101. From what has been said we must infer that this idea is something distinct from the necessary connection, and that it is not correctly expressed in all its purity by the relation contained in the conditional propositions, whether the cause be taken as the condition or as the conditioned. The dependence of the effect on its cause is something more than the simple connection. To say that whatever is necessarily connected, even successively and in a fixed order, is connected by the relation of causality, is to confound the ideas of common language as well as those of philosophy.
[CHAPTER IX.]
NECESSARY AND SUFFICIENT CONDITIONS OF TRUE ABSOLUTE CAUSALITY.
102. We have just seen that the necessary connection of two objects is not enough to establish the character of causality; what circumstances are then necessary?
103. If we conceive an object, B, which begins, and suppose that the object A was necessary to its existence, and that of itself alone it was sufficient for the existence of B, we find in the relation of A to B the true character of the relation of a cause to its effect. For the complete character of absolute cause, two conditions are indispensable: I. The necessity of the existence of A for the existence of B. II. That the existence of A be sufficient for the existence of B, without any thing more being requisite.
These conditions may be expressed in the following propositions or formulas:
If B exists, A exists.
The existence of A alone is sufficient for the existence of B.