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 assume 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 associations which attach to words.  In calling Kant’s doctrine “the critical philosophy,” we are in some danger of uncritically assuming 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 assumptions which it makes, and of the rigor with which it draws inferences upon the basis of such assumptions.  That we may be the better able to withstand “undue influence,” I call attention to the following points:—­