  Smiles, walks, dances, weddings, explosions, hiccups, hand-waves, arrivals and departures, births and deaths, thunder and lightning: the variety of the world seems to lie not only in the assortment of its ordinary citizens—animals and physical objects, and perhaps minds, sets, abstract particulars—but also in the sort of things that happen to or are performed by them. In the last few decades, this view has been a focus of considerable debate in philosophy, with implications reaching far into the concern of other disciplines as well, above all linguistics and the cognitive sciences. Indeed, there is little question that human perception, action, language, and thought manifest at least a prima facie commitment to entities of this sort: