Ayers on Relative Identity

In a recent paper M.R. Ayers attacks two widely held doctrines: (I) Non-arbitary individuation requires principles of individuation and these are supplies only by sortal general terms. (R) It is possible for an item a to be the same as b but not the same as b. I shall follow Ayers in calling a theory which includes both (I) and (R) ‘conceptualist’ or ‘sortalist’ (although I shall also use the more familiar label ‘relative identity theory’), but I shall not allow him to appropriate the honorific term ‘realist’ for his own theory, which I shall term ‘absolutist’. My sole purpose here is to defend (I) and (R) in turn against Ayers’ attacks on them. Thus I shall ignore intermediate positions which accept (R) but reject (I) or vice-versa. Ayers’ paper is long and in many respects obscure; there are many points in it which require discussion but which can't receive it here for lack of space. In particular, I shall ignore his lengthy comments on the constitutive ‘is’, and also the wider metaphysical remarks in his conclusion and the postscript on Dummett.