Decisions

The Great Mental Models: 6 key ideas

by Shane Parrish

The core ideas of The Great Mental Models, each in under a minute, written in our own words. Want the full depth? Get the book.

1. IDEA 1 OF 6

   The map is not the territory

   Models simplify reality and can mislead.

   Check whether your map still matches the ground.

2. IDEA 2 OF 6

   Circle of competence

   Know what you understand deeply and what you don't.

   Make big bets only inside your circle.

3. IDEA 3 OF 6

   First principles

   Break a problem down to basic truths, then rebuild solutions from there instead of copying others.

4. IDEA 4 OF 6

   Second-order thinking

   Ask what happens next, and then after that.

   Many decisions look good until you consider later effects.

5. IDEA 5 OF 6

   Inversion

   Ask how you would guarantee failure, then avoid those things.

   Thinking backwards reveals hidden risks.

6. IDEA 6 OF 6

   Occam's razor

   Simpler explanations are more likely to be right.

   Start with the simplest one that fits the facts.