Why smart people behave stupidly

People are ruled by habits, good and bad. We are slaves to routine. We make knee-jerk assessments instead of thinking things through. We suck at probability and large numbers. We are easily manipulated by advertising. Small adjustments in the way things are framed can lead us into making completely different decisions. We persist in believing foolish things long after the weight of evidence makes their foolishness clear. We're complacent, ignoring serious problems until we can't avoid or deny them any longer.

This isn't just dumb people. People who are demonstrably smart do this too. And I figured out why.

Natural selection drove the human species to develop a big brain. The capacity to think is essential in outwitting bigger, faster, stronger competition. It allowed all kinds of things from social organization to tool use. There's a big but here, though. It's the capacity to think. The problem is that the brain is expensive. It accounts for some 20% of our energy consumption (at rest). Perhaps that was even higher back when we didn't get so many calories.

As a result, evolution favored humans who possessed big brains but avoided using them unless absolutely necessary. It favored big, lazy brains. Humans who were always thinking were always burning calories while rarely gaining by it. We evolved many cognitive shortcuts that resulted in inferior but good enough results at a much lower caloric cost. Smart people being stupid is basically millions of years of evolution. That's hard to fight. Maybe this will help me be more tolerant.