▁theory ▁ent it les ▁the ▁Aust ri ans ▁to ▁aggregate ▁prices ▁at ▁all ; ▁because ▁each ▁price ▁express es ▁a ▁unique ▁subject ive ▁preference , ▁adding ▁up ▁prices ▁is ▁like ▁adding ▁up ▁app les ▁and ▁p ears ; ▁each ▁price ▁refers ▁to ▁a ▁unique ▁set ▁of ▁circumstances . ▁If ▁the ▁Aust ri ans ▁are ▁correct , ▁there ▁can ▁really ▁be ▁nothing ▁" object ive " ▁about ▁the ▁" stat ist ical ▁outcome " — it ▁is ▁merely ▁an ▁interpretation ▁based ▁on ▁numerous ▁valu ation ▁assumptions . ▁ ▁Marx ▁himself ▁thought ▁that ▁the ▁concept ▁of ▁value ▁was ▁necessary ▁to ▁explain ▁the ▁historical ▁orig ins , ▁the ▁development ▁and ▁mode ▁of ▁function ing ▁of ▁capital ism ▁as ▁a ▁social ▁system , ▁under ▁conditions ▁where ▁trad ed , ▁pr iced ▁assets ▁were ▁only ▁a ▁subset ▁of ▁total ▁assets ▁possess ing ▁a ▁potential ▁exchange - value . ▁Short - term ▁price ▁fl uct u ations ▁could ▁not ▁say ▁anything ▁about ▁the ▁long - term ▁development ▁of ▁the ▁capital ist ▁production ▁system ; ▁that ▁required ▁an ▁analysis ▁of ▁the ▁determin ants ▁of ▁long - term ▁average ▁price ▁movements , ▁and ▁struct ural ▁factors . ▁According ▁to ▁primitive ▁econom ics , ▁all ▁prices ▁are ▁of ▁the ▁same ▁kind ▁and ▁differ ▁only ▁quant it atively ; ▁they ▁only ▁express ▁more ▁or ▁less ▁money , ▁and ▁can ▁only ▁go ▁up ▁or ▁down . ▁For ▁Marx , ▁this ▁idea ▁was ▁not ▁only ▁false , ▁but ▁totally ▁abs urd , ▁since ▁different ▁kinds ▁of ▁prices ▁can ▁assume ▁different ▁valu ation ▁principles , ▁contract