andwhichwillgivetohissystemnotsuchunityasarisesfromthedevelopmentofanabstractlogicalprinciple，butsuchasisintroducedintothephysicalscienceswhenweareabletorangealltheindefinitelycomplexphenomenawhichariseundersomesimplelawofforce。IfBentham’saimcouldhavebeenachieved，’utility’wouldhavebeeninlegislativetheorieswhatgravitationisinastronomicaltheories。Allhumanconductbeingruledbypainandpleasure，wecouldcompareallmotivesandactions，andtraceouttheconsequencesofanygivenlaw。Ishallhavehereaftertoconsiderhowthisconceptionworkedindifferentmindsandwasappliedtodifferentproblems：whatwerethetenableresultstowhichitled，andwhatweretheerrorscausedbytheimpliedovernightofsomeessentialconsiderations。
Certainweaknessesarealmosttooobvioustobespecified。Heclaimedtobeconstructingascience，comparabletothephysicalsciences。Theattemptwasobviouslychimericalifwearetotakeitseriously。Themakeshiftdoctrinewhichhesubstitutesforpsychologywouldbeasufficientproofoftheincapacityforhistask。HehadprobablynotreadsuchwritersasHartleyorCondillac，whomighthavesuggestedsomeostensiblysystematictheory。Ifhehadlittlepsychologyhehadnotevenaconceptionof’sociology。’The’felicificcalculus’
isenoughtoshowtheinadequacyofhismethod。Thepurposeistoenableustocalculatetheeffectsofaproposedlaw。Youproposetosendrobberstothegallowsorthegaol。Youmust，saysBentham，reckonupalltheevilsprevented：thesufferingtotherobbed，andtothosewhoexpecttoberobbed，ontheonehand；and，ontheother，theevilscaused，thesufferingtotherobber，andtothetax-payerwhokeepstheconstable；thenstrikeyourbalanceandmakeyourlawiftheevilspreventedexceedtheevilscaused。Somesuchcalculationisdemandedbyplaincommonsense。Itpointstothelineofinquirydesirable。Butcanitbeadequate?Toestimatetheutilityofalawwemusttakeintoaccountallits’effects。’Whatarethe’effects’ofalawagainstrobbery?Theyareallthatisimpliedinthesecurityofproperty。TheycorrespondtothedifferencebetweenEnglandintheeighteenthcenturyandEnglandinthetimeofHengistandHorsa；betweenacountrywherethesupremacyoflawisestablished，andacountrystillundertheruleofthestronghand。Bentham’smethodmaybeapplicableatagivenmoment，whenthesocialstructureisalreadyconsolidatedanduniform。Itwouldrepresentthepracticalargumentsforestablishingthepolice-forcedemandedbyColquhoun，andshowthedisadvantagesoftheoldconstablesandwatchmen。Bentham，thatis，givesanadmirablemethodforsettlingdetailsofadministrativeandlegislativemachinery，anddealingwithparticularcaseswhenoncethemainprinciplesoflawandorderareestablished。Thoseprinciples，too，maydependupon’utility。’
bututilitymustbetakeninawidersensewhenwehavetodealwiththefundamentalquestions。Wemustconsiderthe’utility’ofthewholeorganisation，notthefitnessofseparatedetails。Finally，ifBenthamisweakinpsychologyandinsociology，heisclearlynotsatisfactoryinethics。Moralityis，accordingtohim，onthesameplanewithlaw。Thedifferenceisnotinthespheretowhichtheyapply，orintheendtowhichtheyaredirected；butsolelyinthe’sanction。’Thelegislatorusesthreatsofphysicalsuffering；
themoralistthreatsof’popular’disapproval。Either’sanction’maybemostapplicabletoagivencase；butthequestionismerelybetweendifferentmeanstothesameendundervaryingconditions。Thisimpliesthe’external’