Thereseemtobefourconditions，thecompletefulfilmentofwhichwouldestablishasignificantproposition，apparentlyself-evident，inthehighestdegreeofcertaintyattainable:andwhichmustbeapproximatelyrealisedbythepremisesofourreasoninginanyinquiry，ifthatreasoningistoleaduscogentlytotrustworthyconclusions。
I。Thetermsofthepropositionmustbeclearandprecise。TherivaloriginatorsofmodernMethodology，DescartesandBacon，viewitheachotherinthestressthattheylayonthispoint；andthelatter’swarningagainstthe``notionesmaleterminatæ；’’ofordinarythoughtispeculiarlyneededinethicaldiscussion。InfactmychiefbusinessintheprecedingsurveyhasbeentofreethecommontermsofEthics，asfaraspossible，fromobjectiononthisscore。
II。Theself-evidenceofthepropositionmustbeascertainedbycarefulreflection。Itisneedfultoinsistonthis，becausemostpersonsareliabletoconfoundintuitions，ontheonehandwithmereimpressionsorimpulses，whichtocarefulobservationdonotpresentthemselvesasclaimingtobedictatesofReason；andontheotherhand，withmereopinions，towhichthefamiliaritythatcomesfromfrequenthearingandrepetitionoftengivesafalseappearanceofself-evidencewhichattentivereflectiondisperses。InsuchcasestheCartesianmethodoftestingtheultimatepremisesofourreasonings，byaskingourselvesifweclearlyanddistinctlyapprehendthemtobetrue，maybeofrealuse；thoughitdoesnot，asDescartessupposed，affordacompleteprotectionagainsterror。
Arigorousdemandforself-evidenceinourpremisesisavaluableprotectionagainstthemisleadinginfluenceofourownirrationalimpulsesonourjudgments:whileatthesametimeitnotonlydistinguishesasinadequatethemereexternalsupportofauthorityandtradition，butalsoexcludesthemoresubtleandlatenteffectoftheseinfashioningourmindstoafacileandunquestioningadmissionofcommonbutunwarrantedassumptions。
AndwemayobservethattheapplicationofthistestisespeciallyneededinEthics。