52. The exercise of our will, whether with respect to internal or external acts, likewise gives us the knowledge of the dependence of some things upon others; and the impressions which we receive without our will, or against it, confirm us in this conviction. Without this experience we should see the succession of the phenomena, but should not know their relations of causality; for it is clear that the inclination to assign as the cause of a phenomenon that which preceded it, supposes the idea of cause and the knowledge of the dependence of the phenomena in the relation of causes and effects.
53. Some philosophers say that man has no idea of the creation, from which, without intending it, they come to the conclusion that we have not the idea of any cause. By creation is meant the transition of a substance from not-being to being, by virtue of the productive action of another substance. I hold that this is only the idea of causality in its highest degree, that is, as applied to the production of a substance; but since therefore we have the idea of cause, the idea of creation is not a new and inconceivable idea, but a perfection of an idea which is common to all mankind. We have seen that the idea of cause contains the idea of producing a transition from not-being to being; this power is an attribute of every active being, but with this difference, that finite causes have only the power to produce modifications, whilst the infinite cause has also the power to produce substances.
54. Here we find the same thing as in other branches of our philosophical cognitions: the idea of the essence pertains to reason, the knowledge of its existence depends on experience. The first is independent of the second, and we may reason on the essence by means of the condition of existence, that is, by means of a postulate.[76] We always have this postulate, if in nothing else, at least in the phenomena of our consciousness.
[CHAPTER VI.]
FORMULA AND DEMONSTRATION OF THE PRINCIPLE OF CAUSALITY.
55. The principle of causality, or the proposition: all that commences must have a cause; has been somewhat disputed latterly; hence it is necessary for us to place it beyond the reach of attack. I believe it possible to do this, by presenting the doctrine of the preceding chapters under a clear point of view, which shall drive away all doubt and clear up all difficulty. I beg the reader's attention for a few moments to the argument which I am going to propose.
56. Let us take any being, A. In order that the principle of causality may be applied to it it is necessary that it should have begun to be, and that it should not have existed before; for, if we do not suppose this beginning, A must have existed always.
We can then assign a duration in which A was not, and in which there was not-A. Therefore in the order of duration there has been a little series of two terms:
not-A ... A.