It is not only possible but necessary that these effects proceed from the Eternal. Yet if they do proceed from Him, the Eternal cannot be a fully sufficient cause for any one of them, for had He been so they would have existed alongside Him from all eternity. Hence their doctrine of a sufficient cause collapses—and that is precisely what we sought to show.

However, this reply does not, in itself, rule out the notion of events without a first beginning. One might still maintain that the origination of the Eternal’s first act is conditioned by a second act. On either assumption, though, nothing in the universe is thereby rendered eternal; each entity may still be an occurrence, even if conditioned by a prior occurrence—especially when that occurrence is the act of the Almighty Agent, exalted be He. What al-Rāzī and others have advanced is indeed binding against the opponents, yet it neither dissolves the difficulty nor exposes its full falsity.

We shall now demonstrate that falsity both on their premises and on those of the Muslims. Their argument rests on the claim that there must exist, from pre-eternity, a complete cause; otherwise one would face either an ungrounded preference or an infinite regress. Many of them state the proof just so. The term “infinite regress” may refer to the disputed regress, to the regress unanimously judged impossible by rational people, or even to circularity.

If in pre-eternity there were no sufficient cause and it later became sufficient, the completion of causation itself would have come into being—and that implies the occurrence of an event without an agent. Hence Ibn Sīnā and others put it this way: whenever an agent acts after previously not acting, some new factor must have arisen—knowledge, intention, will, the removal of an impediment, or something else. Otherwise, if his state remains exactly as it was and nothing issued from him before, then nothing should issue from him now; yet events have in fact occurred—an impossibility.