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xx] Venkațanātha's treatment of Inference 229 are not available, the non-existence of the reason in the negative instance cannot be shown. But in such cases the very non-existence of negative instances is itself sufficient to contribute to the notion of kevalā-nvayi concomitance. The validity of kevalā-nvayi concomitance is made patent by the fact that, if the reason remains unchanged, the assumption of a contrary probandum is self-contradictory (vyāhata-sādhya-viparyayāt), and this distinguishes it from the forms of kevalā-nvayi arguments employed by Kulārka in formulating his Mahā-vidyā doctrines.
Rāmānuja's own intention regarding the types of inference that may be admitted seems to be uncertain, as he has never definitely given any opinion on the subject. His intention, therefore, is diversely interpreted by the thinkers of his school. Thus, Meghanādāri gives a threefold classification of inference: (1) of the cause from the effect (kāraņā-numāna); (2) of the effect from the cause (kāryā-numāna); and (3) inference by mental association (anubhavā-numāna—as the inference of the rise of the constellation of Rohiņī from the Kșttikā constellation). As an alternative classification he gives (1) the joint method of agreement and difference (anvaya-vyatireki); (2) inference through universal agreement in which no negative instances are found (kevalā-nvayi); and (3) inference through exclusion, in which no positive instances are found (kevala-vyatireki). Bhattārakaguru and Varadavişņu Misra, who preceded Venkatanātha in working out a consistent system of Rāmānuja logic, seem also to admit the three kinds of inference, viz. anvyayi, kevală-nvayi, and kevala-vyatireki, as is evident from the quotation of their works Tattva-ratnākara and Māna-yāthātmyanirnaya. Venkațanātha, however, tries to explain them away and takes great pains to refute the kevala-vyatireki form of argument? His contention is that there can be no inference through mere negative concomitance, which can never legitimately lead to the affirmation of any positive character when there is no positive proposition purporting the affirmation of any character. If any such positive proposition be regarded as implied in the negative proposition, then also the contention that there can be inference from purely negative proposition fails. One of the conditions of validity
1 Venkatanātha points out that Yamunācārya, also the accredited teacher of Rāmānuja, did not admit the kevala-vyatireki form of inference in his Siddhitraya.
