  Universals are thus conceived of as unstructured, objective properties which necessarily reside in individuals. The postulation of such entities in the Vaiśeṣika schema has explanatory force, accounting for the distinction between ‘natural’ and ‘conventional’ classifications. Intuitively, this is the distinction between groupings such as the class of cows or horses, which reflect natural divisions (“cut nature at the joints”), and those such as the class of Cabinet Ministers or the class of endangered species, which reflect anthropocentric concerns. The Naiyāyikas mark this distinction by calling natural properties “universals” (jāti) and anthropocentric properties “imposed” or “nominal” properties (upādhi). Correlatively, a semantic distinction is drawn between “natural kind terms” (naimittikī), i.e. terms the basis for whose application is a universal, and “imposed kind terms”, terms whose basis for application is an anthropocentric property. Udayana tried to make this distinction more precise by giving a list of criteria for a property to count as natural. Examination of his list (which are called the “jāti-bādhakas”—impediments distinguishing natural properties) will reveal something further about the nature of the natural properties according to Nyāya.