Work in progress... I'm basically just taking notes on the book I'm reading in public. It's getting shoved thru an AI to boot, because man, the book is incomplete!

Charlie Munger's 25 Psychological Tendencies: A Decision-Making Checklist

Charlie Munger, vice chairman of Berkshire Hathaway, spent decades developing what he called a "checklist" approach to avoiding cognitive errors. Drawing from his study of psychology, he identified 25 distinct psychological tendencies that lead to misjudgment. Unlike academic psychology, which Munger felt was too fragmented and impractical, his system was designed to be used—much like a pilot's pre-flight checklist.

The power of this approach lies not in the novelty of the individual tendencies—many were known to psychologists—but in having them organized as an actionable checklist that can be systematically applied to real decisions. Munger also emphasized that roughly half of these tendencies were under-explored or missing entirely from standard psychology textbooks when he first compiled his list.

The 25 Tendencies

1. Reward and Punishment Superresponse Tendency
People respond powerfully to incentives, often in ways that override other considerations including morality and reason. Federal Express couldn't get night shift workers to load planes quickly until they switched from hourly pay to paying per completed shift—suddenly workers finished in half the time.

2. Liking/Loving Tendency
We ignore faults, comply with wishes, and distort facts to support people and things we like or love. A spouse testifying on behalf of their partner in court may genuinely believe favorable testimony that an objective observer would recognize as distorted.

3. Disliking/Hating Tendency
We ignore virtues, reject ideas by association, and distort facts about people and things we dislike or hate. After 9/11, many Pakistanis immediately concluded Hindus were responsible, while many Muslims blamed Jews—each group's hatred shaped their perception of reality.

4. Doubt-Avoidance Tendency
The brain is programmed to quickly eliminate doubt by rushing to decisions, particularly under stress or puzzlement. Religious conversions often happen when people are in states of extreme doubt combined with stress, triggering a rapid leap to certainty.

5. Inconsistency-Avoidance Tendency
The brain resists changing established habits, conclusions, loyalties, and identities, making first impressions and early habits disproportionately important. Max Planck noted that revolutionary physics ideas weren't accepted by the old guard—progress came only when a new generation arrived without the old conclusions in place.

6. Curiosity Tendency
Innate curiosity drives learning and helps counter other destructive psychological tendencies when properly developed. Athens developed mathematics and science from pure curiosity while Rome, focusing only on "practical" engineering, contributed almost nothing to either field.

7. Kantian Fairness Tendency
People expect and display reciprocal fairness—following behavior patterns that would work well if everyone followed them. Drivers on a one-way bridge routinely take turns letting others pass despite no signs or signals, following an implicit fairness principle.

8. Envy/Jealousy Tendency
Envy drives powerful negative reactions, yet is rarely discussed openly despite being a major force in human behavior. Law firms often pay all senior partners identically regardless of contribution because envy over different pay levels would destroy firm cohesion.

9. Reciprocation Tendency
Humans automatically reciprocate both favors and hostilities, often at a subconscious level that can be exploited. When a car salesman gives you coffee and a comfortable seat, you're being primed to reciprocate by accepting a worse deal than you otherwise would.

10. Influence-from-Mere-Association Tendency
The brain links ideas, people, and outcomes through simple association, even when there's no causal connection. Advertisers never show Coca-Cola ads next to news of children dying—they only show Coke associated with happiness, creating positive associations through mere proximity.

11. Simple, Pain-Avoiding Psychological Denial
Reality too painful to bear gets distorted into something more tolerable, particularly around death, love, and addiction. A mother whose son flies off over the Atlantic and never returns may refuse to believe he's dead because accepting the reality is unbearable.

12. Excessive Self-Regard Tendency
People overestimate their own abilities, possessions, and conclusions— 90% of Swedish drivers rate themselves above average. Job candidates who are exceptional "presenters" get hired over more qualified but less charismatic candidates because interviewers overweight their face-to-face impressions.

13. Overoptimism Tendency
People exhibit excessive optimism even when already doing well, leading to poor probability assessment. Lottery play is much higher when people pick their own numbers versus random numbers, despite identical odds, because people are irrationally optimistic about their choices.

14. Deprival-Superreaction Tendency
The pain of losing something far exceeds the pleasure of gaining the same thing, and near-losses trigger reactions similar to actual losses. Slot machines create addiction partly through "near misses" like bar-bar-lemon results that trigger deprival reactions as if the player almost won.

15. Social-Proof Tendency
People automatically think and act as they see others thinking and acting, especially under conditions of stress or uncertainty. In elevator experiments, strangers will turn to face the rear if all other passengers are facing that direction, simply following the group.

16. Contrast-Misreaction Tendency
The nervous system registers contrast rather than absolute measures, causing systematic errors in judgment. Real estate agents show three terrible overpriced houses before showing a merely bad house at a moderate price—the contrast makes the bad house seem acceptable.

17. Stress-Influence Tendency
Stress amplifies other psychological tendencies, with light stress improving performance but heavy stress causing dysfunction. Pavlov's dogs subjected to maximum stress during the Leningrad flood had permanent behavioral changes—dogs that loved their trainers suddenly hated them.

18. Availability-Misweighing Tendency
The mind overweights information that's easily available or vivid while underweighting less available information. After seeing news about plane crashes, people overestimate flying risk despite statistics showing it's safer than driving, because crashes are more vivid and available in memory.

19. Use-It-or-Lose-It Tendency
All skills atrophy without practice, and this applies to rarely-used skills that may be critical in important situations. Munger was a calculus whiz until age 20, then lost the skill entirely through years of non-use despite once being highly proficient.

20. Drug-Misinfluence Tendency
Drugs powerfully distort cognition, and addiction causes reality-denying rationalization that enables continued deterioration. Addicted individuals genuinely believe they remain in respectable condition with good prospects even as objective observers can see their progressive deterioration.

21. Senescence-Misinfluence Tendency
Cognitive abilities naturally decline with age, though the timing and speed vary among individuals. While old people can maintain well-practiced skills like bridge playing into late life, almost no one remains good at learning complex new skills when very old.

22. Authority-Misinfluence Tendency
People automatically follow authority figures even when the authority is clearly wrong or instructions are misunderstood. In Milgram's experiment, ordinary people administered what they believed were dangerous electric shocks to innocent people simply because a professor-authority figure told them to continue.

23. Twaddle Tendency
People naturally produce and consume vast amounts of useless talk that interferes with serious work. Like a confused honeybee doing an incoherent dance when nectar is straight up (outside its genetic programming), humans prattle meaninglessly when facing situations they can't properly handle.

24. Reason-Respecting Tendency
People are more easily taught and persuaded when given reasons, even if the reasons are weak. Compliance practitioners discovered that adding "because" to a request— even with a trivial reason—dramatically increases the likelihood people will agree.

25. Lollapalooza Tendency
Multiple psychological tendencies acting in concert produce extreme, non-linear consequences far beyond the sum of individual effects. Tupperware parties succeeded wildly by combining social proof, reciprocation, commitment, liking, scarcity, and authority tendencies all pushing in the same direction simultaneously.

Using the Checklist

Munger's fundamental advice: before making important decisions, systematically run through the relevant tendencies on this list. Ask which might be affecting your thinking or the thinking of others involved. Pay special attention to situations where multiple tendencies might be combining to create lollapalooza effects.

The checklist approach isn't about memorizing definitions—it's about building a habit of systematic thinking that helps you avoid the standard errors that trip up even intelligent people. As Munger emphasized, knowing these tendencies intellectually isn't enough; you must practice applying them until checking for them becomes automatic.