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Lost in Extremistan with nothing but a Bell Curve Apr 18, 2007 (1070 of 1154 found this helpful)
If, as Socrates would have it, the only true knowledge is knowledge of one's own ignorance, then Nassim Nicholas Taleb is the world's greatest living teacher. In The Black Swan, Taleb's second book for laypeople, he gives a full treatment to concepts briefly explored in his first book "Fooled by Randomness." The Black Swan is basically a sequel to that book, but much more focused, detailed and scholarly. This is a book of serious philosophy that reads like a stand-up comedy routine. (Think Larry David...)
The Black Swan is probably the strongest statement of enlightened empiricism since Ernst Mach refused to acknowledge the existence of the atom. Of course, in theory, everyone today is supposed to be an empiricist - all right-thinking intellectuals claim to base their views solely on positive scientific observation. But very few sincerely confront the implications of rigorous empiricism. Specifically, few confront "the problem of induction," illustrated here by the story of the black swan.
Briefly: observing an event once does not predict it will occur again in the future. This remains true regardless of the number of observations one adds to the pile. Or, as Taleb, recapitulating David Hume, has it: the observation of even a million white swans does not justify the statement "all swans are white." There is no way to know that somewhere out there a black swan is not hiding, disproving the rule and nullifying our "knowledge" of swans. The problem of induction tells us that we cannot really learn from our experiences. It makes knowledge very problematic, if not impossible. And yet, humans do behave -almost without exception- as though they believe that experience teaches us lessons. This is forgivable; there is no better path to knowledge. But before proceeding, one must account for the limits that the problem of induction places on our claims to knowledge. And humans seem, at every turn, to lack this critical self-awareness.
In one of the many humorous anecdotes that seem to comprise this entire book, Taleb recounts how he learned his extreme skepticism from his first boss, a French gentleman trader who insisted that he should not worry about the fluctuating values of economic indicators. (Indeed, Taleb proudly declares that, to this day, he remains blissfully ignorant of supposedly crucial "indicators" like housing starts and consumer spending. This is a shocking statement from a guy whose day job is managing a hedge fund.) Even if these "common knowledge" indicators are predictive of anything (dubious - see above), they are useless to you because everyone else is already accounting for them. They are "white swans," or common sense. Regardless of their magnitude, white swans are basically irrelevant to the trader - they have already been impounded into the market. In this environment, one can only profitably concern oneself with those bets which others are systematically ignoring - bets on those highly unlikely, but highly consequential events that utterly defy the conventional wisdom. What Taleb ought to worry about, the Frenchman warned, was not the prospect of a quarter-percent rise in interest rates, but a plane hitting the World Trade Center!
Yep, the precise facts of 9-11 were actually presaged by this French gentlemen, as a rogue wave that just might be lurking over the horizon. And, to the contemporary American mind, this is THE quintessential Black Swan. Of course, the Frenchman's insight was just a coincidence - the thing with Black Swans is that they cannot be foreseen.
Taleb explains that conventional social scientists use induction to collect data, which is then plotted on the good old Gaussian bellcurve. With characteristic silliness, Taleb dubs the land of the bellcurve "Mediocristan" - and informs us that it is the natural habitat of the white swan. He contrasts Mediocristan with "Extremistan" - where chao
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Chapters 15 - 17 are excellent. The remainder is OK. Jul 30, 2007 (540 of 583 found this helpful)
Starting with the good (chapters 15 - 17), within chapter 15 Taleb explains where the Bell curve works and where it does not. The Bell curve captures well variables that don't deviate much from the mean. Otherwise, it does not work. Taleb suggests we often fool ourselves in believing that correlation, regression coefficients, or standard deviation convey much information. This is because those coefficients are unstable (and can flip sign when possible) depending on the time selected. This is because the underlying variables are often not stationary enough for these coefficients to be stable.
Chapter 16 is excellent as an introduction to Mandelbrot's fractal geometry as an alternative to Gaussian based investment theory. He supports well that these mathematical tools do capture randomness (of non-stationary variables) far better than the Normal distribution. However, he admits that Mandelbrotian models are not predictive. When looking at the same data set, he and numerous colleagues each came up with different underlying parameters to build fractal-like models. And a small difference in such parameters makes a huge difference in outcome. That's why you will not hear much of fractal geometry within the quantitative financial community. Nevertheless, this is a fascinating subject that deserves further exploration. For this purpose, I recommend Mandelbrot's The Misbehavior of Markets
Within Chapter 17, Taleb further elaborates on the flaws of the Normal distribution. He underlines that half of the return of the stock market over the past 50 years was associated with just 10 days with the greatest daily change. This is an example where stock returns have outliers of such magnitude that using the Normal distribution is not appropriate. Taleb describes the run-ins he experienced with the living legends of modern finance including Myron Scholes and Robert Merton due to his rejection of the Normal distribution assumption that underlies all their models.
The remainder of the book is not nearly as good. Hundreds of pages can be summed up in just stating that we can't predict rare events. Taleb goes way overboard in attributing everything to luck. He thinks MicroSoft beat out Apple just due to luck. Taleb does not consider that MicroSoft open system allowed it to mushroom while Apple locked itself into a proprietary corner. Also, according to Taleb both the rise and fall of Rome were due entirely to luck. But, Rome was best at developing military strategy and transportation networks. However, it eventually suffered from imperial overstretch. Explanations are not always narrative fallacies as Taleb believes. They often beat out ignorance.
When it comes to advice, Taleb's recommendation is interesting. It consists in an asset allocation of 85% risk free investments (T-bill) and the 15% remainder into buying way out of the money Calls and Puts. By doing so, he positions his portfolio to capture the occasional mispriced Black Swans.
This book is somewhat uneven in quality and is not nearly as good as his first book: Fooled by Randomness Revision (Not Available in US): The Hidden Role of Chance in the Markets and Life that has become a classic on Wall Street. Otherwise, it still is an interesting reading.
If you find the subject of this book intriguing, let me suggest a few other books that are more rewarding. Scott Plous'sThe Psychology of Judgment and Decision Making explores the flaws in human judgments far more thoroughly and clearly than Taleb in `The Black Swan.' Perry Mehrling's Fischer Black and the Revolutionary Idea of Finance is also an excellent book. Ideally, that may be who Taleb would have liked to become. Fischer Black was brilliant and as skeptical as Taleb regarding much of the body of economics and finance. Yet, he left a great legacy of elegant models that people still use extensively including the
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Many important ideas, many flaws that detract from the message Apr 26, 2007 (763 of 846 found this helpful)
This is an entertaining and enlightening book, and fairly easy to read. It has an important message regarding how the world works; that the world is governed not by the predictable and the average, but by the random, the unknownable, the unpredictable -- big events or discoveries or unusual people that have big consequences. Change comes not uniformly but in unpredictable spurts. These are the Black Swans of the title: completedly unexpected and rare events or novel ideas or technologies that have a huge impact on the world. Indeed, Taleb argues that history itself is primarly driven by these Black Swans.
It is convincing argument, entertainingly presented with plenty of sarcasm, and indeed, anger, by Taleb. For example he rails against the academic community, economists (including specific names), and Nobel Prize committee. Considerable numbers of his arguments "ring true" to me, that is my experience in life confirms that they are more accurate than the traditional approach. Like any important work, 90% of what is in the book is not original; that does not make it less important. Taleb's contribution is in integrating the material together, and showing how these different ideas are tied to the Black Swan.
The themes include: winner-take-all phenonomen, numerous effects of randomness on the world, the invalidity of the Gaussian Bell Curve to most things in world, concepts of scalablity, numerous instabilities in the world, especially the modern world where information travels so quickly, the fallacies about people's inability to predict the future. The importance of these ideas, Taleb's ability to weave them together into a single theory, and the ability of this theory to change the way you look at the world, means the book easily deserves my highest recommendation.
However, the book does have many flaws, unfortunately -- unfortunate because I believe they will take away from the credibility of the message, which is in important one. The are numerous minor flaws such as, for example, the inexplicable invention of a fictional author (disclosed a few pages later), when certainly there must have been some real example that would have worked better. Another example is repeated jabs about the French; these may be amusing but I just don't think they have a place in work like this. There are also diatribes against specific people, including famous economists, which, though amusing, and possibly justified, demonstrate a high level of anger by author and take away from his credibility. Often he also overreaches, for example in saying the usual combination of anti-abortion and pro-death penalty or the opposite combined views of pro-abortion and anti-death penatly cannot be explained logically, when in fact widely known theories such as George Lakoff's (in Moral Politics) have explained hows these groups of views are entirely consistent.
Another flaw is that Taleb seems to go a little toward the extreme of saying that we can predict almost nothing about the future, and though he does not say so explicitly, this seems to imply we have no moral responsibility to the future. This, combined with Taleb's advice to the reader about their behavior based on the "Black Swan" view of world just rubbed me the wrong way, for several reasons. One is that Taleb personally has very little in common with most people; never having as far as I know had a regular career (essentially what he calls non-scalable, e.g. dentist, engineer, baker) he nevertheless recommends that people choose these kinds of careers rather than a scalable career (e.g. financial trader, author, actor which are subject to a few lucky successful people and a lot of failures). This advise is odd first because Taleb is in a non-scalable profession (derivatives trader, then hedge fund manager) -- indeed it appears he is quite wealthy. Even more odd because he says all these types of non-scalable types of work are
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A disappointing follow-up to "Fooled by Randomness" May 10, 2007 (97 of 105 found this helpful)
I'm a mathematician and former trader, and I've always enjoyed Taleb's work, from his technical tome on derivatives, "Dynamic Hedging," to the brilliant "Fooled by Randomness." These books provided a healthy dose of empirical skepticism about a field that sometimes gets carried away with its own "precise" models -- as well as some insightful commentary on why people are bad at recognizing randomness and making predictions, and how we should be wary of charlatans (and fools) trying to sell us false certainty, especially about financial markets. Unfortunately, "The Black Swan" doesn't say much that "Fooled by Randomness" didn't already say (and say better), and I was disappointed by most of the new material.
First, Taleb's ideas on uncertainty have gone a bit over the edge. Before, he denounced the poor use of over-simplified models (i.e. the bell curve) to model uncertainty; he now seems to have given up on models altogether (save for a brief and justified nod to Benoit Mandelbrot). Rather than just attack bad science, and encourage better science in its place, he seems to view the entire scientific enterprise as hopeless -- adopting the somewhat anti-intellectual attitude that we should stop trying to "understand" markets at all, and be more like Fat Tony, the trader from Brooklyn. His portrayal of mathematical finance types is a complete caricature, which is amusing because, whether he likes it or not, he's one of them! (Taleb has taught in the mathematical finance program at NYU's prestigious Courant Institute.) The idea that mainstream academics are too myopic to see beyond their bell-curve models is laughable, and in many cases, decades out of date -- even undergrads learn about the flaws in the Black-Scholes model, and the problem of "fat tails."
While "Fooled by Randomness" suggests (wisely) that we pay attention to the magnitude of events and not just their probabilities, in "The Black Swan" he throws out probability altogether. This results in some bizarre advice, such as that people should structure their lives (and financial portfolios) to capture "positive black swans," i.e. huge but unlikely turns of good fortune, because "unlikely" is a meaningless probabilistic notion. For example, he suggests that people should put 90% of their assets in extremely safe instruments (like T-bills), while gambling the remaining 10% on risky ventures and hoping to hit it big. He claims that this limits one's downside while waiting for a big windfall ... but what happens when the "risky" 10% gets wiped out in a year or two? Do you then start investing your remaining assets (possibly losing more), or do you just stick with low-yield T-bills for the rest of your life? Taleb seemingly hasn't thought it out that far. By the "positive black swan" logic, thousands of unemployed "actors," waiting for that big break that never comes, have the right idea -- not to mention people who waste their money on lottery tickets (hey, the downside is only a buck, but the upside is millions!). This seems to be a complete reversal from "Fooled by Randomness," which had a brighter view of skilled ("Mediocristan") pursuits like dentistry, where one avoids living at the behest of good or bad fortune altogether.
Finally, Taleb has always exuded snobbery in his writing -- in the past it has almost been charming -- but this time it quickly wears out its welcome. He never fails to remind the reader that he sees himself as an erudite "gentleman trader," a rogue philosopher among philistines and eggheads. Yawn.
I still give this book 3 stars, because it does have some decent content, but read "Fooled by Randomness" instead. If you've already read that book, there's no need to buy this one -- but if you're in the mood to read about the problems of uncertainty and prediction in the markets, check out "When Genius Failed" by Lowenstein, "A Random Walk Down Wall Street" by Malkiel, or (for the eggh
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A bad book for all the wrong reasons. Jul 23, 2007 (73 of 79 found this helpful)
I really wish this were a good book, because the basic idea behind it is original, important and clever. That makes Taleb's careless handling of his topic all the more disturbing.
The rock-solid foundation of this book is Taleb's insight that the most important events in history, and presumably to come in the future, are essentially unpredictable; they can't be forecast using the information we have prior to their occurrence. That's a huge point and Taleb goes on to offer some compelling evidence that it is indeed true. He uses the analogy of a Turkey deciding that humans must have his best interests at heart because they show up every day of his life to feed him a good meal, he projects that - based on all of his evidence - this will continue. This works great until a couple of days before Thanksgiving. Suddenly his predictions have failed him catastrophically.
Great idea, and - I believe - true. But Taleb undercuts his own thought baby with shoddy writing, poor research and personal opinion masquerading as evidence.
The writing: A well-written book allows a reader to flow naturally from one paragraph to the next and from one idea to the next, even when the subject matter is complex. Taleb's writing is tough to follow and slow to get through. Beyond that, you really struggle to comprehend what he is trying to get across to you for huge portions of this book.
The research: When Taleb used examples to back his ideas that came from fields with which I was unfamiliar, I felt pretty good about them. However, whenever he used examples from areas where I have deeper knowledge, I noticed that his knowledge was lacking badly (being a trader comes to mind). This started to make me question all of his supporting evidence.
The opinion: Taleb leans heavily on the idea that most of what happens in the world is luck, even when we try desperately to ascribe some sort of tangible cause to it. At one point he uses the example of Mac operating software being far superior to that of Windows, but Windows being dominant in the market. He chalks it up entirely to luck! I'm sure he'd say I'm falling prey to a logical fallacy, but Apple and Steve Jobs had a huge head start on Microsoft, but refused to let anyone else run their operating system - so to run it, you had to buy a Mac. Microsoft let anyone run their operating system and consequently took the dominant share of the market.
This book is really a shame. The idea is just too good to be used this poorly. It made me sad to read this thing. Taleb the thinker deserved a far better writer than Taleb the author. What a waste.
You might still try reading this to understand Taleb's idea, because it's a huge insight, but watch all of his other content because it's riddled with holes.