Although a number of authors have used diagrams extensively in their studies of Navya-Nyāya, they have done so to explain and illustrate concepts, not with the goal of reasoning with the diagrams themselves. Adherents of diagrammatic reasoning have made claims for its potential by pointing to key structural correspondences between diagrams and logical concepts, arguably lacking in sentential representations, and describing these relations using concepts such as “well matchedness” and “iconicity”. A canonical example of this iconicity is the use of (...) Euler diagrams to depict categorical syllogisms. Since the meaning of expressions in Indian logic differs in so many important ways from logic in the Western tradition, the use or adaptation of diagrams developed in the latter would seem to preclude iconicity. Thus, the development of diagrams which reflect the nature of inference in Navya-Nyāya, which centres on the anumāna inference schema, is motivated. In this paper we extend Ganeri’s method of depicting the Vaiśeṣika ontology with graphs to include syntax intended to expose the nature of anumāna. The diagrams are given a formal basis: i.e. abstract syntax, inference rules defined abstractly and a graph-theoretic semantics. These are the first formalised logical diagrams that aim to reflect the nature of the anumāna inference. This paper lays the way for further work in extending the formalism to cover more of Navya-Nyāya, and in exploring a dialogue between properties of the formalism and of Navya-Nyāya. (shrink)

The strainer tests the strength of a definition of a particular kind. Suppose the definition D is stated in terms of an absence, and x is a definiendum of D. The strainer collects each x-token or x-individual that dissatisfies D in a specific case. Then, all the x-individuals put together would be equivalent to the type x. Hence—one would be forced to conclude that—in a sense, x dissatisfies D. This is a case of under-application of D, since, despite being a (...) definiendum of D, x dissatisfies D. Therefore, D would be too narrow. Similarly, the strainer may detect over-application too. By using the strainer, Raghunātha Śiromaṇi demonstrated that Gaṅgeśa’s conclusive definition of pervasion had a defect, and redefined pervasion. The strainer test is based on intuitive principles. It may disqualify a definition that has an absence in its definiens. Therefore, strainer-proofing becomes an important consideration that must be borne in mind every time we formulate such a definition. (shrink)

The present paper is about three concepts which are crucially involved in Gaṅgeśa's interpretation of a Mīmāṃsā argument against the well-known design inference of the existence of God in Nyāya, namely the concepts “cognition” (jñāna), “certitude” (niścaya) and “doubt” (saṃśaya). According to Maheśa Chandra, the author of the Navya-Nyāya manual Brief Notes on the Modern Nyāya System of Philosophy and its Technical Terms, certitude and doubt are the two varieties of cognition. He illustrates the verbal expression of certitudes by means (...) of declaratives and the verbal expression of doubts by means of interrogatives (functioning as polar or alternative questions). He notes also that different credence levels might be associated with the alternatives involved in a speaker’s doubt. A biassed question in the form of a tag interrogative might be an appropriate way to express such a doubt. In Western logic the idea to treat declaratives and interrogatives on a par, which is anticipated by the Navya-Naiyāyikas' use of the unifying concept of “cognition”, goes back to Frege’s distinction between the semantic content (the “thought”) of a sentence and its force and it was recently elaborated by Ciardelli, Farkas, Groenendijk, Roelofsen et al., the founders of a new branch in logic called “inquisitive logic”. In the present paper we will discuss Maheśa Chandra's succinct exposition of the Navya-Naiyāyikas' innovative approach from the perspective of this type of logic. As an offshoot of our analysis we will try to elucidate Gaṅgeśa's apologetic concerns about the well-known design inference of the existence of God in Nyāya and its liability to be vitiated by a dubious upādhi. (shrink)