Misbehaving — Thaler: COMPLETE

Richard Thaler took his doctorate in Rochester and landed as a professor at Cornell, where he taught whimsical MBA students in micro theory. The problem was that the students asked questions he could not answer within the model's framework — and worse: that he himself asked the same questions. Thaler called the phenomena SIF: supposedly irrelevant factors, all the details of the world that theory explained away but which seemed to steer real decisions.

In his free time he therefore kept a list — partly as a joke — of behaviors a Homo economicus would never perform. The list came to be behavioral economics' founding document, and Misbehaving begins with its best entries.

The most famous entry concerns a friend's wine collection. The friend had bought expensive bottles at around 10 dollars each years earlier; auction houses now bid over 100 dollars per bottle. He refuses to sell — but happily drinks them himself, and at a restaurant he simultaneously refuses to pay even 35 dollars for a glass of comparable wine. Thaler pointed out, mediating, that every bottle drunk from the cellar costs 100 dollars in lost sale — the opportunity cost is the same regardless of label.

The friend waved away the objection and kept drinking. Here, in miniature, lies the entire later research: the endowment effect, mental accounting and the reluctance to think in opportunity costs.

The list contained more classics. A friend who bought a lottery ticket refuses to sell it for double the price — the evening before the drawing. The neighbor gladly mows his own lawn one Saturday but would never mow a stranger's for 200 kronor. An executive who was a poor student still refuses, now on a generous salary, to pay extra for Russian salad dressing because it was »luxury« back then. A friend with paid tickets to a basketball game drives through a snowstorm he would never have driven in had the tickets been free.

And in Kahneman and Tversky's classic formulation: whoever has lost the theater ticket does not buy a new one — but whoever has lost a bill of the same value goes in and sees the performance anyway. In the survey, 88 percent said yes after lost bills, but only 54 percent after a lost ticket, even though the financial position is identical.

The turning point came at a dinner in the middle of the 1970s, when Thaler tested his stories on two psychologists. He expected them to explain why the economists were right. Instead they laughed and said that what he was telling was psychology — in fact fairly everyday psychology — and tipped him off about two names: Kahneman and Tversky.

The lesson for an AKM1 analyst is uncomfortable but central: whoever reads a report with V07 gross margin and V12 revenue stability reads it with the same brain as the wine collector. Self-knowledge is not decoration — it is the first variable. Before you examine the company, examine the reader.

The rational model rests on a few axioms: preferences are complete and transitive, decisions are made with consistent utility maximization, risks are valued by expected value, and the future is discounted exponentially. From this, indifference curves, demand functions and the entire neoclassical machinery are built. Thaler respected the machinery — he was trained in it.

His question was humbler and more dangerous: does it predict? Econs and Humans are the book's recurring names for the two creatures. Econs are the model's inhabitants: cold, consistent, immune to framing. Humans are us: warm, inconsistent, sensitive to how the question is posed. Economics' methodological choice was to pretend that we are Econs.

The line of defense was old and distinguished. Milton Friedman argued in 1953 that models should be judged on their predictions, not on their assumptions: a skilled billiard player behaves as if he solves the differential equations that govern the paths of the balls — without knowing a single formula. As long as the market's aggregated behavior looks rational, it does not matter that no individual is.

This »as if« defense is stronger than it sounds, and Thaler takes it seriously in the book. His countermove was to look for situations where aggregation does not cure the individual's missteps: when the deviations are common, when they point in the same direction, and when the market's mechanisms — competition, learning, arbitrage — are weak or expensive.

Here lies an important nuance that the course returns to in the controversy chapter: the model is not worthless. For many questions — what happens to demand when the price rises? — the Econ assumption suffices for a long way. Thaler's claim is that it fails on points that matter: self-control, fairness perceptions, the framing of losses, the accounting of money.

Econs have no mental accounts, no sunk costs, no vengeance in ultimatum games — Humans have all of this, measurably and predictably. Predictably is the key word: random error does not matter, systematic errors reprice the world. Behavioral economics' entire program lies in the difference between noise and bias.

For AKM1 the chapter's practical lesson is this: every variable in the model — V04 P/S, V06 EV/EBITDA, V09 ROE — is an Econ construction that must be read by a Human. The multiple says nothing about itself; it says something about the price in relation to an assumption about future cash flows, and the assumption carries the reader's anchors and mood.

That is why the platform requires normalization, scenarios and margin of safety as a principle without a number: not because the numbers are bad, but because of the reader. The model is the map; the course is about the terrain between the map and the map reader.