in the causal order, it alone cannot bring these constituent parts into existence. The aggregate depends on these parts, so no contingent constituent part can be the cause of the aggregate, either by itself or through the mediation of its effects. The necessary constituent part is different: if it is said to be the cause of an aggregate in its own right and through the mediation of its effects, this sense cannot apply to a contingent existent. Thus, the sense in which the Necessary Existent can be regarded as the cause of an aggregate of which it is itself a member cannot apply to contingent existents. A contingent existent therefore cannot conceivably be the cause of an aggregate of which it is itself a member. This exposes the confusion and error in the objection.

[The fourth response]

It may be said: We do not concede that the Necessary Existent is the cause of the aggregate considered as an aggregate. Rather, the Necessary Existent is the cause of the contingent constituent parts, while the individual constituents are the cause of the aggregate. The same cannot be said of the aggregate of contingent causes or of the aggregate of contingent existents, for none of them can be the cause of all the remaining constituent parts. Each is an effect and cannot be the cause of itself or of its own causes. If every constituent part is an effect, and the aggregate is an effect of its individual constituents, then the aggregate has all the more reason to be an effect.

[The fifth response]

To refute this objection, it may be said: We presented the argument to establish that there is something whose existence is necessary in itself. Either there is among existing things something whose existence is necessary in itself, or there is not. If there is, the intended conclusion has been established; if there is not, the objection is invalid.