Everyday knowledge is the sole field for all possible speculation. The words 'reality,' 'truth,' 'certitude' are defined by the use which ordinary thought makes of them. It is, therefore, a mistake to raise problems with respect to them which would imply a higher or more subtle meaning of the words. In common knowledge the foundation, which consists in a grasp of reality, is indubitable and solid; but the form, wholly practical, is not to be trusted. This form, the result of a separation and a spatialization arranged for the convenience of external or internal discourse, expresses only the relation of things to our power of acting upon them, whether by the body for life -or by the mind for thought.
Science, in spite of the chimerical hopes of those who would make of it the only knowledge worthy of reasonable man, has not for its object the inner life and infinite wealth of concrete reality. As we have seen, it always proceeds by symbolical representation. Its supreme object is the complete reduction of the world to terms of mind. Hence it is wholly relative to a particular point of view, that of discourse, determining what may be called the 'rationalistic' attitude of the mind. In this sense, one may speak of the contingency of scientific truths. Does this mean absolute skepticism? By no means. The only reason why it seems to do so is, that many, perhaps the majority, have a totally wrong conception of truth; for they hold to the scholastic view that truth consists in the conformity of thought to its object. The only possible criteria are those within science itself. There are several such: logical coherence or non-contradiction, the æsthetic joy of thought when contemplating the harmony of its works, etc. Scientific truth is thus, in the last analysis, only fidelity to the essential point of view which defines science itself. This truth is entirely relative to a certain intellectual attitude, to a certain orientation of thought, to a certain project of the mind—very legitimate, no doubt, but nowise unique or preëminent. In short, science receives from common sense the matter which it organizes; in itself it is only a form. Science begins with a 'positive' stage, in which it collects materials, etc. It then passes through an 'experimental' stage, and finally arrives at a third and last stage, the 'rational' stage. With only the resources of discursive reason, it endeavors to construct a model of the world. The rationalistic method, characteristic of completed science, may be applied to any subject-matter, but is able completely to penetrate none. It cannot go beyond symbolical representa- tion. Hence its laws of origin and genesis cannot escape contingency and relativity.
In this article the writer answers objections to his theory and explains more fully such parts as have been misunderstood. After showing that the systems of Descartes, Spinoza, and Leibniz treat living beings as absolute,
