▁not ▁see ▁the ▁world wide ▁co operation ▁of ▁labour - eff ort s ▁that ▁produced ▁it ▁at ▁a ▁certain ▁cost , ▁yet ▁those ▁labour ▁efforts , ▁we ighed ▁against ▁other ▁labour ▁efforts , ▁determine ▁its ▁value . ▁ ▁Aust rian ▁econom ics ▁explicitly ▁reject s ▁the ▁object ivity ▁of ▁the ▁values ▁of ▁goods ▁as ▁log ically ▁and ▁concept ually ▁uns ound . ▁On ▁this ▁view , ▁we ▁cannot ▁valid ly ▁say ▁that ▁products ▁took ▁a ▁certain ▁amount ▁of ▁labour , ▁energy ▁and ▁materials ▁to ▁make , ▁and ▁compare ▁them ▁on ▁that ▁basis . ▁It ▁follows ▁that ▁the ▁Aust rian ▁School ▁thinks ▁most ▁contemporary ▁economic ▁theory ▁is ▁invalid , ▁as ▁it ▁re lies ▁in ▁one ▁way ▁or ▁another ▁on ▁the ▁aggreg ation ▁and ▁comparison ▁of ▁actual ▁and ▁ideal ▁prices . ▁This ▁is ▁force fully ▁argued ▁by ▁Friedrich ▁von ▁Hay ek ▁who ▁therefore ▁was ▁ske pt ical ▁about ▁the ▁object ivity ▁of ▁macro e conom ic ▁aggreg ations ▁as ▁such . ▁However , ▁this ▁ra ises ▁the ▁question ▁of ▁" what ▁is ▁the ▁explan atory ▁power ▁of ▁Aust rian ▁econom ics ", ▁if ▁all ▁we ▁can ▁say ▁about ▁a ▁realized ▁price ▁is ▁that ▁it ▁express es ▁a ▁subject ive ▁preference , ▁given ▁that ▁there ▁are ▁bill ions ▁of ▁subject ive ▁prefer ences ▁which ▁are ▁all ▁different . ▁ ▁E colog ists ▁and ▁environmental ists ▁have ▁critic ized ▁Marx ▁on ▁the ▁ground ▁that ▁natural ▁resources ▁have ▁( or ▁should ▁have ) ▁a ▁value ▁which ▁has ▁nothing ▁to ▁do ▁with ▁production ▁costs ▁in ▁labour ▁time , ▁because