(1) Evidentiary grounds of belief are (a) memory, which is plainly indispensable if we are to learn by experience; and (b) testimony, which must be trusted if language is not to be useless and social co-operation impossible: both these grounds are supposed to rest upon the primary rock of previous perception, but are slippery and treacherous. Memory is only valid so far as it truthfully represents original experience, and testimony only so far as it presents (i) a valid memory, (ii) correctly reported. Hence in serious matters precautions must be taken against their fallibility: otherwise they are not good evidence. A specious memory, so far as it is false, is imagination; and false testimony, so far as it reports (i) a false memory or (ii) an invention of the reporter, is also imagination. Testimony gathers force, as a cause of belief, with the numbers and consideration of those who support it, and is especially strengthened by their unanimity; but, as a ground of belief, it depends only on their knowledge and truthfulness. A third ground of belief is (c) inference; which is necessary to all original adjustment of our conduct to the future or to unperceived circumstances, but highly fallible, and constituting the chief problem for the exercise of Logic when that science arises: especially to explain the conditions of valid observations and experiments, of probability, of the conclusion of an argument being covered by its premises, and of the sufficiency of verification. False inferences that cannot be verified are imaginations.
As the growing mind of society deals with true beliefs they are piled up and classified in systems of science and philosophy: in which systems each belief or judgment strengthens and is strengthened by the rest. Even without systematisation, the mere structural similarity of judgments, formed unconsciously on the same implicit principles of causation and classification, throws them into those loose apperceptive masses which we call “common sense.” Such systems or masses, whether of science or of common sense, readily assimilate and confirm new inferences having the same character, and offer resistance to all inferences having a different structure, such as those about magic and spirits. The selective power of these apperceptive masses over novel ideas constitutes “understanding,” and is the plain solid man’s substitute for Logic; and so it is with many scientists, who often neglect the abstract study of Logic. For these systems or masses of experience are the substance of Logic and Methodology, which are their skeletons abstracted from them. They are the basis of all effective comparison and criticism; agreement or disagreement with them is the test of truth or error. It is the chief defect of common sense that the verification of its judgments depends almost entirely upon repetition of experiences (what Logicians call “simple enumeration”), without that analysis of observations which alone can show the necessary relations of facts; but this defect is in some measure remedied in good minds by that power of unformulated ideas of natural order, the result of unconscious analysis, which we call “good judgment”—a power which the fortunate possessor may be unable to explain.
(2) Non-evidentiary causes of belief are all reducible to bad observations, imaginations, and the causes that excite imagination; and bad observations are caused by false imaginations as to the meaning of sense-data. If it should seem to any one that since imagination consists of ideas it must be by nature incompatible with intense belief, we must consider that memory, the effects of testimony, and inferences also consist entirely of ideas; so that in that character they do not differ from imagination. Even perception depends for its meaning upon implicit ideas, and erroneous perception is due to erroneous ideas. The weakness of imagination-belief which (despite its frequent intensity) always in time becomes manifest, is due to its not being constantly confirmed by experience.
In detail the non-evidentiary causes of belief are as follows: (a) not only the truths of experience become massed or systematised in common sense and science, but the errors of misinterpreted experience and tradition form similar aggregates. Coincidences mistaken for causation, illusions, dreams, tales of thaumaturgy and ghost-stories, so far as they have anything in common in their outlines or emotional tone, form apperceptive masses which function in the same way as scientific systems: each of their constituent beliefs strengthens and is strengthened by the rest; and each mass (as a delusive “understanding”) readily assimilates and confirms any new tale or illusion having its own character, and resists and repels every judgment having a different structure—and, therefore, refuses explanation. And just as science and common sense have a sort of internal skeleton of principles which has been exhibited as Logic, so some of these comparatively obscure and chaotic masses of illusion and tradition contain certain structural principles which, though unconscious at the lowest human level, obtain recognition as culture advances—for example, the principles of mimetic and contagious magic; and then, too, arise such caricatures of science as theogonies and cosmologies, chiromancy, astrology and so forth. But nothing ever emerges from them that can be called a test of truth or methodology; much less, of course, can such a thing be found at lower levels of culture. There you see the accumulating clouds of imagination-belief, which gather together from all the winds and pile themselves up to overshadow poor humanity age after age; which still, in our own world, are by no means dissipated; and to whose persistent influence we may (I suppose) attribute the mysticism that periodically infects philosophy itself.
(b) Contributory to these masses of error are bad observations, confused and distorted memories, dreams and corrupted testimony and tradition, all of them having their origin in some sort of experience and matter-of-fact, and all issuing in vain imaginations. For of course there is no such thing as imagination underived from experience; experience is distorted and corrupted by superstition, but it transfers to superstition the attitude of belief that always belongs to experience, and supplies materials from which (as we shall see) it is often possible to construct such a defence of superstition as, to an unsophisticated mind, must be very plausible and persuasive.[86] Direct experience is often interpreted by a story in such a way as to make the story more credible. If a stone is shown as marking the tomb of a hero, or a cleft in the mountain as proving the prowess of a wizard, one unconsciously transfers the attitude of belief involved in contemplating these relics to all the legends concerning those mighty men of old.
(c) The causes determining belief are reinforced in various ways by feeling and emotion. The agreeableness or disagreeableness of any judgment draws attention to, or diverts it from such a judgment and the evidence for it: except that some disagreeable emotions, especially fear, by a sort of fascination of attention, are favourable to belief in the reality of an imagined evil. They possess the whole mind.
(d) Every desire fixes attention upon beliefs favourable to it, and upon any evidence favourable to them, and diverts attention from conflicting beliefs and considerations. Thus every desire readily forms about itself a relatively isolated mass of beliefs, which resists comparison and, therefore (as Ribot says),[87] does not recognise the principle of contradiction. Incompatible desires may be cherished without our becoming aware of their incompatibility; or, if the fact obtrudes itself upon us, we repudiate it and turn away.
The more immature a mind, again, and the less knowledge it has, the less inhibition of desire is exerted by foresight of consequences that ought to awaken conflicting desires or fears; and the less compassion one has, the less is desire inhibited by its probable consequences to others: therefore, in both cases, the less check there is upon belief.
(e) Voluntary action in connection with any belief, whether of a rational kind or in the routine of rites and ceremonies, favours that belief: (1) by establishing the idea-circuit of means and end, the end suggesting the means to it, and the thought of means running forward to the end—a circuit that resists interruption: (2) by the general effect of habit and prejudice; for every habit of action or of thought has inertia, and, moreover, it is agreeable, and to break it is disagreeable; so that, again, a relatively isolated system is formed, which resists comparison and criticism.
On the influence of desire and of activities for an end depends “the will to believe.” We cannot believe anything by directly willing it; but we can will what to attend to, or what to do, and that determines belief.