How to spot a stupid person with Carlo Cipolla's "golden law of stupidity"

"We don't often call people stupid. Unlike its sibling concepts of dumbness and idiocy, stupidity isn't really a personality trait. Of course, you might think someone is stupid, but when we use the word, we tend to limit it to moments of stupidity. We say "Well, that was a stupid thing to do" or "You're being stupid." Stupidity is a blip."

"In fact, somewhat ironically, stupidity is often defined in contrast to otherwise normal and intelligent activities. We say "you're being stupid" because we expect the person to be sensible otherwise. Stupidity, then, is not a characteristic of being. It's not tied to IQ - as dumbness is - or the ability to assess risks - as being foolish is. Stupidity is an action, one defined by its implications."

""A stupid person is a person who causes losses to another person or group of people when he or she does not benefit and may even suffer losses.""

Stupidity usually refers to isolated actions rather than a stable personality trait, appearing as brief lapses in judgment. The term contrasts with dumbness, which relates to low intelligence, and foolishness, which relates to poor risk assessment. People expect generally sensible behavior, so occasional actions that cause losses to others seem anomalous. The golden law of stupidity defines a stupid person as someone who causes losses to others while deriving no benefit and possibly suffering losses themselves. Anyone can act stupidly, from experts to children. Repeated sequences of such actions can lead observers to label an individual as stupid.

Read at Big Think