[Mike in VA]

So, like, I'm sitting in a restraunt and there's a bunch of loud, obnoxious gangsta-types over there, and there's a bunch of loud, obnoxious preppie-types over there. Guess which ones I'm going to watch more closely? Either group may be capable of doing something stupid, dangerous, and/or violent, but I know how to bet.

Discrimination - from the Latin discrimino, "to know the difference". Discrimination based on prejudice, i.e. lack of specific knowledge, or superficial generalities, is morally & ethically wrong. However, discrimiantion based on knowledge and experience is sound practice, and may, in fact, be part of a moral duty to protect yourself and your loved ones.

Defensive driving - good analogy - assume they're all idiots -- that way you'll never be disappointed, but occasionally pleasantly suprised.