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preservefullemployment。WithoutthisassumptionProfessorPigou\'sanalysisbreaksdownandprovidesnomeansofdeterminingwhatthevolumeofemploymentwillbe。Itis，indeed，strangethatProfessorPigoushouldhavesupposedthathecouldfurnishatheoryofunemploymentwhichinvolvesnoreferenceatalltochangesintherateofinvestmenti。e。tochangesinemploymentinthenon-wage-goodsindustriesdue，nottoachangeinthesupplyfunctionoflabour，buttochangesine。g。eithertherateofinterestorthestateofconfidence。
Histitlethe\'TheoryofUnemployment\'is，therefore，somethingofamisnomer。Hisbookisnotreallyconcernedwiththissubject。Itisadiscussionofhowmuchemploymenttherewillbe，giventhesupplyfunctionoflabour，whentheconditionsforfullemploymentaresatisfied。Thepurposeoftheconceptoftheelasticityoftherealdemandforlabourintheaggregateistoshowbyhowmuchfullemploymentwillriseorfallcorrespondingtoagivenshiftinthesupplyfunctionoflabour。Or¾；alternativelyandperhapsbetter¾；wemayregardhisbookasanon-causativeinvestigationintothefunctionalrelationshipwhichdetermineswhatlevelofrealwageswillcorrespondtoanygivenlevelofemployment。Butitisnotcapableoftellinguswhatdeterminestheactuallevelofemployment；andontheproblemofinvoluntaryunemploymentithasnodirectbearing。
IfProfessorPigouweretodenythepossibilityofinvoluntaryunemploymentinthesenseinwhichIhavedefineditabove，as，perhaps，hewould，itisstilldifficulttoseehowhisanalysiscouldbeapplied。Forhisomissiontodiscusswhatdeterminestheconnectionbetweenxandy，i。e。betweenemploymentinthewage-goodsandnon-wage-goodsindustriesrespectively，stillremainsfatal。
Moreover，heagreesthatwithincertainlimitslabourinfactoftenstipulates，notforagivenrealwage，butforagivenmoney-wage。ButinthiscasethesupplyfunctionoflabourisnotafunctionofF\'x