The fundamental intuitions that are essential to the process of thinking,must be temporarily accepted as unquestionable: leaving the assumption oftheir unquestionableness to be justified by the results. §40. How is it to be justified by the results? As any other assumptionis justified -- by ascertaining that all the conclusions deducible from itcorrespond with the facts as directly observed -- by showing the agreementbetween the experiences. There is no mode of establishing the validity ofany belief except that of showing its congruity with all other beliefs. Ifwe suppose that a mass which has a certain colour and lustre is the substancecalled gold, how do we proceed to prove that it is gold? We represent toourselves certain other impressions which gold produces on us, and then observewhether, under the appropriate conditions, this particular mass produceson us such impressions. We remember that gold has a high specific gravity;and if, on poising this substance on the finger, we find that its weightis great considering its bulk, we take the correspondence between the representedimpression and the presented impression as further evidence that the substanceis gold. Knowing that gold, unlike most metals, is insoluble in nitric acid,we imagine to ourselves a drop of nitric acid placed on the surface of thisyellow, glittering, heavy substance, without causing corrosion; and when,after so placing a drop of nitric acid, no effervescence or other changefollows, we hold this agreement between the anticipation and the experienceto be an additional reason for thinking that the substance is gold. And if,similarly, the great malleability assessed by gold we find to be paralleledby the great malleability of this substance; if, like gold, it fuses at about2,000 deg.; crystallizes in octahedrons; is dissolved by selenic acid; and,under all conditions, does what gold does under such conditions; the convictionthat it is gold reaches what we regard as the highest certainty -- we knowit to be gold in the fullest sense of knowing. For, as we here see, our wholeknowledge of gold consists in nothing more than the consciousness of a definiteset of impressions, standing in definite relations, disclosed under definiteconditions; and if, in a present experience, the impressions, relations,and conditions, perfectly correspond with those in past experiences, thecognition has all the validity of which it is capable. So that, generalizingthe statement, hypotheses, down even to those simple ones which we make frommoment to moment in our acts of recognition, are verified when entire congruityis found between the states of consciousness constituting them, and certainother states of consciousness given in perception, or reflection, or both;and no other knowledge is possible for us than that which consists of theconsciousness of such congruities and their correlative incongruities.

Hence Philosophy, compelled to make those fundamental assumptions withoutwhich thought is impossible, has to justify them by showing their congruitywith all other dicta of consciousness. Debarred as we are from everythingbeyond the relative, truth, raised to its highest form, can be for us nothingmore than perfect agreement, throughout the whole range of our experience,between those representations of things which we distinguish as ideal andthose presentations of things which we distinguish as real. If, by discoveringa proposition to be untrue, we mean nothing more than discovering a differencebetween a thing inferred and a thing perceived; then a body of conclusionsin which no such difference anywhere occurs, must be what we mean by an entirelytrue body of conclusions.

And here, indeed, it becomes also obvious that, setting out with thesefundamental intuitions provisionally assumed to be true, the process of provingor disproving their congruity with all other dicta of consciousness becomesthe business of Philosophy; and the complete establishment of the congruitybecomes the same thing as the complete unification of knowledge in whichPhilosophy reaches its goal. §41. What is this datum, or rather, what are these data, which Philosophycannot do without? Clearly one primordial datum is involved in the foregoingstatement. Already by implication we have assumed that congruities and incongruitiesexist, and are cognizable by us. We cannot avoid accepting as true the verdictof consciousness that some manifestations are like one mother md some areunlike one another. Unless consciousness be a competent judge of the likenessand unlikeness of its states, there can never be established that congruitythroughout the whole of our cognitions which constitutes Philosophy; norcan there ever be established that incongruity by which only any hypothesis,Philosophical or other, can be shown erroneous.

It is useless to say, as Sir W. Hamilton does, that "consciousnessis to be presumed trustworthy until proved mendacious." It cannot beproved mendacious in this, its primordial act; since proof involves a repeatedaCceptance of this primordial act. Nay more, the very thing supposed to beproved cannot be expressed without recognizing this primordial act as valid;since unless we accept the verdict of consciousness that they differ, mendacityand trustworthiness become identical. Process and product of reasoning bothdisappear in the absence of this assumption.

It may, indeed, be often shown that what, after careless comparison, weresupposed to be like states of consciousness, are really unlike; or that whatwere carelessly supposed to be unlike, are really like. But how is this shown?