[The philosophers’ principal argument for the beginninglessness of the world rests on two premises]

The truth of the matter is that these philosophers based their principal argument for the beginninglessness of the world on two premises. The first is that the determination of one possibility rather than another requires a fully sufficient determining factor that necessitates it. The second is that, if such determination came into being, an infinite regress would necessarily follow, and this is impossible.

Yet they contradict themselves, affirming the opposite of both these premises.

[The possibility of an infinite regress]

As for the possibility of an infinite regress, if they mean a successive regress of effects, one after another, they themselves hold this to be possible. In that case, nothing prevents everything other than Allah from having a beginning—from coming to exist after not existing—including the celestial sphere and everything else, even if its coming into being depends upon a cause that came into being before it, and that cause’s coming into being depends upon another cause that came into being before it.

If they mean a concurrent regress—namely, that if something came into being, its causal efficacy would necessarily come into being alongside it, and that, as its causal efficacy became complete, the causal efficacy of the agent would also come into being—then this is invalid according to clear reason, and they agree that it is impossible.

If what they mean by an infinite regress is that, were the determination in favour of action as a kind to come into being, this regress would necessarily follow, then this is true. But this means that no determining factor comes into being that necessitates the determination in favour of action; rather, action as a kind has always existed. This is something the leading Muslim scholars concede to them.