By a survey of laws of various types, logical, mathematical, mechanical, physical, chemical, biological, psychological and sociological, Boutroux endeavours to show that they are constructions built up from facts. Just as nature offers to the scientist facts for data, so the sciences themselves offer these natural laws as data to the philosopher, for his constructed explanation of things which is metaphysics or philosophy. “In the actual condition of our knowledge,” he remarks, “science is not one, but multiple; science, conceived as embracing all the sciences, is a mere abstraction.” This is a remark which recalls Renouvier’s witty saying, “I should very much like to meet this person I hear so much about, called ‘science.’” We have only sciences, each working after its own manner upon a small portion of reality. Man has a thirst for knowledge, and he sees, says Boutroux, in the world an “ensemble” of facts of infinite variety. These facts man endeavours to observe, analyse, and describe with increasing exactness. Science, he points out, is just this description. It is futile to attempt a resolution of all things into the principle of identity. “The world is full of a number of things,” and, therefore, argues Boutroux, the formula A = B can never be strictly and absolutely true. “Nature never offers to us identities, but only resemblances.” This has important bearing upon the law of causality, of which the sciences make so much. For there is such a degree of heterogeneity in the things to which the most elementary and general laws of physics and chemistry are applied that it is impossible to say that the consequent is proportional to the antecedent—that is to say, it is impossible to work out absolutely the statement that an effect is the unique result of a certain invariable cause. The fundamental link escapes us and so, for us, there is a certain contingency in experience. There is, further, a creativeness, a newness, which is unforeseeable. The passage from the inorganic to the organic stresses this, for the observation of the former would never lead us to the other, for it is a creation, a veritable “new” thing. Boutroux is here dealing hard blows at Taine’s conception. He continues it by showing that in the conscious living being we are introduced to a new element which is again absolutely irreducible to physical factors. Life, and consciousness too, are both creators. The life of the mind is absolutely _sui generis_; it cannot be explained by physiology, by reflex action, or looked upon as merely an epiphenomenon. Already Boutroux finds himself facing the central problem of Freedom. He recognises that as psychological phenomena appear to contain qualities not given in their immediate antecedents, the law of proportion of cause to effect does not apply to the actions of the human mind.