▁a ▁volunt ary ▁theory . ▁Par s ons ' ▁first ▁major ▁work , ▁The ▁Str ucture ▁of ▁Social ▁Action ▁( 1 9 3 7 ) ▁discussed ▁the ▁method ological ▁and ▁meta - the oret ical ▁prem ises ▁for ▁the ▁foundation ▁of ▁a ▁theory ▁of ▁social ▁action . ▁It ▁argued ▁that ▁an ▁action ▁theory ▁must ▁be ▁based ▁on ▁a ▁volunt ar istic ▁foundation — c laim ing ▁neither ▁a ▁she er ▁posit iv istic - util itar ian ▁approach ▁nor ▁a ▁she er ▁" ide al istic " ▁approach ▁would ▁satisfy ▁the ▁necessary ▁pr ere quis ites , ▁and ▁propos ing ▁an ▁alternative , ▁system ic ▁general ▁theory . ▁ ▁Par s ons ▁shared ▁posit iv ism ' s ▁desire ▁for ▁a ▁general ▁un ified ▁theory , ▁not ▁only ▁for ▁the ▁social ▁science ▁but ▁for ▁the ▁whole ▁real m ▁of ▁action ▁systems ▁( in ▁which ▁Par s ons ▁included ▁the ▁concept ▁of ▁" l iving ▁systems "). ▁On ▁the ▁other ▁hand , ▁he ▁depart ed ▁from ▁them ▁on ▁the ▁criteria ▁for ▁science , ▁particularly ▁on ▁August e ▁Com te ' s ▁proposition ▁that ▁scient ists ▁must ▁not ▁look ▁for ▁the ▁" ult imate ▁ends " ▁so ▁as ▁to ▁avoid ▁un answer able ▁met aph ys ical ▁questions . ▁Par s ons ▁maintained ▁that , ▁at ▁least ▁for ▁the ▁social ▁sciences , ▁a ▁meaning ful ▁theory ▁had ▁to ▁include ▁the ▁question ▁of ▁ult imate ▁values , ▁which ▁by ▁their ▁very ▁nature ▁and ▁definition , ▁included ▁questions ▁of ▁met aph ys ics . ▁As ▁such ,