Mental Models Cheat Sheet
52 Thinking Tools, Where They Come From and What the Original Says

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). The self-help sense is Munger's, from a talk on 14 April 1994: "You've got to hang experience on a latticework of models in your head".

SOURCE Mental Models Global Laboratory; Munger, USC talk (1994)

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."

SOURCE Munger (1994); Buffett, 1996 letter

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". It is a rule about understanding before change, not against change.

SOURCE Chesterton, "The Drift from Domesticity", The Thing

Alfred Korzybski's, from 1931 and Science and Sanity (1933). The full sentence is not a warning against maps: "if correct, it has a similar structure to the territory, which accounts for its usefulness."

SOURCE Korzybski, Science and Sanity (1933)

The label is modern, and we found no single origin for it. The idea is stated by Bastiat in 1850: an act or a law produces "not one effect but a series of effects", and only the first is seen.

SOURCE Bastiat, Ce qu'on voit et ce qu'on ne voit pas (1850)

The English term is in David I. Green's 1894 paper; the History of Economic Thought website says the doctrine was first introduced "as an all-encompassing theory of cost" in a seminar paper by Friedrich von Wieser (1876). The idea is older: Bastiat's townsman who has spent six francs "cannot spend them on another" thing.

SOURCE Green, QJE (1894); History of Economic Thought website; Bastiat (1850)

The earliest printed attribution to the mathematician Carl Jacobi we found, from 1916, is hearsay: Jacobi "is said to have" taught it. Munger used inversion for avoiding failure: "I wish I knew where I was going to die, and then I'd never go there."

SOURCE Van Vleck, Bull. AMS (1916); Munger (1986)

The idea is Ockham's; the famous wording is not. The Stanford Encyclopedia says the formulation "is nowhere to be found in his texts". It is a rule about needing grounds, not "the simplest explanation is usually right".

SOURCE Stanford Encyclopedia of Philosophy

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.

SOURCE Heinlein, "Logic of Empire" (1941); Bloch (1980)

Pareto studied the unequal distribution of income. The universal "vital few" principle is Joseph Juran's, who later wrote: "I was forced to confess that I had mistakenly applied the wrong name to the principle."

SOURCE Pareto, Cours d'économie politique (1896–97); Juran, "The Non-Pareto Principle; Mea Culpa" (1974)

The famous sentence opens Parkinson's 1955 Economist essay as "a commonplace observation", not his law. His law is about staff: the number of officials and the work to be done "are not related to each other at all."

SOURCE Parkinson, The Economist (19 November 1955)

"When a measure becomes a target" is Marilyn Strathern's wording (1997). Goodhart's own 1975 version was narrower: a statistical regularity "will tend to collapse once pressure is placed upon it for control purposes".

SOURCE Strathern (1997); Goodhart (1975), as quoted by Takeda and Ueda

Kruger and Dunning (1999) found that people in the bottom quarter on their tests "grossly overestimated their test performance and ability". Its size is disputed, and the famous peak-and-valley chart is not in the paper.

SOURCE Kruger & Dunning (1999); Nuhfer et al. (2016); Gignac & Zajenkowski (2020)

Aristotle's: "we do not think that we know a thing until we are acquainted with its primary conditions or first principles". For him they are starting points you grasp, not a brainstorming technique.

SOURCE Aristotle, Physics I.1

Kahneman and Tversky (1974) found base rates "effectively ignored" once a description was given; Koehler (1996) concluded that base rates "are almost always used". Both are reviews of experiments, and they weigh the same studies differently.

SOURCE Tversky & Kahneman, Science (1974); Koehler (1996)

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". How robust that research is remains disputed: a 2021 re-run of 20 scarcity-priming studies found most effects smaller, the original researchers disputed its sample in 2023, and the replicators answered.

SOURCE FranklinCovey; Shah, Mullainathan & Shafir (2012); O'Donnell et al. (2021, correction 2022); Shah et al. (2023)

Published work goes back at least to E. J. Phares in 1957; the idea became famous through Julian B. Rotter's 1966 monograph on "generalized expectancies for internal versus external control of reinforcement".

SOURCE Phares (1957); Rotter, Psychological Monographs (1966)

"Satisfice" in this sense is Herbert Simon's term. Schwartz and colleagues (2002) found negative correlations between maximizing and happiness; a different scale (2008) "did not correlate with life (dis)satisfaction". None shows causation.

SOURCE Simon; Schwartz et al. (2002); Diab et al. (2008)

A measured belief "that one person's gain is possible only at the expense of other persons", tested across 37 nations (2015). A 2026 US study finds it associated with policy views (associations, not causes) and "not primarily a partisan issue".

SOURCE Różycka-Tran et al. (2015); Chinoy et al. (2026)

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.

SOURCE Chadwick, Inquiring Mind (2008)

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.

SOURCE Yeager et al. (2019); Macnamara & Burgoyne (2023); Burnette et al. (2023)

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. Most of the evidence is from animals.

SOURCE Seligman & Maier (1967); Maier & Seligman (2016)

Decision theory's version is expected utility, and "Utiles are typically not taken to be units of currency". The theory has known puzzles, such as the St. Petersburg game.

SOURCE Stanford Encyclopedia of Philosophy

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."

SOURCE Kelly, Bell System Technical Journal (1956)

Gary Klein's, described in Harvard Business Review in September 2007: "team members assume that the project they are planning has just failed". The 30% figure often attached to it could not be checked.

SOURCE Klein, HBR (September 2007)

Jeff Bezos's, in his letter with the 2015 annual report. The "around 70% of the information" rule comes from the next year's letter, hedged with "probably", and written about decisions inside a company.

SOURCE Bezos, letters with the 2015 and 2016 annual reports

Bezos's own account of one decision, in a 2001 interview: "I wanted to project myself forward to age 80". It is one person's way of making one choice.

SOURCE Academy of Achievement interview (4 May 2001)

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.

SOURCE Kahneman & Lovallo, Management Science (1993)

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".

SOURCE Mellers et al., Psychological Science (2014); Perspectives on Psychological Science (2015)

One paragraph of the Treatise, where Hume asks that "a reason should be given" for moving from is to ought. He does not say the step is impossible, and the Stanford Encyclopedia says: "Few passages in Hume's work have generated more interpretive controversy."

SOURCE Hume, Treatise 3.1.1; Cohon, Stanford Encyclopedia

The example "is nowhere to be found in Buridan's writings". A version with a man, not a donkey, is in Aristotle's On the Heavens.

SOURCE Zupko, Stanford Encyclopedia; Aristotle, On the Heavens II.13

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. The Stanford Encyclopedia gives most attention to "the many Gods objection". No verdict here on the religious question.

SOURCE Pascal, Pensées 233; Hájek, Stanford Encyclopedia

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.

SOURCE Freeman, Hansson and Fleurbaey, Stanford Encyclopedia

It began as a rule for interpreting what people mean. Quine (1960) credits the name to N. L. Wilson; his reason: "silliness, beyond a certain point, is less likely than bad translation".

SOURCE Quine, Word and Object (1960); Wilson (1959); Davidson

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.

SOURCE Hitchens, Slate (20 October 2003)

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.

SOURCE Hume, Enquiry X; Laplace, Essai (1814)

Popper's line between science and non-science, not a verdict on worth. He allowed that "in practice a single conflicting or counter-instance is never sufficient methodologically for falsification".

SOURCE Thornton, "Karl Popper", Stanford Encyclopedia

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".

SOURCE Woodruff, "Plato's Shorter Ethical Works", Stanford Encyclopedia

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". The "golden" comes from Horace's aurea mediocritas, "golden moderation" (Odes 2.10).

SOURCE Aristotle, Nicomachean Ethics II.6; Horace, Odes 2.10

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.

SOURCE Plutarch, Theseus 23.1; Hobbes, De Corpore II.11

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.

SOURCE Plutarch, Pyrrhus 21; Diodorus 22.6

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".

SOURCE Suetonius, Julius 31-32; Plutarch, Caesar 32; Caesar, Civil War 1

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".

SOURCE Cicero, Tusculan Disputations 5.61-62

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."

SOURCE Arrian, Anabasis 2.3; Plutarch, Alexander 18

Fabius did avoid pitched battle with Hannibal, and was mocked for it at the time. The strike-hard part came from a motto on the Fabian Society's first tract ("when the time comes you must strike hard"), whose own historian said such mottoes "are not to be discovered in any history".

SOURCE Polybius 3.89; Pease, History of the Fabian Society

Cortés wrote that he had his ships beached "on the pretext that they were unseaworthy". The Tariq story is unverified; the oldest of the three versions is Xiang Yu sinking his boats in the Shiji.

SOURCE Cortés, second letter; Díaz, Memoirs; Gayangos; Shiji 7

Thomas Hobson was a real Cambridge carrier, but the stable story was printed in The Spectator in 1712, which calls him "Tobias Hobson".

SOURCE The Spectator No. 509; Dictionary of National Biography

No one we could find has produced a colonial record, date or official for the Delhi cobra bounty. The documented case is Hanoi's rat bounty of 1902, where people were "cutting off their tails to collect the bounty, and then letting them go free to breed more rats".

SOURCE Vann, French Colonial History (2003) and interview (2020)

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. No forecast here.

SOURCE Allison, The Atlantic (2015); Sutton, Classical Antiquity (2025)

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. It is a pattern for some things, not all: human lifespans "doesn't exhibit even a broad Lindy effect".

SOURCE New Republic index (1964); Ord, arXiv (2023)

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".

SOURCE Livy 3.26-29

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. Eyewitnesses describe a staged tour of real, partly unfinished settlements.

SOURCE de Ligne, in Ségur, Mémoires; Memoirs of Prince Potemkin (1813)