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.
The principle of causality and the principle of the conservation of energy are m themselves scientific “shibboleths,” and neither of them, asserts Boutroux, can be worked out so absolutely as to justify themselves as ultimate descriptions of the universe. They are valuable as practical maxims for the scientist, whose object is to follow the threads of action in this varied world of ours. They are incomplete, and have merely a relative value. Philosophy cannot permit their application to the totality of this living, pulsing universe. For cause, we must remember, does not in its strictly scientific meaning imply creative power. The cause of a phenomenon is itself a phenomenon. “The positive sciences in vain pretend to seize the divine essence or reason behind things.”[36] They arrive at descriptive formulæ and there they leave us. But, as Boutroux well reminds us in concluding his thesis, formulas never explain anything because they cannot even explain themselves. They are simply constructions made by observation and abstraction and which themselves require explanation.