The discipline of writing down what you must not forget, precisely because your mind can't be trusted to remember it under pressure.
Munger's own answer to the 25 psychological tendencies catalogued in Poor Charlie's Almanack was not willpower — it was a checklist. A pilot doesn't rely on memory before takeoff, no matter how many hours they've flown; a decision-maker facing bias, incentive, and fatigue shouldn't either.
A new Boeing bomber prototype crashed on a demonstration flight after an experienced crew missed a single control-lock step.
Pilots adopted short, simple checklists for routine but critical steps, rather than trusting expertise alone.
Checklist discipline became standard across aviation, then spread to surgery, and to Munger's own investment process.
After a 1935 crash involving Boeing's new bomber prototype was traced to a single missed step, test pilots developed a short written checklist rather than concluding the aircraft was simply "too much plane for one man." Checklist discipline became a cornerstone of aviation safety culture from then on.
Surgeon and writer Atul Gawande's 2009 book documented how a simple surgical safety checklist, tested across hospitals internationally, measurably reduced complications and deaths — extending aviation's checklist logic into an entirely different high-stakes field.
Munger treated the 25 psychological tendencies described in Poor Charlie's Almanack as a personal pre-flight checklist for investment decisions — a deliberate, written counterweight to the overconfidence, incentive-driven reasoning, and social proof that undermine even experienced investors.
Write down the mistakes you've actually made before — a checklist built from real failures, not hypothetical ones.
Keep it short enough to actually use under pressure; a checklist no one reads is decoration.
Run it before the decision, not after — the point is prevention, not a post-mortem.
Apply it especially when you feel most confident — that's when tendencies like overconfidence do the most damage.
Revise it every time it fails to catch something; treat each miss as new material.
A written checklist doesn't insult your intelligence — it accounts for the fact that intelligence alone has never been proof against bias.