" ▁based ▁on ▁kar ma , ▁d har ma , ▁and ▁soci etal ▁norm s . ▁H indu ism ▁is ▁a ▁categor ization ▁of ▁distinct ▁intellectual ▁or ▁philosoph ical ▁points ▁of ▁view , ▁rather ▁than ▁a ▁rig id , ▁common ▁set ▁of ▁belief s . ▁H indu ism , ▁with ▁about ▁one ▁billion ▁follow ers ▁is ▁the ▁world ' s ▁third ▁largest ▁religion , ▁after ▁Christian ity ▁and ▁Islam . ▁H indu ism ▁has ▁been ▁called ▁the ▁" old est ▁religion " ▁in ▁the ▁world ▁and ▁is ▁tradition ally ▁called ▁, ▁" the ▁et ernal ▁law " ▁or ▁the ▁" et ernal ▁way "; ▁beyond ▁human ▁orig ins . ▁Western ▁sch ol ars ▁regard ▁H indu ism ▁as ▁a ▁fusion ▁or ▁synth esis ▁of ▁various ▁Indian ▁cult ures ▁and ▁trad itions , ▁with ▁diverse ▁roots ▁and ▁no ▁single ▁founder . ▁ ▁Some ▁of ▁the ▁earliest ▁surv iving ▁philosoph ical ▁texts ▁are ▁the ▁Up an ish ads ▁of ▁the ▁later ▁V edic ▁period ▁( 1 0 0 0 – 5 0 0 ▁B CE ). ▁Import ant ▁Indian ▁philosoph ical ▁concepts ▁include ▁d har ma , ▁kar ma , ▁s ams ara , ▁m ok sha ▁and ▁ah im sa . ▁Indian ▁philosoph ers ▁developed ▁a ▁system ▁of ▁ep ist em ological ▁reasoning ▁( pr am ana ) ▁and ▁logic ▁and ▁investig ated ▁topics ▁such ▁as ▁Ont ology ▁( met aph ys ics , ▁Bra h man - At man , ▁Sun y ata - An atta ), ▁reliable ▁means ▁of ▁knowledge ▁( ep