According to the Navya Naiyāyikas, inference is the knowledge, which is produced out of consideration. But what is to be understood by the term ‘consideration’ or ‘parāmarśa’? According to them, parāmarśa or consideration is the factor through the operation of which the inferential conclusion can be attained. Parāmarśa has been defined as the knowledge of the existence of the hetu or reason in the pakṣa or subject, which reason is characterized by its being concomitant with the sādhya, the knowledge in the form of parāmarśa is actually caused by the knowledge of invariable concomitance of probans (hetu) with the probandum (sādhya) and the knowledge of the existence of the hetu in the subject (pakṣa). It has been said by Viśvanātha that the cognition of the existence of probans or hetu in the subject of inference along with the cognition of the prabans or hetu as pervaded by sādhya is called parāmarśa (pakṣasya vyāpyavṛttitvadhīḥ parāmarśa ucyate). The invariable co-existence in the form ‘where there is smoke, there is fire’ is known as vyāpti or invariable concomitance. Here the invariable coexistence (avyabhicārī sāhacarya) between the probans and probandum (i.e., smoke and fire) is the definition of vyāpti. The term ‘co-existence’ means remaining in the same locus of the probans with the probandum, which is not the counter positive of the absolute negation existing in the locus of the hetu. To Gangeśa, the knowledge of the co-existence of the probans and probandum along with the absence of the knowledge of deviation of the probans is the cause of ascertaining vyāpti. Repeated observations, of course, sometimes act as a promoter (prayojaka) in ascertaining vyāpti by removing the doubt of deviation. The doubt of deviation can be removed sometimes by Tarka or sometimes by the absence of the collocation of causes of doubt, which is called svataḥsiddhaḥ. Gangeśa admits sāmānyalakṣaṇā as a pratyāsatti in ascertaining vyāpti between smoke-in-general and fire-in-general. To him, the super-normal connection through universal (sāmānyalakṣaṇā pratyāsatti) has got a prominent role in ascertaining vyāpti. If somebody challenges about the validity of the syllogistic argument in the form “The mountain is fiery as it possesses smoke” (parvato vahnimān dhūmāt), the philosophers of Nyāya and Navya-nyāya persuasion will justify the same with the help of five constituents (avayava-s). The process is called parāthānumāna (syllogistic argument for making others understand). The constituents of a syllogism are proposition (pratijňā), reason (hetu), example (udāharaṇa), application (upanaya), and conclusion (nigamana).
