Thusheregardsthe’physiologicalmetaphysicsofthepresentday’asan’idlewasteoflabourandingenuityonquestionstowhichthehumanmindisaltogetherincompetent。’39*TheprinciplesfoundbyinductiveobservationareasindependentofthesespeculationsasNewton’stheoryofgravitationofanultimatemechanicalcauseofgravitation。
Hartley’sfollowers，however，coulddropthe’vibration’theory；andtheirdoctrinethenbecameoneof’associationofideas。’Tothisfamoustheory，whichbecamethesheet-anchoroftheempiricalschool，Stewartisnotaltogetheropposed。Wefindhimspeakingof’indissolubleassociation’inlanguagewhichremindsusoftheMills。40*Humehadspokenofassociationascomparabletogravitation——thesoleprinciplebywhichour’ideas’and’impressions’
arecombinedintoawhole；atheory，ofcourse，correspondingtohisdoctrineof’belief’asamerecustomofassociating。StewartusestheprincipleratherasLockehaddone，asexplainingfallaciesdueto’casualassociations。’
Itsupposes，ashesays，thepreviousexistenceofcertainprinciples，andcannotbeanultimateexplanation。Theonlyquestioncanbeatwhatpointwehavereachedan’originalprinciple，’andarethereforeboundtostopouranalysis。41*Overthisquestionheglidesrathertoolightly，asishiscustom；butfromhispointofviewthebelief，forexample，inanexternalworld，cannotbeexplainedbyassociation，inasmuchasitrevealsitselfasanultimatedatum。
Inregardtothephysicalsciences，then，Stewart’spositionapproximatesverycloselytothepurely’empirical’view。Whenwecometoadifferentapplicationofhisprinciples，wefindhimtakingacuriouslybalancedpositionbetweendifferentschools。’Commonsense’naturallywishestoadaptitselftogenerallyacceptedbeliefs；andwithsoflexibleadoctrineasthatof’intuitions’itisnotdifficulttodiscovermethodsofprovingtheordinarydogmas。Stewart’stheologyischaracteristicofthistendency。Hedescribestheso-calledaprioriproof，asformulatedbyClarke。Butwithoutdenyingitsforce，hedoesnotliketolaystressuponit。Hedreads’ontology’toomuch。Hethereforeconsidersthattheargumentatoncemostsatisfactorytothephilosopherandmostconvincingtoordinarymenistheargumentfromdesign。ThebeliefinGodisnot’intuitive，’butfollowsimmediatelyfromtwofirstprinciples：theprinciplethatwhateverexistshasacause，andtheprinciplethata’combinationofmeansimpliesadesigner。’42*Thebeliefinacausearisesonourperceptionofchangeasourbeliefintheexternalworldarisesuponoursensations。Thebeliefindesignmustbea’firstprinciple’becauseitincludesabeliefin’necessity’whichcannotarisefrommereobservationof’contingenttruths。’43*HenceStewartacceptsthetheoryoffinalcausesasstatedbyPaley。ThoughPaley’sethicsoffendedhim，hehasnothingbutpraisefortheworkuponNaturalTheology。44*Thus，although’commonsense’doesnotenableustolaydownthecentraldoctrineoftheologyasaprimarytruth，itdoesenableustointerpretexperienceintheologicalterms。Inotherwords，histheologyisofthepurelyempiricalkind，whichwas，asweshallsee，thegeneralcharacteristicofthetime。