Exception paradox

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Exception paradox: if every rule has an exception, then there must be an exception to the rule that every rule has an exception.

From the logical point of view, this can be taken as a proof that the sentence "every rule has an exception" is false - a simple example of a proof technique known as reductio ad absurdum.

The Exception paradox is quite similar to the liar paradox, in which either answer creates an infinite loop of questions which again leads back to the beginning of each initial question being asked (or answered).

A similar idea is this: If everything is possible, then it is possible for anything to be impossible.