Carlo Cipolla’s brilliant essay on the basic laws of human stupidity (which you can download here) is highly recommended. His five laws run as follows.
1. People always underestimate the number of stupid people around.
2. The probability that a person is stupid is independent of any other of their characteristics, for example the level of their formal education, how rich they are, their position in a hierarchy, their prestige, age, ethnicity or sex.
3. A stupid person causes losses to others while deriving no gain for themselves and possibly even incurring losses.
4. Non-stupid people always underestimate the damaging power of stupid people; they constantly forget that choosing to associate with stupid people is always a costly mistake.
5. A stupid person is the most dangerous type of person. Corollary: a stupid person is more dangerous than a bandit.
I’ve whittled and rearranged. Please copy, amend to your purposes, stick on noticeboards or wherever. In the age of the internet this insight is liberating and increasingly important.
1. The stupid damage other people while deriving no benefit and sometimes damaging themselves.
2. The probability that a person is stupid is independent of any other characteristic.
3. Stupid people are the most dangerous, more dangerous than bandits.
4. The non-stupid underestimate how many stupid people are around.
5. The non-stupid also underestimate the damaging power of the stupid, and they often forget that associating with stupid people is always a costly mistake.