The five laws of stupidity

I bet you didn't know that there are laws governing stupidity. Neither did I until an acquaintance e-mailed me this. Around 20 years ago, the late Carlo M. Cipolla, Emeritus Professor of Economics at UC Berkeley, proposed these laws:

1. Always and inevitably everyone underestimates the number of stupid individuals in circulation.
2. The probability that a certain person will be stupid is independent of any other characteristic of that person.
3. A stupid person is a person who causes losses to another person or to a group of persons while himself deriving no gain and even possibly incurring losses.
4. Non-stupid people always underestimate the damaging power of stupid individuals. In particular non-stupid people constantly forget that at all times and places and under any circumstances to deal and/or associate with stupid people always turns out to be a costly mistake.
5. A stupid person is the most dangerous type of person.

For a detailed explanation and justification, look here. I find it very hard to argue with his logic.