Poor Charlie's Almanack: The Essential Wit and Wisdom of Charles T. Munger · chapter 3 · id poor-charlies-almanack-c3-03-you-need-approximately-80-100-

“You need approximately 80-100 mental models from multiple disciplines to make good investment decisions -- 'to a man with a hammer, everything looks like a nail.'”

needs contextconfidence: medium✓ ZHP-verified + red-teamed

Receipts

Philip Tetlock, 'Expert Political Judgment,' Princeton University Press (2005)DOI registry: valid

Tetlock tracked 284 experts making 28,000+ predictions over 20 years. 'Foxes' who drew from many frameworks dramatically outperformed 'hedgehogs' who relied on one big idea.

Kahneman & Klein, 'Conditions for Intuitive Expertise,' American Psychologist (2009)DOI registry: valid

Expert judgment is only valid in 'high-validity environments' with regular feedback. Investing is a LOW-validity environment with delayed, noisy feedback.

Fama & French, 'Luck versus Skill in the Cross-Section of Mutual Fund Returns,' Journal of Finance (2010)DOI registry: valid

The majority of active manager outperformance is statistically indistinguishable from luck.

This claim is a stable, citable object. If you can falsify a verdict, tell us — corrections are loud here.