The text uses the expression “the claim is not established.” Within a formal reductio it represents assuming the denial of the claim, not merely lacking evidence for it.
“I do not know whether this claim is proved” reports an epistemic state.
“The claim is false” denies the proposition.
Reductio proceeds from the second kind of assumption. Not yet possessing a proof is not the same as proving a proposition false.
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Qiyās al-Khalf: Compound Reductio, Impossibility and Proof of the Claim
The text uses the expression “the claim is not established.” Within a formal reductio it represents assuming the denial of the claim, not merely lacking evidence for it.
“I do not know whether this claim is proved” reports an epistemic state.
“The claim is false” denies the proposition.
Reductio proceeds from the second kind of assumption. Not yet possessing a proof is not the same as proving a proposition false.