On the Function of Identity Criteria

In this paper we shall try to answer the following questions: is there a function played by criteria of identity? And, if there is one, which one? An answer is to say that identity criteria are used to confer respectability on some entities. In other words, an entity is ontologically acceptable iff we have a clear determination of its identity criterion. This is, in non-quinian terms, the quinian answer. Many attempts have been made to honour such demand for entities such as properties, events, abstract and material objects. M. Jubien in his paper The Myth of Identity Conditions (Jubien 1996) questioned the legitimacy of the demand for criteria of identity with respect to any sort of entity. His goal was to argue that such demand is ill conceived. The notion of identity criterion is, in his opinion, a philosophical “myth”. Criteria of identity have no function at all. Even if we agree with Jubien’s pars destruens concerning identity criteria, we think that the last word on identity criteria has not been said yet. In particular, one has still to analyse if there is a connection and, if there is one, how to characterise it, between identity criteria and essential properties. The paper consists of four sections. In (I) we introduce two functions usually ascribed to identity criteria: the epistemological and the metaphysical function; in (II) we argue against the epistemological function of identity criteria; in (III), after a distinction of the metaphysical function in an analytical and an ontological view, we consider some problems connected with the metaphysical view in general. In particular, a criticism to this view, circularity, applies in a similar vein if we use a criterion of identity for the fs as a definition of ‘x=y’, when applied to fs, where ‘x’ and ‘y’ are individual variables and ‘f’ is replaced by a sortal predicate. We ask if it is possible to avoid the criticism of circularity for identity criteria. We isolate two metaphysical alternatives connected with such a problem, one that seems to avoid circularity, one not. In (IV) we introduce another specification of the metaphysical view concerning the function played by identity criteria in the distinction between essential and accidental properties and we list some difficulties and open problems connected with such a function of identity criteria.