In spite of the sense ordinarily attached to the name, the apriorists have more respect for the facts. Since they do not admit it as a truth established by evidence that the categories are made up of the same elements as our sensual representations, they are not obliged to impoverish them systematically, to draw from them all their real content, and to reduce them to nothing more than verbal artifices. On the contrary, they leave them all their specific characteristics. The apriorists are the rationalists; they believe that the world has a logical aspect which the reason expresses excellently. But for all that, it is necessary for them to give the mind a certain power of transcending experience and of adding to that which is given to it directly; and of this singular power they give neither explanation nor justification. For it is no explanation to say that it is inherent in the nature of the human intellect. It is necessary to show whence we hold this surprising prerogative and how it comes that we can see certain relations in things which the examination of these things cannot reveal to us. Saying that only on this condition is experience itself possible changes the problem perhaps, but does not answer it. For the real question is to know how it comes that experience is not sufficient unto itself, but presupposes certain conditions which are exterior and prior to it, and how it happens that these conditions are realized at the moment and in the manner that is desirable. To answer these questions it has sometimes been assumed that above the reason of individuals there is a superior and perfect reason from which the others emanate and from which they get this marvellous power of theirs, by a sort of mystic participation: this is the divine reason. But this hypothesis has at least the one grave disadvantage of being deprived of all experimental control; thus it does not satisfy the conditions demanded of a scientific hypothesis. More than that, the categories of human thought are never fixed in any one definite form; they are made, unmade and remade incessantly; they change with places and times. On the other hand, the divine reason is immutable. How can this immutability give rise to this incessant variability? Such are the two conceptions that have been pitted against each other for centuries; and if this debate seems to be eternal, it is because the arguments given are really about equivalent. If reason is only a form of individual experience, it no longer exists. On the other hand, if the powers which it has are recognized but not accounted for, it seems to be set outside the confines of nature and science. In the face of these two opposed objections the mind remains uncertain. But if the social origin of the categories is admitted, a new attitude becomes possible, which we believe will enable us to escape both of the opposed difficulties.