[23] Vol. 2, chap. xviii., _De la Certitude des Sciences et leur Classification rationnelle_, pp. 139-186, including later observations on Spencer.
Renouvier’s line is not, it must be remembered in this connection, a purely imaginary one. It is a real line, an actual gap. For him there is a real discontinuity in the universe. Taine’s doctrine of a universal explanation, of a rigid unity and continuity, is, for Renouvier, anathema, _c’est la mathématisation a l’outrance_. This appears most markedly in the pages which he devotes to the consideration of _la synthèse totale_.
An important section of his _Traité de Logique_ (the first _Essai de Critique générale_) deals with the problem of this Total Synthesis of all phenomena.[24] This is a conception which Renouvier affirms to be unwarrantable and, indeed, in the last analysis impossible. A general synthesis, an organisation or connected hierarchy of sciences, is a fond hope, an illusion only of a mind which can overlook the real discontinuity which exists between things and between groups of things.
[24] Vol. I, pp. 107-115, and also vol. 2, pp. 202-245.
He sees in it the fetish of the Absolute and the Infinite and the lure of pantheism, a doctrine to which he opposes his “Personalism.” He reminds the scientists that personality is the great factor to which all knowledge is related, and that all knowledge is relative. A law is a law, but the guarantee of its permanence is not a law. It is no more easy, claims Renouvier, to say why phenomena do not stop than it is to know why they have begun. Laws indeed abide, but “not apart from conscious personalities who affirm them.”[25] Further, attacking the self-confident and dogmatic attitude in the scientists, Renouvier reminds them that it is impossible to demonstrate _every_ proposition; and in an important note on “Induction and the Sciences”[26] he points out that induction always implies a certain _croyance_. This is no peculiar, mystical thing; it is a fact, he remarks, which colours all the interesting acts of human personality. He here approaches Cournot in observing that all speculation is attended by a certain coefficient of doubt or uncertainty and so becomes really rational belief. With Cournot, too, Renouvier senses the importance of analogy and probability in connection with hypotheses in the world of nature and of morals. In short, he recognises as central the problem of freedom.