Rationality in Metaphysics is considered as the means by which one steps back to more objective views. Indian philosophical literature abounds with lists, enumerations, catalogues and classifications. There are lists of the different means of knowing, of the categories of knowable things, of the variety of psychological and physical constituents of a person, and, generally, of the modes, realms and states of existence. There is rationality behind all these classifications. Philosophers suggest that there are many ways of dividing objects into groups - and the choice of one particular way of dividing from the others is the selection of ontology. One approach to the Indian categories, indeed the traditional approach, has therefore been to explore the reasons for choosing one way of classifying rather than another. Remembering that the classifications are given rather than chosen for all but the original compilers of the sutra-texts, the real interest is in the methods of rationalisation - how a predetermined list is made sense of, and in the methods of revision - how the list is modified in accordance with the principles by which it is rationalised.

Vaisesika school, towards the study of the metaphysical structure of the natural world, examines too the logical theory that is integral to this ontology, as it was formulated and developed by the Nyaya logicians. Mathematical concepts play no part in Indian philosophical thought about order in the natural world. The classical conception of qualities and motions makes them almost identical: they both inhere only in substances, and they both are inhered in only by universals. It is also believed that it is quite difficult to find any principled way to distinguish between qualities and motions. Metaphysics as conceived as an investigation into the eventual nature of mind-independent reality is rather a rationally crucial intellectual discipline. It is maintained that it is not a plain exercise in theoretical analysis, because the primary objective of this discipline is rather a prescriptive one. Thus, rationality in metaphysics is considered nothing less than an attempt to comprehend adequately the essences of both actual and possible things with the view to understand the fundamental structure of reality as a whole.