A is B – the sky is blue – compels thought to ask how it is that a thing can be what it is not.