"in order to fix their own thinking" is worse than that-- "fix" is just plain wrong, since it implies a permanent repair. "Improve" would be better as well as less hostile.
I'm not sure that most people would recognize "prior probabilities in Bayes' theorem" as math-- it might just come through as way too technical to be worth the trouble.
I told an intelligent, well-educated friend about Less Wrong, so she googled, and got "Less Wrong is an online community for people who want to apply the discovery of biases like the conjunction fallacy, the affect heuristic, and scope insensitivity in order to fix their own thinking." and gave up immediately because she'd never heard of the biases.
While hers might not be the best possible attitude, I can't see that we win anything by driving people away with obscure language.
Possible improved introduction: "Less Wrong is a community for people who would like to think more clearly in order to improve their own and other people's lives, and to make major disasters less likely."