ON TRUTH. CHAPTER I. EVIDENCE AND CERTAINTY. Certainty exists, and universal doubt is unreasonable. There must be ultimate truths which do not need proof. The ground on which we believe them is their self-evidence, and no better criterion is possible. The pursuit of truth and of truths-Need of certainty-Two mental associations-Certainty exists-Unhealthy and irrational scepticism-Reflex mental acts-Some views as to what truths are most indisputable-This inquiry refers to the grounds and criterion of beliefs, not to their origins-Ultimate truths cannot be provedSelf-evidence is the criterion of truth-General, or abstract, necessary truths-Three orders of fundamental certainty-Is a better criterion than evidence possible? - The task of the inquirer after truth. MOST of us are eager for truth. The popularity of science and the spread of criticism show it. The spirit of inquiry was possibly as keen three hundred years ago, though, perhaps, mainly prompted by ideas of advantage in this world or the next. Now, there are multitudes who seek truth for its own sake, apart from any advantage it may bring with it. A passionate devotion to truth is the well-founded boast of our scientific worthies, who are above all things anxious not "to believe a lie." A special inquiry as to our perception of truth, will be made in our seventeenth chapter. of truth and of truths. Yet this popular pursuit of truth is mainly an indirect pursuit of it. It is not, after all, so much a pursuit of "truth" as a pursuit of "truths." It is not the endeavour to discover what is most certain and fundamental in all knowledge, but an endeavour to become acquainted with facts and laws of different branches of knowledge. The pursuit There is one very important difference between these two quests: a student of any branch of science must, if he would succeed, follow the footsteps of its masters and, at least provisionally, abide by their dicta. It is true that no bonds are imposed except such as originate from, and are justifiable by, observation and deduction. It is true that a questioning attitude is emphatically the scientific attitude, and that in the bracing air of free inquiry physical science has thriven wonderfully, and history has become a pursuit very much more attractive and fruitful of results than ever before. Nevertheless it is impossible for the student of science to dispense with the observations and reasonings of his contemporaries and predecessors, and he will risk failure if he rashly refuses to allow them their proper weight, or to accept some of them, at first, simply upon authority. In the pursuit of truth itself, it is otherwise. The inquirer, in this case, can only appeal to, and must abide by the declarations of, his own reason. He must clearly see the truth attending every step he takes, from the very first. Such direct inquiry concerning truth, though it is not and is not likely to become a popular pursuit, yet counts many more followers amongst us to-day than it did half a century ago. One cause of this increase, is the advance of physical science with its eager spirit of inquiry. Questions more and more fundamental concerning each branch of physical science naturally lead to questions which underlie all physical science. This impulse has been keenly felt by many of our own scientific leaders, who have largely promoted inquiry of this fundamental kind. Now, modesty, no less than caution, is a characteristic of the true man of science. Naturally, then, our scientific leaders have sought, and sought with success, to impress upon their followers a modest estimate of their power of knowing, and the fact that it has very definite limits. certainty. But every one is aware how apt men are, in trying to avoid one extreme, to fall into an opposite one. Doubt and scepticism, which are not only legitimate but necessary in science, are indeed doubly so in the inquiry concerning truth itself. Therein we should assent to nothing which is not clearly and evidently true to our minds. Nevertheless there may be exaggeration in this as in other things. It is possible to be so strongly impressed by the existence and legitimacy of doubt, as to forget the existence and legitimacy of certainty. Yet it is Need of manifest that life could not be carried on as it is, if we had not practical certainty as to its ordinary concerns. We may say more than this; for with regard to many matters which are not of ordinary concern, we have now greater certainty than our forefathers had. Side by side with an increasing scepticism, there has run along an increasing certainty. Thus with respect to the world we live in, most educated men are now certain as to its daily and annual revolutions, as also that its crust is largely composed of sedimentary rocks, containing remains of animals and plants more or less different from those which now live. No one, indeed, can deny that we may rely with absolute confidence and entire certainty upon a variety of such assertions. Science constantly advances, but its advance would be impossible if we could not, by observations and inferences, become so certain of facts previously doubtful, as to be able to make them starting-points for fresh observations and inferences. Nevertheless the certainty which most men feel about such matters cannot, from the nature of the case, be due to their own observations, but must depend upon their confidence in the generally received opinions of experts. The degree of their confidence also, will vary according to circumstances, as is the case with respect to their trust in human testimony generally. A reasonable man who has never been to Berlin and who never saw Napoleon III., will yet be absolutely certain as to the present existence of that city and the past existence of that man. He may feel very differently, however, with respect to some remote antarctic land or ancient Egyptian king. In spite, then, of increased and increasing a. sociations. certainty as to matters scientifically established, it is none the less true that, as a general rule, things which are very distant, or which happened a long time ago, are known to us only in round-about ways, and we feel more or less uncertainty about them. On the other hand, our convictions concerning the things about us at any given moment can be tested by our senses, and we are practically certain Two mental regarding them. Now, if we have had several times two feelings or ideas in close conjunction, thenceforth when one of these comes to be freshly experienced, the other tends to arise spontaneously in the mind, which is said to have "associated" the two together. Thus it comes about that we associate a feeling of "uncertainty" with statements about what is remote, and a feeling of "certainty" with what concerns the present. The value of this mental association we will consider later on. A second mental association which men commonly form is that between "what is especially true" and what is "demonstrable by reasoning." This association is due to the fact that most of our knowledge is gained indirectly and by inference. No truths are brought more strikingly home to our minds than those mathematical ones demonstrated by Euclid. We commonly ask for the "proof" of any proposition we are called on to believe, and we feel a special certainty about statements which we know we can prove by unanswerable reasoning. Thus it is many men have, rightly or wrongly, a feeling that "to believe anything which cannot be proved," is "to believe blindly." exists. It is very important to note these two facts of association with respect to our feelings of certainty. As to matters of everyday life, as distinguished from scientific truths, though we therein generally act on reasonable Certainty probabilities, yet certainty meets us at every turn. Thus we are absolutely certain that a door must be either shut or open; that if having been open it is now shut, some person or thing must have shut it; that we cannot both spend our money and keep it; that we feel warm or sad if we have either of those feelings; that we are the same individuals in the afternoon as we were in the morning; that if every man of a company has a red coat, then each |