Inthefirstplace，itmustbenoticedthatthetheoryitselfhadbeenalreadyemphaticallystatedbyDestuttdeTracy。HamiltonaccusesBrownofplagiarism。21Whetherhisaccusationbejustifiableornot，itiscertainlytruethatBrownhadinsomewayreachedthesameprincipleswhichhadbeenalreadysetforthbyaleading’ideologist’Brown，thatis，thoughtheofficialexponentoftheScottishphilosophy，wasinthisphilosophicaltenetatonewiththeschoolwhichtheyregardedasmaterialisticorsceptical，thepathbywhichhereacheshisconclusionsisalsocharacteristic。
BrownhasreversedtheinterpretationofReid’sexperimentumcrucis，Iwillgiveupmycase，saysReid，ifyoucanmaketheexternalworldoutofsensations，that，repliesBrown，ispreciselywhatwecando。HowfromsensationsdowegetwhatBerkeleycalled’outness’?Wegetit，saysBrown，fromthesenseofresistanceor’impededeffort，’thatrevealstousthefactthatthereissomethingindependentofourselves，andthebeliefinsuchasomethingispreciselywhatwemean，andallthatwemean，bythebeliefinanexternalworld。，Consistentlywiththis，BrownrejectsReid’sdistinctionbetweentheprimaryandsecondaryqualities。Thedistinctioncorrespondsnodoubttosomerealdifferences，butthereisnodifferenceofthekindsuggestedbyReid。’All[thequalities]
arerelativeandequallyrelative——ourperceptionofextensionandresistanceasmuchasourperceptionoffragranceandbitterness。’22Weascribethesensationsto’externalobjects，’buttheobjectsareonlyknownbythe’medium’ofoursensations。Inotherwords，thewholeworldmayberegardedasasetofsensations，whetherofsight，smell，touch，orresistancetomuscularmovement，accompaniedbythebeliefthattheyarecausedbysomethingnotourselves，andofwhichsomethingwecanonlysaythatitisnotourselves。
Oncemore，theanalysisoftheprocessbywhichthebeliefisgeneratedissignificant。Fromresistance，orthesensationproducedwhensomething’resistsourattemptstograspit，’wegetthe’outness，’thenperceptionis’nothingmorethantheassociationofthiscomplexnotionwithourothersensations——thenotionofsomethingextendedandresisting，suggestedbythesesensations，whenthesuggestionsthemselveshavepreviouslyarisen，andsuggestedinthesamemannerandonthesameprincipleasanyotherassociatefeelingsuggestsanyotherassociatefeeling。’23Theodourorcolourofaroserecallsthesensationoftouchingandofresistancetoourgrasp。Thusweregardthewholegroupofsensationsasduetotheexternalcausewhichproducesthesensationofresistance。Brownseemstohesitatealittleastowhetherheshallappealtoan’intuition’orto’association，’but’asIratherthink，’hesays，thebeliefisfounded’onassociationsaspowerfulasintuition，’24
Whatever，then，maybetheoriginofthebelief——’intuition’or’association’——itisclearthatitcangiveusnoknowledgeexceptsuchasisderivedfromsensations。