When we come to the brutes, the case is distinctly worse. We think that we can attain to some notion of the minds to be attributed to such animals as the ape, the dog, the cat, the horse, and it is not nonsense to speak of an animal psychology. But who will undertake to tell us anything definite of the mind of a fly, a grasshopper, a snail, or a cuttlefish? That they have minds, or something like minds, we must believe; what their minds are like, a prudent man scarcely even attempts to say. In our distribution of minds may we stop short of even the very lowest animal organisms? It seems arbitrary to do so.
More than that; some thoughtful men have been led by the analogy between plant life and animal life to believe that something more or less remotely like the consciousness which we attribute to animals must be attributed also to plants. Upon this belief I shall not dwell, for here we are evidently at the limit of our knowledge, and are making the vaguest of guesses. No one pretends that we have even the beginnings of a plant psychology. At the same time, we must admit that organisms of all sorts do bear some analogy to each other, even if it be a remote one; and we must admit also that we cannot prove plants to be wholly devoid of a rudimentary consciousness of some sort.
As we begin with man and descend the scale of beings, we seem, in the upper part of the series, to be in no doubt that minds exist. Our only question is as to the precise contents of those minds. Further down we begin to ask ourselves whether anything like mind is revealed at all. That this should be so is to be expected. Our argument for other minds is the argument from analogy, and as we move down the scale our analogy grows more and more remote until it seems to fade out altogether. He who harbors doubts as to whether the plants enjoy some sort of psychic life, may well find those doubts intensified when he turns to study the crystal; and when he contemplates inorganic matter he should admit that the thread of his argument has become so attenuated that he cannot find it at all.
43. THE DOCTRINE OF MIND-STUFF.—Nevertheless, there have been those who have attributed something like consciousness even to inorganic matter. If the doctrine of evolution be true, argues Professor Clifford,[4] "we shall have along the line of the human pedigree a series of imperceptible steps connecting inorganic matter with ourselves. To the later members of that series we must undoubtedly ascribe consciousness, although it must, of course, have been simpler than our own. But where are we to stop? In the case of organisms of a certain complexity, consciousness is inferred. As we go back along the line, the complexity of the organism and of its nerve-action insensibly diminishes; and for the first part of our course we see reason to think that the complexity of consciousness insensibly diminishes also. But if we make a jump, say to the tunicate mollusks, we see no reason there to infer the existence of consciousness at all. Yet not only is it impossible to point out a place where any sudden break takes place, but it is contrary to all the natural training of our minds to suppose a breach of continuity so great."
We must not, says Clifford, admit any breach of continuity. We must assume that consciousness is a complex of elementary feelings, "or rather of those remoter elements which cannot even be felt, but of which the simplest feeling is built up." We must assume that such elementary facts go along with the action of every organism, however simple; but we must assume also that it is only when the organism has reached a certain complexity of nervous structure that the complex of psychic facts reaches the degree of complication that we call Consciousness.
So much for the assumption of something like mind in the mollusk, where Clifford cannot find direct evidence of mind. But the argument does not stop here: "As the line of ascent is unbroken, and must end at last in inorganic matter, we have no choice but to admit that every motion of matter is simultaneous with some . . . fact or event which might be part of a consciousness."
Of the universal distribution of the elementary constituents of mind Clifford writes as follows: "That element of which, as we have seen, even the simplest feeling is a complex, I shall call Mind-stuff. A moving molecule of inorganic matter does not possess mind or consciousness; but it possesses a small piece of mind-stuff. When molecules are so combined together as to form the film on the under side of a jellyfish, the elements of mind-stuff which go along with them are so combined as to form the faint beginnings of Sentience. When the molecules are so combined as to form the brain and nervous system of a vertebrate, the corresponding elements of mind-stuff are so combined as to form some kind of consciousness; that is to say, changes in the complex which take place at the same time get so linked together that the repetition of one implies the repetition of the other. When matter takes the complex form of a living human brain, the corresponding mind-stuff takes the form of a human consciousness, having intelligence and volition."
This is the famous mind-stuff doctrine. It is not a scientific doctrine, for it rests on wholly unproved assumptions. It is a play of the speculative fancy, and has its source in the author's strong desire to fit mental phenomena into some general evolutionary scheme. As he is a parallelist, and cannot make of physical phenomena and of mental one single series of causes and effects, he must attain his end by making the mental series complete and independent in itself. To do this, he is forced to make several very startling assumptions:—
(1) We have seen that there is evidence that there is consciousness somewhere—it is revealed by certain bodies. Clifford assumes consciousness, or rather its raw material, mind-stuff, to be everywhere. For this assumption we have not a whit of evidence.
(2) To make of the stuff thus attained a satisfactory evolutionary series, he is compelled to assume that mental phenomena are related to each other much as physical phenomena are related to each other. This notion he had from Spinoza, who held that, just as all that takes place in the physical world must be accounted for by a reference to physical causes, so all happenings in the world of ideas must be accounted for by a reference to mental causes, i.e. to ideas. For this assumption there is no more evidence than for the former.
(3) Finally, to bring the mental phenomena we are familiar with, sensations of color, sound, touch, taste, etc., into this evolutionary scheme, he is forced to assume that all such mental phenomena are made up of elements which do not belong to these classes at all, of something that "cannot even be felt." For this assumption there is as little evidence as there is for the other two.
The fact is that the mind-stuff doctrine is a castle in the air. It is too fanciful and arbitrary to take seriously. It is much better to come back to a more sober view of things, and to hold that there is evidence that other minds exist, but no evidence that every material thing is animated. If we cannot fit this into our evolutionary scheme, perhaps it is well to reexamine our evolutionary scheme, and to see whether some misconception may not attach to that.
[1] "Collected Essays," Vol. I, p. 219, New York, 1902.
[2] "On the Nature of Things-in-Themselves," in "Lectures and Essays," Vol. II.
[3] "Examination of Sir William Hamilton's Philosophy," Chapter XII.
[4] "On the Nature of Things-in-Themselves."
CHAPTER XI
OTHER PROBLEMS OF WORLD AND MIND
44. IS THE MATERIAL WORLD A MECHANISM?—So far we have concerned ourselves with certain leading problems touching the external world and the mind,—problems which seem to present themselves unavoidably to those who enter upon the path of reflection. And we have seen, I hope, that there is much truth, as well as some misconception, contained in the rather vague opinions of the plain man.
But the problems that we have taken up by no means exhaust the series of those that present themselves to one who thinks with patience and persistency. When we have decided that men are not mistaken in believing that an external world is presented in their experience; when we have corrected our first crude notions of what this world is, and have cleared away some confusions from our conceptions of space and time; when we have attained to a reasonably clear view of the nature of the mind, and of the nature of its connection with the body; when we have escaped from a tumble into the absurd doctrine that no mind exists save our own, and have turned our backs upon the rash speculations of the adherents of "mind-stuff"; there still remain many points upon which we should like to have definite information.
In the present chapter I shall take up and turn over a few of these, but it must not be supposed that one can get more than a glimpse of them within such narrow limits. First of all we will raise the question whether it is permissible to regard the material world, which we accept, as through and through a mechanism.
There can be little doubt that there is a tendency on the part of men of science at the present day so to regard it. It should, of course, be frankly admitted that no one is in a position to prove that, from the cosmic mist, in which we grope for the beginnings of our universe, to the organized whole in which vegetable and animal bodies have their place, there is an unbroken series of changes all of which are explicable by a reference to mechanical laws. Chemistry, physics, and biology are still separate and distinct realms, and it is at present impossible to find for them a common basis in mechanics. The belief of the man of science must, hence, be regarded as a faith; the doctrine of the mechanism of nature is a working hypothesis, and it is unscientific to assume that it is anything more.
There can be no objection to a frank admission that we are not here walking in the light of established knowledge. But it does seem to savor of dogmatism for a man to insist that no increase in our knowledge can ever reveal that the physical world is an orderly system throughout, and that all the changes in material things are explicable in terms of the one unified science. Earnest objections have, however, been made to the tendency to regard nature as a mechanism. To one of the most curious of them we have been treated lately by Dr. Ward in his book on "Naturalism and Agnosticism."
It is there ingeniously argued that, when we examine with care the fundamental concepts of the science of mechanics, we find them to be self-contradictory and absurd. It follows that we are not justified in turning to them for an explanation of the order of nature.
The defense of the concepts of mechanics we may safely leave to the man of science; remembering, of course, that, when a science is in the making, it is to be expected that the concepts of which it makes use should undergo revision from time to time. But there is one general consideration that it is not well to leave out of view when we are contemplating such an assault upon the notion of the world as mechanism as is made by Dr. Ward. It is this.
Such attacks upon the conception of mechanism are not purely destructive in their aim. The man who makes them wishes to destroy one view of the system of things in order that he may set up another. If the changes in the system of material things cannot be accounted for mechanically, it is argued, we are compelled to turn for our explanation to the action and interaction of minds. This seems to give mind a very important place in the universe, and is believed to make for a view of things that guarantees the satisfaction of the highest hopes and aspirations of man.
That a recognition of the mechanical order of nature is incompatible with such a view of things as is just above indicated, I should be the last to admit. The notion that it is so is, I believe, a dangerous error. It is an error that tends to put a man out of sympathy with the efforts of science to discover that the world is an orderly whole, and tempts him to rejoice in the contemplation of human ignorance.
But the error is rather a common one; and see to what injustice it may lead one. It is concluded that the conception of matter is an obscure one; that we do not know clearly what we mean when we speak of the mass of a body; that there are disputes as to proper significance to be given to the words cause and effect; that the laws of motion, as they are at present formulated, do not seem to account satisfactorily for the behavior of all material particles. From this it is inferred that we must give up the attempt to explain mechanically the order of physical things.
Now, suppose that it were considered a dangerous and heterodox doctrine, that the changes in the system of things are due to the activities of minds. Would not those who now love to point out the shortcomings of the science of mechanics discover a fine field for their destructive criticism? Are there no disputes as to the ultimate nature of mind? Are men agreed touching the relations of mind and matter? What science even attempts to tell us how a mind, by an act of volition, sets material particles in motion or changes the direction of their motion? How does one mind act upon another, and what does it mean for one mind to act upon another?
If the science of mechanics is not in all respects as complete a science as it is desirable that it should be, surely we must admit that when we turn to the field of mind we are not dealing with what is clear and free from difficulties. Only a strong emotional bias can lead a man to dwell with emphasis upon the difficulties to be met with in the one field, and to pass lightly over those with which one meets in the other.
One may, however, refuse to admit that the order of nature is throughout mechanical, without taking any such unreasonable position as this. One may hold that many of the changes in material things do not appear to be mechanical, and that it is too much of an assumption to maintain that they are such, even as an article of faith. Thus, when we pass from the world of the inorganic to that of organic life, we seem to make an immense step. No one has even begun to show us that the changes that take place in vegetable and animal organisms are all mechanical changes. How can we dare to assume that they are?
With one who reasons thus we may certainly feel a sympathy. The most ardent advocate of mechanism must admit that his doctrine is a working hypothesis, and not proved to be true. Its acceptance would, however, be a genuine convenience from the point of view of science, for it does introduce, at least provisionally, a certain order into a vast number of facts, and gives a direction to investigation. Perhaps the wisest thing to do is, not to combat the doctrine, but to accept it tentatively and to examine carefully what conclusions it may seem to carry with it—how it may affect our outlook upon the world as a whole.
45. THE PLACE OF MIND IN NATURE.—One of the very first questions which we think of asking when we contemplate the possibility that the physical world is throughout a mechanical system is this: How can we conceive minds to be related to such a system? That minds, and many minds, do exist, it is not reasonable to doubt. What shall we do with them?
One must not misunderstand the mechanical view of things. When we use the word "machine," we call before our minds certain gross and relatively simple mechanisms constructed by man. Between such and a flower, a butterfly, and a human body, the difference is enormous. He who elects to bring the latter under the title of mechanism cannot mean that he discerns no difference between them and a steam engine or a printing press. He can only mean that he believes he might, could he attain to a glimpse into their infinite complexity, find an explanation of the physical changes which take place in them, by a reference to certain general laws which describe the behavior of material particles everywhere.
And the man who, having extended his notion of mechanism, is inclined to overlook the fact that animals and men have minds, that thought and feeling, plan and purpose, have their place in the world, may justly be accused of a headlong and heedless enthusiasm. Whatever may be our opinion on the subject of the mechanism of nature, we have no right to minimize the significance of thought and feeling and will. Between that which has no mind and that which has a mind there is a difference which cannot be obliterated by bringing both under the concept of mechanism. It is a difference which furnishes the material for the sciences of psychology and ethics, and gives rise to a whole world of distinctions which find no place in the realm of the merely physical.
There are, then, minds as well as bodies; what place shall we assign to these minds in the system of nature?
Several centuries ago it occurred to the man of science that the material world should be regarded as a system in which there is constant transformation, but in which nothing is created. This way of looking at things expressed itself formerly in the statement that, through all the changes that take place in the world, the quantity of matter and motion remains the same. To-day the same idea is better expressed in the doctrine of the eternity of mass and the conservation of energy. In plain language, this doctrine teaches that every change in every part of the physical world, every motion in matter, must be preceded by physical conditions which may be regarded as the equivalent of the change in question.
But this makes the physical world a closed system, a something complete in itself. Where is there room in such a system for minds?
It does indeed seem hard to find in such a system a place for minds, if one conceives of minds as does the interactionist. We have seen (section 36) that the interactionist makes the mind act upon matter very much as one particle of matter is supposed to act upon another. Between the physical and the mental he assumes that there are causal relations; i.e. physical changes must be referred to mental causes sometimes, and mental changes to physical. This means that he finds a place for mental facts by inserting them as links in the one chain of causes and effects with physical facts. If he is not allowed to break the chain and insert them, he does not know what to do with them.
The parallelist has not the same difficulty to face. He who holds that mental phenomena must not be built into the one series of causes and effects with physical phenomena may freely admit that physical phenomena form a closed series, an orderly system of their own, and he may yet find a place in the world for minds. He refuses to regard them as a part of the world-mechanism, but he relates them to physical things, conceiving them as parallel to the physical in the sense described (sections 37-39). He insists that, even if we hold that there are gaps in the physical order of causes and effects, we cannot conceive these gaps to be filled by mental phenomena, simply because they are mental phenomena. They belong to an order of their own. Hence, the assumption that the physical series is unbroken does not seem to him to crowd mental phenomena out of their place in the world at all. They must, in any case, occupy the place that is appropriate to them (section 38).
It will be noticed that this doctrine that the chain of physical causes and effects is nowhere broken, and that mental phenomena are related to it as the parallelist conceives them to be, makes the world-system a very orderly one. Every phenomenon has its place in it, and can be accounted for, whether it be physical or mental. To some, the thought that the world is such an orderly thing is in the highest degree repugnant. They object that, in such a world, there is no room for free-will; and they object, further, that there is no room for the activity of minds. Both of these objections I shall consider in this chapter.
But first, I must say a few words about a type of doctrine lately insisted upon,[1] which bears some resemblance to interactionism as we usually meet with it, and, nevertheless, tries to hold on to the doctrine of the conservation of energy. It is this:—
The concept of energy is stretched in such a way as to make it cover mental phenomena as well as physical. It is claimed that mental phenomena and physical phenomena are alike "manifestations of energy," and that the coming into being of a consciousness is a mere "transformation," a something to be accounted for by the disappearance from the physical world of a certain equivalent—perhaps of some motion. It will be noticed that this is one rather subtle way of obliterating the distinction between mental phenomena and physical. In so far it resembles the interactionist's doctrine.
In criticism of it we may say that he who accepts it has wandered away from a rather widely recognized scientific hypothesis, and has substituted for it a very doubtful speculation for which there seems to be no whit of evidence. It is, moreover, a speculation repugnant to the scientific mind, when its significance is grasped. Shall we assume without evidence that, when a man wakes in the morning and enjoys a mental life suspended or diminished during the night, his thoughts and feelings have come into being at the expense of his body? Shall we assume that the mass of his body has been slightly diminished, or that motions have disappeared in a way that cannot be accounted for by a reference to the laws of matter in motion? This seems an extraordinary assumption, and one little in harmony with the doctrine of the eternity of mass and the conservation of energy as commonly understood. We need not take it seriously so long as it is quite unsupported by evidence.
46. THE ORDER OF NATURE AND "FREE-WILL."—In a world as orderly as, in the previous section, this world is conceived to be, is there any room for freedom? What if the man of science is right in suspecting that the series of physical causes and effects is nowhere broken? Must we then conclude that we are never free?
To many persons it has seemed that we are forced to draw this conclusion, and it is not surprising that they view the doctrine with dismay. They argue: Mental phenomena are made parallel with physical, and the order of physical phenomena seems to be determined throughout, for nothing can happen in the world of matter unless there is some adequate cause of its happening. If, then, I choose to raise my finger, that movement must be admitted to have physical causes, and those causes other causes, and so on without end. If such a movement must always have its place in a causal series of this kind, how can it be regarded as a free movement? It is determined, and not free.
Now, it is far from a pleasant thing to watch the man of science busily at work trying to prove that the physical world is an orderly system, and all the while to feel in one's heart that the success of his efforts condemns one to slavery. It can hardly fail to make one's attitude towards science that of alarm and antagonism. From this I shall try to free the reader by showing that our freedom is not in the least danger, and that we may look on unconcerned.
When we approach that venerable dispute touching the freedom of the will, which has inspired men to such endless discussions, and upon which they have written with such warmth and even acrimony, the very first thing to do is to discover what we have a right to mean when we call a man free. As long as the meaning of the word is in doubt, the very subject of the dispute is in doubt. When may we, then, properly call a man free? What is the normal application of the term?
I raise my finger. Every man of sense must admit that, under normal conditions, I can raise my finger or keep it down, as I please. There is no ground for a difference of opinion so far. But there is a further point upon which men differ. One holds that my "pleasing" and the brain-change that corresponds to it have their place in the world-order; that is, he maintains that every volition can be accounted for. Another holds that, under precisely the same circumstances, one may "please" or not "please"; which means that the "pleasing" cannot be wholly accounted for by anything that has preceded. The first man is a determinist, and the second a "free-willist." I beg the reader to observe that the word "free-willist" is in quotation marks, and not to suppose that it means simply a believer in the freedom of the will.
When in common life we speak of a man as free, what do we understand by the word? Usually we mean that he is free from external compulsion. If my finger is held by another, I am not free to raise it. But I may be free in this sense, and yet one may demur to the statement that I am a free man. If a pistol be held to my head with the remark, "Hands up!" my finger will mount very quickly, and the bystanders will maintain that I had no choice.
We speak in somewhat the same way of men under the influence of intoxicants, of men crazed by some passion and unable to take into consideration the consequences of their acts, and of men bound by the spell of hypnotic suggestion. Indeed, whenever a man is in such a condition that he is glaringly incapable of leading a normal human life and of being influenced by the motives that commonly move men, we are inclined to say that he is not free.
But does it ever occur to us to maintain that, in general, the possession of a character and the capacity of being influenced by considerations make it impossible for a man to be free? Surely not. If I am a prudent man, I will invest my money in good securities. Is it sensible to say that I cannot have been free in refusing a twenty per cent investment, because I am by nature prudent? Am I a slave because I eat when I am hungry, and can I partake of a meal freely, only when there is no reason why I should eat at all?
He who calls me free only when my acts do violence to my nature or cannot be justified by a reference to anything whatever has strange notions of freedom. Patriots, poets, moralists, have had much to say of freedom; men have lived for it, and have died for it; men love it as they love their own souls. Is the object of all this adoration the metaphysical absurdity indicated above?
To insist that a man is free only in so far as his actions are unaccountable is to do violence to the meaning of a word in very common use, and to mislead men by perverting it to strange and unwholesome uses. Yet this is done by the "free-willist." He keeps insisting that man is free, and then goes on to maintain that he cannot be free unless he is "free." He does not, unfortunately, supply the quotation marks, and he profits by the natural mistake in identity. As he defines freedom it becomes "freedom," which is a very different thing.
What is this "freedom"? It is not freedom from external constraint. It is not freedom from overpowering passion. It is freedom from all the motives, good as well as bad, that we can conceive of as influencing man, and freedom also from oneself.
It is well to get this quite clear. The "free-willist" maintains that, in so far as a man is "free," his actions cannot be accounted for by a reference to the order of causes at all—not by a reference to his character, hereditary or acquired; not by a reference to his surroundings. "Free" actions, in so far as they are "free," have, so to speak, sprung into being out of the void. What follows from such a doctrine? Listen:—
(1) It follows that, in so far as I am "free," I am not the author of what appear to be my acts; who can be the cause of causeless actions?
(2) It follows that no amount of effort on my part can prevent the appearance of "free" acts of the most deplorable kind. If one can condition their appearance or non-appearance, they are not "free" acts.
(3) It follows that there is no reason to believe that there will be any congruity between my character and my "free" acts. I may be a saint by nature, and "freely" act like a scoundrel.
(4) It follows that I can deserve no credit for "free" acts. I am not their author.
(5) It follows that, in so far as I am "free," it is useless to praise me, to blame me, to punish me, to endeavor to persuade me. I must be given over to unaccountable sainthood or to a reprobate mind, as it happens to happen. I am quite beyond the pale of society, for my neighbor cannot influence my "free" acts any more than I can.
(6) It follows that, in so far as I am "free," I am in something very like a state of slavery; and yet, curiously enough, it is a slavery without a master. In the old stories of Fate, men were represented as puppets in the hand of a power outside themselves. Here I am a puppet in no hand; but I am a puppet just the same, for I am the passive spectator of what appear to be my acts. I do not do the things I seem to do. They are done for me or in me—or, rather, they are not done, but just happen.
Such "freedom" is a wretched thing to offer to a man who longs for freedom; for the freedom to act out his own impulses, to guide his life according to his own ideals. It is a mere travesty on freedom, a fiction of the philosophers, which inspires respect only so long as one has not pierced the disguise of its respectable name. True freedom is not a thing to be sought in a disorderly and chaotic world, in a world in which actions are inexplicable and character does not count. Let us rinse our minds free of misleading verbal associations, and let us realize that a "free-will" neighbor would certainly not be to us an object of respect. He would be as offensive an object to have in our vicinity as a "free-will" gun or a "free-will" pocketknife. He would not be a rational creature.
Our only concern need be for freedom, and this is in no danger in an orderly world. We all recognize this truth, in a way. We hold that a man of good character freely chooses the good, and a man of evil character freely chooses evil. Is not this a recognition of the fact that the choice is a thing to be accounted for, and is, nevertheless, a free choice?
I have been considering above the world as it is conceived to be by the parallelist, but, to the reader who may not incline towards parallelism, I wish to point out that these reasonings touching the freedom of the will concern the interactionist just as closely. They have no necessary connection with parallelism. The interactionist, as well as the parallelist, may be a determinist, a believer in freedom, or he may be a "free-willist."
He regards mental phenomena and physical phenomena as links in the one chain of causes and effects. Shall he hold that certain mental links are "free-will" links, that they are wholly unaccountable? If he does, all that has been said above about the "free-willist" applies to him. He believes in a disorderly world, and he should accept the consequences of his doctrine.
47. THE PHYSICAL WORLD AND THE MORAL WORLD.—I have said a little way back that, when we think of bodies as having minds, we are introduced to a world of distinctions which have no place in the realm of the merely physical. One of the objections made to the orderly world of the parallelist was that in it there is no room for the activity of minds. Before we pass judgment on this matter, we should try to get some clear notion of what we may mean by the word "activity." The science of ethics must go by the board, if we cannot think of men as doing anything, as acting rightly or acting wrongly.
Let us conceive a billiard ball in motion to come into collision with one at rest. We commonly speak of the first ball as active, and of the second as the passive subject upon which it exercises its activity. Are we justified in thus speaking?
In one sense, of course, we are. As I have several times had occasion to remark, we are, in common life, justified in using words rather loosely, provided that it is convenient to do so, and that it does not give rise to misunderstandings.
But, in a stricter sense, we are not justified in thus speaking, for in doing so we are carrying over into the sphere of the merely physical a distinction which does not properly belong there, but has its place in another realm. The student of mechanics tells us that the second ball has affected the first quite as much as the first has affected the second. We cannot simply regard the first as cause and the second as effect, nor may we regard the motion of the first as cause and the subsequent motion of the second as its effect alone. The whole situation at the one instant—both balls, their relative positions and their motion and rest—must be taken as the cause of the whole situation at the next instant, and in this whole situation the condition of the second ball has its place as well as that of the first.
If, then, we insist that to have causal efficiency is the same thing as to be active, we should also admit that the second ball was active, and quite as active as the first. It has certainly had as much to do with the total result. But it offends us to speak of it in this way. We prefer to say that the first was active and the second was acted upon. What is the source of this distinction?
Its original source is to be found in the judgments we pass upon conscious beings, bodies with minds; and it could never have been drawn if men had not taken into consideration the relations of minds to the changes in the physical world. As carried over to inanimate things it is a transferred distinction; and its transference to this field is not strictly justifiable, as has been indicated above.
I must make this clear by an illustration. I hurry along a street towards the university, because the hour for my lecture is approaching. I am struck down by a falling tile. In my advance up the street I am regarded as active; in my fall to the ground I am regarded as passive.
Now, looking at both occurrences from the purely physical point of view, we have nothing before us but a series of changes in the space relations of certain masses of matter; and in all those changes both my body and its environment are concerned. As I advance, my body cannot be regarded as the sole cause of the changes which are taking place. My progress would be impossible without the aid of the ground upon which I tread. Nor can I accuse the tile of being the sole cause of my demolition. Had I not been what I was and where I was, the tile would have fallen in vain. I must be regarded as a concurrent cause of my own disaster, and my unhappy state is attributable to me as truly as it is to the tile.
Why, then, am I in the one case regarded as active and in the other as passive? In each case I am a cause of the result. How does it happen that, in the first instance, I seem to most men to be the cause, and in the second to be not a cause at all? The rapidity of my motion in the first instance cannot account for this judgment. He who rides in the police van and he who is thrown from the car of a balloon may move with great rapidity and yet be regarded as passive.
Men speak as they do because they are not content to point out the physical antecedents of this and that occurrence and stop with that. They recognize that, between my advance up the street and my fall to the ground there is one very important difference. In the first case what is happening may be referred to an idea in my mind. Were the idea not there, I should not do what I am doing. In the second case, what has happened cannot be referred to an idea in my mind.
Here we have come to the recognition that there are such things as purposes and ends; that an idea and some change in the external world may be related as plan and accomplishment. In other words, we have been brought face to face with what has been given the somewhat misleading name of final cause. In so far as that in the bringing about of which I have had a share is my end, I am active; in so far as it is not my end, but comes upon me as something not planned, I am passive. The enormous importance of the distinction may readily be seen; it is only in so far as I am a creature who can have purposes, that desire and will, foresight and prudence, right and wrong, can have a significance for me.
I have dwelt upon the meaning of the words "activity" and "passivity," and have been at pains to distinguish them from cause and effect, because the two pairs of terms have often been confounded with each other, and this confusion has given rise to a peculiarly unfortunate error. It is this error that lies at the foundation of the objection referred to at the beginning of this section.
We have seen that certain men of science are inclined to look upon the physical world as a great system, all the changes in which may be accounted for by an appeal to physical causes. And we have seen that the parallelist regards ideas, not as links in this chain, but as parallel with physical changes.
It is argued by some that, if this is a true view of things, we must embrace the conclusion that the mind cannot be active at all, that it can accomplish nothing. We must look upon the mind as an "epiphenomenon," a useless decoration; and must regard man as "a physical automaton with parallel psychical states."
Such abuse of one's fellow-man seems unchristian, and it is wholly uncalled for on any hypothesis. Our first answer to it is that it seems to be sufficiently refuted by the experiences of common life. We have abundant evidence that men's minds do count for something. I conclude that I want a coat, and I order one of my tailor; he believes that I will pay for it, he wants the money, and he makes the coat; his man desires to earn his wages and he delivers it. If I had not wanted the coat, if the tailor had not wanted my money, if the man had not wanted to earn his wages, the end would not have been attained. No philosopher has the right to deny these facts.
Ah! but, it may be answered, these three "wants" are not supposed to be the causes of the motions in matter which result in my appearing well-dressed on Sunday. They are only concomitant phenomena.
To this I reply: What of that? We must not forget what is meant by such concomitance (section 39). We are dealing with a fixed and necessary relation, not with an accidental one. If these "wants" had been lacking, there would have been no coat. So my second answer to the objector is, that, on the hypothesis of the parallelist, the relations between mental phenomena and physical phenomena are just as dependable as that relation between physical phenomena which we call that of cause and effect. Moreover, since activity and causality are not the same thing, there is no ground for asserting that the mind cannot be active, merely because it is not material and, hence, cannot be, strictly speaking, a cause of motions in matter.
The plain man is entirely in the right in thinking that minds are active. The truth is that nothing can be active except as it has a mind. The relation of purpose and end is the one we have in view when we speak of the activity of minds.
It is, thus, highly unjust to a man to tell him that he is "a physical automaton with parallel psychical states," and that he is wound up by putting food into his mouth. He who hears this may be excused if he feels it his duty to emit steam, walk with a jerk, and repudiate all responsibility for his actions. Creatures that think, form plans, and act, are not what we call automata. It is an abuse of language to call them such, and it misleads us into looking upon them as we have no right to look upon them. If men really were automata in the proper sense of the word, we could not look upon them as wise or unwise, good or bad; in short, the whole world of moral distinctions would vanish.
Perhaps, in spite of all that has been said in this and in the preceding section, some will feel a certain repugnance to being assigned a place in a world as orderly as our world is in this chapter conceived to be—a world in which every phenomenon, whether physical or mental, has its definite place, and all are subject to law. But I suppose our content or discontent will not be independent of our conception of what sort of a world we conceive ourselves to be inhabiting.
If we conclude that we are in a world in which God is revealed, if the orderliness of it is but another name for Divine Providence, we can scarcely feel the same as we would if we discovered in the world nothing of the Divine. I have in the last few pages been discussing the doctrine of purposes and ends, teleology, but I have said nothing of the significance of that doctrine for Theism. The reader can easily see that it lies at the very foundation of our belief in God. The only arguments for theism that have had much weight with mankind have been those which have maintained there are revealed in the world generally evidences of a plan and purpose at least analogous to what we discover when we scrutinize the actions of our fellow-man. Such arguments are not at the mercy of either interactionist or parallelist. On either hypothesis they stand unshaken.
With this brief survey of some of the most interesting problems that confront the philosopher, I must content myself here. Now let us turn and see how some of the fundamental problems treated in previous chapters have been approached by men belonging to certain well-recognized schools of thought.
And since it is peculiarly true in philosophy that, to understand the present, one must know something of the past, we shall begin by taking a look at the historical background of the types of philosophical doctrine to which reference is constantly made in the books and journals of the day.
[1] Ostwald, "Vorlesungen über Naturphilosophie," s. 396. Leipzig, 1902.
IV. SOME TYPES OF PHILOSOPHICAL THEORY
CHAPTER XII
THEIR HISTORICAL BACKGROUND
48. THE DOCTRINE OF REPRESENTATIVE PERCEPTION.—We have seen in Chapter II that it seems to the plain man abundantly evident that he really is surrounded by material things and that he directly perceives such things. This has always been the opinion of the plain man and it seems probable that it always will be. It is only when he begins to reflect upon things and upon his knowledge of them that it occurs to him to call it in question.
Very early in the history of speculative thought it occurred to men, however, to ask how it is that we know things, and whether we are sure we do know them. The problems of reflection started into life, and various solutions were suggested. To tell over the whole list would take us far afield, and we need not, for the purpose we have in view, go back farther than Descartes, with whom philosophy took a relatively new start, and may be said to have become, in spirit and method, at least, modern.
I have said (section 31) that Descartes (1596-1650) was fairly well acquainted with the functioning of the nervous system, and has much to say of the messages which pass along the nerves to the brain. The same sort of reasoning that leads the modern psychologist to maintain that we know only so much of the external world as is reflected in our sensations led him to maintain that the mind is directly aware of the ideas through which an external world is represented, but can know the world itself only indirectly and through these ideas.
Descartes was put to sore straits to prove the existence of an external world, when he had once thus placed it at one remove from us. If we accept his doctrine, we seem to be shut up within the circle of our ideas, and can find no door that will lead us to a world outside. The question will keep coming back: How do we know that, corresponding to our ideas, there are material things, if we have never perceived, in any single instance, a material thing? And the doubt here suggested may be reinforced by the reflection that the very expression "a material thing" ought to be meaningless to a man who, having never had experience of one, is compelled to represent it by the aid of something so different from it as ideas are supposed to be. Can material things really be to such a creature anything more than some complex of ideas?
The difficulties presented by any philosophical doctrine are not always evident at once. Descartes made no scruple of accepting the existence of an external world, and his example has been followed by a very large number of those who agree with his initial assumption that the mind knows immediately only its own ideas.
Preëminent among such we must regard John Locke, the English philosopher (1632-1704), whose classic work, "An Essay concerning Human Understanding," should not be wholly unknown to any one who pretends to an interest in the English literature.
Admirably does Locke represent the position of what very many have regarded as the prudent and sensible man,—the man who recognizes that ideas are not external things, and that things must be known through ideas, and yet holds on to the existence of a material world which we assuredly know.
He recognizes, it is true, that some one may find a possible opening for the expression of a doubt, but he regards the doubt as gratuitous; "I think nobody can, in earnest, be so skeptical as to be uncertain of the existence of those things which he sees and feels." As we have seen (section 12), he meets the doubt with a jest.
Nevertheless, those who read with attention Locke's admirably clear pages must notice that he does not succeed in really setting to rest the doubt that has suggested itself. It becomes clear that Locke felt so sure of the existence of the external world because he now and then slipped into the inconsistent doctrine that he perceived it immediately, and not merely through his ideas. Are those things "which he sees and feels" external things? Does he see and feel them directly, or must he infer from his ideas that he sees and feels them? If the latter, why may one not still doubt? Evidently the appeal is to a direct experience of material things, and Locke has forgotten that he must be a Lockian.
"I have often remarked, in many instances," writes Descartes, "that there is a great difference between an object and its idea." How could the man possibly have remarked this, when he had never in his life perceived the object corresponding to any idea, but had been altogether shut up to ideas? "Thus I see, whilst I write this," says Locke,[1] "I can change the appearance of the paper, and by designing the letters tell beforehand what new idea it shall exhibit the very next moment, by barely drawing my pen over it, which will neither appear (let me fancy as much as I will), if my hand stands still, or though I move my pen, if my eyes be shut; nor, when those characters are once made on the paper, can I choose afterward but see them as they are; that is, have the ideas of such letters as I have made. Whence it is manifest, that they are not barely the sport and play of my own imagination, when I find that the characters that were made at the pleasure of my own thought do not obey them; nor yet cease to be, whenever I shall fancy it; but continue to affect the senses constantly and regularly, according to the figures I made them."
Locke is as bad as Descartes. Evidently he regards himself as able to turn to the external world and perceive the relation that things hold to ideas. Such an inconsistency may escape the writer who has been guilty of it, but it is not likely to escape the notice of all those who come after him. Some one is sure to draw the consequences of a doctrine more rigorously, and to come to conclusions, it may be, very unpalatable to the man who propounded the doctrine in the first instance.
The type of doctrine represented by Descartes and Locke is that of Representative Perception. It holds that we know real external things only through their mental representatives. It has also been called Hypothetical Realism, because it accepts the existence of a real world, but bases our knowledge of it upon an inference from our sensations or ideas.
49. THE STEP TO IDEALISM.—The admirable clearness with which Locke writes makes it the easier for his reader to detect the untenability of his position. He uses simple language, and he never takes refuge in vague and ambiguous phrases. When he tells us that the mind is wholly shut up to its ideas, and then later assumes that it is not shut up to its ideas, but can perceive external things, we see plainly that there must be a blunder somewhere.
George Berkeley (1684-1753), Bishop of Cloyne, followed out more rigorously the consequences to be deduced from the assumption that all our direct knowledge is of ideas; and in a youthful work of the highest genius entitled "The Principles of Human Knowledge," he maintained that there is no material world at all.
When we examine with care the objects of sense, the "things" which present themselves to us, he argues, we find that they resolve themselves into sensations, or "ideas of sense." What can we mean by the word "apple," if we do not mean the group of experiences in which alone an apple is presented to us? The word is nothing else than a name for this group as a group. Take away the color, the hardness, the odor, the taste; what have we left? And color, hardness, odor, taste, and anything else that may be referred to any object as a quality, can exist, he claims, only in a perceiving mind; for such things are nothing else than sensations, and how can there be an unperceived sensation?
The things which we perceive, then, he calls complexes of ideas. Have we any reason to believe that these ideas, which exist in the mind, are to be accepted as representatives of things of a different kind, which are not mental at all? Not a shadow of a reason, says Berkeley; there is simply no basis for inference at all, and we cannot even make clear what it is that we are setting out to infer under the name of matter. We need not, therefore, grieve over the loss of the material world, for we have suffered no loss; one cannot lose what one has never had.
Thus, the objects of human knowledge, the only things of which it means
anything to speak, are: (1) Ideas of Sense; (2) Ideas of Memory and
Imagination; (3) The Passions and Operations of the Mind; and (4) The
Self that perceives all These.
From Locke's position to that of Berkeley was a bold step, and it was much criticised, as well it might be. It was felt then, as it has been felt by many down to our own time, that, when we discard an external world distinct from our ideas, and admit only the world revealed in our ideas, we really do lose.
It is legitimate to criticise Berkeley, but it is not legitimate to misunderstand him; and yet the history of his doctrine may almost be called a chronicle of misconceptions. It has been assumed that he drew no distinction between real things and imaginary things, that he made the world no better than a dream, etc. Arbuthnot, Swift, and a host of the greater and lesser lights in literature, from his time to ours, have made merry over the supposed unrealities in the midst of which the Berkeleian must live.
But it should be remembered that Berkeley tried hard to do full justice to the world of things in which we actually find ourselves; not a hypothetical, inferred, unperceived world, but the world of the things we actually perceive. He distinguished carefully between what is real and what is merely imaginary, though he called both "ideas"; and he recognized something like a system of nature. And, by the argument from analogy which we have already examined (section 41), he inferred the existence of other finite minds and of a Divine Mind.
But just as John Locke had not completely thought out the consequences which might be deduced from his own doctrines, so Berkeley left, in his turn, an opening for a successor. It was possible for that acutest of analysts, David Hume (1711-1776), to treat him somewhat as he had treated Locke.
Among the objects of human knowledge Berkeley had included the self that perceives things. He never succeeded in making at all clear what he meant by this object; but he regarded it as a substance, and believed it to be a cause of changes in ideas, and quite different in its nature from all the ideas attributed to it. But Hume maintained that when he tried to get a good look at this self, to catch it, so to speak, and to hold it up to inspection, he could not find anything whatever save perceptions, memories, and other things of that kind. The self is, he said, "but a bundle or collection of different perceptions which succeed each other with inconceivable rapidity, and are in a perpetual flux and movement."
As for the objects of sense, our own bodies, the chairs upon which we sit, the tables at which we write, and all the rest—these, argues Hume, we are impelled by nature to think of as existing continuously, but we have no evidence whatever to prove that they do thus exist. Are not the objects of sense, after all, only sensations or impressions? Do we not experience these sensations or impressions interruptedly? Who sees or feels a table continuously day after day? If the table is but a name for the experiences in question, if we have no right to infer material things behind and distinct from such experiences, are we not forced to conclude that the existence of the things that we see and feel is an interrupted one?
Hume certainly succeeded in raising more questions than he succeeded in answering. We are compelled to admire the wonderful clearness and simplicity of his style, and the acuteness of his intellect, in every chapter. But we cannot help feeling that he does injustice to the world in which we live, even when we cannot quite see what is wrong. Does it not seem certain to science and to common sense that there is an order of nature in some sense independent of our perceptions, so that objects may be assumed to exist whether we do or do not perceive them?
When we read Hume we have a sense that we are robbed of our real external world; and his account of the mind makes us feel as a badly tied sheaf of wheat may be conceived to feel—in danger of falling apart at any moment. Berkeley we unhesitatingly call an Idealist, but whether we shall apply the name to Hume depends upon the extension we are willing to give to it. His world is a world of what we may broadly call ideas; but the tendencies of his philosophy have led some to call it a Skepticism.
50. THE REVOLT OF "COMMON SENSE."—Hume's reasonings were too important to be ignored, and his conclusions too unpalatable to satisfy those who came after him. It seemed necessary to seek a way of escape out of this world of mere ideas, which appeared to be so unsatisfactory a world. One of the most famous of such attempts was that made by the Scotchman Thomas Reid (1710-1796).
At one time Reid regarded himself as the disciple of Berkeley, but the consequences which Hume deduced from the principles laid down by the former led Reid to feel that he must build upon some wholly different foundation. He came to the conclusion that the line of philosophers from Descartes to Hume had made one capital error in assuming "that nothing is perceived but what is in the mind that perceives it."
Once admit, says Reid, that the mind perceives nothing save ideas, and we must also admit that it is impossible to prove the existence either of an external world or of a mind different from "a bundle of perceptions." Hence, Reid maintains that we perceive—not infer, but perceive—things external to the mind. He writes:[2]—
"Let a man press his hand against the table—he feels it hard. But what is the meaning of this? The meaning undoubtedly is, that he hath a certain feeling of touch, from which he concludes, without any reasoning, or comparing ideas, that there is something external really existing, whose parts stick so firmly together that they cannot be displaced without considerable force.
"There is here a feeling, and a conclusion drawn from it, or some way suggested by it. In order to compare these, we must view them separately, and then consider by what tie they are connected, and wherein they resemble one another. The hardness of the table is the conclusion, the feeling is the medium by which we are led to that conclusion. Let a man attend distinctly to this medium, and to the conclusion, and he will perceive them to be as unlike as any two things in nature. The one is a sensation of the mind, which can have no existence but in a sentient being; nor can it exist one moment longer than it is felt; the other is in the table, and we conclude, without any difficulty, that it was in the table before it was felt, and continues after the feeling is over. The one implies no kind of extension, nor parts, nor cohesion; the other implies all these. Both, indeed, admit of degrees, and the feeling, beyond a certain degree, is a species of pain; but adamantine hardness does not imply the least pain.
"And as the feeling hath no similitude to hardness, so neither can our reason perceive the least tie or connection between them; nor will the logician ever be able to show a reason why we should conclude hardness from this feeling, rather than softness, or any other quality whatsoever. But, in reality, all mankind are led by their constitution to conclude hardness from this feeling."
It is well worth while to read this extract several times, and to ask oneself what Reid meant to say, and what he actually said. He is objecting, be it remembered, to the doctrine that the mind perceives immediately only its own ideas or sensations and must infer all else. His contention is that we perceive external things.
Does he say this? He says that we have feelings of touch from which we conclude that there is something external; that there is a feeling, "and a conclusion drawn from it, or some way suggested by it;" that "the hardness of the table is the conclusion, and the feeling is the medium by which we are led to the conclusion."
Could Descartes or Locke have more plainly supported the doctrine of representative perception? How could Reid imagine he was combatting that doctrine when he wrote thus? The point in which he differs from them is this: he maintains that we draw the conclusion in question without any reasoning, and, indeed, in the absence of any conceivable reason why we should draw it. We do it instinctively; we are led by the constitution of our nature.
In effect Reid says to us: When you lay your hand on the table, you have a sensation, it is true, but you also know the table is hard. How do you know it? I cannot tell you; you simply know it, and cannot help knowing it; and that is the end of the matter.
Reid's doctrine was not without its effect upon other philosophers. Among them we must place Sir William Hamilton (1788-1856), whose writings had no little influence upon British philosophy in the last half of the last century.
Hamilton complained that Reid did not succeed in being a very good Natural Realist, and that he slipped unconsciously into the position he was concerned to condemn. Sir William tried to eliminate this error, but the careful reader of his works will find to his amusement that this learned author gets his feet upon the same slippery descent. And much the same thing may be said of the doctrine of Herbert Spencer (1820-1903), who claims that, when we have a sensation, we know directly that there is an external thing, and then manages to sublimate that external thing into an Unknowable, which we not only do not know directly, but even do not know at all.
All of these men were anxious to avoid what they regarded as the perils of Idealism, and yet they seem quite unable to retain a foothold upon the position which they consider the safer one.
Reid called his doctrine the philosophy of "Common Sense," and he thought he was coming back from the subtleties of the metaphysicians to the standpoint of the plain man. That he should fall into difficulties and inconsistencies is by no means surprising. As we have seen (section 12), the thought of the plain man is far from clear. He certainly believes that we perceive an external world of things, and the inconsistent way in which Descartes and Locke appeal from ideas to the things themselves does not strike him as unnatural. Why should not a man test his ideas by turning to things and comparing the former with the latter? On the other hand, he knows that to perceive things we must have sense organs and sensations, and he cannot quarrel with the psychologists for saying that we know things only in so far as they are revealed to us through our sensations. How does he reconcile these two positions? He does not reconcile them. He accepts them as they stand.
Reid and various other philosophers have tried to come back to "Common Sense" and to stay there. Now, it is a good position to come back to for the purpose of starting out again. The experience of the plain man, the truths which he recognizes as truths, these are not things to be despised. Many a man whose mind has been, as Berkeley expresses it, "debauched by learning," has gotten away from them to his detriment, and has said very unreasonable things. But "Common Sense" cannot be the ultimate refuge of the philosopher; it can only serve him as material for investigation. The scholar whose thought is as vague and inconsistent as that of the plain man has little profit in the fact that the apparatus of his learning has made it possible for him to be ponderously and unintelligibly vague and inconsistent.
Hence, we may have the utmost sympathy with Reid's protest against the doctrine of representative perception, and we may, nevertheless, complain that he has done little to explain how it is that we directly know external things and yet cannot be said to know things except in so far as we have sensations or ideas.
51. THE CRITICAL PHILOSOPHY.—The German philosopher, Immanuel Kant (1724-1804), was moved, by the skeptical conclusions to which Hume's philosophy seemed to lead, to seek a way of escape, somewhat as Reid was. But he did not take refuge in "Common Sense"; he developed an ingenious doctrine which has had an enormous influence in the philosophical world, and has given rise to a Kantian literature of such proportions that no man can hope to read all of it, even if he devotes his life to it. In Germany and out of it, it has for a hundred years and more simply rained books, pamphlets, and articles on Kant and his philosophy, some of them good, many of them far from clear and far from original. Hundreds of German university students have taken Kant as the subject of the dissertation by which they hoped to win the degree of Doctor of Philosophy;—I was lately offered two hundred and seventy-four such dissertations in one bunch;—and no student is supposed to have even a moderate knowledge of philosophy who has not an acquaintance with that famous work, the "Critique of Pure Reason."
It is to be expected from the outset that, where so many have found so much to say, there should reign abundant differences of opinion. There are differences of opinion touching the interpretation of Kant, and touching the criticisms which may be made upon, and the development which should be given to, his doctrine. It is, of course, impossible to go into all these things here; and I shall do no more than indicate, in untechnical language and in briefest outline, what he offers us in place of the philosophy of Hume.
Kant did not try to refute, as did Reid, the doctrine, urged by Descartes and by his successors, that all those things which the mind directly perceives are to be regarded as complexes of ideas. On the contrary, he accepted it, and he has made the words "phenomenon" and "noumenon" household words in philosophy.
The world which seems to be spread out before us in space and time is, he tells us, a world of things as they are revealed to our senses and our intelligence; it is a world of manifestations, of phenomena. What things-in-themselves are like we have no means of knowing; we know only things as they appear to us. We may, to be sure, talk of a something distinct from phenomena, a something not revealed to the senses, but thought of, a noumenon; but we should not forget that this is a negative conception; there is nothing in our experience that can give it a filling, for our experience is only of phenomena. The reader will find an unmistakable echo of this doctrine in Herbert Spencer's doctrine of the "Unknowable" and its "manifestations."
Now, Berkeley had called all the things we immediately perceive ideas. As we have seen, he distinguished between "ideas of sense" and "ideas of memory and imagination." Hume preferred to give to these two classes different names—he called the first impressions and the second ideas.
The associations of the word "impression" are not to be mistaken. Locke had taught that between ideas in the memory and genuine sensations there is the difference that the latter are due to the "brisk acting" of objects without us. Objects impress us, and we have sensations or impressions. To be sure, Hume, after employing the word "impression," goes on to argue that we have no evidence that there are external objects, which cause impressions. But he retains the word "impression," nevertheless, and his use of it perceptibly colors his thought.
In Kant's distinction between phenomena and noumena we have the lineal descendant of the old distinction between the circle of our ideas and the something outside of them that causes them and of which they are supposed to give information. Hume said we have no reason to believe such a thing exists, but are impelled by our nature to believe in it. Kant is not so much concerned to prove the nonexistence of noumena, things-in-themselves, as he is to prove that the very conception is an empty one. His reasonings seem to result in the conclusion that we can make no intelligible statement about things so cut off from our experience as noumena are supposed to be; and one would imagine that he would have felt impelled to go on to the frank declaration that we have no reason to believe in noumena at all, and had better throw away altogether so meaningless and useless a notion. But he was a conservative creature, and he did not go quite so far.
So far there is little choice between Kant and Hume. Certainly the former does not appear to have rehabilitated the external world which had suffered from the assaults of his predecessors. What important difference is there between his doctrine and that of the man whose skeptical tendencies he wished to combat?
The difference is this: Descartes and Locke had accounted for our knowledge of things by maintaining that things act upon us, and make an impression or sensation—that their action, so to speak, begets ideas. This is a very ancient doctrine as well as a very modern one; it is the doctrine that most men find reasonable even before they devote themselves to the study of philosophy. The totality of such impressions received from the external world, they are accustomed to regard as our experience of external things; and they are inclined to think that any knowledge of external things not founded upon experience can hardly deserve the name of knowledge.
Now, Hume, when he cast doubt upon the existence of external things, did not, as I have said above, divest himself of the suggestions of the word "impression." He insists strenuously that all our knowledge is founded upon experience; and he holds that no experience can give us knowledge that is necessary and universal. We know things as they are revealed to us in our experience; but who can guarantee that we may not have new experiences of a quite different kind, and which flatly contradict the notions which we have so far attained of what is possible and impossible, true and untrue.
It is here that Kant takes issue with Hume. A survey of our knowledge makes clear, he thinks, that we are in the possession of a great deal of information that is not of the unsatisfactory kind that, according to Hume, all our knowledge of things must be. There, for example, are all the truths of mathematics. When we enunciate a truth regarding the relations of the lines and angles of a triangle, we are not merely unfolding in the predicate of our proposition what was implicitly contained in the subject. There are propositions that do no more than this; they are analytical, i.e. they merely analyze the subject. Thus, when we say: Man is a rational animal, we may merely be defining the word "man"—unpacking it, so to speak. But a synthetic judgment is one in which the predicate is not contained in the subject; it adds to one's information. The mathematical truths are of this character. So also is the truth that everything that happens must have a cause.
Do we connect things with one another in this way merely because we have had experience that they are thus connected? Is it because they are given to us connected in this way? That cannot be the case, Kant argues, for what is taken up as mere experienced act cannot be known as universally and necessarily true. We perceive that these things must be so connected. How shall we explain this necessity?
We can only explain it, said Kant, in this way: We must assume that what is given us from without is merely the raw material of sensation, the matter of our experience; and that the ordering of this matter, the arranging it into a world of phenomena, the furnishing of form, is the work of the mind. Thus, we must think of space, time, causality, and of all other relations which obtain between the elements of our experience, as due to the nature of the mind. It perceives the world of phenomena that it does, because it constructs that world. Its knowledge of things is stable and dependable because it cannot know any phenomenon which does not conform to its laws. The water poured into a cup must take the shape of the cup; and the raw materials poured into a mind must take the form of an orderly world, spread out in space and time.
Kant thought that with this turn he had placed human knowledge upon a satisfactory basis, and had, at the same time, indicated the limitations of human knowledge. If the world we perceive is a world which we make; if the forms of thought furnished by the mind have no other function than the ordering of the materials furnished by sense; then what can we say of that which may be beyond phenomena? What of noumena?
It seems clear that, on Kant's principles, we ought not to be able to say anything whatever of noumena. To say that such may exist appears absurd. All conceivable connection between them and existing things as we know them is cut off. We cannot think of a noumenon as a substance, for the notions of substance and quality have been declared to be only a scheme for the ordering of phenomena. Nor can we think of one as a cause of the sensations that we unite into a world, for just the same reason. We are shut up logically to the world of phenomena, and that world of phenomena is, after all, the successor of the world of ideas advocated by Berkeley.
This is not the place to discuss at length the value of Kant's contribution to philosophy.[3] There is something terrifying in the prodigious length at which it seems possible for men to discuss it. Kant called his doctrine "Criticism," because it undertook to establish the nature and limits of our knowledge. By some he has been hailed as a great enlightener, and by others he has been accused of being as dogmatic in his assumptions as those whom he disapproved.
But one thing he certainly has accomplished. He has made the words "phenomena" and "noumena" familiar to us all, and he has induced a vast number of men to accept it as established fact that it is not worth while to try to extend our knowledge beyond phenomena. One sees his influence in the writings of men who differ most widely from one another.