Inference, Indian theories of

The use of argument in rational inquiry in India reaches almost as far back in time as its oldest extant literature. Even in very early texts, one finds the deliberate use of modus tollens, for example, to refute positions thought to be false. In light of such practice, it is not surprising to discover that Indian thinkers came to identify certain forms of reasoning and to study them systematically.

The study of inference in India is, as Karl Potter (1977) has emphasized, not the study of valid reasoning as reflected in linguistic or paralinguistic forms, but the study of the circumstances in which knowledge of some facts permits knowledge of another fact, and of when acceptance by one person of some state of affairs as a fact requires that that person accept another as a fact. Still, the form of inference which came to be systematically investigated in India can be given schematically (see below).

At the core of the study of inference in India is the use of a naïve realist ontology. The world consists of individual substances or things (dravya), universals (sāmānya), and relations between them. The fundamental relation is the one of occurrence (vṛtti). The relata of this relation are known as substratum (dharmin) and superstratum (dharma) respectively. The relation has two forms: contact (saṃyoga) and inherence (samavāya). So, for example, one individual substance, say a pot, may occur on another, say the ground, by the relation of contact. In this case, the pot is the superstratum and the ground is the substratum. Or a universal, say brownness, may occur in an individual substance, say a pot, by the relation of inherence. Here, brownness, the superstratum, inheres in the pot, the substratum. The converse of the relation of occurrence is the relation of possession.

Another important relation is the relation that one superstratum bears to another. This relation, known as pervasion (vyāpti), can be defined in terms of the occurrence relation. One superstratum pervades another just in case wherever the second occurs the first occurs. The converse of the pervasion relation is the concomitance relation. As a result of these relations, the world embodies a structure: if one superstratum H is concomitant with another superstratum S, and if a particular substratum p possesses the former superstratum, then it possesses the second. This structure is captured in this inferential schema:

Here are two paradigmatic cases of such an inference: