Nassim Nicholas Taleb

"You may not be able to change the world but can at least get some entertainment and make a living out of the epistemic arrogance of the human race."

"It is now the scientific consensus that our risk-avoidance mechanism is not mediated by the cognitive modules of our brain, but rather by the emotional ones. This may have made us fit for the Pleistocene era. Our risk machinery is designed to run away from tigers; it is not designed for the information-laden modern world."

"Much of the research into humans' risk-avoidance machinery shows that it is antiquated and unfit for the modern world; it is made to counter repeatable attacks and learn from specifics. If someone narrowly escapes being eaten by a tiger in a certain cave, then he learns to avoid that cave."

"We should reward people, not ridicule them, for thinking the impossible."

"Delivering advice assumes that our cognitive apparatus rather than our emotional machinery exerts some meaningful control over our actions."

"It does not matter how frequently something succeeds if failure is too costly to bear."

"Trading forces someone to think hard; those who merely work hard generally lose their focus and intellectual energy. In addition, they end up drowning in randomness; work ethics draw people to focus on noise rather than the signal."

"Mild success can be explainable by skills and labor. Wild success is attributable to variance."

"Lucky fools do not bear the slightest suspicion that they may be lucky fools - by definition, they do not know that they belong to such a category."

"Unlike a well-defined, precise game like Russian roulette, where the risks are visible to anyone capable of multiplying and dividing by six, one does not observe the barrel of reality."

"[T]he epic poet did not judge heroes by the result... their fate depended on totally external forces... Heroes are heroes because they are heroic in behavior, not because they won or lost."

"Mixing forecast and prophecy is symptomatic of randomness-foolishness..."

"I do not dispute that arguments should be simplified to their maximum... but people often confuse complex ideas that cannot be simplified into a media-friendly statement as symptomatic of a confused mind. ...MBAs tend to blow up in financial markets, as they are trained to simplify... beyond... requirement. (...I am myself the unhappy holder of the degree.)"

"[T]he mental probabilistic map in one's mind is so geared toward the sensational that one would realize informational gains by dispensing with the news."

"From the standpoint of an institution, the existence of a risk manager has less to do with actual risk reduction than it has to do with the impression of risk reduction."

"In the early 1990s... I became addicted to the various Monte Carlo engines, which I taught myself to build... The dividend of the computer revolution... did not come in... e-mail messages and... chat rooms; it was in the sudden availability of fast processors capable of generating a million sample paths per minute."

"My models showed that ultimately almost nobody really survived; bears dropped like flies in the rally and bulls ended up being slaughtered... But there was one exception... option buyers... could buy the insurance against blowup..."

"I have two ways of learning from history: from the past, by reading the elders; and from the future, thanks to my Monte Carlo toy."

"A... vicious effect of... is that those that are good at predicting the past... think of themselves as good at predicting the future... [W]e live in a world where important events are not predictable..."

"[H]istory cannot lend itself to experimentation. But... is potent enough... to eventually bury the bad guy. Bad trades catch up with you... Mathematicians of probability give that a... name: '. [R]oughly... properties of a very... long sample path would be similar to the Monte Carlo properties of an average of shorter ones. ...Those unlucky... in spite of their skills would eventually rise. The lucky fool... would slowly converge to the state of a less-lucky idiot. Each ...would revert to his long-term properties."

"[A]ge is beauty. ...[M]y instinct is to value distilled thought over newer thinking, regardless of its apparent sophistication—another reason to accumulate the hoary volumes by my bedside... For an idea to have survived so many cycles is indicative of its relative fitness. Noise, at least some noise, was filtered out. ...[P]rogress means that some new information is better than past information, not that the average of new information will supplant past information..."

"There are hordes of thoughtful journalists... [I]t is just that prominent media journalism is a thoughtless process of providing the noise that captures people's attention and there exists no mechanism for separating the two."

"I... found a significant advantage in selecting aged traders, using as a selection criterion their cumulative years of experience rather than their absolute success... [O]lder people have been exposed longer to the rare event and can be, convincingly, more resistant to it."

"Over a short time increment, one observes the variability of the portfolio, not the returns. ...[O]ne sees the variance, little else. ...Our emotions are not designed to understand the point. ...I deal with it by having no access to information. ...I prefer to read poetry."

"[N]ews... is full of noise and... history is largely stripped of it."

"A trader's mental construction should direct him to do precisely what other people do not do."

"Veteran trader Marty O'Connell calls this the firehouse effect. ...[F]iremen ...who talk to each other for too long come to agree on many things that an outside, impartial observer would find ludicrous..."

"[A]t any point in time, the richest traders are often the worst traders. This I will call the cross-sectional problem: At a given time... the most successful traders are likely to be those fit for the latest cycle."

"[T]hey share the traits of the acute successful randomness fool who, in addition, operates in the most random of environments. ...[T]heir bosses and employers shared the same trait. They, too, are permanently out of the market."

"There is a saying that bad traders divorce their spouse sooner than abandon their positions. Loyalty to ideas is not a good thing for traders, scientists - or anyone."

"Just as an animal could have survived because its sample path was lucky... free of the evolutionary rare event, the "best" operators in a given business can... One vicious attribute is that the longer these... can go without encountering the rare event, the more vulnerable they will be to it. ...[S]hould one extend time to infinity, then by , that event will happen with certainty—the species will be wiped out! For evolution means fitness to... only one time series, not the average of all possible environments."

"Why do [people] confuse probability and expectation, that is, probability [vs.] probability times payoff? Mainly because much... schooling comes from examples in symmetric environments... the... bell curve... is entirely symmetric."

"I have organized my career and business in such a way as to... benefit... I am profiting from the rare event, with asymmetric bets."

"In most disciplines... asymmetry does not matter. ...People in most fields ...do not have problems eliminating extreme values from their sample, when the difference in payoff between different outcomes is not significant ...A professor ...removes the ...s, and takes the average of the remaining ones, without ...being ...unsound. A casual weather forecaster does the same ...So people in finance borrow the technique and ignore infrequent events, not knowing that the effect ...can bankrupt a company."

"Many scientists... are... subject to such foolishness... One flagrant example is... global warming... These scientists initially ignored the fact that these [high temperature] spikes, although rare, had the effect of adding disproportionately to the cumulative melting of the ice caps. ...[A]n event, although rare, that brings large consequences cannot be ignored."

"Sometimes market data becomes a simple trap; it shows you the opposite of its nature... [e.g.,] Currencies that exhibit the largest historical stability... are the most prone to crashes."

"I reject a sole time series of the past as an indication of future performance; I need a lot more than data."

"[W]e read too much into shallow recent history... but not from history in general [which] teaches us that things that never happened before do happen. ...outside of the narrowly defined time series; the broader the look, the better the lesson."

"[T]here is a category of traders who have inverse rare events, for whom volatility is often the bearer of good news. Those traders lose money frequently, but in small amounts, and make money rarely, but in large amounts. ...crisis hunters. I am happy to be one of them."

"Statistics... is all based on... the steady augmentation of the confidence level... [F]or an n times increase in sample size, we increase our knowledge by the square root on n. ...Where statistics ...fails us, is when we have distributions that are not symmetric... If there is a very small probability of finding a red ball in an urn dominated by black ones, then our knowledge about the absence of red balls will increase [even more] slowly. ...On the other hand, our knowledge of the presence of red balls will dramatically improve once one of them is found. This asymmetry in knowledge... is the central philosophical problem for... David Hume and Karl Popper."

"David Hume posed the issue in the following way (as rephrased in the black swan problem by... John Stuart Mill) No amount of observations of white swans can allow the inference that all swans are white, but the observation of a single black swan is sufficient to refute that conclusion."

"Science had shifted, thanks to Bacon, into an emphasis on empirical observation. The problem is that, without a proper method, empirical observations can lead you astray. Hume came to... stress the need for some rigor in the gathering and interpretation of knowledge... epistemology... Hume is the first modern epistemologist... he was an obsessive skeptic and never believed... that a link between two items could be established as being causal."

"Maximizing the probability of winning does not lead to maximizing the expectation from the game when one's strategy may include , i.e., a small chance of a large loss and a large chance of a small win. If you engaged in a Russian Roulette-type strategy... you are likely to show up as the winner in almost all samples—except in the year when you are dead."

"[W]e like to emit logical and rational ideas but we do not enjoy this execution."

"What is easier to remember, a collection of facts glued together, or a story, something that offers a series of logical links? Causality is easier to commit to memory. ...What is induction exactly? ...It is very handy, as the general takes much less room in onel's memory than a collection of particulars. The effect of such compression is the reduction in the degree of detected randomness."

"I will use statistics and inductive methods to make aggressive bets, but I will not use them to manage my risks and exposure. ...[A]ll the surviving traders I know seem to have done the same. ...[T]hey make sure the cost of being wrong is limited ...they know ...which events would prove their conjecture wrong and allow for it ...They would then terminate their trade. This is called a stop loss ...I find it rarely practiced."

"A mistake is not something to be determined after the fact, but in the light of the information until that point."

"I always remind myself that what one observes is at best a combination of variance and returns, not just returns."

"I try to make money infrequently, as infrequently as possible simply because I believe that rare events are not fairly valued, and that the rarer the event, the more undervalued it will be in price."

"My major hobby is teasing people who take themselves and the quality of their knowledge too seriously and those who don’t have the guts to sometimes say: I don’t know...."