The Black Swan

A Black Swan, in Taleb's sense, is an outlier that carries extreme impact and that people rationalize in hindsight as predictable. The book's targets are the habits that blind us to such events: the narrative fallacy, silent evidence (the failures we never see), the ludic fallacy, and epistemic arrogance. Its central distinction is between Mediocristan, where no single observation moves the total, such as human height, and Extremistan, where one observation can dominate it, such as wealth. Bell-curve statistics work in the first and fail badly in the second, which Taleb argues is where financial markets live.

Taleb writes from the trading floor. He traded options at firms including Credit Suisse First Boston and UBS, founded Empirica Capital in 1999, wrote Dynamic Hedging and Fooled by Randomness, and became a professor of risk engineering at NYU in 2008. The book spent 36 weeks on the New York Times bestseller list, and the Sunday Times named it one of the twelve most influential books since World War II.

It is digressive, combative and full of invented characters. Gregg Easterbrook's New York Times review was critical, Giles Foden found it dumbed-down next to Fooled by Randomness, and statistician David Aldous praised the finance material but thought other parts exaggerated. Daniel Kahneman said it changed his view of how the world works.

Risk managers, portfolio managers and anyone who uses value-at-risk or normal-distribution models should read it.

1. Know which world you're in. In Extremistan, where wealth, sales and market returns live, a single event can dominate the total, and bell-curve tools will understate the risk.
2. A long calm record proves little. The turkey is most confident the day before Thanksgiving; years of steady gains from selling tail risk say nothing about the tail.
3. Distrust tidy stories. The narrative fallacy makes the past look predictable, and silent evidence hides the many who took the same risks and failed.
4. Manage exposure, not forecasts. Since you can't predict Black Swans, shape positions so negative ones can't ruin you and positive ones can pay off.
5. Barbell the portfolio. Taleb suggests keeping 85 to 90 percent in the safest instruments and 10 to 15 percent in highly speculative bets, avoiding the middle where risk is most often mismeasured.

After a prologue on the black swan of the title, the book runs in four parts, plus the 2010 postscript essay.

1. Umberto Eco's antilibrary, or how we seek validation. Taleb's apprenticeship as an empirical skeptic in war-torn Lebanon and on trading desks, the split between scalable and non-scalable careers, the turkey fed for a thousand days, confirmation bias, the narrative fallacy, silent evidence and the ludic fallacy.
2. We just can't predict. The poor record of expert forecasts, epistemic arrogance, the role of accident in discovery, and what to do when prediction fails.
3. Those gray swans of Extremistan. The move from Mediocristan to Extremistan, power laws and Benoit Mandelbrot's fractal randomness, the bell curve as a great intellectual fraud, and the misuse of Gaussian tools in economics and finance.
4. The end. A short practical section: be hyperconservative where errors can ruin you and hyperaggressive where they can only help, and expose yourself to positive Black Swans.
5. On Robustness and Fragility. The postscript explains how systems become fragile, defines the Fourth Quadrant where errors are most dangerous, and offers ten principles for a society robust to Black Swans.

The Black Swan is a standalone book in Nassim Nicholas Taleb’s landmark Incerto series, an investigation of opacity, luck, uncertainty, probability, human error, risk, and decision-making in a world we don’t understand. The other books in the series are Fooled by Randomness, Antifragile, and The Bed of Procrustes. A black swan is a highly improbable event with three principal characteristics: It is unpredictable; it carries a massive impact; and, after the fact, we concoct an explanation that makes it appear less random, and more predictable, than it was. The astonishing success of Google was a black swan; so was 9/11. For Nassim Nicholas Taleb, black swans underlie almost everything about our world, from the rise of religions to events in our own personal lives. Why do we not acknowledge the phenomenon of black swans until after they occur? Part of the answer, according to Taleb, is that humans are hardwired to learn specifics when they should be focused on generalities. We concentrate on things we already know and time and time again fail to take into consideration what we don’t know. We are, therefore, unable to truly estimate opportunities, too vulnerable to the impulse to simplify, narrate, and categorize, and not open enough to rewarding those who can imagine the impossible.” For years, Taleb has studied how we fool ourselves into thinking we know more than we actually do. We restrict our thinking to the irrelevant and inconsequential, while large events continue to surprise us and shape our world. In this revelatory book, Taleb explains everything we know about what we don’t know, and this second edition features a new philosophical and empirical essay, On Robustness and Fragility,” which offers tools to navigate and exploit a Black Swan world. Elegant, startling, and universal in its applications, The Black Swan will change the way you look at the world. Taleb is a vastly entertaining writer, with wit, irreverence, and unusual stories to tell. He has a polymathic command of subjects ranging from cognitive science to business to probability theory. The Black Swan is a landmark book—itself a black swan. Praise for Nassim Nicholas Taleb The most prophetic voice of all.”—GQ Praise for The Black Swan [A book] that altered modern thinking.”—The Times (London) A masterpiece.”—Chris Anderson, editor in chief of Wired, author of The Long Tail Idiosyncratically brilliant.”—Niall Ferguson, Los Angeles Times The Black Swan changed my view of how the world works.”—Daniel Kahneman, Nobel laureate [Taleb writes] in a style that owes as much to Stephen Colbert as it does to Michel de Montaigne. . . . We eagerly romp with him through the follies of confirmation bias [and] narrative fallacy.”—The Wall Street Journal Hugely enjoyable—compelling . . . easy to dip into.”—Financial Times Engaging . . . The Black Swan has appealing cheek and admirable ambition.”—The New York Times Book Review From the Hardcover edition.