general

the law of

tion.

nothing but "facts," however numerous and solid they may be. To do that we also need the aid of luminous general principles to guide us in the arrangement of our facts, and valid reasoning to connect them firmly together. In our endeavour to show clearly that there is such a thing as certainty, some very plain truths were cited,* as examples of matters about which no sane person can doubt; and in explaining the nature of "abstract truths," or "general laws," or "general principles," or "necessary truths," two truths were selected,† which it will suit our purpose to here somewhat dilate upon. The first of these two thus First selected abstract truths is called "the law of contradiction," principle, and may be thus expressed: "A thing cannot, at one and contradic the same time, both be and not be." If we reflect upon this truth we shall see that it is an absolute and necessary one-that it must be true even to the remotest regions of space, and that it must be true both for all the ages that have past and for all the ages that are yet to come. But some readers may here once more be tempted to impatience at being asked to reflect about anything, the truth of which is so manifestly undeniable. In deprecation of such impatience, we would again urge the same considerations as we before urged ‡ in deprecation of impatience respecting our inquiry as to the possibility of self-knowledge. Other readers may feel discouraged because they do not at once see the universal necessity of the law of contradiction. It is possible that some persons may doubt as to how things in this respect now are in the Dog Star, or how they have been in this part of space during some unimaginable abyss of past time, ages before the beginning of our world's separate existence. It does, indeed, at first seem not a little difficult to believe that a creature of the very limited powers which man possesses can know such a thing as absolute, necessary, and universal truth. How, it may be asked, Difficulties can a being who, for a few fleeting moments, dwells in an acceptation. inconspicuous atom of a boundless universe, know that anything whatever is and must be true for all ages, and for every possible region of that universe, however eternally inaccessible to him? At first sight a reasonable modesty See above, p. 16.

See above, pp. 6, 7.

† See above, p. 12.

in its

seems here to characterize the sceptic, and rash presumption the dogmatist. Nevertheless, if instead of considering this truth in its abstract form, we examine it in one of its concrete instances, its certainty will become clearly manifest. For example, let any one who doubts if something somewhere may not both "be" and "not be," consider whether it is possible for him (according to the illustration before given) both to possess his two eyes here and now, and at the same time to have only one of them; let him also think whether he could do so any better in any other place than the place where he is, or whether it could have been possible for him at any other time which he can conceive of. Again, let him ask himself whether he could both have lived in the reign of Edward III., and yet have never lived at all till the reign of Queen Victoria. He will, surely, then see clearly that this is impossible to him, as also that what is thus impossible for him, is impossible for other men also. But that abstract truth, the law of contradiction just quoted, is but the summing-up in one general expression of all concrete, separate cases of this kind.

Here, however, another objection may occur to the reader. He may say, "It is very true that I cannot imagine having two eyes and only one eye at the same time, and so I must practically acquiesce in the statement that we cannot simultaneously have both eyes and only one, simply because I am compelled thereto by my inability to imagine otherwise." But so to represent the matter, is to represent it not only inadequately but in a mistaken way, the error of which requires to be pointed A mistaken out, and ought to be clearly seen. It needs to be so seen proposed in because this mistaken representation is by some persons considered to be a supreme and ultimate rule of truth, and, in place of the law of contradiction, it has been laid down that "we must accept as true, propositions we cannot help thinking, because we cannot imagine the contrary." But if the reader will reflect over what his mind tells him when it unmistakably pronounces that he cannot, at the same time, both have eyes in his head and not have them, he will see that this perception of his is a clear positive

principle

place of it.

perception of incompatibility and consequent positive impossibility. He will not find his mind become a blank, and declare nothing but its own inability to answer, as he will find it do if he asks himself, "What is the disposition of the surface of the invisible side of the moon?" or, "Is the number of the heavenly bodies odd or even?" His mind has indeed been active, and not impotent; it has not declared that it was unable to answer his question, but has declared very clearly that he positively cannot have two eyes and, at the same time, have none, or only one. In other words, it has in this concrete instance, as in every other such instance, implicitly affirmed the law of contradiction. There are many things which we cannot think, merely through an impotence-a negative, passive inability, -to think them; as when we cannot think of all the units one after another, which would make a million. But such an impotence is a very different thing from positively seeing that anything cannot be because it is positively impossible. This truth will be further illustrated when we come to speak of the distinction between our powers of imagination and of intellectual conception. To say merely, "We cannot conceive the contrary of such proposition," is to make a mere assertion of inability, and is therefore a quite inadequate description of that active power of positive perception which we all act upon when we have to choose between two alternatives. A mere mental impotence will not guide us in our actions, but our actions are constantly guided by our implicit conviction of the truth expressed in the law of contradiction, though we may never in our lives have explicitly recognized it, or ever heard a word about it. The simplest rustic knows that if his wages have been paid to him, they are no longer owing, and that if he has put his cart horse in the stable, it is no longer between the shafts. The most learned of mankind are, of course, likewise continually guided in like manner, and to such guidance we owe every scientific deduction. If, then, perceptions of the kind were due to a mere mental disability, we might well exclaim, not "Oh, holy simplicity!" but "Oh, most mighty impotence!"

See below, ch. x., Imagination and Conception."

Denial of

the law involves absolute scepticism.

The distinction here drawn between positive and negative perceptions as to possibility, we believe to be a most important distinction, which deserves to be very carefully noted. By the former perception we see clearly that a thing is "positively impossible "—an expression often familiarly used. By the latter perception we recognize cither merely that a thing is unknown to us, or that it is impossible for us to know it. The former perception refers to the objective reality of things; the latter refers only to our own actual ignorance, or to our inability to become the subject of such knowledge.

If we deny or doubt about the law of contradiction, we are thereby landed in absolute scepticism, which, as we have seen, is absurd. We are so landed because, if we do not admit the validity of that law, then we can be certain of nothing. To have read or heard arguments against that law, which arguments have convinced us of its unsoundness, will then no longer suffice to disprove an assertion that we have also never read and never heard any such arguments at all, and that we are all the time convinced of its soundness. If anything can, at the same time, both be and not be, then nothing can be affirmed as true without the possibility of its being simultaneously untrue, and so we are reduced to a condition of utter intellectual paralysis, whereby no word and no thought can have any definite meaning for us. That nothing can both be and not be at the same time is, then, a positive truth, known to us by its own evidence. It is no mere law of our own minds, but is also a law which applies to all things; for we have seen that it so declares, if it declares anything, in those examples we selected for testing it, and we cannot accept its declarations as both absolutely true and partly false, for to do so would really be to reject it altogether. It plainly declares itself not to be a mere "form of thought" imposed on our intellect, but objectively certain, independently of our intellect. It declares itself to be absolutely and positively true, both universally and necessarily. To regard it, then, as a mere "form of thought" is to fall into utter scepticism, for it is to contradict that, the certainty * As to the term "objective," see above, p. 35.

of which is most evident to us of all propositions. It is thus a fundamental truth, upon which not only all reasoning depends, but which applies to everything which exists; since we see clearly that even a Supreme and Omnipotent Being could not-however different the existence of such a Being may be from our own-both be and be non-existent.

jection.

An objection has indeed been made against the truth An obof the law of contradiction and against every necessary and universal law of the kind, on the ground that such laws may be no more than truths for us-truths regulating our mental processes and controlling our thoughts, but not necessarily holding good for the universe external to us. But this objection is futile, because, as we have seen, what our minds declare is, not that a law exists and that we are passively unable to get beyond it, but that we actively and positively see that the law controls things external also. If anything whatever is declared to us, the real objective validity of the law is declared to us. This objective validity is affirmed by our consciousness as much as anything else is affirmed by it, and if we are to accept the declarations of consciousness at all-that is, if we are to rise out of utter and universal scepticism-we must accept the whole of what each such declaration tells us, and not gratuitously omit part of it or transform it into something else. We have already seen, in our study of memory,* that our mind unquestionably has the power of knowing not only its own states and laws, but also objective existences and conditions, and has, further, the power of recognizing such existences and conditions as being actually objective existences and conditions. What our mind declares is, not that we cannot think that a man's head has been really cut off, and, at the same time, really remains on, but it declares that, in a real world external to us, a man's head could not at one and the same time be both cut off and not cut off; and it also affirms that every sane mind and every being possessed of real intelligence must see that nowhere and at no time could a man's head be both cut off and not cut off at one and the same instant.

* See above, p. 36.