Abstract

The paper is a survey of contemporary quidditism, understood as two interrelated metaphysicalpositions — recombinatorial quidditism, which is an account of the nature of possibilities, andindividuation quidditism, which is concerned with the problem of how to individuate properties.I have three aims: to examine the commitments and consequences of both views, to investigatethe relationships between them, and to sketch the logic of the dispute between structuralism andquidditism. I explain how these views relate to Ramseyan humility, according to which we cannotknow the fundamental structure of the world.