Aristotle - The Organon - index for ANALYTICA PRIORIA Book 2 Part 5

Circular and reciprocal proof

Paragraph 1 Circular and reciprocal proof means proof by means of the conclusion, i.e. by converting one of the premisses simply and inferring the premiss which was assumed in the original syllogism:
Paragraph 2 In negative syllogisms reciprocal proof is as follows.
Paragraph 3 In particular syllogisms it is not possible to demonstrate the universal premiss through the other propositions, but the particular premiss can be demonstrated.

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