his own experience has furnished him with this knowledge. Once question or deny the reason assigned, and the skeptical conclusion can no longer be maintained by the skeptic without dogmatic assertion of the reason as self-evident or without the production of a new reason, which, when disputed, shares the fate of its predecessor. In other words, upon examination it is clear that skepticism cannot recommend itself as an escape from the danger of dogmatic assertion or of an infinite regress of proofs; for we cannot accept skepticism without proof, and if the skeptic is right, proof involves either unwarranted dogmatism or impossible regress of argument to infinity.

The

But it may be said that this inconsistency and illogicality of skepticism is no refutation of skepticism. Perhaps not; but it makes it necessary for the skeptic to bring forward other reasons for the unfaith that is in him; and when he does, these new reasons can be met in the same way. The skeptic must assume the validity of his argument in order by argument to convict his opponent of error or of unreasonableness. But, again. it may be asked: Why may not the skeptic hold to his skepticism without attempting to establish his position or to dislodge his opponent? answer is that to cherish any view without proof is to be dogmatic, and this is what the skeptic is, above all things, anxious to avoid. But still, again, it may be urged that instead of believing in the impossibility of knowledge, one may merely doubt its possibility. It is often said by writers against skepticism that a skeptical skepticism is unassailable. In one sense it is. If a man will persist in listening to no reason and in observing no laws of thought, then no argument directed against him will reach him, so long as he takes refuge behind the bulwark of unthinkingness. But what we can do is to convince ourselves by valid reasoning that skepticism, whether dogmatic or doubting, is untenable by a reasonable being. That is, if we follow the laws of thought we cannot become skeptical with regard to all our knowledge, however skeptical we may be on some of its details. To summarize our argument so far, let us say that we cannot reasonably doubt anything without good reason, and good reason is known reason, and known reason implies the validity of knowledge.

The insight into this truth enables us to appreciate the skeptic's rationality perhaps better than he does himself. Whenever we find a skep tic in philosophy we find a man who is trying to reason consistently, and who in this endeavor to be consistent even goes so far as to say that all knowledge is impossible. In such a case it is better worth our while to see what his fundamental assumptions are than to grieve or be merry over his conclusions. Now, one assumption is made by every skeptic, as by every other thinker-viz. that a thinker must make the objects of his thought consistent. It is the demand for consistency which drives all thinkers on to their conclusions, whatever these may be. Let us now examine this logical demand for consistency, and see what it is and what it involves.

This logical demand for consistency involves, as a presupposition, that there be some object-matter in dealing with which a thinker is to be consistent. In other words, consistency is a relation, thought thus to obtain between objects. To think consistently is to think objects into consistency. The

law of consistency, like all other laws of thought (see LOGIC), is a law directing the disposition which thought is to make of its objects. It is true that we may demand consistency in our processes of thought as well as in the disposition of objects. But this is because we objectify our thinking processes. We may then compare one process with another, or one part of a process with another part, and may find that they are not consistent. We may then come to demand order in our thinking as well as order in the things we think about. But it must be understood that this is possible only when our own thinking is a thing we think about; i.e. only when thought becomes an object of thought. We may therefore safely say that consistency as a logical law is a demand that the objects of thought be made to accord with each other. It is this demand which impels the child to constitute his sensations into an ordered world of experience. He tries to think them into some consistent relation with each other. Such an attempt to a large extent succeeds, but the success is slow. The work is done by means of categories (q.v.), or principles of connection which the thinker recognizes as obtaining between different objects. One may say that the reduction of experience into consistency is nothing but the ascertainment of such relations, or principles of connection, between objects as make it possible to think them together without having them conflict with each other as they appear in thought. For instance, in a certain dish on a stove I see one minute a

clear, transparent, solid cube; the next minute in the same pan I see a clear, transparent liquid. In order to be able to think these two objects as one, which the continuity of the objects under my gaze prompts me to do, I must be able to think of the cold, solid cube as changing into the liquid. Change is thus a category, or a principle of connection recognized as existing between two objects and making them consistent with each other. In the case of our example there are other categories; e.g. those of attribute and substance; and, provided I think of the experience as my experience, those of subject and object.

Now, one pair of correlative categories that appears quite early in the development of thought is that of reality and illusion. A careful study of these will enable us to understand the skeptic's position. A changing object does not deceive us, provided we know enough about the order of the changes. The trouble comes when an unexpected change occurs which throws us off our calculation. For example, we are accustomed to see broken sticks, and by some sort of operation we may be able to put the two broken ends together and practically make a whole stick again. But this requires time and work. We are not accustomed to seeing broken sticks straighten themselves of their own accord when they are moved. But now suppose we come upon a stick projecting out of a clear pool of water. It looks broken; i.e. there is a break in the outline of the object as seen. Suppose now we lift it out of the water. It becomes straight in the operation. We didn't expect this change, and we are fooled. We find, however, that by passing our hand along the stick it feels straight; that is, the character and order of our tactual sensations in this case are what they usually are when objects look straight. We dip the stick back into the water. It looks broken again. Still keeping it under water, we

pass our hands down the length of it and find that it feels straight although it looks crooked. We now lean on it. It bears our weight just as we have learned that straight-looking sticks do. Is the stick broken or not? We naturally answer: It seems to be broken, but really it is not. The broken appearance is an illusion.

Now, what is the meaning of this answer? The most obvious meaning is, doubtless, the true one, as is suggested by the etymology of the word 'illusion.' The broken appearance fools us; if we proceed on the supposition that it is broken we are disappointed. If, however, we proceed on the opposite supposition, we find that the event conforms to our expectation. The real qualities of the stick are those which do not deceive us when we want to use it. The stick is really straight, because we can use it as we use straight sticks; we cannot use it as we do broken ones. Hence its brokenness is an illusion. In other words, the distinction between reality and appearance is at first a practical distinction. At this stage the two correlative categories are reality and illusion; if ‘appearance' is used it means 'illusion.' The important thing is that not every experience is an appearance. Only those experiences that fool us are not real. But after a while another stage of development is reached. It comes, for instance, to be noticed that a thin disk presents a circular outline when in one position, an oval outline when in another; it even has a rectilinear outline at times. None of these different qualities of outline is apt to deceive a keen observer who has had considerable experience. Hence in the preceding stage they were not called illusions. But now attention gets directed to this peculiar variability of the qualities of objects. Which of these variations is the real quality? Obviously again the one which is the basis for our calculations in our dealings with the object. The disk therefore is circular, though it looks oval or rectilinear. These various appearances are not illusions, because they do not usually fool us, but they are not real in the sense that they are variations from the qualities which the usable object has. Appearance in this connection might be defined as a quality not itself real in the sense of belonging to the usable object; but also not necessarily illusory. Our eyes do not always see the object as it is, but still they do not deceive us. What we do see helps us to infer what we do not see, or the real quality. This real quality, however, can be seen if we put ourselves in the proper condition. For instance, the disk does have a visible circular outline if we hold it at right angles to our line of vision. Otherwise its outline, which in vision is elliptical or otherwise, is interpreted in thought as circular.

But it is quite natural that this distinction between reality and appearance should not long satisfy. A further distinction is suggested by some such argument as the following: If our sense of sight can present an object in some other form than that which it really has, how can we tell when its presentations are real or merely apparent? If the oval shape of the disk is merely an apparent shape, why may not the circular and every other shape be apparent also? In short, can our senses give us any other knowledge except that of appearances? It is clear that such a question involves a change in the meaning of reality, which has hitherto had a practical rather

than a theoretical significance. This change appears to be forced on us, when we have our attention called to the fact that all our senses may deceive us. So long as it is our sense of sight that presents objects not as they really are, we can find what they are by appealing to the other senses. Reality is still a sensible thing. But what if every sense stands on the same footing with sight? Can one any longer appeal from sense to sense when every sense may give us only appearance? Must not reality be something supersensible? And if thought may miscarry, as it often does, must we not say that reality transcends even thought? Then how can we know that we know anything about it?

The discovery of the fallibility of every sense and of thought is the beginning of philosophic sorrow. The doctrine of the relativity (q.v.) of our knowledge begins to prevail. Historically there have been two different consequences of this doctrine. A thinker may either hold to the notion of a reality opposed to appearance, or he may find it so shadowy and unwarrantable a conception that he gives it up altogether. Let us consider the former case, where the thinker gets into difficulty by being unable to say what reality really is. The difficulty is for him insoluble, because he fails to see that he is trying to make a distinction to which no actually known difference corresponds. He is employing the cate gories of appearance and reality beyond their proper limits. The relation between appearance and reality was first recognized as holding between actually experienced qualities. Gradually the apparent qualities encroached on the preserves of the real, until at last all real qualities were entirely ousted from the region of experi Or, to put the same thing in other terms, a distinction which was first made as a recognition of a certain practical difference is now employed when that practical difference is no longer the matter in point.

ence.

The continued use of the distinction gets its plausibility from the fact that the terms used have clear meanings within the original limits of their application. A thinker is therefore tempted to assume that the terms still have definite significance in their new sphere of application. An example of the change of meaning in the word 'really' as we pass from popular to chemical usage will show that it is unsafe to treat the word 'real' as if it expressed an unchanging, definite positive conception whenever used. The ordinary man of affairs would say unhesitatingly that charcoals and diamonds are really different. The analytical chemist would be tempted to say that they are really identical. There is no contradiction in these two statements, because 'really' for the layman means for the ordinary pur poses of life,' and for the chemist it means from the point of view of chemical analysis.' Now, if the word 'really' can change so much when we are still within the limits of experience. is it not well to ask ourselves what it means when we go beyond the limits of actual and possible experience and say that apparently things are as we find them in our experience, but what they really are we never shall know? Really here has no positive meaning; at least it has no practical meaning. It seems merely to serve notice of an attempt to carry out a practical distinction when there is no longer any possibility of any practical advantage from it. But is there not a theoretical