Some time ago, I compiled a list of awesome Unicode code points. One of the code points I added was U+2E2E REVERSED QUESTION MARK, the irony mark “⸮”. I’ve described it with the sentence
A useful character⸮
Pieter Fiers noted today, that this sentence might be the wrong way around. While thinking of an answer, I noticed, that in fact it constitutes a rather nice paradox.
Epimenides, an inhabitant of Crete, is quoted with the following sentence:
All Cretans are liars.
If you think of it, this sentence is somewhat peculiar. If you believe it, Epimenides was right. Therefore he is no liar, although he’s a Cretan. This means, his sentence is wrong. But that contradicts your initial assumption, that the sentence is true.
My statement about the usefulness of the irony mark works in a similar way. If you believe, that the irony mark is useless, then the sentence
A useful character⸮
is ironic, and the “⸮” marks this irony. Hence the mark fulfills its purpose and is not useless. You end with a contradiction. If you think, that the mark is a sensible tool in the set of punctuation characters, you accept the above sentence at face value, and especially unironic. But then you have to acknowledge, that in this specific case the mark missed its usefulness.
Of course, the true inspiration for the sentence was much more profane. It was this scene from The Simpsons.