Vātsyāyana (5th century)

Vātsyāyana belonged to the Nyāya school of Indian philosophy, and his Nyāyabhāṣya is the first extant commentary on the Nyāyasūtra, the foundational text of that school. In it, he emphasized the distinctive epistemological and logical character of the topics he deemed appropriate for treatment by Nyāya philosophers. In so doing, he helped both to establish the authority of the Nyāya school in matters related to logical reasoning, and to demarcate the enterprise of the Nyāya school from that of the earlier, more traditional, soteriological approach of the Upaniṣads. His commentary on the Nyāyasūtra set the agenda for succeeding generations of Nyāya commentators and their Buddhist opponents. In particular, Vātsyāyana initiated arguments that were to become crucial in the Nyāya defence of its characteristic brand of realism.