The initial work of early Tibetan Buddhist philosophers was in translation of classical Indian philosophical treatises and the writing of commentaries. This initial period is from the 8th to the 10th century. Early Tibetan commentator philosophers were heavily influenced by the work of Dharmakirti and these include Ngok Lo-dza-wa (1059-1109) and Cha-ba (1182-1251). Their works are now lost. The 12th and 13th centuries saw the translation of the works of Chandrakirti, the promulgation of his views in Tibet by scholars such as Patsab Nyima Drakpa, Kanakavarman and Jayananda (12th century) and the development of the Tibetan debate between the prasangika and svatantrika views which continues to this day among Tibetan Buddhist schools. The main disagreement between these views is the use of reasoned argument. For Śāntarakṣita, Kamalaśīla and their defenders, reason is useful in establishing arguments that lead one to a correct understanding of emptiness, then, through the use of meditation, one can reach non-conceptual gnosis that does not rely on reason. For Chandrakirti, however, this is wrong, because meditation on emptiness cannot possibly involve any object. Reason's role here is to negate any essence or essentialist views, and then eventually negate itself along with any Conceptual proliferation.