"In the non-Buddhist traditions of Indian philosophical thought, and perhaps also in early Buddhist thought, there appears to be a tacit acceptance of the possibility of acquiring
knowledge of reality. However, Nâgârjuna (about AD 250), a later Buddhist dialectical thinker, raised serious doubts about the possibility of acquiring knowledge by pointing out the
self-contradictory character of all means of acquiring knowledge, Nâgârjuna's objections stimulated and compelled all subsequent philosophers provide a solid foundation to epistemology and logic
before proceeding with the formulations of their philosophical positions.
In Buddhist circles Asanga (about AD 405) and Vasubandhu (about AD 410) made pioneering attempts to construct epistemology and logic on the Buddhist pattern. However it was Dignâga
(about AD 450) who put Buddhist epistemology and logic on a solid footing and gave them a distinctive character. He is, therefore, rightly regarded as the father of Buddhist epistemology and logic,
and also of medieval Indian epistemology and logic in general, for he not only gave a precise formulation to Buddhist epistemology and logic but also imparted a new direction to Indian epistemology
and logic by way of composing independent treatises on epistemology and logic and interspersing the treatment of metaphysical problems within them, a style which was later on followed by Gangesa
(about the twelfth century AD), the founder of the school of Navya-Nyaya. Buddhist literature prior to Dignaga deals with the problem of knowledge and the means of knowing either very casually or not
at all. There seems to be no work devoted to the problem. But Dignaga felt the necessity for a distinct treatise on epistemology and logic to establish the Buddhist doctrines in a logical manner. He
explicitly mentions in the Pramâna-samuccaya that its composition was led by the need to establish the means of valid cognition.
The task initiated by Dignaga was brilliantly continued by Dharmakirti (about 635), a doyen of Buddhist epistemology and logic. His Pramâna-vârtika, Pramânaviniscaya and Nyaya-bindu
are masterpieces of Buddhist epistemology and logic. When Dignaga undertook an examination of the logical tenets of other philosophical schools in his treatise there were reactions from the latter.
For instance, Uddyotakara and Kumarila (about AD 500) tried to controvert the views of Dignaga. Dharmakirti therefore defended and modified the views of Dignaga, thereby strengthening the foundations
of Buddhist epistemology and logic. However, his exposition, which was ended to explain and defend the views of Dignaga, superseded and eclipsed the original by its superior merit. This tradition of
Dharmakirti was carried forward by Darmottara (about AD 847) and subsequently by, amongst others, Jnanasrimitra about AD 1040)."
From: S. R. Bhatt - Logic and language in Buddhism in: Brian Carr, Indira Mahalingam (eds.) - Companion Encyclopedia of Asian philosophy - London, Routledge, 1997,
"(...) from the origin of Buddhism in the 6th century b.C. to its expansion into four philosophical schools in the 4th century A.D., there were no systematic Buddhist works on
Logic, but only a few stray references to that science in the works on philosophy and religion. Nagàrjuna, about 300 A.D., wrote a tract on Logic which was a mere review of the common topics of the
Ancient School of Brahmanic Logic. During 400-500 A.D., Maitreya, Asanga and Vasubandhu handled Logic, but their treatment of it was merely incidental, being mixed up with the problems of the
Yogacara and Vaibhasika schools of philosophy. Vasubandhu's three works on Pure Logic mentioned by Hwen-thsang are now lost and consequently their merits cannot be judged. With 450 A.D. began a
period when Logic was completely differentiated from general philosophy, and a large number of Buddhist writers gave their undivided attention to that branch of learning. The works brought out by
these. writers, along with those brought out by the Jainas, constitute the Mediaeval School of Indian Logic. Dignaga is the earliest known writer of this school."
From: Satis Chandra Vidyabhusana - A history of Indian logic. Ancient, Mediaeval and Modern Schools - (1920) Reprinted by Motilal Barnasidass, Delhi, 2002 p. 270.
(to be continued...)