They said that though it is true that everything which is...

They said that though it is true that everything which is hadith (preceded by non-existence) needs a cause, but the criterion for the hadith's need for a cause is not its huduth but something else. They also said that eternity is in no way the criterion of self-sufficience, perfection and absence of dependence.

The philosophers claimed that the criterion of ontic deficiency and perfection, and of need and self-sufficience, should be sought in the essence and quiddity (mahiyyah) of beings, not in previous non-existence, huduth, or eternal existence, qidam. Things in their essence (dhat), from the point of view of being, are of two kinds-or at least can be assumed to be of two kinds.

The first is the case where their being is their actual essence, that is, they do not have any essence (mahiyyah) apart from their existence. In other words their essence and their existence are one and the same. The second case is where the essence of a thing is something distinct from its existence and nonexistence. We call the first kind necessary being (wajib al-wujud), and the second, contingent being (mumkin al-wujud).

The Necessary Being, from the standpoint of being existence itself-it being senseless for a thing to be devoid of itself, and impossible for it not to exist while being existence itself-is not in need of a cause, because causality implies that the cause brings the being of the effect into existence, and when the essence (dhat) of a thing is actual existence and there is no vacuum in it in this regard, the need for a cause does not exist.

But a contingent being, from the viewpoint that it is neither existent nor non-existent in itself, being equally indifferent with respect to both the sides and having a vacuum in relation to both of them, needs something else to fill this vacuum, and that something is the cause. The existence of the cause fills that vacuum with existence, and that which is contingent-existent-in-itself (mumkin al-wujud bi al-dhat) becomes necessarily-existence-through-another (wajib al-wujdd bi al-ghayr).

The nonexistence of a cause fills that vacuum with non-existence and a contingent-existent-in-itself becomes impossible due to the absence of its cause (mumtani' al-wu jad bi al-ghayr). The philosophers call this [ontic] vacuum "essential contingency" (imkan dhati) and consider it to be the criterion for requiring a cause. Similarly, they name [ontic] plenitude "essential necessity" (wujub dhati).