A quick reference to the mental models checked on this site. Each card gives the popular version, a verdict and the key fact from the source. Open a card for the detail; the full evidence is on the five longer pages linked below.
The verdicts
01 "Charlie Munger invented mental models" ◐Partly In psychology the idea goes back to Kenneth Craik (1943), who proposed that the mind builds "small-scale models" of reality, and to Philip Johnson-Laird's Mental Models (1983).
02 Circle of competence: "Buffett's idea" ◐Partly A Berkshire idea; the earliest use we found is Munger's, in his 1994 talk: "Every person is going to have a circle of competence." Buffett's 1996 letter adds the part people drop: "The size of that circle is not very important; knowing its boundaries, however, is vital."
03 Chesterton's fence ◐Partly Chesterton (The Thing, 1929) says to find out what a fence was for before removing it, and that a reformer who knows may find "they were bad purposes" or ones "no longer served".
04 "The map is not the territory" ✓Holds up Alfred Korzybski's, from 1931 and Science and Sanity (1933).
05 Second-order thinking ◐Partly The label is modern, and we found no single origin for it.
06 Opportunity cost: "Wieser coined it" ◐Partly The English term is in David I.
07 Inversion: "Invert, always invert" ?Can't confirm The earliest printed attribution to the mathematician Carl Jacobi we found, from 1916, is hearsay: Jacobi "is said to have" taught it.
08 Occam's razor ◐Partly The idea is Ockham's; the famous wording is not.
09 Hanlon's razor: "Heinlein said it" ◐Partly Robert Heinlein's 1941 story "Logic of Empire" has a close ancestor: "You have attributed conditions to villainy that simply result from stupidity." The earliest version with the name known to Quote Investigator is from 1980.
10 The Pareto principle (80/20) ◐Partly Pareto studied the unequal distribution of income.
11 Parkinson's law ◐Partly The famous sentence opens Parkinson's 1955 Economist essay as "a commonplace observation", not his law.
12 Goodhart's law ◐Partly "When a measure becomes a target" is Marilyn Strathern's wording (1997).
13 The Dunning-Kruger effect ⇄Still argued Kruger and Dunning (1999) found that people in the bottom quarter on their tests "grossly overestimated their test performance and ability".
14 First principles ✓Holds up Aristotle's: "we do not think that we know a thing until we are acquainted with its primary conditions or first principles".
15 Base rates: "people ignore them" ⇄Still argued Kahneman and Tversky (1974) found base rates "effectively ignored" once a description was given; Koehler (1996) concluded that base rates "are almost always used".
16 Scarcity vs abundance mindset ◐Partly Two ideas share a word: a self-help attitude from The 7 Habits of Highly Effective People, and Mullainathan and Shafir's research on how scarcity "changes how people allocate attention".
17 Locus of control ✓Holds up Published work goes back at least to E.
18 Maximizers are less happy than satisficers ⇄Still argued "Satisfice" in this sense is Herbert Simon's term.
19 Zero-sum thinking ✓Holds up A measured belief "that one person's gain is possible only at the expense of other persons", tested across 37 nations (2015).
20 Beginner's mind: "Suzuki's sentence" ◐Partly The famous sentence is in Zen Mind, Beginner's Mind (1970), but David Chadwick reports that a transcript of Suzuki's 1965 lecture has a plainer version, and "Only when Trudy polished it" did it take its famous form.
21 Growth mindset ⇄Still argued Reviews disagree on how much interventions help: a 2019 national experiment found gains for lower-achieving students, while one 2023 meta-analysis found the effect "nonsignificant after correcting for potential publication bias" and another found a small effect for targeted groups.
22 Learned helplessness: "you learn to stop trying" ◐Partly The 1967 dog experiments were real, but in 2016 the same two researchers wrote that "the original theory got it backward": passivity is the default, and what animals learn is control.
23 "Always choose the highest expected value" ◐Partly Decision theory's version is expected utility, and "Utiles are typically not taken to be units of currency".
24 The Kelly criterion "is an investing formula" ◐Partly J. L. Kelly Jr.'s 1956 paper is about information: "the maximum exponential rate of growth of the gambler's capital is equal to the rate of transmission of information over the channel."
25 The pre-mortem ✓Holds up Gary Klein's, described in Harvard Business Review in September 2007: "team members assume that the project they are planning has just failed".
26 One-way and two-way doors ✓Holds up Jeff Bezos's, in his letter with the 2015 annual report.
27 Regret minimisation ✓Holds up Bezos's own account of one decision, in a 2001 interview: "I wanted to project myself forward to age 80".
28 The inside view ✓Holds up Kahneman and Lovallo (1993): "overly optimistic forecasts result from the adoption of an inside view of the problem", paired with a second problem, overly cautious attitudes to risk.
29 Superforecasting ✓Holds up It rests on a real tournament with published results (2014), finding "three psychological drivers of accuracy: training, teaming, and tracking"; a 2015 paper describes putting top performers into "elite teams of superforecasters".
30 "Hume proved you can't get an ought from an is" ◐Partly One paragraph of the Treatise, where Hume asks that "a reason should be given" for moving from is to ought.
31 Buridan's ass: "Buridan wrote it" ✕Doesn't hold up The example "is nowhere to be found in Buridan's writings".
32 Pascal's wager: "believe in God just in case" ◐Partly Its premise is that "Reason can decide nothing here"; it is an argument about what to do under uncertainty, not a proof that God exists.
33 The veil of ignorance: "Rawls invented it" ◐Partly The phrase is Rawls's (1971), but John Harsanyi used the device of choosing without knowing your place in 1953 and 1955, and drew the opposite conclusion.
34 The principle of charity: "read the strongest version" ◐Partly It began as a rule for interpreting what people mean.
35 Hitchens's razor ✓Holds up Christopher Hitchens, Slate, 20 October 2003: "what can be asserted without evidence can also be dismissed without evidence." It licenses setting a claim aside, not disproving it.
36 "Extraordinary claims require extraordinary evidence" is Sagan's rule ◐Partly Popularly Carl Sagan's, but the idea runs back through Laplace (1814) to Hume (1748): "A wise man, therefore, proportions his belief to the evidence." Laplace also warned against denying what cannot yet be explained.
37 Falsifiability: "one counter-example kills a theory" ◐Partly Popper's line between science and non-science, not a verdict on worth.
38 The Socratic method: "asking questions until the student finds the answer" ◐Partly One form of it, the elenchus, usually tests a claim to know something and often ends in aporia, "an impasse"; "the partner (not the audience if there is one) judges the outcome".
39 The golden mean: "moderation in everything" ◐Partly Aristotle's mean is "the intermediate not in the object but relatively to us", and "not every action nor every passion admits of a mean".
40 The ship of Theseus: "Plutarch's paradox" ◐Partly Plutarch reports an existing debate about the rebuilt ship; the second ship made from the old planks is Hobbes's addition, and Hobbes's answer is to ask under what name you are asking.
41 A Pyrrhic victory ◐Partly Plutarch reports the remark with "we are told", Diodorus gives it differently, and Diodorus says the proverb for such a win was "Cadmean", not Pyrrhic.
42 Crossing the Rubicon: "a snap point of no return" ◐Partly Caesar did cross, but his own Civil War does not mention the river, and Plutarch's scene is one of long hesitation, crossing at last "as if abandoning calculation".
43 The sword of Damocles: "a danger hanging over you" ◐Partly Cicero's story is about the tyrant's fear, not the guest's danger: "there can be no happiness for one who is under constant apprehensions".
44 Cutting the Gordian knot ⇄Still argued The sources split between the sword and pulling out the pin of the wagon-pole, and Arrian will not decide: "I cannot affirm with confidence."
45 Fabian strategy ✓Holds up Fabius did avoid pitched battle with Hannibal, and was mocked for it at the time.
46 Burning the boats: "Cortés burned his ships" ✕Doesn't hold up Cortés wrote that he had his ships beached "on the pretext that they were unseaworthy".
47 Hobson's choice ◐Partly Thomas Hobson was a real Cambridge carrier, but the stable story was printed in The Spectator in 1712, which calls him "Tobias Hobson".
48 The cobra effect ?Can't confirm No one we could find has produced a colonial record, date or official for the Delhi cobra bounty.
49 The Thucydides trap: "Thucydides' own idea" ⇄Still argued The phrase is Graham Allison's; the case count is his team's own; and he adds "War, however, is not inevitable." A 2025 classics article reads Thucydides as hinting at self-fulfilling prophecy.
50 The Lindy effect: "the longer it has lasted, the longer it will last" ◐Partly The name comes from a 1964 anecdote about comedians' careers; in 1982 Mandelbrot named his own rule "Lindy's Law" after it, and it is not clear the two describe the same principle.
51 Cincinnatus: "left his plough, saved Rome, gave up power at once" ◐Partly Livy does not know whether he was ploughing or digging a ditch, and he stayed in office for the trial of his son's accuser before he "laid down his dictatorship on the sixteenth day".
52 Potemkin villages: "fake fronts built to fool Catherine" ⇄Still argued The cardboard-village tale was already a "conte ridicule" to the Prince de Ligne, who was on the journey; a later memoir hedges the fronts ("It has even been asserted") while stating that peasants were moved along the route.
6 of 52 shown · a mix of every verdict
How to read the sheet
The verdict is about the claim as it is usually passed around, not about whether the tool is useful. A partly true tool may be worth using exactly as it is; it usually means the popular version dropped a condition or the original author’s caveat. Disputed means researchers disagree; unverified means we could not trace the claim to a source.
A conditionCircle of competence: Buffett adds the part people drop, that knowing the circle’s boundaries is vital.
A conditionChesterton’s fence is a rule about understanding before change, not against change.
The contextThe sword of Damocles is about the tyrant’s fear, not the guest’s danger.
The credit“When a measure becomes a target” is Marilyn Strathern’s wording; Goodhart’s own version was narrower.
The tool is real, but the popular version drops a condition, the context or the credit.
| Mental models | Credited to Munger; in psychology the idea goes back to Kenneth Craik. |
| Circle of competence | Called Buffett’s idea; the earliest use found is Munger’s. |
| Veil of ignorance | The phrase is Rawls’s, but John Harsanyi used the device earlier and drew the opposite conclusion. |
| Extraordinary claims | Popularly Sagan’s; the idea runs back through Laplace to Hume. |
| Principle of charity | Quine credits the name to N. L. Wilson. |
How we checked this · Last checked September 2026
- Every row summarises a longer, fact-checked page on this site, linked in the Sources, where the quotations and sources are given in full.
- Each of those pages lists its primary sources in full.
Checked September 2026.
Sources
- Mental models, checked: 15 thinking tools
- Mindsets, checked: 7 popular ideas
- Deciding under uncertainty: 7 decision tools
- Mental models from philosophy: 11 tools
- Mental models from history: 12 sayings
Each of those pages lists its primary sources in full.
The main sources behind the rows, for readers who want to go straight to them:
- Charlie Munger, Talk Two (USC, 1994), in Poor Charlie’s Almanack.
- G. K. Chesterton, “The Drift from Domesticity”, The Thing.
- Frédéric Bastiat, Ce qu’on voit et ce qu’on ne voit pas (1850).
- History of Economic Thought website, essay on opportunity cost.
- E. B. Van Vleck, Bulletin of the American Mathematical Society (1916).
- Stanford Encyclopedia of Philosophy, “William of Ockham”.
- J. M. Juran, “The Non-Pareto Principle; Mea Culpa” (1974).
- C. Northcote Parkinson, “Parkinson’s Law”, The Economist (19 November 1955).
- Aristotle, Physics I.1 and Nicomachean Ethics II.6.
- Shah, Mullainathan & Shafir, Science (2012).
- J. B. Rotter, Psychological Monographs (1966).
- Schwartz et al., on maximizing and satisficing (2002).
- Różycka-Tran et al., on zero-sum beliefs (2015).
- David Chadwick in Inquiring Mind (2008).
- Macnamara & Burgoyne, Psychological Bulletin (2023).
- Maier & Seligman, Psychological Review (2016).
- Gary Klein, “Performing a Project Premortem”, Harvard Business Review (September 2007).
- Jeff Bezos, letter to shareholders with the 2015 annual report, and his Academy of Achievement interview.
- Kahneman & Lovallo, Management Science (1993).
- Mellers et al., Psychological Science (2014).
- David Hume, A Treatise of Human Nature and An Enquiry Concerning Human Understanding.
- Blaise Pascal, Pensées.
- Stanford Encyclopedia of Philosophy: “John Buridan”, “Risk”, “Karl Popper” and “Plato’s Shorter Ethical Works”.
- Christopher Hitchens, Slate (20 October 2003).
- Plutarch, Lives: Theseus, Pyrrhus and Caesar (LacusCurtius).
- Cicero, Tusculan Disputations, tr. Yonge.
- Arrian, Anabasis.
- Polybius, Histories book 3 (LacusCurtius).
- Hernán Cortés, second letter, tr. MacNutt.
- The Spectator No. 509.
- Michael Vann, interview (2020).
- Graham Allison, The Atlantic (2015).
- Toby Ord, arXiv (2023).
- Livy, History of Rome, tr. Spillan.
- Prince de Ligne, letter in Ségur, Mémoires vol. 2.
