What do you call an argument (or statement) that is an example of the very thing it seeks to refute.

For example: "Ad hominem arguments are the tools of scoundrels and blackguards. Therefore, they are invalid."

See here for more hilarious (well, funny) examples.

For the time being, I have borrowed autologica: the word for words like "word" from another thread.

It reminds me of an aporia, such as: "All written statements are false" (which, ex hypothesi, etc.) but seems to want its own Latinate sesquipedalianism.