What convinced you that it's false? Use that. (Note that "what convinced you" might not have been a direct argument, but perhaps a particular way of looking at the problem.)
I'm not convinced that it's false- I'm hoping someone could help me with that.
This is a thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. The previous "stupid" questions thread went to over 800 comments in two and a half weeks, so I think it's time for a new one.