100 Little Ideas

Lists of mental models have proliferated across the internet for the past decade, and most of them either stop at the same twenty familiar concepts or expand into a compendium so large it's useful only as a reference. Housel's 2020 list is interesting for a different reason: it reads as an argument about what kinds of ideas are worth carrying around, embedded in a format (the list) that is deliberately too fast for careful reading. That tension is probably intentional.nnThe first key move is the range. Housel pulls from evolutionary biology (Semmelweis Reflex, Ringelmann Effect), statistics (Berkson's Paradox, Anscombe's Quartet), economics (Cobra Effect, Braess's Paradox), psychology (Ironic Process Theory, Golem Effect), and philosophy (Chronological Snobbery, quoted at length from C.S. Lewis). The implicit argument is the same one Munger makes about his latticework: reality doesn't sort itself into disciplines, so your thinking tools shouldn't either. The person who only knows psychology will explain everything as a bias; the person who knows Braess's Paradox understands why adding capacity can make a system worse.nnThe second and more memorable move is the self-undermining ending. After 99-ish items, Housel adds the 'Fact-Check Scarcity Principle': "This article is called 100 Little Ideas but there are fewer than 100 ideas. 99% of readers won't notice because they're not checking, and most of those who notice won't say anything. Don't believe everything you read." That the author of a list about cognitive bias would plant a cognitive-bias demonstration inside it is either very clever or very fitting. Probably both.nnWe picked this because the list is practically useful as a vocabulary for seeing common situations more clearly — useful for anyone who reads decisions for a living. The question worth carrying is how many of the concepts you recognised immediately, and what that tells you about which domains you have been paying attention to.