Over at the Cosmic Variance blog there is an interesting discussion about how to reassure the lay public that the Large Hadron Collider isn't going to destroy the world.
Part of the problem is that scientists don't like absolutes, so they say "small chance" when a layperson would say "it could never happen". I'm guilty of this myself, saying that if there is ANY chance it will destroy the world it shouldn't be done. In reality the odds are about as likely as all the atoms in my underwear simultaneously jumping three feet to my left (thank you Douglas Adams).
The argument of some physicists boils down to "because I said so" or "you're too stupid to understand", and in this case they are probably right. I don't have the time, money, desire or - let's be honest - ability to learn enough theoretical physics to determine the risk for myself. I have to trust the experts.
That's the problem. I must have faith that the experts are capable of accurately assessing the risk, and faith that they even care! I have no doubt some LHC researchers would happily throw the switch even if they determined it had significant risk, as long as it would give them the Higgs boson.
It's a matter of faith and trust, and for LHC researchers I have neither. But I'm not worried. If they're wrong, hey, it was just about time to hit the "reset" button anyway.