Inversion
Charlie Munger
Instead of asking how to succeed, ask: what would guarantee failure? Then avoid those.
Second-Order Thinking
Howard Marks
And then what? Trace consequences two and three steps past the obvious first effect.
First-Principles Thinking
Aristotle / Musk
Strip the problem to physics-level truths. Rebuild from primitives, not analogies.
The Vanishing Options Test
Chip & Dan Heath
Someone takes every option you are weighing off the table. What would you do then? That answer is usually the one worth having.
The Fool's Choice
Crucial Conversations
"Either I stay quiet or I blow this up." That's a false pair. Ask what it'd take to get both things you want.
What Would Have to Be True?
Roger Martin
Stop arguing about which option is right. Ask what each one needs to be true, then go check the shakiest one.
Occam's Razor
William of Ockham
Among competing explanations, the one needing the fewest assumptions usually wins.
Chesterton's Fence
G.K. Chesterton
Before removing something, understand why it was put there. Don't reform what you can't first justify.
Pre-Mortem
Gary Klein
Imagine the decision failed catastrophically. Walk backward: what killed it?
Margin of Safety
Benjamin Graham
Build buffer for the case where you're wrong. Don't price assumptions to perfection.
Kill Criteria
Annie Duke
Write down now the signal that would tell you to stop. Decide it while you can still think straight about it.
Black Swan Defense
Nassim Taleb
Plan for the unmodeled rare event. The most damaging surprises come from outside the distribution you considered.
Pascal's Wager (Asymmetric Risk)
Blaise Pascal
When the downside is catastrophic and the upside is only moderate, or the other way around, the math alone won't save you. Weigh which side is bigger.
Worst-Case / Best-Case / Likely
Scenario Planning
Spell out all three. Can you live with the worst case? If yes, the upside is mostly free.
Cobra Effect
Horst Siebert
When the fix creates the very problem it was meant to solve, or does more damage than the thing it was treating. What could this cure break?
Two-Way vs. One-Way Doors
Jeff Bezos
Reversible decisions deserve speed. Irreversible ones deserve patience and process.
Optionality
Nassim Taleb
Prefer choices that keep future doors open at low cost. Pair a safe floor with a few small bets that gain from surprise, and skip the mediocre middle.
Path Dependence
Paul David
Today's options are constrained by yesterday's choices. Which doors does this decision close on your future self?
The 70% Rule
Jeff Bezos
Decide when you have ~70% of the info. Waiting for 90% is usually slower than course-correcting.
The 37% Rule
Optimal Stopping
Spend the first third of your search learning what's out there. After that, take the first option better than everything you've already seen.
OODA Loop
John Boyd
Observe, orient, decide, act, then go again faster than the situation changes. When iteration speed beats getting it right the first time.
Parkinson's Law
C. Northcote Parkinson
Work expands to fill the time given. Shrink the timebox and the decision gets sharper.
Planning Fallacy
Kahneman & Tversky
You underestimate what your own plans will cost and how long they'll take, even when you know about this. It runs long even when you pad it for running long. Use what similar things actually took.
The Riskiest Assumption Test
Testing Business Ideas
Name the one belief this whole thing rests on. Find the cheapest way to test it this week instead of debating it.
Falsifiability
Karl Popper
A belief you can't imagine ever being wrong is not a conclusion, it's an identity. Say out loud what would change your mind.
Steelmanning
Julia Galef / Rationality
Build the strongest version of the opposing view, then argue with that. You're a scout mapping the ground, not a soldier defending it.
Five Whys
Toyota / Taiichi Ohno
Ask "why" five times in succession to drill from the surface symptom to the actual root cause.
Probabilistic Thinking
Annie Duke
Stop asking "will it work?" Start asking "what are the odds?" and act on the distribution.
Base Rates
Tversky & Kahneman
What's the historical batting average for decisions like this one? Anchor there before the story.
Bayesian Updating
Thomas Bayes
Start with a prior. Update incrementally as evidence arrives. Hold no belief with 100% confidence.
Expected Value
Probability Theory
Multiply outcomes by probabilities. Choose the bet with the best long-run math, not the best feeling.
Evidence Plus Preference
Cribsheet
Facts narrow the field, they don't pick for you. Separate what the research actually says from what you actually want, then decide.
Survivorship Bias
Abraham Wald
You're studying the winners. The full picture also requires the silent losers you'll never hear from.
Kelly Criterion
John Kelly
Even a positive-EV bet ruins you at the wrong stake size. Size the bet to the edge and the odds, not to your conviction.
Reversion to the Mean
Francis Galton
Extreme results — good or bad — tend to drift back toward average. Don't extrapolate a hot streak.
The Pareto Frontier
Economics
Among multiple goals, find options that can't be improved on one axis without sacrificing another. Stop optimizing inside dominated choices.
ICE / RICE Scoring
Product Management
Score by Impact × Confidence × Ease (and Reach). Forces you to commit to numbers, not vibes.
HALT
Recovery Tradition
Hungry, angry, lonely, tired. Fix whichever one is true before you decide anything you can't undo.
Solomon's Paradox
Igor Grossmann
You give better advice than you take. What would you tell a friend sitting exactly where you're sitting?
Circle of Competence
Warren Buffett
Know the perimeter of what you actually understand. Decisions inside it are cheap, outside it expensive. Feeling certain on unfamiliar ground usually means you're past the line.
The Counsel of Many
Proverbs 15:22
Plans fail for lack of counsel and succeed with many advisers. Who have you actually asked, and did you ask anyone likely to tell you no?
The Dichotomy of Control
Epictetus / Stoicism
Separate what's in your control from what isn't. Spend zero effort outside the line.
Two-System Thinking
Daniel Kahneman
System 1 is fast and emotional. System 2 is slow and deliberate. Big decisions deserve System 2; small ones don't need it.
Decision Journal
Annie Duke / Shane Parrish
Write down what you decided, why, and what you expected. Review later. Separates good decisions from lucky outcomes.
Sunk Cost Fallacy
Behavioral Economics
Past investment is gone. Decide forward only on future value, not past commitment.
Loss Aversion
Kahneman & Tversky
Losses feel about twice as strong as the same size gain. Are you saying no out of fear, not strategy?
Status Quo Bias
Psychology
We default to "no change" even when change is the better play. The cost of doing nothing is real.
Confirmation Bias
Psychology
You weigh evidence that fits your hypothesis more heavily. Actively hunt for what would prove you wrong.
Anchoring Bias
Kahneman & Tversky
The first number or framing sets the reference point. Reset to absolutes before judging "good" or "bad."
Endowment / IKEA Effect
Thaler / Norton, Mochon & Ariely
You overvalue what you already own and what you personally built. Would you actively choose this today if you didn't already hold it?
Hyperbolic Discounting
Behavioral Economics
You over-weight the near-term reward against the long-term payoff. It's why "future you" keeps getting betrayed by "present you."
Mimetic Desire
René Girard
We want what others want, not what we actually want. Strip the social signal: would you still want this if no one knew you chose it?
Fundamental Attribution Error
Lee Ross
You explain other people's behavior by character and your own by circumstance. Are you reading the situation, or just reading the person?
Availability Heuristic
Kahneman & Tversky
Vivid recent examples feel more probable than they are. Are you over-weighting one memorable story?
Hindsight Bias
Baruch Fischhoff
"I knew it all along" rewrites the past so the outcome looks inevitable. Distorts the lessons you draw from your last big decision.
Counterfactual Thinking
Philosophy
What would have happened anyway, without your action? Subtract the noise to measure your real contribution.
Hanlon's Razor
Robert Hanlon
Never attribute to malice what is adequately explained by incompetence or oversight.
The Empty Chair
Stakeholder Thinking
Pull up a chair for whoever isn't in the room but has to live with this. Say the decision out loud to them and see if it still sounds right.
The Veil of Ignorance
John Rawls
Would you choose this if you didn't know which role you'd play in the outcome? A fairness stress-test.
The Front-Page Test
Ethics
Picture this printed on the front page with your name on it. Still fine? If you'd explain it one way in public and another in private, that's your answer.
Skin in the Game
Nassim Taleb
Trust forecasts only from people who bear the downside if they're wrong. Whose advice survives if it backfires on them too?
Game Theory
John Nash
Other players are optimizing too. What's their best response to your move? Reason about where it settles.
Goodhart's Law
Charles Goodhart
When a measure becomes the target, it stops being a good measure. Watch what your metric is quietly distorting.
Tragedy of the Commons
Garrett Hardin
Individually rational behavior produces collectively destructive results. If everyone in your position did the same thing, what breaks?
Schelling Point
Thomas Schelling
Without communication, what would each party naturally converge on? Use focal points to coordinate.
Bike-Shedding (Law of Triviality)
C. Northcote Parkinson
Groups burn disproportionate time on trivial details they can easily opine on. Are you debating the easy 5% to avoid the hard 95%?
Opportunity Cost
Economics
The real cost of a "yes" is every "no" it forces. What are you giving up?
Pareto Principle (80/20)
Vilfredo Pareto
Roughly 80% of effect comes from 20% of causes. Find that 20% before anything else.
Via Negativa
Nassim Taleb
Improvement often comes from removal, not addition. What should you stop doing instead of layering on something new?
Maximizing vs. Satisficing
If You're So Smart, Why Aren't You Happy?
Set what good enough looks like, then take the first option that clears it. People who hold out for the very best end up less happy with what they get.
Hedonic Adaptation
If You're So Smart, Why Aren't You Happy?
The raise, the house, the title all stop feeling good faster than you expect. Count how long the good part actually lasts.
Enough
John Bogle
Past a certain point, more money and more status stop buying anything. Have you named your number, or are you still running a race with no finish line?
Eisenhower Matrix
Dwight Eisenhower
Sort by urgent and important. Do the important-not-urgent before it becomes the urgent crisis.
Hell Yeah or No
Derek Sivers
If it's not a "hell yeah," it's a no. The middle is where commitment quietly drains out of life.
Regret Minimization Framework
Jeff Bezos
Project yourself to 80 and ask which choice you'll regret not having tried. For smaller ones, ask how it'll feel in 10 minutes, 10 months, and 10 years.
Transformative Choice
L.A. Paul
Some choices change who you are, so the person deciding isn't the person who has to live with it. You can't run the numbers on becoming someone new.
Eulogy vs. Résumé Virtues
David Brooks
One list gets read at your funeral, the other gets read by recruiters. Which list does this decision add to?
Who Does This Serve?
Every Good Endeavor
Name who's better off if this goes well, besides you. Work aimed only at your own advancement runs out of fuel.
Compounding
Mathematics
Small advantages, repeated, beat large advantages, abandoned. What is the version of this decision that compounds?
Systems Over Goals
Atomic Habits
You don't rise to your goals, you fall to your systems. Which option leaves you with a better routine, not just a better outcome?
Flywheel Effect
Jim Collins
Many small pushes in one direction compound into momentum. Which version of this builds a flywheel instead of starting from rest every time?
Hedgehog Concept
Jim Collins
Focus where what you love, what you're best at, and what pays intersect. A filter for opportunity-rich, attention-poor decisions.
Lindy Effect
Nassim Taleb
For ideas and non-perishables, the longer it's been around, the longer it'll likely stay. Bet with time.
Map vs. Territory
Alfred Korzybski
Your model is a simplification. Watch where the model breaks against the actual terrain.
Cynefin Framework
Dave Snowden
Diagnose the domain — simple, complicated, complex, chaotic — before picking a method. Most bad decisions are a domain mismatch.
Doorman Fallacy
Rory Sutherland
Don't reduce a role to its narrowest function. The doorman opens the door; he also signals luxury, safety, and ceremony.