from revelation that deserves to be called evidence because its premises are sound and known to be true, then evidence from revelation must necessarily be given precedence over it, as all rational people agree.
It is thus clear that, however they characterize the category of evidence they favor, the other category can be characterized in analogous terms and given precedence in the same way. This is because they have established a faulty principle, giving precedence to what deserves no such precedence on either rational or revealed grounds. It thereby becomes clear that giving precedence to one category over another is invalid. Rather, the two particular conflicting proofs must be examined, and precedence given to whichever is conclusive—or, if both yield only probability, to whichever is stronger—whether it comes from revelation or reason. This invalid principle, which opens the way to religious deviation, is thereby refuted.
[The Fifth Argument]
Once the validity of revelation is known, and it is known that whatever the Messenger reports is true, one either knows that he reported the matter in dispute, considers it probable that he reported it, or neither knows nor considers it probable.
If it is known that he reported it, reason cannot contain anything that contradicts what is known through revelation or otherwise. For when something is known to be established or negated, no proof can establish the contrary.
If it is only probable that he reported it, reason may provide certain knowledge that negates it. In that case, certain knowledge must be given precedence over probability—not because it comes from reason or revelation, but because it is certain knowledge. Likewise, what is known with certainty through revelation must be given precedence over what is considered probable through reason. If the conflicting rational evidence also yields only probability, judgment must be suspended when the two are equally strong; otherwise, precedence is given to the stronger.
If revelation provides neither certain knowledge nor probability concerning the matter, there is no conflict in the first place. It is therefore clear that categorically giving reason precedence in all cases is error and misguidance.