brought about the other. Nonexistence has no effect on anything whatsoever. Rather, its nonexistence entails the nonexistence of its cause, and the nonexistence of its cause entails its own nonexistence, without either instance of nonexistence exerting any effect upon the other.

Its existence, however, requires a complete efficient cause. When that complete efficient cause is present, its existence becomes necessary; otherwise, its existence is impossible.

For this reason, people have disputed whether prior nonexistence is a condition of being contingent. The view held by the ancient philosophers, such as Aristotle, and his earlier and later followers, such as Ibn Rushd and others—including al-Fārābī, their Second Teacher, Aristotle being their First Teacher—is that a contingent thing must have been nonexistent, and that contingency is inconceivable in anything that has never been nonexistent. Even Ibn Sīnā and his followers agreed with them on this, although they contradicted themselves. This is also the position of the majority of scholars of rational inquiry among Muslims and adherents of other religions.

Yet Ibn Sīnā and his followers held that an eternal thing whose existence is through another can be described as contingent, even if it is beginningless and has always been necessary through another. Nevertheless, he and his followers explicitly stated the opposite in several places, agreeing with the majority. Elsewhere, I have quoted some of his statements from his book entitled al-Shifāʾ (The Healing). His fellow philosophers who followed Aristotle and his followers joined the majority in rejecting this view of his. They said that, through it, he had departed from their predecessors, just as he had departed from the majority of scholars of rational inquiry and from what he himself had explicitly stated in several places.