▁things ▁( An ic ca ), ▁and ▁a ▁certain ▁ske ptic ism ▁about ▁met aph ys ical ▁questions . ▁Buddh ist ▁think ers ▁in ▁India ▁and ▁subsequently ▁in ▁East ▁Asia ▁have ▁covered ▁topics ▁as ▁varied ▁as ▁phenomen ology , ▁eth ics , ▁ont ology , ▁ep ist em ology , ▁logic ▁and ▁philosophy ▁of ▁time . ▁ ▁Later ▁Buddh ist ▁philosoph ical ▁trad itions ▁developed ▁complex ▁phenomen ological ▁psych ologies ▁term ed ▁' Ab h id har ma '. ▁Mah ay ana ▁philosoph ers ▁such ▁as ▁Nag ar j una ▁and ▁Vas ub and hu ▁developed ▁the ▁theories ▁of ▁Sh un y ata ▁( empt iness ▁of ▁all ▁phen omena ) ▁and ▁V ij na pt i - mat ra ▁( app earance ▁only ), ▁a ▁form ▁of ▁phenomen ology ▁or ▁trans c endent al ▁ideal ism . ▁The ▁D ign ā ga ▁( c . ▁ 4 8 0 – 5 4 0 ) ▁school ▁of ▁Pr am ā ṇ a ▁promoted ▁a ▁complex ▁form ▁of ▁ep ist em ology ▁and ▁Buddh ist ▁logic . ▁This ▁tradition ▁contributed ▁to ▁what ▁has ▁been ▁called ▁an ▁" ep ist em ological ▁turn " ▁in ▁Indian ▁philosophy . ▁Through ▁the ▁work ▁of ▁D harm ak ir ti , ▁this ▁tradition ▁of ▁Buddh ist ▁logic ▁has ▁become ▁the ▁major ▁ep ist em ological ▁system ▁used ▁in ▁Tib et an ▁Buddh ist ▁philosophy ▁and ▁debate . ▁ ▁After ▁the ▁disapp earance ▁of ▁Buddh ism ▁from ▁India , ▁these ▁philosoph ical ▁trad itions ▁continued ▁to ▁develop ▁in ▁the