لكن المحال ليس بثابت، فبالضرورة ثبت المدعى
But the impossible is not established; necessarily, therefore, the claim is established.
This states the final inference. If denial of the claim entails something impossible, and that impossible consequence cannot hold, the denial is rejected.
The original claim follows because a proposition and its genuine contradictory cannot both be false.
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Qiyās al-Khalf: Compound Reductio, Impossibility and Proof of the Claim
لكن المحال ليس بثابت، فبالضرورة ثبت المدعى
But the impossible is not established; necessarily, therefore, the claim is established.
This states the final inference. If denial of the claim entails something impossible, and that impossible consequence cannot hold, the denial is rejected.
The original claim follows because a proposition and its genuine contradictory cannot both be false.