Smart People Don't Call Others Stupid
Smart people don't think others are stupid
Derek Sivers argues that calling someone stupid is itself an act of stupidity, because it means you've stopped thinking and jumped to a conclusion. Being smart is about thinking things through, not taking the easy answer. Saying "I don't know" is often the smartest response because it refuses to quit the game. Therefore, truly smart people don't think others are stupid.
So when someone says, "They're so stupid!" it means they've stopped thinking.