[1] "Outlines of Psychology," pp. 64-65, English translation, 1891.
[2] "The Limits of Evolution, and Other Essays," revised edition. New York, 1905.
CHAPTER XV
RATIONALISM, EMPIRICISM, CRITICISM, AND CRITICAL EMPIRICISM
60. RATIONALISM.--As the content of a philosophical doctrine must be determined by the _initial a.s.sumptions_ which a philosopher makes and by the _method_ which he adopts in his reasonings, it is well to examine with some care certain broad differences in this respect which characterize different philosophers, and which help to explain how it is that the results of their reflections are so startlingly different.
I shall first speak of _Rationalism_, which I may somewhat loosely define as the doctrine that the reason can attain truths independently of observation--can go beyond experienced fact and the deductions which experience seems to justify us in making from experienced fact. The definition cannot mean much to us until it is interpreted by a concrete example, and I shall turn to such. It must, however, be borne in mind that the word "rationalism" is meant to cover a great variety of opinions, and we have said comparatively little about him when we have called a man a rationalist in philosophy. Men may agree in believing that the reason can go beyond experienced fact, and yet may differ regarding the particular truths which may be thus attained.
Now, when Descartes found himself discontented with the philosophy that he and others had inherited from the Middle Ages, and undertook a reconstruction, he found it necessary to throw over a vast amount of what had pa.s.sed as truth, if only with a view to building up again upon a firmer foundation. It appeared to him that much was uncritically accepted as true in philosophy and in the sciences which a little reflection revealed to be either false or highly doubtful.
Accordingly, he decided to clear the ground by a sweeping doubt, and to begin his task quite independently.
In accordance with this principle, he rejected the testimony of the senses touching the existence of a world of external things. Do not the senses sometimes deceive us? And, since men seem to be liable to error in their reasonings, even in a field so secure as that of mathematical demonstration, he resolved further to repudiate all the reasonings he had heretofore accepted. He would not even a.s.sume himself to be in his right mind and awake; might he not be the victim of a diseased fancy, or a man deluded by dreams?
Could anything whatever escape this all-devouring doubt? One truth seemed unshakable: his own existence, at least, emerged from this sea of uncertainties. I may be deceived in thinking that there is an external world, and that I am awake and really perceive things; but I surely cannot be deceived unless I exist. _Cogito, ergo sum_--I think, hence I exist; this truth Descartes accepted as the first principle of the new and sounder philosophy which he sought.
As we read farther in Descartes we discover that he takes back again a great many of those things that he had at the outset rejected as uncertain. Thus, he accepts an external world of material things. How does he establish its existence? He cannot do it as the empiricist does it, by a reference to experienced fact, for he does not believe that the external world is directly given in our experience. He thinks we are directly conscious only of our _ideas_ of it, and must somehow prove that it exists over against our ideas.
By his principles, Descartes is compelled to fall back upon a curious roundabout argument to prove that there is a world. He must first prove that G.o.d exists, and then argue that G.o.d would not deceive us into thinking that it exists when it does not.
Now, when we come to examine Descartes" reasonings in detail we find what appear to us some very uncritical a.s.sumptions. Thus, he proves the existence of G.o.d by the following argument:--
I exist, and I find in me the idea of G.o.d; of this idea I cannot be the author, for it represents something much greater than I, and its cause must be as great as the reality it represents. In other words, nothing less than G.o.d can be the cause of the idea of G.o.d which I find in me, and, hence, I may infer that G.o.d exists.
Where did Descartes get this notion that every idea must have a cause which contains as much external reality as the idea does represented reality? How does he prove his a.s.sumption? He simply appeals to what he calls "the natural light," which is for him a source of all sorts of information which cannot be derived from experience. This "natural light" furnishes him with a vast number of "eternal truths", these he has not brought under the sickle of his sweeping doubt, and these help him to build up again the world he has overthrown, beginning with the one indubitable fact discussed above.
To the men of a later time many of Descartes" eternal truths are simply inherited philosophical prejudices, the results of the reflections of earlier thinkers, and in sad need of revision. I shall not criticise them in detail. The important point for us to notice is that we have here a type of philosophy which depends upon truths revealed by the reason, independently of experience, to carry one beyond the sphere of experience.
I again remind the reader that there are all sorts of rationalists, in the philosophical sense of the word. Some trust the power of the unaided reason without reserve. Thus Spinoza, the pantheist, made the magnificent but misguided attempt to deduce the whole system of things physical and things mental from what he called the attributes of G.o.d, Extension and Thought.
On the other hand, one may be a good deal of an empiricist, and yet something of a rationalist, too. Thus Professor Strong, in his recent brilliant book, "Why the Mind has a Body," maintains that we know intuitively that other minds than our own exist; know it without gathering our information from experience, and without having to establish the fact in any way. This seems, at least, akin to the doctrine of the "natural light," and yet no one can say that Professor Strong does not, in general, believe in a philosophy of observation and experiment.
61. EMPIRICISM.--I suppose every one who has done some reading in the history of philosophy will, if his mother tongue be English, think of the name of John Locke when empiricism is mentioned.
Locke, in his "Essay concerning Human Understanding," undertakes "to inquire into the original, certainty, and extent of human knowledge, together with the grounds and degrees of belief, opinion, and a.s.sent."
His sober and cautious work, which was first published in 1690, was peculiarly English in character; and the spirit which it exemplifies animates also Locke"s famous successors, George Berkeley (1684-1753), David Hume (1711-1776), and John Stuart Mill (1806-1873). Although Locke was a realist, Berkeley an idealist, Hume a skeptic, and Mill what has been called a sensationalist; yet all were empiricists of a sort, and emphasized the necessity of founding our knowledge upon experience.
Now, Locke was familiar with the writings of Descartes, whose work he admired, but whose rationalism offended him. The first book of the "Essay" is devoted to the proof that there are in the mind of man no "innate ideas" and no "innate principles." That is to say, Locke tries to show that one must not seek, in the "natural light" to which Descartes turned, a distinct and independent source of information,
"Let us, then," he continues, "suppose the mind to be, as we say, white paper, void of all characters, without any ideas; how comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it, with an almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer in one word, from experience; in that all our knowledge is founded, and from that it ultimately derives itself. Our observation, employed either about external sensible objects, or about the internal operations of our minds, perceived and reflected on by ourselves, is that which supplies our understandings with all the materials of thinking. These two are the fountains of knowledge, from whence all the ideas we have, or can naturally have, do spring." [1]
Thus, all we know and all we ever shall know of the world of matter and of minds must rest ultimately upon observation,--observation of external things and of our own mind. We must clip the erratic wing of a "reason" which seeks to soar beyond such knowledge; which leaves the solid earth, and hangs suspended in the void.
"But hold," exclaims the critical reader; "have we not seen that Locke, as well as Descartes (section 48), claims to know what he cannot prove by direct observation or even by a legitimate inference from what has been directly observed? Does he not maintain that the mind has an immediate knowledge or experience only of its own ideas? How can he prove that there are material extended things outside causing these ideas? And if he cannot prove it by an appeal to experience, to direct observation, is he not, in accepting the existence of the external world at all, just as truly as Descartes, a rationalist?"
The objection is well taken. On his own principles, Locke had no right to believe in an external world. He has stolen his world, so to speak; he has taken it by violence. Nevertheless, as I pointed out in the section above referred to, Locke is not a rationalist of _malice prepense_. He _tries_ to be an empiricist. He believes in the external world because he thinks it is directly revealed to the senses--he inconsistently refers to experience as evidence of its existence.
It has often been claimed by those who do not sympathize with empiricism that the empiricists make a.s.sumptions much as others do, but have not the grace to admit it. I think we must frankly confess that a man may try hard to be an empiricist and may not be wholly successful.
Moreover, reflection forces us to the conclusion that when we have defined empiricism as a doctrine which rests throughout upon an appeal to "experience" we have not said anything very definite.
What is _experience_? What may we accept as directly revealed fact?
The answer to such questions is far from an easy one to give. It is a harder matter to discuss intelligently than any one can at all realize until he has spent some years in following the efforts of the philosophers to determine what is "revealed fact." We are supposed to have experience of our own minds, of s.p.a.ce, of time, of matter. What are these things as revealed in our experience? We have seen in the earlier chapters of this book that one cannot answer such questions off-hand.
62. CRITICISM.--I have in another chapter (section 51) given a brief account of the philosophy of Immanuel Kant. He called his doctrine "Criticism," and he distinguished it from "Dogmatism" and "Empiricism."
Every philosophy that transcends experience, without first critically examining our faculty of knowledge and determining its right to spread its wings in this way, Kant calls "dogmatism." The word seems rather an offensive one, in its usual signification, at least; and it is as well not to use it. As Kant used the word, Descartes was a dogmatist; but let us rather call him a rationalist. He certainly had no intention of proceeding uncritically, as we shall see a little later.
If we call him a dogmatist we seem to condemn him in advance, by applying to him an abusive epithet.
Empiricism, according to Kant, confines human knowledge to experience, and thus avoids the errors which beset the dogmatist. But then, as Hume seemed to have shown, empiricism must run out into skepticism. If all our knowledge has its foundations in experience, how can we expect to find in our possession any universal or necessary truths? May not a later experience contradict an earlier? How can we be sure that what has been will be? Can we _know_ that there is anything fixed and certain in our world?
Skepticism seemed a forlorn doctrine, and, casting about for a way of escape from it, Kant hit upon the expedient which I have described. So long as we maintain that our knowledge has no other source than the experiences which the world imprints upon us, so to speak, from without, we are without the power of prediction, for new experiences may annihilate any generalizations we have founded upon those already vouchsafed us; but if we a.s.sume that the world upon which we gaze, the world of phenomena, is made what it is by the mind that perceives it, are we not in a different position?
Suppose, for example, we take the statement that there must be an adequate cause of all the changes that take place in the world. Can a mere experience of what has been in the past guarantee that this law will hold good in the future? But, when we realize that the world of which we are speaking is nothing more than a world of phenomena, of experiences, and realize further that this whole world is constructed by the mind out of the raw materials furnished by the senses, may we not have a greater confidence in our law? If it is the nature of the mind to connect the phenomena presented to it with one another as cause and effect, may we not maintain that no phenomenon can possibly make its appearance that defies the law in question? How could it appear except under the conditions laid upon all phenomena? If it is our nature to think the world as an orderly one, and if we can know no world save the one we construct ourselves, the orderliness of all the things we can know seems to be guaranteed to us.
It will be noticed that Kant"s doctrine has a negative side. He limits our knowledge to phenomena, to experiences, and he is himself, in so far, an empiricist. But in that he finds in experience an order, an arrangement of things, not derived from experience in the usual sense of the word, he is not an empiricist. He has paid his own doctrine the compliment of calling it "criticism," as I have said.
Now, I beg the reader to be here, as elsewhere, on his guard against the a.s.sociations which attach to words. In calling Kant"s doctrine "the critical philosophy," we are in some danger of uncritically a.s.suming and leading others to believe uncritically that it is free from such defects as may be expected to attach to "dogmatism" and to empiricism. Such a position should not be taken until one has made a most careful examination of each of the three types of doctrine, of the a.s.sumptions which it makes, and of the rigor with which it draws inferences upon the basis of such a.s.sumptions. That we may be the better able to withstand "undue influence," I call attention to the following points:--
(1) We must bear in mind that the attempt to make a critical examination into the foundations of our knowledge, and to determine its scope, is by no means a new thing. Among the Greeks, Plato, Aristotle, the Stoics, the Epicureans, and the Skeptics, all attacked the problem.
It did not, of course, present itself to these men in the precise form in which it presented itself to Kant, but each and all were concerned to find an answer to the question: Can we know anything with certainty; and, if so, what? They may have failed to be thoroughly critical, but they certainly made the attempt.
I shall omit mention of the long series of others, who, since that time, have carried on the tradition, and shall speak only of Descartes and Locke, whom I have above brought forward as representatives of the two types of doctrine that Kant contrasts with his own.
To see how strenuously Descartes endeavored to subject his knowledge to a critical scrutiny and to avoid unjustifiable a.s.sumptions of any sort, one has only to read that charming little work of genius, the "Discourse on the Method of Rightly Conducting the Reason."
In his youth Descartes was, as he informs us, an eager student; but, when he had finished the whole course of education usually prescribed, he found himself so full of doubts and errors that he did not feel that he had advanced in learning at all. Yet he had been well tutored, and was considered as bright in mind as others. He was led to judge his neighbor by himself, and to conclude that there existed no such certain science as he had been taught to suppose.
Having ripened with years and experience, Descartes set about the task of which I have spoken above, the task of sweeping away the whole body of his opinions and of attempting a general and systematic reconstruction. So important a work should be, he thought, approached with circ.u.mspection; hence, he formulated certain Rules of Method.
"The first," he writes, "was never to accept anything for true which I did not clearly know to be such; that is, carefully to avoid haste and prejudice, and to include nothing more in my judgments than what was presented to my mind so clearly and distinctly as to exclude all reason for doubt."
Such was our philosopher"s design, and such the spirit in which he set about it. We have seen the result above. It is as if Descartes had decided that a certain room full of people did not appear to be free from suspicious characters, and had cleared out every one, afterwards posting himself at the door to readmit only those who proved themselves worthy. When we examine those who succeeded in pa.s.sing muster, we discover he has favored all his old friends. He simply _cannot_ doubt them; are they not vouched for by the "natural light"? Nevertheless, we must not forget that Descartes sifted his congregation with much travail of spirit. He did try to be critical.
As for John Locke, he reveals in the "Epistle to the Reader," which stands as a preface to the "Essay," the critical spirit in which his work was taken up. "Were it fit to trouble thee," he writes, "with the history of this Essay, I should tell thee, that five or six friends meeting at my chamber, 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 a while 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 to see what objects our understandings were, or were not, fitted to deal with."
This problem, proposed by himself to his little circle of friends, Locke attacked with earnestness, and as a result he brought out many years later the work which has since become so famous. The book is literally a critique of the reason, although a very different critique from that worked out by Kant.
"If, by this inquiry into the nature of the understanding," says Locke, "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." [2]
To the difficulties of the task our author is fully alive: "The understanding, like the eye, whilst it makes us see and perceive all other things, takes no notice of itself; and it requires art and pains to set it at a distance, and make it its own object. But whatever be the difficulties that lie in the way of this inquiry, whatever it be that keeps us so much in the dark to ourselves, sure I am that all the light we can let in upon our own minds, all the acquaintance we can make with our own understandings, will not only be very pleasant, but bring us great advantage, in directing our thoughts in the search, of other things." [3]
(2) Thus, many men have attempted to produce a critical philosophy, and in much the same sense as that in which Kant uses the words. Those who have come after them have decided that they were not sufficiently critical, that they have made unjustifiable a.s.sumptions. When we come to read Kant, we will, if we have read the history of philosophy with profit, not forget to ask ourselves if he has not sinned in the same way.
For example, we will ask;--