بعض الإنسان ليس بحيوان
Some human is not an animal.
This is the contradictory of “Every human is an animal.” A universal affirmative is contradicted by a particular negative, asserting at least one exception.
“No human is an animal” is a universal negative, not the formal contradictory of the original universal affirmative. Confusing these forms spoils the first step of reductio.
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Qiyās al-Khalf: Compound Reductio, Impossibility and Proof of the Claim
بعض الإنسان ليس بحيوان
Some human is not an animal.
This is the contradictory of “Every human is an animal.” A universal affirmative is contradicted by a particular negative, asserting at least one exception.
“No human is an animal” is a universal negative, not the formal contradictory of the original universal affirmative. Confusing these forms spoils the first step of reductio.