Where this is not possible, where the delicate and fleeting shades between the real and unreal intuitions are so slight as to mingle the one with the other, we must either renounce for the time being at least the knowledge of what really happened (and this we often do), or we must fall back upon conjecture, verisimilitude, probability. The principle of verisimilitude and of probability in fact dominates all historical criticism. Examination of sources and authorities is devoted to establishing the most credible evidence. And what is the most credible evidence, save that of the best observers, that is, of those who best remember and (be it understood) have not wished to falsify, nor had interest in falsifying the truth of things?
Historical scepticism.
From this it follows that intellectualistic scepticism finds it easy to deny the certainty of any history, for the certainty of history differs from that of science. It is the certainty of memory and of authority, not that of analysis and demonstration. To speak of historical induction or demonstration is to make a metaphorical use of these expressions, which bear a quite different meaning in history to that which they bear in science. The conviction of the historian is the undemonstrable conviction of the juryman, who has heard the witnesses, listened attentively to the case, and prayed Heaven to inspire him. Sometimes, without doubt, he is mistaken, but the mistakes are in a negligible minority compared with the occasions when he grasps the truth. That is why good sense is right against the intellectualists in believing in history, which is not a "fable agreed upon," but what the individual and humanity remember of their past. We strive to enlarge and to render as precise as possible this record, which in some places is dim, in others very clear. We cannot do without it, such as it is, and taken as a whole it is rich in truth. Only in a spirit of paradox can one doubt that there ever was a Greece or a Rome, an Alexander or a Cæsar, a feudal Europe overthrown by a series of revolutions, that on the 1st of November 1517 the theses of Luther were fixed to the door of the church at Wittemberg, or that the Bastile was taken by the people of Paris on the 14th of July 1789.
"What proof hast thou of all this?" asks the sophist, ironically. Humanity replies: "I remember it."
Philosophy as perfect science. The so-called natural sciences, and their limits.
The world of what has happened, of the concrete, of historical fact, is the world called real, natural, including in this definition both the reality called physical and that called spiritual and human. All this world is intuition; historical intuition, if it be shown as it realistically is; imaginary or artistic intuition in the narrow sense, if presented in the aspect of the possible, that is to say, of the imaginable.
Science, true science, which is not intuition but concept, not individuality but universality, cannot be anything but science of the spirit, that is, of what reality has of universal: Philosophy. If natural sciences be spoken of, apart from philosophy, we must observe that these are not perfect sciences: they are aggregates of cognitions, arbitrarily abstracted and fixed. The so-called natural sciences indeed themselves recognize that they are surrounded by limitations, and these limitations are nothing but historical and intuitive data. They calculate, measure, establish equalities and uniformities, create classes and types, formulate laws, show in their own way how one fact arises out of other facts; but while doing this they are constantly running into facts known intuitively and historically. Even geometry now states that it rests altogether on hypotheses, since threedimensional or Euclidean space is but one of the possible spaces, selected for purposes of study because more convenient. What is true in the natural sciences is either philosophy or historical fact. What of properly naturalistic they contain, is abstraction and caprice. When the natural sciences wish to become perfect sciences, they must leave their circle and enter philosophy. They do this when they posit concepts which are anything but naturalistic, such as those of the unextended atom, of ether or vibration, of vital force, of non-intuitional space, and the like. These are true and proper attempts at philosophy, when they are not mere words void of meaning. The concepts of natural science are, without doubt, most useful; but one cannot obtain from them that system which belongs only to the spirit.
These historical and intuitive data which cannot be eliminated from the natural sciences furthermore explain not only how, with the advance of knowledge, what was once believed to be true sinks gradually to the level of mythological belief and fantastic illusion, but also how among natural scientists some are to be found who call everything in their sciences upon which reasoning is founded mythical facts, verbal expedients, or conventions. Natural scientists and mathematicians who approach the study of the energies of the spirit without preparation, are apt to carry thither such mental habits and to speak in philosophy of such and such conventions as "decreed by man." They make conventions of truth and morality, and a supreme convention of the Spirit itself! But if there are to be conventions, something must exist which is no convention, but is itself the author of conventions. This is the spiritual activity of man. The limitation of the natural sciences postulates the illimitability of philosophy.
The phenomenon and the noumenon.