Wasnotthedisproofreal?Doesnotarealevasionlurkunderthephrase’tendency’?Youmaysaythattheearthhasatendencytofallintothesun，andanother’tendency’tomoveawayfromthesun。Butitwouldbeabsurdtoarguethatwewerethereforeindangerofbeingburntorofbeingfrozen。Toexplainthelawofavitalprocess，wemayhavetoanalyseit，andthereforetoregarditasduetoconflictingforces；buttheforcesdonotreallyexistseparately，andinconsideringthewholeconcretephenomenonwemusttakethemasmutuallyimplied。Amanhasa’tendency’togrowtoofat；andanother’tendency’togrowtoothin。Thatsurelymeansthatonthewholehehasa’tendency’topreservethedesirablemean。Thephrase，then，canonlyhaveadistinctmeaningwhentheconflictingforcesrepresenttwoindependentorreallyseparableforces。TouseanillustrationgivenbyMalthus，wemightsaythatamanhada’tendency’togrowupwards；butwasrestrainedbyaweightonhishead。Themanhasthe’tendency，’becausewemayregardtheweightasaseparableaccident。Whenbothforcesareoftheessence，theseparate，tendencies，correspondmerelytoourwayofanalysingthefact。Butifonecanbeproperlyregardedasrelativelyaccidental，the’tendency’meansthewayinwhichtheotherwillmanifestitselfinactualcases。
In1829，SeniorputthispointtoMalthus。25What，heasked，doyouunderstandbya’tendency’
whenyouadmitthatthetendencyisnormallyoverbalancedbyothers?Malthusexplainshismeaningtobethateverynationsuffersfromevils’specificallyarisingfromthepressureofpopulationagainstfood。’Thewagesofthelabourerinoldcountrieshaveneverbeensufficienttoenablehimtomaintainalargefamilyatease。Thereisovercrowding，wemaysay，inEnglandnowastherewasinEnglandattheConquest；thoughfoodhasincreasedinagreaterproportionthanpopulation；andthepressurehasthereforetakenamilderform。This，again，isprovedbythefactthat，wheneverarelaxationofthepressurehasoccurred，whenplagueshavediminishedpopulation，orimprovementsinagricultureincreasedtheirsupplyoffood，thegaphasbeenatoncefilledup。Thepeoplehavenottakenadvantageofthetemporaryrelaxationofthechecktopreservethenewequilibrium，buthavetakenouttheimprovementbyamultiplicationofnumbers。Thestatementthenappearstobethatatanygiventimethepopulationisinexcess。
Menwouldbebetteroffiftheywerelessnumerous。But，ontheotherhand，thetendencytomultiplydoesnotrepresentaconstantforce，anirresistibleinstinctwhichwillalwaysbringmendowntothesamelevel，butsomethingwhich，infact，mayvarymaterially。Malthusadmits，infact，thatthe’elasticity’iscontinuallychanging；andthereforerepudiatestheinterpretationwhichseemedtomakeallimprovementhopeless。Why，then，distinguishthe’check’assomethingapartfromtheinstinct?If，inanycase，weacceptthisexplanation，doesnotthetheorybecomea’truism，’oratleastacommonplace，inoffensivebuthardlyinstructive?Doesitamounttomorethantheobviousstatementthatprudenceandforesightaredesirableandareunfortunatelyscarce?
III。MORALRESTRAINT