indirect proof

American  

noun

1. an argument for a proposition that shows its negation to be incompatible with a previously accepted or established premise.

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indirect proof British  

noun

1. logic maths proof of a conclusion by showing its negation to be self-contradictory; reductio ad absurdum Compare direct

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Example Sentences

They have never been seen directly, though an indirect proof of their existence, based on studying a pair of collapsed stars, was rewarded with the 1993 Nobel prize in physics.

From Economist • Mar. 20, 2014

I was about to begin going over the steps of indirect proof when I heard Danny say, “You’re always sleeping! What a sleepyhead you are!” and I opened my eyes.

From "The Chosen" by Chaim Potok

But these exceptional measures give indirect proof of the very insufficient manner in which the question was generally settled.

From Villainage in England Essays in English Mediaeval History by Vinogradoff, Paul

The very ferocity with which the pretensions of the Court were assailed in certain quarters was indirect proof of its power, but there was also direct testimony of a high order.

From John Marshall and the Constitution; a chronicle of the Supreme court by Corwin, Edward Samuel

At present I am content with the indirect proof that the existence of such a standard is necessary to the existence of the arts.

From Statesman by Plato