Wednesday, February 28, 2007

Tilting at windmills

Tyler recently blogged about the new book "The Black Swan" by Nissim Taleb.
Coincidentally, the Economist recently carried a story that governments are now seriously working on preventing what could have been the greates Black Swan of all- an asteroid colliding with the Earth.

The preferred way to deal with rogue asteroids is still a Hollywood-style heroic space mission to knock the object off course, or possibly blow it up—although almost surely as an unmanned effort. However, Edward Lu, of NASA's Johnson Space Centre, has recently proposed an intriguing alternative, which he outlined to the meeting in San Francisco. The idea is to send a satellite to hover alongside a threatening asteroid and, using the gravitational attraction between the two objects, to pull the asteroid gradually off course. Even though the force acting on the asteroid would be extremely small, the cumulative effect over a week or so should be enough to do the trick.

NASA no plans to test any asteroid-deflection scheme, but the ESA does, and they have a sense of humor:

the European Space Agency does have such a project in the pipeline. With an irony the organisers have not, perhaps, properly appreciated, it is known as Don Quijote. The mission will have two craft, Hidalgo and Sancho. As in Cervantes's novel, the servant will observe while his master makes a fool of himself by crashing blithely into the target asteroid. If all such asteroids turn out to be harmless windmills, it will have been a wasted effort. But if one does, indeed, turn out to be a threatening giant, future generations may be very glad of the Don's headlong charge

Edge .org has an interesting article by Nissim Taleb- first published in the New York Times. As he puts it

A black swan is an outlier, an event that lies beyond the realm of normal expectations. Most people expect all swans to be white because that's what their experience tells them; a black swan is by definition a surprise. Nevertheless, people tend to concoct explanations for them after the fact, which makes them appear more predictable, and less random, than they are. Our minds are designed to retain, for efficient storage, past information that fits into a compressed narrative. This distortion, called the hindsight bias, prevents us from adequately learning from the past.

Black swans can have extreme effects: just a few explain almost everything, from the success of some ideas and religions to events in our personal lives. Moreover, their influence seems to have grown in the 20th century, while ordinary events — the ones we study and discuss and learn about in history or from the news — are becoming increasingly inconsequential.

Consider: How would an understanding of the world on June 27, 1914, have helped anyone guess what was to happen next? The rise of Hitler, the demise of the Soviet bloc, the spread of Islamic fundamentalism, the Internet bubble: not only were these events unpredictable, but anyone who correctly forecast any of them would have been deemed a lunatic (indeed, some were). This accusation of lunacy would have also applied to a correct prediction of the events of 9/11 — a black swan of the vicious variety.

He points out that

There is a silly book called A Millionaire Next Door, and one of the authors wrote an even sillier book called The Millionaire's Mind. They interviewed a bunch of millionaires to figure out how these people got rich. Visibly they came up with bunch of traits. You need a little bit of intelligence, a lot of hard work, and a lot of risk-taking. And they derived that, hey, taking risk is good for you if you want to become a millionaire. What these people forgot to do is to go take a look at the less visible cemetery — in other words, bankrupt people, failures, people who went out of business — and look at their traits. They would have discovered that some of the same traits are shared by these people, like hard work and risk taking. This tells me that the unique trait that the millionaires had in common was mostly luck.

Note that he is himself a multi-millionaire trader.
More than a year ago, Tyler Cowen blogged about Philip Tetlock's book "Expert Political Judgement", quoting the book matter how unequivocal the evidence that experts cannot outpredict chimps or extrapolation algorithms, we should expect business to unfold as usual: pundits will continue to warn us on talk shows and op-ed pages of what will happen unless we dutifully follow their policy prescriptions. We -- the consumers of expert pronouncements -- are in thrall to experts for the same reasons that our ancestors submitted to shamans and oracles: our uncontrollable need to believe in a controllable world and our flawed understanding of the laws of chance. We lack the willpower and good sense to resist the snake oil products on offer. Who wants to believe that, on the big questions, we could do as well tossing a coin as by consulting accredited experts?

What Tyler wrote then applies here as well

Assume that the experts are usually wrong in their novel predictions. The consensus views of a science still might be worth listening to. Economists cannot forecast business cycles very well, but you should listen when they tell you that a deflationary shock is bad news. Each new forecast or new theory is an example of individual hubris and in expected value terms it is stupid. But the body of experts as a whole, over time, absorbs what is correct. A large number of predictions creates a Hayekian discovery process with increasing returns to scale. Social knowledge still comes out ahead, and in part because of the self-deceiving vanities put forward every day. You can find that point in Jonathan Swift's Gulliver's Travels.

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