This reminds me of Ramsey’s argument against intuitionism. Saying p or ~p as if you are being informative always looks amusingly silly. If p or ~p was not trivially true, then what you said would be informative. If what you said was informative, then it would not look amusingly silly. If intuitionism is true, p or ~p is not always trivially true. Conclusion: intuitionism is not true. Unfortunately I don’t have a copy of Ramsey at home, so I can’t find the citation on the spot. (It’s at the start of Mathematical Logic I think.) I am interpolating slightly, and of course Ramsey was half-or-more-joking
in making the argument, but it is still kind of cute.

(Just in case you care, I think an intuitionist should probably deny premise 3 here. If you think that p or ~p is uninformative, then someone saying it as if it is informative will look silly. But all that shows is you think intuitionism is false, not that it is false. Since you are fallible, not much follows.)

Link via Atrios.

UPDATE: Looking more closely at the picture to which I linked, I’m not sure it hasn’t been doctored. (Not that I ever said that it had not been!) The letters are suspiciously clear, and the caption is not parallel to the bottom of the screen. And, most worryingly, most of the folks that have been reporting the story are generally somewhat counter-indicative. So, as I’m sure you would have done without my advice, don’t believe everything you see on the internet.