every believer knows that once the Prophet—peace and blessings be upon him—forbids a thing, that thing is indeed forbidden.

Now, if someone were to say, “The evidence for its prohibition is that it is an intoxicant,” then, provided the addressee already knows that the substance is intoxicating and that every intoxicant is unlawful, he will accept the ruling. His difficulty lay only in having been heedless of, or ignorant about, the fact that it is an intoxicant.

Likewise, if one were to argue, “Because it is wine,” and the interlocutor acknowledges that it is wine, the prohibition is thereby established. Should he acknowledge this only after first denying it, the reason may be that he was ignorant and then learned, or forgetful and then remembered; for not everyone who knows something is constantly mindful of it.

The dispute over whether knowing the two premises is sufficient for knowing the conclusion, or whether an additional awareness is required:

For this reason the logicians disagreed: Is knowledge of the two premises enough to guarantee knowledge of the conclusion, or must one also notice a third factor? The latter view is that of Ibn Sīnā and others. They maintain that a person might know that a mule does not give birth, yet forget it; then, on seeing a mule with a swollen belly, he asks, “Is this animal pregnant or not?” He is told, “Do you not know it is a mule?” He answers, “Yes.” He is then asked, “Do you not know that a mule does not give birth?” He says, “Yes.” Only then does he realize that it cannot be pregnant.

Al-Rāzī and others challenged this, saying: This is weak. If the inclusion of one premise under the other constitutes something distinct from the two premises, that very inclusion becomes a third premise which itself requires derivation, and the question of how it joins the first two is identical to the question of how the first two join—leading to an infinite regress of premises. If, however, that inclusion is not distinct from the two premises, it cannot be a necessary condition of the inference, for a condition must be separate from the thing conditioned, and here there is no such separation.

As for the mule example, it is possible only when one of the two premises—either the minor or the major—is present in the mind. When both are simultaneously present, we do not concede that any doubt about the conclusion can arise at all.

I say: In truth, this entire debate arose because they assumed that only two premises are ever needed.