Abstract

The Identity Theory of properties (IDT) is an increasingly popular metaphysical view that aims to be a middle way between pure powerism and pure categoricalism. This paper’s goal is to highlight three major difficulties that IDT should address in order to be a plausible account of the nature of properties. First, although IDT needs a clear definition of the notion of qualitativity which is both adequate and compatible with the tenets of the theory, all the extant proposals fail to provide such a definition. Second, the suggested definitions of qualitativity are characterised by a metaphysical ‘neutrality’ that threatens to trivialise the important metaphysical debate regarding the question whether properties confer by themselves dispositions on their bearers (and so they are inherently modal and active) or need the ‘assistance’ of laws of nature to do that. Finally, none of the extant alternative understandings of the core identity-claim of IDT can adequately meet the objection that the claim in question is unintelligible.