Mental Models

A mental model is a small model of how the world works that you carry around in your head. According to Wikipedia, the concept was first put forward in 1943 by the psychologist Kenneth Craik in The Nature of Explanation.¹ The idea is that people hold a scaled-down model of reality in their heads, and run it to test in advance how things will turn out. ²

Charlie Munger was fond of the term, and blogs like Farnam Street spread it, until its meaning widened to "using the core principles of many fields as tools for thinking." So these days, ways of thinking such as first principles thinking, and even "don't do X" style maxims, get called mental models. The definition has become somewhat vague and muddled. Anyway, you can think of it as a good way of thinking that applies regardless of field. What matters is less having a precise definition of mental models than collecting a variety of them.

In 1994, at the USC business school, Charlie Munger said we should build up a latticework of mental models. As the saying goes, if all you have is a hammer, everything looks like a nail. So you shouldn't rely on just one or two mental models; you should gather them from many disciplines. The more mental models you accumulate, the wiser you can be said to become. That's because mental models are the kind of thing that transfers easily between fields.

Here is a list of mental models.

• first principles thinking
• second-order thinking
• 쪼갤까 말까 할 때는 쪼개지 마라
• diverge, then converge
• Chain Systems
• Don't Fight the Gorilla

I once made a video about mental models.