He works out in his thesis the doctrine that efficient causes can be deduced from the formal laws of thought. This was Taine’s position, and it was the limit of Taine’s doctrine. Lachelier goes further and undermines Taine’s theories by upholding final causes, which he shows depend upon the conception of a totality, a whole which is capable of creating its parts. This view of the whole is a philosophical conception to which the natural sciences never rise, and which they cannot, by the very nature of their data and their methods, comprehend. Yet it is only such a conception which can supply any rational basis for the unity of phenomena and of experience. Only by seeing the variety of all phenomena in the light of such an organic unity can we find any meaning in the term universe, and only thus, continues Lachelier, only on the principle of a rational and universal order and on the reality of final causes, can we base our inductions. The “uniformity of nature,” that fetish of the scientists which, as Lachelier well points out, is merely the empirical regularity of phenomena, offers no adequate basis for a single induction. Lachelier developed his doctrines further in the article, _Psychologie et Métaphysique_. We can observe in it the marks which so profoundly distinguish the new spiritualism from the old, as once taught by Cousin. The old spiritualism had no place between its psychology and its metaphysics for the natural sciences. Indeed it was quite incapable of dealing with the problem which their existence and success presented, and so it chose to ignore them as far as possible. The new spiritualism, of which Lachelier is perhaps the profoundest speculative mind, not only is acquainted with the place and results of the sciences, but it feels itself equal to a criticism of them, an advance which marks a highly important development in philosophy. In this article Lachelier endeavours to pass beyond the standpoint of Cousin, and in so doing we see not only the influence of Ravaisson’s ideas of the creative activity of the spirit, but also of the discipline of the Kantian criticism, with which Lachelier, unlike many of his contemporaries in France at that time, was well acquainted.