THE SIGNIFICANT MOVEMENT OF THOUGHT known as the Enlightenment, or Aufklärung, falls in the main within the period of the eighteenth century. It is seldom, however, that the turn of a century happens to coincide exactly with the beginning or the end of a great epoch, either political, religious or philosophical. The period in philosophy which is referred to in a general way as the eighteenth century begins virtually in the year 1690 with the publication of Locke famous Essay Concerning Human Understanding, and is brought to its close in the year 1781 with the appearance of Kant Critique of Pure Reason. They are the natural boundaries of this “philosophical century.”
It was an age characterised by a restless spirit of inquiry — a century of challenge. A new life was awake and stirred in the minds of men. Traditions which had been long venerated became the objects of searching investigation and criticism. The authority of the church, of the state and of the school was no longer regarded as the court of last appeal. The old beliefs which failed to justify themselves at the bar of reason were discarded. The foundations of time-honoured systems seemed shifting and uncertain. There was an insistent demand for the free play of the individual judgment. There was, also, a constant reference to the light of reason, the inner illumination shining bright and clear in contrast to the shadows of mysticism, or to the false and flickering light of dogmatism. Hence the name of the age of illumination, or enlightenment, — the name, also, of the age of reason.
In this period there was more particularly a spirit of protest against metaphysical speculation, that is, against all attempts to explain the phenomena of human existence in any manner which transcends the ordinary processes of reason, and consequently possesses no firm foundation of reality. And reality, in turn, was conceived as that which is akin to nature and to the general course of natural phenomena as perceived through the channels of the various senses. There was an attempt to reduce the problems of thought to the basis of extreme simplicity, and to make a common-sense view of things everywhere prevail.
The spirit of the age might find characteristic expression in some such words as these: Let us not concern ourselves with idle speculation in reference to things which the mind of man can never compass and understand. Why busy ourselves concerning the deeper significance and purpose of nature which our thought is utterly incapable of penetrating? While we may observe and classify the phenomena of nature, and formulate the laws of their behaviour, we can never hope to comprehend their inner meaning, forever veiled and obscure. Nature, which seems so near — of which, indeed, we ourselves are a part —nevertheless lies far beyond our ken. And the being and nature of God, who must be regarded as dwelling in a sphere far out and beyond the outermost bounds of nature, must remain still more incomprehensible. If we cannot understand the inscrutable mysteries’ of the world which we have seen, much less the mystery of God whom we have not seen. From the contemplation, therefore, of the world and of God, we must turn our eyes to the more rewarding study of the inner self. Let every man examine the phenomena of life as they unfold themselves within this inner world of his own consciousness. Here at least is the light in which he can see light. To every one who thus mines the treasures of his own nature there must come the quiet satisfaction of being able to insist, I know myself. Such is the spirit of this age. It is reflected in Pope’s line,
“The proper study of mankind is man.”
In this search after knowledge, while inquiry was introspective, it was not by any means reflective. It lacked penetration, and while moving freely and thoroughly in a careful surface investigation, it was never able to fathom and explore the lower depths of thought.
It was a restricted area of inquiry, therefore, which the philosophy of the Enlightenment set for itself. If in this region, it was urged, there can be found no evidence for the existence of God, then faith must not hold what reason cannot prove; if there are no immutable principles of morality clearly attested, then man must be content with a working ethic of prudence and expediency; if there are no intimations of immortality, one can at least live in the fulness of the present; if the foundations of the state are shaken, then let the state itself fall with them; but in spite of what may be lost or of what may be saved, let no one’s convictions transcend the actual and indisputable facts upon which they are observed to rest. Let man once for all penetrate “the mist and veil of words,” and get at the truth of things. If there is no appeal to “the god of things as they are,” there is, at least, the appeal direct to things as they are themselves.
With all of its obvious limitations and defects, this method of inquiry was nevertheless frank, openminded and ingenuous. The right of individual opinion was respected; a spirit of tolerance prevailed; and philosophy was afforded a free forum.
The key-note of the age was set by John Locke scholar of Christ Church, Oxford, trained in the diplomatic service, widely travelled, secretary of the first Earl of Shaftesbury, a profound student of the theory of government, champion of toleration, a man of affairs, and withal a philosopher, whose habit of mind fitted him in an eminent degree to deal with speculative problems from a practical point of view. In his Essay Concerning Human Understanding, Locke insists that all knowledge comes to us from two sources only — from sensation and reflection. Therefore we ought scrupulously to eliminate from our philosophy everything which it is not possible to trace to this elemental origin. Aught else of speculation, of sentiment or of opinion rests upon a basis of fancy and not of fact. All inquiry, consequently, must be limited to the problems which arise in this field. Beyond these lies not only the undiscovered country, but the undiscoverable as well.
The world of knowledge from this point of view shows a variety of manifold forms, but is of one and the same substance throughout, namely, that which is constantly supplied by the ceaseless activity of the senses. Thus we find the problem of knowledge reduced to its lowest terms. By restricting the area of knowledge, the area of difficulty is likewise diminished; for many perplexing problems are thus eliminated, and a common-sense method of interpreting actually observed facts of experience commends itself as involving only clear ideas which all mankind can understand and appreciate. It was, indeed, a characteristic feature of this age, the demand that all ideas should be clear and self-illuminating. It was a part of the heritage which had come to that generation from Descartes, who had emphatically insisted that clear and distinct ideas are to be regarded as the sole test of truth. Locke placed before his own mind the same standard, and sought to realise it by a simplification of the sources of knowledge. It is here that the development of thought in the age of the Enlightenment had its beginning.
The history of this development illustrates certain fundamental principles concerning the progress of thought which are not only of interest in themselves, but will serve also to stimulate the critical insight and appreciation of any one who undertakes the serious study of this period of philosophy. We find in the eighteenth century a great movement of thought, which furnishes us a basis for an historical study of the theory of knowledge. But this is not all. It may be regarded also as the type of great thought movements in general. It has in this respect peculiarly a representative value; for if we interpret aright the controlling forces which underlie this development, and the various phases of their manifestation, there will be disclosed, in rough outline at least, the programme which every progressive movement of thought tends to follow. There are three stages of such a development. The first is that in which some significant idea finds expression, and, because not yet fully developed, it is necessarily partial, one-sided or extreme. The second stage is that of controversy. The idea must be subjected to a running fire of criticism. Whatever it may conceal as contradictory, incoherent or absurd, will thus be brought to light. The third stage is always a period of reconstruction, wherein contradictions are resolved, limitations are removed, and whatever may have been inadequate is completed by supplying the complementary elements which were wanting in the original doctrine or theory. This Hegelian procedure is illustrated in the progress of philosophical thought which the eighteenth century produced. And such a method of thought development is by no means a fanciful conceit of Hegel’s. It is a process which is familiar to every one who, in his own thinking, has become conscious of the expanding and transforming stages through which his various opinions have passed, from the initial assertion, through the testing of criticism and controversy, until the final reconstruction and restatement of the original belief is reached.
At the beginning of such a development as that which the eighteenth century exhibits, the content of philosophical thought is reduced to a minimum. Its simplicity, however, is that of a germ possessing in a high degree the potential of an exceedingly complex growth. Any idea which starts a great movement of thought must be subjected to the practical test of its power to adapt itself to all possible varieties of mental environment. It must be received into many and various types of minds; it must adjust itself to many different temperaments, and be regarded from many points of view. It is only in this manner that its full significance can be revealed, and its true worth adequately appreciated. In this period of trying out, whatever is potential in the initial idea will be rendered actual; its logical implications will be made explicit, and their necessary consequences set forth in a rigorous and complete manner; whatever is partial will be revealed, and all latent error will be eliminated.
This is exactly what occurred in reference to Locke’s fundamental contention that we know only that which comes through the avenues of the senses, and what may follow from reflection upon the material which is thus furnished. An exceedingly simple statement of the sources of knowledge. But there is no statement, however simple, which is not beset with difficulties and which may not become the subject of radical differences of opinion, and possibly of heated controversy. This simple statement of the Lockian theory of knowledge experienced two diametrically opposite phases of development, which in itself indicates its indefiniteness and incompleteness. One of these phases was essentially idealistic and the other materialistic, and each in turn grounded in the original premisses of Locke concerning the sources of knowledge.
The idealistic interpretation is represented by Bishop Berkeley. Starting from Locke’s stand-point that the elemental springs of knowledge are to be traced to the sensations, Berkeley insists that inasmuch as every sensation is an experience occurring in the individual consciousness, it must be composed, therefore, at the last analysis, of that which is mental and not physical. Whatever appears in consciousness must partake of the character of the very element in which it appears. As to the physical object of sensation which is supposed to be outside of us and is regarded crudely as its cause, we know absolutely nothing. We know only the passing phenomena of consciousness whose parts are fashioned of mental elements or thought entities. To say, as Locke does, that we know only sensations originally, means, therefore, according to Berkeley’s interpretation, that we know merely the objects of knowledge as they appear to us in consciousness, wrought of the elements of the mind only. Ideas, therefore, are the stuff out of which our experience is formed. While Locke had said that there was some external object corresponding to every perception, although its true nature could never be known to the observing mind, Berkeley insists that there is no external object to know other than the idea in the mind. Our ideas which come to us through sense perception do not represent a world lying beyond them; they are that world itself.
At the same time and, strangely enough, under the same influence, there developed a sensationalistic philosophy, which in its extreme form drifted inevitably into materialism. It flourished not only on British soil, but survived its transplanting into France, and with the changed environment gained in vigour and extent. In England this phase of the movement is represented by Hartley, Priestley, Erasmus Darwin and others; in France by that brilliant coterie of writers who gave to the world the French Encyclopædia and the revolutionary philosophy. Of this group the most pronounced in the creed of materialism were Diderot, Helvetius and Holbach.
Here surely is an anomaly. How can the same premisses yield so widely different conclusions? How can Locke’s empirical beginnings develop on the one hand into Berkeley’s idealism, and on the other into Holbach’s materialistic and atheistic Le Sysètme de la nature? The situation, however, is not an impossible one. Upon a closer consideration, it will be seen to be both logical and natural. For we may lay it down as a general principle characteristic of every great movement of thought that, starting from a statement which is merely a partial expression of the complete truth, it must necessarily give rise to opposed results according to radical differences in the point of view and the method of interpretation. Moreover, every movement of thought must find its beginnings in some partial and indefinite expression of truth; for if it should start with a complete statement of truth, it would then be absurd to expect any possible development of it.
This, therefore, may be regarded as the first characteristic of every significant movement of thought, an initial doctrine, regarded from a single and circumscribed point of view, developing diametrically opposed conclusions. The simplicity of the original statement thus at once breaks up in the process of interpretation and elaboration into a complexity of contradictory opinions, and these contradictions clearly prove the original incompleteness.
The inadequacy of the beginnings of thought may also be illustrated more directly and particularly by. showing that the conclusions which logically follow from them are unsatisfactory as a final explanation, and that the seemingly firm foundations upon which they rest are shifting and uncertain. In reference to the philosophical position of Locke, we find the task of exposing its fundamental weakness falling to the lot of David Hume. The philosophy of Hume is a natural reaction from the extreme position of Berkeley, and at the same time its logical outcome. Because of the unsatisfactory results which Hume reaches in the logical unfolding of Locke’s theory of knowledge, his attitude becomes one of radical scepticism. If Berkeley’s position is tenable that Locke’s doctrine leaves us only ideas as the material of our knowledge, then, Hume insists, we may, it is true, construct these elemental ideas into a world in which we can live and move and have our being; but we have no assurance whatsoever that the component elements are held together by any bonds of necessary connection, or that they possess any inherent substantiality. We think that there are real substances, individually separate and distinct, and we think there is some underlying relation of cause and effect which is the cohesive tie uniting them all into a system of interdependent parts. But such a way of looking at things is only a convenient mental habit which we take for granted as a matter of course, because we have never paused seriously to question it. We must remember that our thinking it true does not make it true, and that the most obvious assumption which the mind may entertain does not of itself guarantee its trustworthiness. Berkeley was correct in denying the existence of matter, Hume would say, but he should have gone further and have denied also the reality of ideas themselves as regards their substantial essence, and their necessary connection in any system of knowledge.
This negative criticism, which in itself marks no real progress of thought, is nevertheless an exceedingly important factor in any such progress. It shows the inadequacy of half truths, and sweeps the board of all inconsistencies and confusions of thought. If nothing remains, that very fact of itself is of advantage in inciting to renewed effort along lines which will swing clear of initial misconceptions, unwarrantable assumptions and partial premises. As Descartes has very wisely said: “Those who travel very slowly may yet make far greater progress, provided they keep always to the straight road, than those who, however well they run, forsake it.”
Thus, if an initial idea leads through the various phases of its logical unfolding to an untenable position, then by this process of a reductio ad absurdum, the original idea itself must be challenged at its source. This is Hume’s peculiar contribution — that of enlightening the thought of the eighteenth century as to the inadequacy of Locke’s foundations of knowledge as interpreted by Berkeley. Inasmuch, therefore, as Locke’s position, that we know only sensations as the beginning of all knowledge, seems to lead on one hand to an extreme idealism, and on the other to extreme materialism, or else to a point of view of radical scepticism, we are naturally forced to the conclusion that Locke must have overlooked an essential and significant factor in his account of the sources of knowledge. Is there any trace of such a factor in the midst of the eighteenth century philosophy? There undoubtedly is. For when the influence of Locke Essay began to be felt in Germany, and his empirical philosophy had gained a hearing and a following as well, there came into conflict with it an opposite stream of tendency in philosophical thinking which may be traced through Leibniz to Spinoza and Descartes, and which in the eighteenth century was represented most conspicuously in the philosophy of Wolff, namely, that of rationalism.
The point of view of rationalism has regard particularly to the nature of reason itself. It insists that there are certain clear and distinct ideas native to the very character of thought which serve as a body of primary truths from which it is possible to develop by logical procedure an entire system of philosophical dogma. Moreover, such a system is supposed to sketch, in broad outline at least, the general field of knowledge. During the latter half of the eighteenth century this method of philosophical thought had developed an extreme philosophical position, and under the dominance of Wolff’s mechanical and artificial habit of mind had become a system of dry-as-dust scholastic formulae. It was a body of knowledge, but lacked the breath of life.
Through these opposed tendencies of empiricism and rationalism, each forced by the momentum of thought to an extreme expression, the way was prepared for a complete reconstruction of philosophical doctrine which was achieved by the genius of Immanuel Kant. His masterly insight discovered in the empiricism of Locke the germs of rationalism, and in the rationalism of Liebniz the potential elements of empiricism.
It was Hume whose scepticism first impressed Kant with the unsatisfactory results of the traditional methods of philosophical thinking, and opened before him the new way. The office of a sceptic in philosophy is most perfectly illustrated in the influence which Hume exerted upon the mind of Kant, leading him in the first place to a destructive analysis of the philosophical dogma in which he had been schooled, and then beyond that to the more serious task of constructive interpretation. Scepticism as an essential moment in the philosophy of the Enlightenment expresses not a final goal, but merely a transition stage in the progress of reflective thought.
Kant’s problem was that of marking the precise limits of empiricism and rationalism, and of demonstrating thereby their complementary rather than contradictory nature. He examines the extreme positions of empiricism and rationalism, and then proceeds to build into a single system whatever elements of truth these seemingly opposed doctrines contain.
This marks the third stage of the movement of thought, the construction of a fully rounded body of truth by filling out the half truth which marks its initial expression. The antithesis of a rationalistic and an empirical philosophy was reconciled in the Kantian synthesis, according to which the material of our ideas is furnished by the senses in its crude state, but the form which this material is constrained to take in consciousness is the labour of the reason. As Kant succinctly puts it, “ideas without any perception by the senses are empty, but mere sensations without ideas are blind.” Upon the raw material of sensation the mind brings to bear its organising and constructing activity, ordering all things according to the compulsion of its own nature. We are in error when we say that we receive impressions through the avenues of the senses. The mind is never passive, but actively creative in every sense perception, however simple and elemental it may appear. A merely receptive experience, therefore, may not be regarded as the sole beginning of knowledge, for the experience is nothing without the thought which renders the elements of experience intelligible. Mere sensations in themselves, or any combination which may be made of them, can never produce a body of knowledge any more than crude ore can fashion itself into a curiously chased jewel. The simple sensation as the primal element of knowledge is a philosophical fiction. The simplest possible sensation at its first appearance in consciousness is already indefinitely complex, shot through and through with the threads of necessary connections and relations determined by the very nature of the thought processes in whose medium it necessarily comes into being. This, accordingly, is Kant’s peculiar office, that of uniting these two opposed points of view, the empirical and the rational, upon a higher plane, wherein the elements of truth in each may be harmoniously conserved and ordered according to their mutual relations and functions.
Moreover, Kant also insisted most emphatically that such a position as that of Locke’s was too circumscribed, and therefore could not represent in any adequate manner the full wealth of our conscious life. The tendency of the following of Locke in France, and in Germany as well, had been to emphasise unduly the function of reason as they conceived it. It is true, Kant confesses, that by the pure reason we can come to know only the phenomena of experience, the world of appearance; and no activity of the speculative reason is able to transcend this surface show of things, and reveal the substantial nature and significance of things as they are in themselves, the world of reality. But it must not be overlooked that there is also the practical reason, that quality of reason which feels and wills and acts, yet, nevertheless, maintains its essential character as reason. In this view Kant was influenced to no small extent by the insistence of Rousseau, who protested most vehemently against the methods of the age of reason, and insisted that man must be regarded as something more than a mere logical machine. Under the stimulus of Rousseau, Kant was not slow to see that the world of experience is not a world of knowledge exclusively. It is a world, also, of values; a world of purpose and of achievement. We feel an instinctive need of certain fundamental concepts which will make such a world intelligible, and which, at the same time, will offer an adequate and worthy end for human endeavour. These concepts, or postulates, of the practical reason compose that Kantian trinity of ideas, namely, God, freedom and immortality.
This is the last phase in the development of thought which proceeded from Locke’s sensational basis of knowledge as its starting-point. And in the light of this development, there emerge certain general conclusions which indicate the fundamental characteristics of the necessities of thought. They are as follows:
It is impossible to solve a philosophical problem satisfactorily by reducing the area of difficulty. We may cut the knot, but we fail to disentangle it. It seems, at the first glance, to simplify philosophical difficulties incalculably, by drawing the line so as to exclude rigorously all metaphysical considerations; by endeavouring to beat out all perplexities in the sphere of the particular facts of experience; and by a method of common-sense interpretation of such facts for what they are worth in themselves and in accordance with their obvious face value. While such a procedure seems to be eminently fair, and is most attractive, appealing as it does to man’s instinctive predisposition to regard favourably any method which is simple and straightforward, nevertheless the post-Lockian development of philosophical thought demonstrates that the simple phenomena of experience are not self-explanatory. It is better to profess some principles of metaphysics rather than to repudiate them, and yet, at the same time, in the course of one’s thinking, unwittingly to assume them when under the pressure of logical necessity itself. Nothing leads to such confusion and obscurity of thought as the assumption of a crude metaphysic, the presence of which in one’s thinking is not recognised, and whose significance, therefore, as an essential and determining factor is not appreciated. Reduction to simplest terms is not necessarily explanation. This is the lesson of the Aufklärung on its speculative side.
Every philosophical movement, moreover, which possesses vitality should affect the life of an age on its practical side also. Otherwise it cannot be considered a great movement of thought. Philosophy is not of the school merely, although many seem to think that it is; it exercises a profound influence also upon the thought, and therefore upon the life, of a people, both directly and indirectly. This is illustrated in a marked degree by the philosophy of the Enlightenment. In France and Germany especially, philosophical questions were discussed generally by the people as well as by the scholarly class. There was everywhere during the latter half of the eighteenth century a popular demand for a “philosophy for the masses.” With the principles of Locke widely disseminated and discussed in the café and salon and even among the rank and file of the people generally, the empirical philosophy exerted a remarkable influence upon the religious, the moral and the political life of that age.
In religion there was an evident tendency toward deism, which, particularly in France, gradually drifted toward atheism.
In ethics the principles of utilitarianism prevailed, and became the dominant moral creed.
In politics there was a tendency toward extreme individualism, accompanied by an urgent plea for a return of man to the state of nature, and a protest against all existing institutions, social as well as political.
This practical development, it is evident, was the inevitable outcome of Locke’s position. The process is a logical one, from the premise that we know only that which is given to us by the activity of the senses, to the conclusion that, if God exists, it must be in a region quite beyond the world as we know it through experience. For God surely cannot be discovered in the sensory sources of knowledge, and therefore, if He exists at all, it must be in a sphere transcending a world which is composed wholly of original elements given in sensation. This is deism, and the way is not far from deism to atheism, and many there were in that age who found it. In France the logical outcome of the deistical trend of thought was the endeavour to substitute for the worship of a God, a religion of nature and a worship of reason.
The utilitarian basis of ethics also is related to the position of Locke; for starting with sensations as the sole source of knowledge, one comes instinctively to value sensations according to the pleasure or the pain which may accompany them. Consequently the pleasure or pain accompaniments of our sensations will be regarded naturally as the standards of conduct, and this is essentially the psychological ground of the ethic of utilitarianism. It is the practical working out in conduct of Locke’s theory of knowledge.
As regards the political phase of the philosophy of the Enlightenment, we find that the emphasis which that age placed upon the individual as the supreme tribunal of last appeal, turned the attention of all minds to the rights of the individual as against the traditional rights of the classes and the divine right of kings. The insistence upon a return to the fundamental basis of human nature as the primary source of knowledge was transferred to the sphere of politics by Rousseau, who urged a return, in a modified sense, to the natural state of man as the ideal of the communal as well as the individual life. Locke had likened the beginnings of all consciousness in the experience of the individual to a tabula rasa, a clean sheet, containing no record of the past, no hereditary tracings of predisposition, no potentiality of constructive and organising powers. Such a doctrine was peculiarly adaptable to the political disposition of that age, and met with a natural response in the general spirit of discontent with the old, and a yearning after a new order of things. The new order was to begin with a tabula rasa, a clean page, upon which to write the history of regenerate days.
As with the speculative ideas of this age, so also these more practical results were felt to be one-sided in their development. They, too, needed the correcting and supplementing influence of some larger comprehensive idea which should serve to unify them, a fundamental principle of truth whose office might prove constructive rather than destructive, capable of clearing the vision and of grounding conviction upon a surer foundation. Again, it was necessary to show that these most complex phenomena cannot be explained by reducing them to their lowest terms, and also that the final phase in the course of a progressive development is not to be explained merely by tracing it back to its elemental beginnings, but that these beginnings, the rather, are to be understood and interpreted in the light of the more complex results which grow out of them.
Here, again, Kant rendered an inestimable service. He found God not outside of the world but in it. He could not be conceived as dwelling apart from the world of thought and activity, but must be discovered in His central place, as author and governor of the moral order which constitutes our world of purpose and desire, a God immanent as well as transcendent. So, also, in protest against the utilitarian trend of his day, Kant insisted upon the recognition of the law of moral obligation, and upon a reverence of that law as the supreme standard of conduct. Such a principle cannot be reduced to the canons of prudence and expediency; it is a principle which it is impossible to trace to any naturalistic basis as its ground. It takes its rise in our moral consciousness. It becomes a constant and controlling power in our lives, subduing the wayward and whimsical sway of the senses. In the sphere of the body politic, moreover, Kant’s voice was raised in vehement protest against the prevalent doctrine which regarded man as essentially a creature whose desires are to receive fullest gratification, and whose maximum of happiness it is the office of government to secure. He, on the contrary, laid peculiar stress upon the dignity and worth of man regarded as a person, and upon the duties as well as the rights which grow out of this idea of personality. Man is not merely a bundle of sensory reactions, a child of nature impelled by the full flood of animal life, a thing, a means to an end; he is to be regarded always as an end in himself, and thereby responding to his vocation as a person in the deepest significance of that designation. Moreover, the individual is constrained, by his very nature as a rational being, to regard every other person as an end in himself, and never as a means to an end. It is a common inheritance such as this, and the appreciation of the responsibilities which it entails, that tend to bind mankind together in a society so strongly knit that it will prove capable of withstanding the shock of revolution as well as the ordinary disintegrating forces which sap a nation’s strength and vitality.
The tendencies which appear on a large scale in a great movement of thought are to be met with, also, on a smaller scale in the experience of every individual as he may endeavour to think himself out of the manifold difficulties which attend the formulation of a philosophy of life. These tendencies may be briefly summarised as the desire to reduce the area of perplexity in philosophical thinking to its minimum dimensions, the exclusion of metaphysical explanation, the tendency to develop an extreme position which reveals its own weakness, and, finally, the tendency to drift into an attitude of scepticism concerning all philosophical theories whatsoever. Then, if happily a reaction occurs, which indicates health and vigour of mind, there comes an inner compulsion to seek some comprehensive constructive principle by which the scattered fragments of a destructive criticism may be built anew upon solid foundations.
Kant himself passed through these several phases of thought in the development of his philosophical system. In his own experience he exhibits a recapitulation of the philosophical movement of his century. Early in his career he came under the influence of the traditional rationalism; later on he experienced a reaction due to the principles of the Lockian empiricism; and, finally, the influence of Hume helped to bring about a transition stage of scepticism, from which he eventually emerged upon that higher plane in which his constructive genius found free play and scope.
Every one who feels upon him the burden and mystery of life must pass through some such process of thought as this. For truth does not appear to us full formed, nor is she always clothed in the garb of simplicity, nor does she speak a language easy to understand. She must be wooed and won, in the face of difficulties and in spite of doubts, by the patient labour of the mind.
There is, moreover, in our day and generation as strong if not a stronger tendency to reduce all the experiences of our intellectual life to the simple basis of natural phenomena. It is the popular demand for a philosophy of naturalism. There is much talk at present of the science of ethics and of the science of religion; of a philosophy without a metaphysic, of a psychology without a soul. At the beginning of the twentieth century it would be well to reflect that the eighteenth century was confronted with certain problems in the process of the historical development of philosophical thought which were solved once for all. Chief among these historical conclusions is this, that, in addition to the phenomena of human nature, we are compelled to recognise some fundamental principle of reason which can give them unity, and present some worthy purpose as the end of their activity. Whatever that principle may be, whether the “synthetic unity of apperception,” according to Kant, or one of the “moments of the eternal spirit,” according to Hegel, or simply the ordering and organising power of the mind as we, in the habit of an old-fashioned view of things, have been wont to consider it, we are nevertheless constrained to recognise it as the supreme principle of reason, of feeling and of conduct.
THE BEGINNINGS OF THE PHILOSOPHICAL movement which is to be the subject of our study we find in Locke (1632- 1704). In the Essay Concerning Human Understanding Locke proposes to construct the world of knowledge by exhibiting its natural evolution from the original elements of experience as they appear in their simplest expression, to the most complex and abstruse ideas which the mind is capable of entertaining. He regards the process throughout as a continuous one, and also as self-explanatory. Upon this undertaking Locke enters with a most admirable spirit, being led to his inquiry through a sincere and impartial love of the truth; and actuated, moreover, by the desire to discover that truth by his own reason, freed from the trammels of authority and tradition. Some idea of the peculiar importance of Locke’s contribution to the history of philosophical thought may be gathered from a remark of A. Riehl: “The Essay Concerning Human Understanding marks not merely a new epoch in philosophy, but rather a new philosophy itself.” In the midst of a busy life, with its exacting demands and increasing burdens of responsibility, Locke found some quiet moments in which to question the workings of his own mind, and thereby discover, to some extent at least, the true nature of its mysterious functions.
The idea of this excursion into the undiscovered regions of the inner life of thought was suggested to him, in the first instance, by a chance discussion which arose among a group of his friends. The account which he himself gives of the origin of the Essay is of such interest that I venture to quote it at length: “Were it fit to trouble thee with the history of this Essay, I should tell thee that five or six friends meeting at my chamber (at the home of Lord Ashley (Shaftesbury), in Exeter House, London), and discoursing on a subject very remote from this, found themselves quickly at a stand by the difficulties that rose on every side. After we had awhile puzzled ourselves, without coming any nearer a resolution of those doubts which perplexed us, it came into my thoughts that we took a wrong course; and that before we set ourselves upon inquiries of that nature it was necessary to examine our own abilities, and see what objects our understandings were or were not fitted to deal with. This I proposed to the company, who all readily assented; and thereupon it was agreed that this should be our first inquiry. Some hasty and undigested thoughts on a subject I had never before considered, which I set down against our next meeting, gave the first entrance in this discourse; which, having been thus begun by chance, was continued by entreaty; written by incoherent parcels; and after long intervals of neglect, resumed again, as my humour or occasions permitted; and at last, in a retirement (in Holland) where an attendance on my health gave me leisure, it was brought into that order thou now seest it.”
“To examine our own abilities, and see what objects our understandings were or were not fitted to deal with,” is a task similar to that which Kant set for himself in the Critique of Pure Reason. In this respect Locke is the forerunner of Kant, but only in the sense that it was vouchsafed to him merely to behold the land from afar which, however, he was not able himself to possess. The Essay is a plea for the recognition of intellectual freedom, in much the same manner as his Epistola de Tolerentia is a plea for religious liberty, and his Treatises on Government, for political liberty. In the attempt, however, to free the mind from the domination of innate ideas, and to provide a clean page upon which to write the record of its own activity, he overlooked the significant truth that the mind cannot be made independent of itself, but must be determined by the necessities of its own nature. This is the point which Locke failed to grasp, and which, therefore, marks the fundamental defect of his otherwise masterly inquiry. For intellectual freedom can never be a freedom from the inner constraint of the processes of thought themselves, which like the pressure of the atmosphere are after all no obstacle to free movement, but the rather make such free movement possible. But criticism must not precede exposition. Therefore let us turn our attention to a more particular examination of the method and point of view of the Essay.
Locke’s method is essentially psychological; it is an attempt to trace the natural history of our ideas to their simplest beginnings in consciousness. And all speculations which reach beyond the scope of this method of inquiry Locke rigorously excludes. As to the purpose, and the corresponding limitations of the field of his investigations, Locke clearly states his position as follows: “It shall suffice to my present purpose to consider the discerning faculties of a man, as they are employed about the objects which they have to do with. And I shall imagine I have not wholly misemployed myself in the thoughts I shall have on this occasion if, in this historical plain method, I can give any account of the ways whereby our understandings come to attain those notions of things we have, and can set down any measures of the certainty of our knowledge. . . . If, by this inquiry into the nature of the understanding, I can discover the powers thereof; how far they reach; to what things they are in any degree proportionate; and where they fail us, I suppose it may be of use to prevail with the busy mind of man to be more cautious in meddling with things exceeding its comprehension; to stop when it is at the utmost extent of its tether; and to sit down in a quiet ignorance of those things which, upon examination, are found to be beyond the reach of our capacities. We should not then, perhaps, be so forward, out of an affectation of an universal knowledge, to raise questions, and perplex ourselves and others with disputes about things to which our understandings are not suited, and of which we cannot frame in our minds any clear or distinct impressions, or whereof (as it has perhaps too often happened) we have not any notions at all. . . . How far short soever men’s knowledge may come of an universal or perfect comprehension of whatsoever is, it yet secures their great concernments, that they have light enough to lead them to the knowledge of their Maker, and the sight of their own duties.”
I have quoted these passages in order to show in Locke’s own words his general conception of the undertaking before him, and as an illustration also of certain characteristic features of the philosophy of the Enlightenment in its empirical phase, namely, the insistence upon inquiry within the range of concrete facts, the demand that the various ideas corresponding to these facts must be distinct and clear, the silencing of all questions concerning matters too deep or too obscure for the human mind to comprehend, and the complete satisfaction in being able to frame at least a practical philosophy of life. The pragmatic point of view is evident throughout the Essay, as when Locke, for instance, insists later in the Introduction that “our business here is not to know all things, but those which concern our conduct. If we can find out those measures whereby a rational creature, put in that state in which man is in this world, may and ought to govern his opinions, and actions depending thereon, we need not be troubled that some other things escape our knowledge.”
The sources of all knowledge Locke finds in sensation and reflection. The first book of the Essay is devoted to his preliminary and fundamental contention that there are no innate ideas either speculative or practical. He then proceeds to show that the mind is like a dark room, wholly shut off from the light save through a single opening. Through this the light streams from a central source resident in the senses. Through this process of illumination there is a complete representation of things as they lie without the mind. They thus picture themselves upon the screen of consciousness. There is, therefore, an inner world of ideas, and an outer world of things which correspond to them. The inner world of consciousness is illumined by the light which enters from without. Locke’s figure of a dark cabinet with an opening to admit the light from the external world reminds one of Plato’s illustration of the cave, wherein the various forms outlined on the wall of the cavern are merely the shadow symbols of the real substances which they all too inadequately portray.
The one inlet through which the light enters from the outer world, according to Locke, is that of sensation. The senses furnish the elemental materials of all our knowledge, so that a man begins to have ideas when he first has any sensation.
In addition to sensation, which constitutes the external sense, there is an internal sense, that of reflection, which is to be regarded as the source of ideas also. By reflection Locke means “the perception of the operations of our own mind within us as it is employed about the ideas it has got; which operations, when the soul comes to reflect on, and consider, do furnish the understanding with another set of ideas which could not be had from things without. And such are perception, thinking, doubting, believing, reasoning, knowing, willing and all the different actings of our own mind.”
Reflection, therefore, is a term which is used by Locke to signify our consciousness of the nature of the active machinery of the mind. It is a consciousness, however, of processes merely, and not of their content. The actual content of knowledge is furnished by the senses, to which all of our ideas can be eventually traced. The operations of the mind, of which reflection makes us conscious, and the ideas which they furnish, are phrases sufficiently comprehensive in themselves, as well as sufficiently indefinite, to embrace any conceivable theory of knowledge whatsoever. Their meaning must be more specifically determined. The essential point, therefore, in reference to the system which we are to examine is this: What is the peculiar significance which Locke attaches to such phrases; and in what sense does he use them in his account of the process by which the higher and more complex forms of thought are developed out of the material presented to the mind through the simple experiences of sense perception? While it must be allowed that in addition to the primary sensations, as the source whence the materials of knowledge are constantly supplied, Locke also recognises the active powers of the mind as operative in constructing this material into an ordered body of knowledge; nevertheless, he fails to appreciate in any due sense the proper function of this activity, and the full significance of the rôle which it plays in the life of the intellect. It is in this respect that his theory of knowledge has proved inadequate, and has opened the way to misunderstandings and contradictions on the part of the many who have built upon his foundations.