ABSTRACT
This chapter briefly considers three kinds of non-temporal identity which are of some general interest: spatial, visuo-tactual and qualitative. A feature of identity statements about concrete individuals that has come to be recognised is that the A and B of an identity-statement must be taken to fall under or be instances of the same substantival concept of a thing or natural kind. Most philosophically important and interesting problem of identity concerns identity through time. The peculiarities about identity suggest that give serious consideration to the view that the identity of things through time is due to the presence in them of an identifying component or substance, an identifier. The classical form of this doctrine is the substance theory of the Ionian cosmologists, reaching its fullest development in the atomism of Democritus, which traces the identity of a thing to the total set of its ultimate parts.
