We perceive physical phenomena, and these phenomena obey laws. This means: (i) that phenomena _a, b, c, d,_ previously perceived, can occur again in the same shape; (2) that a certain phenomenon _P,_ which appeared after the conditions _a, b, c, d,_ and after these conditions only, will not fail to recur as soon as the same conditions are again present. If the principle of causality told us nothing more, as the empiricists claim, we should willingly grant these philosophers that their principle is derived from experience; but it would no longer prove anything against our freedom. For it would then be understood that definite antecedents give rise to a definite consequent _wherever_ experience shows us this regular succession; but the question is whether this regularity is found in the domain of consciousness too, and that is the whole problem of free will. We grant you for a moment that the principle of causality is nothing but the summing up of the uniform and unconditional successions observed in the past: by what right, then, do you apply it to those deep-seated states of consciousness in which no regular succession has yet been discovered, since the attempt to foresee them ever fails? And how can you base on this principle your argument to prove the determinism of inner states, when, according to you, the determinism of observed facts is the sole source of the principle itself? In truth, when the empiricists make use of the principle of causality to disprove human freedom, they take the word cause in a new meaning, which is the very meaning given to it by common sense. To assert the regular succession of two phenomena is, indeed, to recognize that, the first being given, we already catch sight of the second. But this wholly subjective connexion between two ideas is not enough for common sense. It seems to common sense that, if the idea of the second phenomenon is already implied in that of the first, the second phenomenon itself must exist objectively, in some way or other, within the first phenomenon. And common sense was bound to come to this conclusion, because to distinguish exactly between an objective connexion of phenomena and a subjective association between their ideas presupposes a fairly high degree of philosophical culture. We thus pass imperceptibly from the first meaning to the second, and we picture the causal relation as a kind of prefiguring of the future phenomenon in its present conditions. Now this prefiguring can be understood in two very different ways, and it is just here that the ambiguity begins. [Sidenote: Causality, as the prefiguring of the future phenomenon in its present conditions, in one form destroys concrete phenomena.]