Learn English – What’s the word — an ironic situation

single-word-requests

Is there a word or idiom describing a situation where a rebuttal to an argument is evidence to it (especially when it is ironic/meta)?

A very simple example:

John: “You can talk!”

Mary: “No I can't!”

John put forth an argument, and Mary rebutted it; in doing so, she inadvertently gave evidence to the contrary.

Best Answer

The word is self-refuting (or self-defeating).

In his Introduction to Logic, Harry Gensler defines a self-refuting statement as “[A] statement that makes negative claims so sweeping that it ends up denying itself.”

For instance, Truth does not exist (Is that a true statement?); Nothing is absolute (Is that absolutely true?); "I cannot speak a word of English”

There is a difference between self-contradiction and self-refutation.

Are you asleep? yes (self-refutation).

I am sleeping and not sleeping. (self contradiction)