By era
Early 20th century
46 entries
Alfred Adler
The psychiatrist who broke with Freud to argue that people are pulled forward by a striving to overcome felt inferiority, not pushed by buried sexual drives.
11 min
ThinkerAmartya Sen
The economist and philosopher who reframed development as the expansion of human capabilities and freedoms, not the growth of national income.
10 min
ThinkerAntonio Gramsci
The Marxist thinker who argued that ruling classes maintain power less through force than through cultural and intellectual leadership, a dominance he called hegemony.
9 min
ThinkerCarl Jung
The psychiatrist who broke with Freud to argue the unconscious is not only personal but collective, patterned by inherited, universal forms he called archetypes.
10 min
Mental modelChesterton's Fence
Before you tear down a fence, find out why it was put up; the reformer who cannot explain a thing has not yet earned the right to remove it.
7 min
IdeologyCouncil Communism
The Marxist current that rejected both the reformist party and the vanguard party, holding that workers' councils are themselves the organs of revolution and of rule.
11 min
ConceptCreative Destruction
Capitalism progresses by destroying what it has built, as new innovations render old industries, firms, and methods obsolete.
7 min
IdeologyDistributism
A third way between capitalism and socialism that seeks to distribute productive property as widely as possible, so that most people own the means of their own living.
11 min
ThinkerEdward Tolman
The behaviorist who proved rats build "cognitive maps," keeping internal representation alive until neuroscience found it in the brain.
11 min
ConceptEmotivism
The theory that moral statements do not describe facts but express feeling and work on the feelings of others: 'stealing is wrong' means, roughly, 'Boo to stealing.'
8 min
ConceptExposure and Extinction
Conditioned fear weakens when the feared thing is faced without the expected harm, and avoidance is what keeps the fear alive.
7 min
ConceptExternalities
An externality is a cost or benefit that falls on someone who had no say in the transaction that produced it.
7 min
ConceptFalsificationism
A theory is scientific only if it forbids something observable and could in principle be proven wrong; science grows by bold guesses and hard attempts to refute them.
9 min
Mental modelGame Theory
The mathematics of strategic decisions, where the best thing to do depends on what everyone else is deciding to do.
8 min
ConceptGestalt Principles of Perception
The mind groups raw sensory fragments into organized wholes by rules like proximity, similarity, closure, and continuity, rather than building perception up piece by piece.
9 min
TraditionGestalt Psychology
The claim that perception and thought are organized into structured wholes that cannot be built up from separate sensory parts.
12 min
Thought experimentInsight Learning
Wolfgang Köhler's chimpanzees solved problems by a sudden reorganization of the whole situation, not by gradual trial and error, and that challenged the behaviorist account of how learning works.
9 min
ThinkerJean Piaget
The psychologist who mapped childhood into stages, arguing that a child's mind is not a small adult's but a different kind of reasoning machine built anew at each age.
10 min
ThinkerJohn Maynard Keynes
The economist who argued that markets can fail catastrophically and that governments must act to restore employment.
9 min
ThinkerJoseph Schumpeter
The economist who saw capitalism as a system defined not by equilibrium but by the perpetual upheaval of creative destruction.
9 min
ThinkerKaren Horney
The neo-Freudian analyst who moved neurosis from instinct to culture and relationships, and who dismantled Freud's account of women from inside psychoanalysis.
11 min
IdeologyKeynesianism
The claim that total spending, not thrift, drives output and jobs, so government can and should steady the economy when private demand fails.
12 min
ConceptKnightian Uncertainty
The line between risk, which has a knowable probability distribution and can be insured against, and true uncertainty, which is unique and unmeasurable, and which is the source of genuine entrepreneurial profit.
9 min
IdeologyLeninism
Marxism rebuilt around a disciplined revolutionary party that seizes state power in capitalism's weakest link and rules in the name of the working class.
12 min
ThinkerLev Vygotsky
The Soviet psychologist who argued that the higher mind is built from the outside in, through social interaction and cultural tools, before it becomes private thought.
11 min
ThinkerLudwig Wittgenstein
The philosopher who twice tried to dissolve philosophy itself: first by drawing the limits of what language can picture, then by showing that meaning is not picturing at all but use.
13 min
Mental modelMargin of Safety
Buy a thing for meaningfully less than it is worth, so that error, bad luck, and the unforeseen cannot ruin you.
8 min
Mental modelMaslow's Hierarchy of Needs
Human motivation is organized into tiers, with basic bodily and safety needs generally pressing before higher needs for belonging, esteem, and self-actualization.
8 min
IdeologyNazism
A German racial and genocidal variant of fascism that built a total state to wage a war of conquest and to murder Europe's Jews.
12 min
Thought experimentOperant Conditioning
Behavior that is rewarded tends to recur, behavior that is punished or ignored tends to fade, and Skinner built a whole science out of that one fact.
9 min
TraditionPhenomenology
The disciplined description of experience exactly as it is lived, from the first-person standpoint, before any theory is laid over it.
12 min
ConceptReliability and Validity
The two axes of measurement quality: reliability is whether a measure is consistent, validity is whether it measures the thing it claims to.
8 min
ConceptResearch Ethics and Its Failures
The rules that now govern experiments on people were written in reaction to specific abuses, and each principle is a scar left by a study that went wrong.
10 min
IdeologyStalinism
The system Joseph Stalin built in the Soviet Union: rapid state-driven industrialization and forced collectivization, enforced by mass terror, a vast prison-camp economy, and a cult of the leader.
12 min
ConceptStatistical Power
The probability that a study will detect a real effect if one exists, and the quiet reason so many studies fail to.
8 min
ConceptStatistical Significance
The p-value measures how surprising your data would be if nothing were going on, and almost everyone reads it as something else.
10 min
IdeologySyndicalism
The doctrine that workers should abolish the state and capitalism through their own industrial unions, using direct action and the general strike rather than the ballot or the party.
11 min
TraditionThe Frankfurt School
A tradition of Marxist social theory that turned from economics to culture, asking why reason and enlightenment produced domination rather than freedom.
12 min
Mental modelThe Map Is Not the Territory
A representation of reality is never the reality itself, and mistaking the two is a basic and costly error.
7 min
ConceptThe Naturalistic Fallacy
Moore's charge that any attempt to define the property good in terms of a natural property (pleasure, desire, fitness) mistakes what good is.
8 min
ConceptThe Open Question Argument
Moore's test: if 'is X good?' still feels like a real question, then 'good' cannot simply mean X.
8 min
ConceptThe Sapir-Whorf Hypothesis
The claim that the language you speak shapes how you think, strongly supported in its modest form and rejected in its extreme one.
9 min
Mental modelThe Yerkes-Dodson Law
Performance improves as arousal rises but only up to a peak, and that peak sits lower for hard tasks than for easy ones.
8 min
ConceptTheories of Aggression
Three accounts of why people harm one another, aversive circumstance, learned imitation, and evolved biology, that turn out to describe different stages of one process rather than rival answers.
10 min
ConceptTheories of Emotion
Four rival answers to a single question: does feeling come from the body, the brain, the label you give your arousal, or the meaning you assign to the situation.
8 min
ConceptTheories of Intelligence
From Spearman's single general factor to Gardner's many independent intelligences, the century-long argument over whether mental ability is one thing or many, and what IQ tests actually capture.
7 min