Front Page Titles (by Subject) CHAPTER I.: METHOD. - The Principles of Psychology
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CHAPTER I.: METHOD. - Herbert Spencer, The Principles of Psychology 
The Principles of Psychology (London: Longman, Brown, Green and Longmans, 1855).
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§ 106. It is a dominant characteristic of Intelligence, viewed in its successive stages of evolution, that its processes, which, as originally performed, were not accompanied with a consciousness of the manner in which they were performed, or of their adaptation to the ends achieved, become eventually both conscious and systematic. Not simply is this seen on comparing the actions popularly distinguished as instinctive and rational; but it is seen on comparing the successive phases of rationality itself. Thus, children reason, but do not know it. Youths know empirically what reason is, and when they are reasoning. Cultivated adults reason intentionally, with a view to certain results. The more advanced of such presently inquire after what manner they reason. And finally, a few reach a state in which they consciously conform their reasonings to those logical principles which analysis discloses. Clearly to exhibit this law of mental progress, and to show the extent of its application, sundry illustrations may be cited.
Classification supplies us with one. All intelligent action presupposes a grouping together of things possessing like properties. To know what is eatable and what not; which creatures to pursue and which to fly; what materials are fit for these purposes and what for those; alike imply the arrangement of objects into classes of such nature, that from certain sensible characteristics of each, certain other characteristics are foreseen. It is manifest that throughout all life, brute and human, more or less of this discrimination is exercised; that it is more exercised by higher creatures than by lower; and that successful action is in part dependent on the extent to which it is pushed. Now it needs but to open a work on Chemistry, Mineralogy, Botany, or Zoology, to see how this classification which the child, the savage, and the peasant, carry on spontaneously, and without thinking what they are doing, is carried on by men of science systematically, knowingly, and with deliberate purpose. It needs but to watch their respective proceedings, to see that the degrees of likeness and unlikeness, which unconsciously guide the ignorant in forming classes and subclasses, are consciously used by the cultured to the same end. And it needs but to contrast the less advanced men of science with the more advanced, to see that this process of making groups, which the first pursue with but little perception of its ultimate use, is pursued by the last with clear ideas of its value as a means of achieving higher objects.
So too is it with nomenclatures. Few will hesitate to admit that in the first stages of language, things were named incidentally—not from a recognition of the value of names as facilitating communication; but under the pressure of particular ideas which it was desired to convey. The poverty of aboriginal tongues, which contain words only for the commonest and most conspicuous objects, serves of itself to show, that systems of verbal signs were, in the beginning, unconsciously extended as far only as necessity impelled. Now, however, nomenclatures are made intentionally. A new star, a new island, a new mineral, a new plant or animal, are severally named by their discoverers as soon as found; and are so named with more or less comprehension of the purpose which names subserve. Moreover it may be remarked that whereas, in the primitive unconscious process of naming, the symbols employed were, as far as might be, descriptive of the things signified; so, in our artificial systems of names—and especially in our chemical one—a descriptive character has been designedly given. Add to which, that whereas there spontaneously grew up in natural nomenclatures, certain habitual ways of combining and inflecting names to indicate composite and modified objects; so, in the nomenclatures of science, systematic modes of forming compound names have been consciously adopted.
Again, a similar progress may be traced in the making of inductions. As is now commonly acknowledged, all general truths are either immediately or mediately inductive—are either themselves derived from aggregations of observed facts, or are deduced from truths that are so derived. The grouping together of the like coexistences and sequences presented by experience, and the formation of a belief that future coexistences and sequences will resemble past ones, is the common type of all initial inferences, whether they be those of the infant or the philosopher. Up to the time of the Greeks, mankind had pursued this process of forming conclusions, unknowingly, as the mass of them pursue it still. Aristotle recognized the fact that certain classes of conclusions were thus formed; and to some extent taught the necessity of so forming them. But it was not until Bacon lived, that the generalization of experiences was erected into a method. Now, however, that all educated men are in a sense Bacon's disciples, we may daily see followed out systematically, and with design, in the investigations of science, those same mental operations which mankind at large have all along unwittingly gone through, in gaining their commonest knowledge of surrounding things. And further, in the valuable “System of Logic” of John Mill, we have now exhibited to us in an organized form, those more complex intellectual procedures which acute thinkers have ever employed, to some extent, in verifying the aboriginal inductive process—procedures which the most advanced inquirers are now beginning to employ with premeditation, and with a recognition of their nature and their purpose.
Another illustration may be drawn from the first part of this work. On reconsidering the chapter treating of the Universal Postulate, it will be seen that the canon of belief there enunciated as the one to be used in testing every premiss, every step in an argument, every conclusion, is one which men have from the beginning used to these ends; that beliefs which are proved by the inconceivableness of their negations to invariably exist, men have, of necessity, always held to be true, though they have not knowingly done this; and that the step remaining to be taken, was simply to apply this test consciously and systematically. It will also be seen that the like may be said of the second canon of belief contained in that chapter; viz. that the certainty of any conclusion is great, in proportion as the assumptions of the Universal Postulate made in reaching it are few. For as was pointed out (§ 8), people in general habitually show but little confidence in results reached by elaborate calculations, or by long chains of reasoning; whilst they habitually show the greatest confidence in results reached by direct perception; and these contrasted classes of results are those which respectively presuppose very many and very few assumptions of the Universal Postulate. In this case therefore, as in the other, the rational criterion is simply the popular criterion analyzed, systematized, and applied with premeditation.
In further exemplification of this law I might enlarge upon the fact, that having found habit to generate facility, we intentionally habituate ourselves to those acts in which facility is desired; upon the fact, that having seen how the mind masters its problems by proceeding from the simple to the complex, we now consciously pursue our scientific inquiries in the same order; upon the fact, that having, in our social operations, spontaneously fallen into division of labour, we now, in any new undertaking, introduce division of labour intentionally. But without multiplying illustrations, it will by this time be sufficiently clear, that, as above said, not only between the so-called instinctive processes and rational ones, is there a difference in respect of the consciousness with which they are performed, but there are analogous differences between the successive gradations of rationality itself.
§ 107. Are we not here then, led to a general doctrine of methods? In each of the cases cited, we see an arranged course of action deliberately pursued with a view to special ends—a method; and on inquiring how one of these methods differs from any conscious intelligent procedure not dignified by the title, we find that it differs only in length and complication. Neglecting this distinction as a merely conventional one—ceasing to regard methods objectively, as written down in books, and regarding them subjectively, as elaborate modes of operation by which the mind reaches certain results—we shall see that they may properly be considered as the highest self-conscious manifestations of the rational faculty. And if, viewed analytically, all methods are simply complex intellectual processes, standing towards conscious reasoning much as conscious reasoning stands towards unconscious reasoning, and as unconscious reasoning stands towards processes lower in the scale—if further, in the several instances above given, methods arose by the systematization and deliberate carrying out of mental operations which were before irregularly and unwittingly pursued—may we not fairly infer that all methods arise after this manner? That they become methods, when the processes they embody have been so frequently repeated as to assume an organized form? And that it is the frequent repetition, which serves alike to give them definiteness, and to attract consciousness to them as processes by which certain ends have been achieved. Is it not indeed obvious, à priori, that no method can be practicable to the intellect save one which harmonizes with its pre-established modes of action? Is it not obvious that the conception of a method by its promulgator implies in the experiences of his own mind, cases in which he has successfully followed such method? Is it not obvious that the advance he makes, consists in observing the processes through which his mind passed on those occasions, and generalizing and arranging them into a system? And is it not then obvious that, both in respect of origin and applicability, no method is possible but such as consists of an orderly and habitual use of the procedures which the intellect spontaneously pursues, but pursues fitfully, incompletely, and unconsciously? The answers can scarcely be doubtful.
By thus carrying consciousness a stage higher, and recognizing the method by which methods are evolved, we may perhaps see our way to further devices in aid of scientific inquiry. As in the case of deductive logic, and classification, and nomenclature, and induction, and the rest, it happened that by becoming conscious of the mode in which the mind wrought in these directions, men were enabled to organize its workings, and consequently to reach results previously unattainable; so, it is possible that by becoming conscious of the method by which methods are formed, we may be assisted in our search after further methods. If in the instances given, the method of forming methods was that of observing the operations by which from time to time the mind spontaneously achieved its ends, and arranging these into a general scheme of action to be constantly followed in analogous cases; then, in whatever directions our modes of inquiry are at present unmethodized, our policy must be to trace the steps by which success is occasionally achieved in these directions; in the hope that by so doing, we may be enabled to frame systems of procedure which shall render future successes more or less sure. That there is scope for this cannot be doubted. On remembering how much, even of the best thinking, is done in an irregular way; how little of the whole chain of thought by which a discovery is made, is included in the bare logical processes; and how unorganized is the part not so included; it will be manifest that there are intellectual operations still remaining to be methodized. And here may fitly be introduced an example, to which, in fact, the foregoing considerations are in a manner introductory.
§ 108. Every generalization is at first an hypothesis. In seeking out the law of any class of phenomena, it is needful to make assumptions respecting it, and then to gather evidence to prove the truth or untruth of the assumptions. The most rigorous adherent of the inductive method, cannot dispense with such assumptions; seeing that without them, he can neither know what facts to look for, nor how to interrogate such facts as he may have. Hypotheses, then, being the indispensable stepping-stones to generalizations—every generalization having to pass through the hypothetic stage—it becomes a question whether there exists any mode of guiding ourselves towards true hypotheses. At present, hypotheses are chosen unsystematically—are suggested by cursory inspections of the phenomena; and the seizing of right ones, seems, in the great majority of cases, a matter of accident. May we not infer however, from the peculiar skill which some men have displayed in the selection of true hypotheses, that there is a special kind of intellectual action by which they are distinguishable. To call the faculty shown by such men, genius, or intuition, is merely to elude the question. If mental phenomena conform to fixed laws, then, an unusual skill in choosing true hypotheses, means nothing else than an unusual tendency to pursue that mental process by which true hypotheses are reached; and this implies that such a process exists.
To identify this process is the problem: to find how, when seeking the law of any group of phenomena, we may make a probable assumption respecting them—how we may guide ourselves to a point of view from which the facts to be generalized can be seen in their fundamental relations. Evidently, as the thing wanted is always an unknown thing, the only possible guidance must be that arising from a foreknowledge of whereabouts it is to be found, or of its general aspect, or of both. If all true generalizations (excluding the merely empirical ones) should possess a peculiarity in common; and this peculiarity should be one not difficult of recognition; the desired guidance may be had. That such a peculiarity exists, will by this time have been inferred; and it now remains to inquire what it is.
§ 109. Most are familiar with the observation, that viewed in one of its chief aspects, scientific progress is constantly towards larger and larger generalizations—towards generalizations, that is, which include the generalizations previously established. Further, the remark has been made, that every true generalization commonly affords an explanation of some other series of facts than the series out of the investigation of which it originated. In both of which propositions we have partial statements of the truth, that each onward step in science is achieved when a group of phenomena to be generalized is brought under the same generalization with some connate group previously considered separate. Let us look at a few cases.
In the Calculus it was thus, when the relationships of extension, linear, superficial, and solid, were found to conform to the same law with those of numbers that are multiplied into each other; and again, when numbers themselves, whether representing spaces, forces, times, objects, or what not, were found to possess certain general properties, capable of being expressed algebraically, which remain the same whatever the magnitudes of the numbers. In Mechanics it was thus, when a formula was discovered which brought the equilibrium of the scales, under the same generalization with the equilibrium of the lever with unequal arms: and again, when the discovery that fluids press equally in all directions, afforded explanations, alike of their uniform tendency towards horizontality, and of their power to support floating bodies. Thus too was it in Astronomy, when the apparently erratic movements of the planets, and the comparatively regular movement of the moon, were explained as both due to similar orbital revolutions; and when the celestial motions, and the falling of rain-drops, were explained as different manifestations of the same force. It was thus in Optics, when the composite nature of light was discovered to be the passive cause of the prismatic spectrum, of the rainbow, and of the colours of objects; in Thermotics, when the expansion of mercury, the rising of smoke, and the boiling of water, were recognized as different manifestations of the same law of expansion by heat; in Acoustics, when the doctrine of undulations was found to apply equally to the phenomena of harmonies, of discords, of pulses, of sympathetic vibrations. Similarly, it was thus in Chemistry, when the burning of coal, the rusting of iron, and the wasting away of starved animals, were generalized as instances of oxidation. It was thus too, when the electro-positive and electro-negative relations of the elements, were brought in elucidation of their chemical affinities. And once more it was thus, when, by the investigations of Œrsted and Ampère, the phenomena of Electricity and Magnetism were reduced to the same category; and the behaviour of the magnetic needle was assimilated to that of a needle subjected to the influence of artificial electric currents.
Now this circumstance, that a true generalization usually brings within one formula groups of phenomena which at first sight seem unallied, is itself a more or less reliable index of the truth of a generalization. For manifestly, to have found for any series of facts, a law which equally applies to some apparently distinct series, implies that we have laid hold of a truth more general than the truths presented by either series regarded separately—more general than the truths which give the special character to either series. If, in the instances above cited, and in hosts of others, we find that the most general fact displayed by any class of phenomena, is also the most general fact displayed by another class, or by several other classes; then, we may conversely infer, on finding a general fact to be true of several cases in each of two separate classes, that there is considerable probability of its being true of all the cases in each class. Or, to exhibit the proposition in another form:—A peculiarity observed to be common to cases that are widely distinct, is more likely to be a fundamental peculiarity, than one which is observed to be common to cases that are nearly related.
Hence, then, is deducible, a method of guiding ourselves towards true hypotheses. For if a characteristic seen equally in instances usually placed in different categories, is more likely to be a general characteristic than one seen equally in instances belonging to the same category; then, it is obviously our policy, when seeking the most general characteristic of any category, not to compare the instances contained in it with each other, but to compare them with instances contained in some allied category. We must seek out all the categories with which alliance is probable; compare some of the phenomena included in each with some of the phenomena under investigation; ascertain by each comparison what there is common to both kinds; and then, if there be any characteristic common to both, inquire whether it is common to all the phenomena we are aiming to generalize: in doing which we may with advantage still act out the same principle, by comparing first the cases that are most strongly contrasted. The adoption of this course secures two advantages. Not only must any peculiarity which may be hit upon, as common to phenomena of separate classes, have a greater probability of being a generic peculiarity, than any one of the many peculiarities possessed in common by phenomena of the same class; but further, we shall be more likely to observe all that there is in common between diverse phenomena placed side by side, than we shall to observe all that there is in common between phenomena so much alike as to be classed together. Fewer hypotheses are possible; all that are possible are likely to be thought of; and of those thought of, each has a much higher chance of being true.
§ 110. And now let us avail ourselves of this method, in searching out a generalization on which to base a synthetic Psychology. We have seen that it is a characteristic of progressive intelligence, eventually to perform consciously, processes which were originally performed unconsciously. We have seen that this truth is illustrated by the erecting into systematic modes of procedure, those higher mental operations which had before been followed irregularly and unconsciously. We have seen that by consciously pursuing this method by which methods are arrived at, there is a probability that further methods may be reached. We have sought by doing this, to find a method of choosing probable hypotheses; and have reached a definite conclusion. Here, leaving these preliminary inquiries, it remains to take advantage of this conclusion in commencing the investigation before us.