>...is a cop-out (no offense intended). Somewhat like saying "Well, driving a car is dangerous, so
>I might as well ignore all the traffic laws; at least I'll get there faster", ignoring the fact
>that many traffic laws (not all :) make driving easier and correlate strongly with common sense.
>Hmm, perhaps that analogy isn't very good; oh well. ;)

I agree that both analogies are poor.

But speaking of common sense; People don't think in terms of classes.
There's been some psychological research into how people catagorize things and the
theory of prototypes was one of the results of this work.

Lakoff's  _Women, Fire, and Dangerous Things_ (recommended by David Ungar) is an good
book on the subject.

Steve