Don’t let the Nobel prize fool you. Economics is not a science

The award glorifies economists as tellers of timeless truths, fostering hubris and leading to disaster

Joris Luyendijk in The Guardian


 

‘A Nobel prize in economics implies that the human world operates much like the physical world.’ Photograph: Jasper Rietman


Business as usual. That will be the implicit message when the Sveriges Riksbank announces this year’s winner of the “Prize in Economic Sciences in Memory of Alfred Nobel”, to give it its full title. Seven years ago this autumn, practically the entire mainstream economics profession was caught off guard by the global financial crash and the “worst panic since the 1930s” that followed. And yet on Monday the glorification of economics as a scientific field on a par with physics, chemistry and medicine will continue.

The problem is not so much that there is a Nobel prize in economics, but that there are no equivalent prizes in psychology, sociology, anthropology. Economics, this seems to say, is not a social science but an exact one, like physics or chemistry – a distinction that not only encourages hubris among economists but also changes the way we think about the economy.

A Nobel prize in economics implies that the human world operates much like the physical world: that it can be described and understood in neutral terms, and that it lends itself to modelling, like chemical reactions or the movement of the stars. It creates the impression that economists are not in the business of constructing inherently imperfect theories, but of discovering timeless truths.

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To illustrate just how dangerous that kind of belief can be, one only need to consider the fate of Long-Term Capital Management, a hedge fund set up by, among others, the economists Myron Scholes and Robert Merton in 1994. With their work on derivatives, Scholes and Merton seemed to have hit on a formula that yielded a safe but lucrative trading strategy. In 1997 they were awarded the Nobel prize. A year later, Long-Term Capital Management lost $4.6bn (£3bn)in less than four months; a bailout was required to avert the threat to the global financial system. Markets, it seemed, didn’t always behave like scientific models.

In the decade that followed, the same over-confidence in the power and wisdom of financial models bred a disastrous culture of complacency, ending in the 2008 crash. Why should bankers ask themselves if a lucrative new complex financial product is safe when the models tell them it is? Why give regulators real power when models can do their work for them?

Many economists seem to have come to think of their field in scientific terms: a body of incrementally growing objective knowledge. Over the past decades mainstream economics in universities has become increasingly mathematical, focusing on complex statistical analyses and modelling to the detriment of the observation of reality.

Consider this throwaway line from the former top regulator and London School of Economics director Howard Davies in his 2010 book The Financial Crisis: Who Is to Blame?: “There is a lack of real-life research on trading floors themselves.” To which one might say: well, yes, so how about doing something about that? After all, Davies was at the time heading what is probably the most prestigious institution for economics research in Europe, located a stone’s throw away from the banks that blew up.

 Howard Davies, pictured in 2006. Photograph: Eamonn McCabe for the Guardian

All those banks have “structured products approval committees”, where a team of banking staff sits down to decide whether their bank should adopt a particular new complex financial product. If economics were a social science like sociology or anthropology, practitioners would set about interviewing those committee members, scrutinising the meetings’ minutes and trying to observe as many meetings as possible. That is how the kind of fieldwork-based, “qualitative” social sciences, which economists like to discard as “soft” and unscientific, operate. It is true that this approach, too, comes with serious methodological caveats, such as verifiability, selection bias or observer bias. The difference is that other social sciences are open about these limitations, arguing that, while human knowledge about humans is fundamentally different from human knowledge about the natural world, those imperfect observations are extremely important to make.

Compare that humility to that of former central banker Alan Greenspan, one of the architects of the deregulation of finance, and a great believer in models. After the crash hit, Greenspan appeared before a congressional committee in the US to explain himself. “I made a mistake in presuming that the self-interests of organisations, specifically banks and others, were such that they were best capable of protecting their own shareholders and their equity in the firms,” said the man whom fellow economists used to celebrate as “the maestro”.

Nobel Prizes in science: strictly a man’s game?



In other words, Greenspan had been unable to imagine that bankers would run their own bank into the ground. Had the maestro read the tiny pile of books by financial anthropologists he may have found it easier to imagine such behaviour. Then he would have known that over past decades banks had adopted a “zero job security” hire-and-fire culture, breeding a “zero-loyalty” mentality that can be summarised as: “If you can be out of the door in five minutes, your horizon becomes five minutes.”

While this was apparently new to Greenspan it was not to anthropologist Karen Ho, who did years of fieldwork at a Wall Street bank. Her book Liquidated emphasises the pivotal role of zero job security at Wall Street (the same system governs the City of London). The financial sociologist Vincent Lépinay’s Codes of Finance, a book about the division in a French bank for complex financial products, describes in convincing detail how institutional memory suffers when people switch jobs frequently and at short notice.

Perhaps the most pernicious effect of the status of economics in public life has been the hegemony of technocratic thinking. Political questions about how to run society have come to be framed as technical issues, fatally diminishing politics as the arena where society debates means and ends. Take a crucial concept such as gross domestic product. As Ha-Joon Chang makes clear in 23 Things They Don’t Tell You About Capitalism, the choices about what not to include in GDP (household work, to name one) are highly ideological. The same applies to inflation, since there is nothing neutral about the decision not to give greater weight to the explosion in housing and stock market prices when calculating inflation.

  Ha-Joon Chang, pictured at the Hay-on-Wye festival, Wales. Photograph: David Levenson/Getty Images

GDP, inflation and even growth figures are not objective temperature measurements of the economy, no matter how many economists, commentators and politicians like to pretend they are. Much of economics is politics disguised as technocracy – acknowledging this might help open up the space for political debate and change that has been so lacking in the past seven years.

Would it not be extremely useful to take economics down one peg by overhauling the prize to include all social sciences? The Nobel prize for economics is not even a “real” Nobel prize anyway, having only been set up by the Swedish central bank in 1969. In recent years, it may have been awarded to more non-conventional practitioners such as the psychologist Daniel Kahneman. However, Kahneman was still rewarded for his contribution to the science of economics, still putting that field centre stage.

Think of how frequently the Nobel prize for literature elevates little-known writers or poets to the global stage, or how the peace prize stirs up a vital global conversation: Naguib Mahfouz’s Nobel introduced Arab literature to a mass audience, while last year’s prize for Kailash Satyarthi and Malala Yousafzai put the right of all children to an education on the agenda. Nobel prizes in economics, meanwhile, go to “contributions to methods of analysing economic time series with time-varying volatility” (2003) or the “analysis of trade patterns and location of economic activity” (2008).

A revamped social science Nobel prize could play a similar role, feeding the global conversation with new discoveries and insights from across the social sciences, while always emphasising the need for humility in treating knowledge by humans about humans. One good candidate would be the sociologist Zygmunt Bauman, whose writing on the “liquid modernity” of post-utopian capitalism deserves the largest audience possible. Richard Sennett and his work on the “corrosion of character” among workers in today’s economies would be another. Will economists volunteer to share their prestigious prize out of their own acccord? Their own mainstream economic assumptions about human selfishness suggest they will not.

The maths formula linked to the financial crash

Black-Scholes: The maths formula linked to the financial crash

By Tim Harford BBC Radio 4, More or Less
 

It's not every day that someone writes down an equation that ends up changing the world. But it does happen sometimes, and the world doesn't always change for the better. It has been argued that one formula known as Black-Scholes, along with its descendants, helped to blow up the financial world.

Black-Scholes was first written down in the early 1970s but its story starts earlier than that, in the Dojima Rice Exchange in 17th Century Japan where futures contracts were written for rice traders. A simple futures contract says that I will agree to buy rice from you in one year's time, at a price that we agree right now.

By the 20th Century the Chicago Board of Trade was providing a marketplace for traders to deal not only in futures but in options contracts. An example of an option is a contract where we agree that I can buy rice from you at any time over the next year, at a price that we agree right now - but I don't have to if I don't want to.

You can imagine why this kind of contract might be useful. If I am running a big chain of hamburger restaurants, but I don't know how much beef I'll need to buy next year, and I am nervous that the price of beef might rise, well - all I need is to buy some options on beef.

But then that leads to a very ticklish problem. How much should I be paying for those beef options? What are they worth? And that's where this world-changing equation, the Black-Scholes formula, can help.

"The problem it's trying to solve is to define the value of the right, but not the obligation, to buy a particular asset at a specified price, within or at the end of a specified time period," says Professor Myron Scholes, professor of finance at the Stanford University Graduate School of Business and - of course - co-inventor of the Black-Scholes formula.

The young Scholes was fascinated by finance. As a teenager, he persuaded his mother to set up an account so that he could trade on the stock market. One of the amazing things about Scholes is that throughout his time as an undergraduate and then a doctoral student, he was half-blind. And so, he says, he got very good at listening and at thinking.

When he was 26, an operation largely restored his sight. The next year, he became an assistant professor at MIT, and it was there that he stumbled upon the option-pricing puzzle.

One part of the puzzle was this question of risk: the value of an option to buy beef at a price of - say - $2 (£1.23) a kilogram presumably depends on what the price of beef is, and how the price of beef is moving around.

But the connection between the price of beef and the value of the beef option doesn't vary in a straightforward way - it depends how likely the option is to actually be used. That in turn depends on the option price and the beef price. All the variables seem to be tangled up in an impenetrable way.
Scholes worked on the problem with his colleague, Fischer Black, and figured out that if I own just the right portfolio of beef, plus options to buy and sell beef, I have a delicious and totally risk-free portfolio. Since I already know the price of beef and the price of risk-free assets, by looking at the difference between them I can work out the price of these beef options. That's the basic idea. The details are hugely complicated.

"It might have taken us a year, a year and a half to be able to solve and get the simple Black-Scholes formula," says Scholes. "But we had the actual underlying dynamics way before."

The Black-Scholes method turned out to be a way not only to calculate value of options but all kinds of other financial assets. "We were like kids in a candy story in the sense that we described options everywhere, options were embedded in everything that we did in life," says Scholes.

But Black and Scholes weren't the only kids in the candy store, says Ian Stewart, whose book argues that Black-Scholes was a dangerous invention.

"What the equation did was give everyone the confidence to trade options and very quickly, much more complicated financial options known as derivatives," he says.

Scholes thought his equation would be useful. He didn't expect it to transform the face of finance. But it quickly became obvious that it would.

"About the time we had published this article, that's 1973, simultaneously or approximately a month thereafter, the Chicago Board Options Exchange started to trade call options on 16 stocks," he recalls.
Scholes had just moved to the University of Chicago. He and his colleagues had already been teaching the Black-Scholes formula and methodology to students for several years.

"There were many young traders who either had taken courses at MIT or Chicago in using the option pricing technology. On the other hand, there was a group of traders who had only intuition and previous experience. And in a very short period of time, the intuitive players were essentially eliminated by the more systematic players who had this pricing technology."

That was just the beginning.

"By 2007 the trade in derivatives worldwide was one quadrillion (thousand million million) US dollars - this is 10 times the total production of goods on the planet over its entire history," says Stewart. "OK, we're talking about the totals in a two-way trade, people are buying and people are selling and you're adding it all up as if it doesn't cancel out, but it was a huge trade."

The Black-Scholes formula had passed the market test. But as banks and hedge funds relied more and more on their equations, they became more and more vulnerable to mistakes or over-simplifications in the mathematics.

"The equation is based on the idea that big movements are actually very, very rare. The problem is that real markets have these big changes much more often that this model predicts," says Stewart. "And the other problem is that everyone's following the same mathematical principles, so they're all going to get the same answer."

Now these were known problems. What was not clear was whether the problems were small enough to ignore, or well enough understood to fix. And then in the late 1990s, two remarkable things happened.

"The inventors got the Nobel Prize for Economics," says Stewart. "I would argue they thoroughly deserved to get it."

Fischer Black died young, in 1995. When in 1997 Scholes won the Nobel memorial prize, he shared it not with Black but with Robert Merton, another option-pricing expert.

Scholes' work had inspired a generation of mathematical wizards on Wall Street, and by this stage both he and Merton were players in the world of finance, as partners of a hedge fund called Long-Term Capital Management.

"The whole idea of this company was that it was going to base its trading on mathematical principles such as the Black-Scholes equation. And it actually was amazingly successful to begin with," says Stewart. "It was outperforming the traditional companies quite noticeably and everything looked great."

But it didn't end well. Long-Term Capital Management ran into, among other things, the Russian financial crisis. The firm lost $4bn (£2.5bn) in the course of six weeks. It was bailed out by a consortium of banks which had been assembled by the Federal Reserve. And - at the time - it was a very big story indeed. This was all happening in August and September of 1998, less than a year after Scholes had been awarded his Nobel prize.

Stewart says the lessons from Long-Term Capital Management were obvious. "It showed the danger of this kind of algorithmically-based trading if you don't keep an eye on some of the indicators that the more conventional people would use," he says. "They [Long-Term Capital Management] were committed, pretty much, to just ploughing ahead with the system they had. And it went wrong."

Scholes says that's not what happened at all. "It had nothing to do with equations and nothing to do with models," he says. "I was not running the firm, let me be very clear about that. There was not an ability to withstand the shock that occurred in the market in the summer and fall of late 1998. So it was just a matter of risk-taking. It wasn't a matter of modelling."

This is something people were still arguing about a decade later. Was the collapse of Long-Term Capital Management an indictment of mathematical approaches to finance or, as Scholes says, was it simply a case of traders taking too much risk against the better judgement of the mathematical experts?

Ten years after the Long-Term Capital Management bail-out, Lehman Brothers collapsed. And the debate over Black-Scholes and LTCM is now a broader debate over the role of mathematical equations in finance.

Ian Stewart claims that the Black-Scholes equation changed the world. Does he really believe that mathematics caused the financial crisis?

"It was abuse of their equation that caused trouble, and I don't think you can blame the inventors of an equation if somebody else comes along and uses it badly," he says.

"And it wasn't just that equation. It was a whole generation of other mathematical models and all sorts of other techniques that followed on its heels. But it was one of the major discoveries that opened the door to all this."

Black-Scholes changed the culture of Wall Street, from a place where people traded based on common sense, experience and intuition, to a place where the computer said yes or no.

But is it really fair to blame Black-Scholes for what followed it? "The Black-Scholes technology has very specific rules and requirements," says Scholes. "That technology attracted or caused investment banks to hire people who had quantitative or mathematical skills. I accept that. They then developed products or technologies of their own."

Not all of those subsequent technologies, says Scholes, were good enough. "[Some] had assumptions that were wrong, or they used data incorrectly to calibrate their models, or people who used [the] models didn't know how to use them."

Scholes argues there is no going back. "The fundamental issue is that quantitative technologies in finance will survive, and will grow, and will continue to evolve over time," he says.

But for Ian Stewart, the story of Black-Scholes - and of Long-Term Capital Management - is a kind of morality tale. "It's very tempting to see the financial crisis and various things which led up to it as sort of the classic Greek tragedy of hubris begets nemesis," he says.

"You try to fly, you fly too close to the sun, the wax holding your wings on melts and you fall down to the ground. My personal view is that it's not just tempting to do that but there is actually a certain amount of truth in that way of thinking. I think the bankers' hubris did indeed beget nemesis. But the big problem is that it wasn't the bankers on whom the nemesis descended - it was the rest of us."

Additional reporting by Richard Knight

Nassim Nicholas Taleb: the prophet of boom and doom

 Bryan Appleyard 
 

A noisy cafe in Newport Beach, California. Nassim Nicholas Taleb is eating three successive salads, carefully picking out anything with a high carbohydrate content.

He is telling me how to live. "The only way you can say 'F*** you' to fate is by saying it's not going to affect how I live. So if somebody puts you to death, make sure you shave."

After lunch he takes me to Circuit City to buy two Olympus voice recorders, one for me and one for him. The one for him is to record his lectures – he charges about $60,000 for speaking engagements, so the $100 recorder is probably worth it. The one for me is because the day before he had drowned my Olympus with earl grey tea and, as he keeps saying, "I owe you." It didn't matter because I always use two recorders and, anyway, I had bought a replacement the next morning.

But it's important and it's not, strictly speaking, a cost to him. Every year he puts a few thousand dollars aside for contingencies – parking tickets, tea spills – and at the end of the year he gives what's left to charity. The money is gone from day one, so unexpected losses cause no pain. Now I have three Olympus recorders.

He spilt the tea – bear with me; this is important – while grabbing at his BlackBerry. He was agitated, reading every incoming e-mail, because the Indian consulate in New York had held on to his passport and he needed it to fly to Bermuda. People were being mobilised in New York and, for some reason, France, to get the passport.

The important thing is this: the lost passport and the spilt tea were black swans, bad birds that are always lurking, just out of sight, to catch you unawares and wreck your plans. Sometimes, however, they are good birds. The recorders cost $20 less than the marked price owing to a labelling screw-up at Circuit City. Stuff happens. The world is random, intrinsically unknowable. "You will never," he says, "be able to control randomness."

To explain: black swans were discovered in Australia. Before that, any reasonable person could assume the all-swans-are-white theory was unassailable. But the sight of just one black swan detonated that theory. Every theory we have about the human world and about the future is vulnerable to the black swan, the unexpected event. We sail in fragile vessels across a raging sea of uncertainty.

"The world we live in is vastly different from the world we think we live in."

Last May, Taleb published The Black Swan: The Impact of the Highly Improbable. It said, among many other things, that most economists, and almost all bankers, are subhuman and very, very dangerous. They live in a fantasy world in which the future can be controlled by sophisticated mathematical models and elaborate risk-management systems. Bankers and economists scorned and raged at Taleb. He didn't understand, they said. A few months later, the full global implications of the sub-prime-driven credit crunch became clear. The world banking system still teeters on the edge of meltdown. Taleb had been vindicated. "It was my greatest vindication. But to me that wasn't a black swan; it was a white swan. I knew it would happen and I said so. It was a black swan to Ben Bernanke [the chairman of the Federal Reserve]. I wouldn't use him to drive my car. These guys are dangerous. They're not qualified in their own field."

In December he lectured bankers at Société Générale, France's second biggest bank. He told them they were sitting on a mountain of risks – a menagerie of black swans. They didn't believe him. Six weeks later the rogue trader and black swan Jérôme Kerviel landed them with $7.2 billion of losses.
As a result, Taleb is now the hottest thinker in the world. He has a $4m advance on his next book. He gives about 30 presentations a year to bankers, economists, traders, even to Nasa, the US Fire Administration and the Department of Homeland Security. But he doesn't tell them what to do – he doesn't know. He just tells them how the world is. "I'm not a guru. I'm just describing a problem and saying, 'You deal with it.'"

Getting to know Taleb is a highly immersive experience. Everything matters. "Why are you not dressed Californian?" he asks at our first meeting. Everything in Newport Beach is very Californian. I'm wearing a jacket: it's cold. He's wearing shorts and a polo shirt. Clothes matter; they send signals. He warns against trusting anybody who wears a tie – "You have to ask, 'Why is he wearing a tie?'"
He has rules. In California he hires bikes, not cars. He doesn't usually carry his BlackBerry because he hates distraction and he really hates phone charges. But he does carry an Apple laptop everywhere and constantly uses it to illustrate complex points and seek out references. He says he answers every e-mail. He is sent thousands. He reads for 60 hours a week, but almost never a newspaper, and he never watches television.

"If something is going on, I hear about it. I like to talk to people, I socialise. Television is a waste of time. Human contact is what matters."

But the biggest rule of all is his eccentric and punishing diet and exercise programme. He's been on it for three months and he's lost 20lb. He's following the thinking of Arthur De Vany, an economist – of the acceptable type – turned fitness guru. The theory is that we eat and exercise according to our evolved natures. Early man did not eat carbs, so they're out. He did not exercise regularly and he did not suffer long-term stress by having an annoying boss. Exercise must be irregular and ferocious – Taleb often does four hours in the gym or 360 press-ups and then nothing for 10 days. Jogging is useless; sprinting is good. He likes to knacker himself completely before a long flight. Stress should also be irregular and ferocious – early men did not have bad bosses, but they did occasionally run into lions.

He's always hungry. At both lunches he orders three salads, which he makes me share. Our conversation swings from high philosophy and low economics back to dietary matters like mangoes – bad – and apples – good as long as they are of an old variety. New ones are bred for sugar content. His regime works. He looks great – springy and fit. He shows me an old identity card. He is fat and middle-aged in the photo. He looks 10 years younger than that. "Look at me! That photo was taken seven years ago. No carbs!"

This is risk management – facing up to those aspects of randomness about which something can be done. Some years ago he narrowly survived throat cancer. The change in his voice was at first misdiagnosed as damaged vocal cords from his time on the trading floor. It can recur. Also he has a high familial risk of diabetes. He is convinced the diet of civilisation – full of carbs and sugar – is the problem. The grand doctors who once announced that complex carbohydrates are good for you are, to him, criminals responsible for thousands of deaths.

So, you are wondering, who is this guy? He was born in 1960 in Lebanon, though he casts doubt on both these "facts". The year is "close enough" – he doesn't like to give out his birth date because of identity theft and he doesn't believe in national character. He has, however, a regional identity; he calls himself a Levantine, a member of the indecipherably complex eastern Mediterranean civilisation. "My body and soul are Mediterranean."

Both maternal and paternal antecedents are grand, privileged and politically prominent. They are also Christian – Greek Orthodox. Startlingly, this great sceptic, this non-guru who believes in nothing, is still a practising Christian. He regards with some contempt the militant atheism movement led by Richard Dawkins.

"Scientists don't know what they are talking about when they talk about religion. Religion has nothing to do with belief, and I don't believe it has any negative impact on people's lives outside of intolerance. Why do I go to church? It's like asking, why did you marry that woman? You make up reasons, but it's probably just smell. I love the smell of candles. It's an aesthetic thing."

Take away religion, he says, and people start believing in nationalism, which has killed far more people. Religion is also a good way of handling uncertainty. It lowers blood pressure. He's convinced that religious people take fewer financial risks.

He was educated at a French school. Three traditions formed him: Greek Orthodox, French Catholic and Arab. They also taught him to disbelieve conventional wisdom. Each tradition had a different history of the crusades, utterly different. This led him to disbelieve historians almost as much as he does bankers.

But, crucially, he also learnt from a very early age that grown-ups have a dodgy grasp of probability. It was in the midst of the Lebanese civil war and, hiding from the guns and bombs, he heard adults repeatedly say the war would soon be over. It lasted 15 years. He became obsessed with probability and, after a degree in management from the Wharton business school at Pennsylvania University, he focused on probability for his PhD at the University of Paris.

For the non-mathematician, probability is an indecipherably complex field. But Taleb makes it easy by proving all the mathematics wrong. Let me introduce you to Brooklyn-born Fat Tony and academically inclined Dr John, two of Taleb's creations. You toss a coin 40 times and it comes up heads every time. What is the chance of it coming up heads the 41st time? Dr John gives the answer drummed into the heads of every statistic student: 50/50. Fat Tony shakes his head and says the chances are no more than 1%. "You are either full of crap," he says, "or a pure sucker to buy that 50% business. The coin gotta be loaded."

The chances of a coin coming up heads 41 times are so small as to be effectively impossible in this universe. It is far, far more likely that somebody is cheating. Fat Tony wins. Dr John is the sucker. And the one thing that drives Taleb more than anything else is the determination not to be a sucker. Dr John is the economist or banker who thinks he can manage risk through mathematics. Fat Tony relies only on what happens in the real world.

In 1985, Taleb discovered how he could play Fat Tony in the markets. France, Germany, Japan, Britain and America signed an agreement to push down the value of the dollar. Taleb was working as an options trader at a French bank. He held options that had cost him almost nothing and that bet on the dollar's decline. Suddenly they were worth a fortune. He became obsessed with buying "out of the money" options. He had realised that when markets rise they tend to rise by small amounts, but when they fall – usually hit by a black swan – they fall a long way.

The big payoff came on October 19, 1987 – Black Monday. It was the biggest market drop in modern history. "That had vastly more influence on my thought than any other event in history."

It was a huge black swan – nobody had expected it, not even Taleb. But the point was, he was ready. He was sitting on a pile of out-of-the-money eurodollar options. So, while others were considering suicide, Taleb was sitting on profits of $35m to $40m. He had what he calls his "f***-off money", money that would allow him to walk away from any job and support him in his long-term desire to be a writer and philosopher.

He stayed on Wall Street until he got bored and moved to Chicago to become a trader in the pit, the open-outcry market run by the world's most sceptical people, all Fat Tonys. This he understood.
His first book, Dynamic Hedging: Managing Vanilla and Exotic Options, came out in 1997. He was moving away from being a pure trader, or "quant" – a quantitative analyst who applies sophisticated maths to investments – to being the philosopher he wanted to be. He was using the vast data pool provided by the markets and combining it with a sophisticated grasp of epistemology, the study of how and what we know, to form a synthesis unique in the modern world.

In the midst of this came his purest vindication prior to sub-prime. Long-Term Capital Management was a hedge fund set up in 1994 by, among others, Myron Scholes and Robert C Merton, joint winners of the 1997 Nobel prize in economics. It had the grandest of all possible credentials and used the most sophisticated academic theories of portfolio management. It went bust in 1998 and, because it had positions worth $1.25 trillion outstanding, it almost took the financial system down with it. Modern portfolio theory had not accounted for the black swan, the Russian financial crisis of that year. Taleb regards the Nobel prize in economics as a disgrace, a laughable endorsement of the worst kind of Dr John economics. Fat Tony should get the Nobel, but he's too smart. "People say to me, 'If economists are so incompetent, why do people listen to them?' I say, 'They don't listen, they're just teaching birds how to fly.' "

Taleb created his own hedge fund, Empirica, designed to help other hedge funds hedge their risks by using a refined form of his options wins – running small losses in quiet times and winning big in turbulent markets. It did okay but, after a good first year, performed poorly when the market went though a quiet spell. He's still involved in the markets, but mainly as a hobby – "like chess".

Finally, with two books – Fooled by Randomness: The Hidden Role of Chance in the Markets and in Life, and The Black Swan – and a stream of academic papers, he turned himself into one of the giants of modern thought. They're still trying to tear him down, of course; last year The American Statistician journal devoted a whole issue to attacking The Black Swan. But I wouldn't bother. A bad but rather ignorant review in The New York Times resulted in such a savage rebuttal from Taleb on his website, www.fooledbyrandomness.com, that reviewers across the US pulled out in fear of his wrath. He knows his stuff and he keeps being right.

And what he knows does not sound good. The sub-prime crisis is not over and could get worse. Even if the US economy survives this one, it will remain a mountain of risk and delusion. "America is the greatest financial risk you can think of."

Its primary problem is that both banks and government are staffed by academic economists running their deluded models. Britain and Europe have better prospects because our economists tend to be more pragmatic, adapting to conditions rather than following models. But still we are dependent on American folly.

The central point is that we have created a world we don't understand. There's a place he calls Mediocristan. This was where early humans lived. Most events happened within a narrow range of probabilities – within the bell-curve distribution still taught to statistics students. But we don't live there any more. We live in Extremistan, where black swans proliferate, winners tend to take all and the rest get nothing – there's Bill Gates, Steve Jobs and a lot of software writers living in a garage, there's Domingo and a thousand opera singers working in Starbucks. Our systems are complex but over-efficient. They have no redundancy, so a black swan strikes everybody at once. The banking system is the worst of all.

"Complex systems don't allow for slack and everybody protects that system. The banking system doesn't have that slack. In a normal ecology, banks go bankrupt every day. But in a complex system there is a tendency to cluster around powerful units. Every bank becomes the same bank so they can all go bust together."

He points out, chillingly, that banks make money from two sources. They take interest on our current accounts and charge us for services. This is easy, safe money. But they also take risks, big risks, with the whole panoply of loans, mortgages, derivatives and any other weird scam they can dream up. "Banks have never made a penny out of this, not a penny. They do well for a while and then lose it all in a big crash."

On top of that, Taleb has shown that increased economic concentration has raised our vulnerability to natural disasters. The Kobe earthquake of 1995 cost a lot more than the Tokyo earthquake of 1923. And there are countless other ways in which we have built a world ruled by black swans – some good but mostly bad. So what do we do as individuals and the world? In the case of the world, Taleb doesn't know. He doesn't make predictions, he insults people paid to do so by telling them to get another job. All forecasts about the oil price, for example, are always wrong, though people keep doing it. But he knows how the world will end.

"Governments and policy makers don't understand the world in which we live, so if somebody is going to destroy the world, it is the Bank of England saving Northern Rock. The biggest danger to human society comes from civil servants in an environment like this. In their attempt to control the ecology, they don't understand that the link between action and consequences can be more vicious. Civil servants say they need to make forecasts, but it's totally irresponsible to make people rely on you without telling them you're incompetent."

Bear Stearns – the US Northern Rock – was another vindication for Taleb. He's always said that whatever deal you do, you always end up dealing with J P Morgan. It was JPM that picked up Bear at a bargain-basement price. Banks should be more like New York restaurants. They come and go but the restaurant business as a whole survives and thrives and the food gets better. Banks fail but bankers still get millions in bonuses for applying their useless models. Restaurants tinker, they work by trial and error and watch real results in the real world. Taleb believes in tinkering – it was to be the title of his next book. Trial and error will save us from ourselves because they capture benign black swans. Look at the three big inventions of our time: lasers, computers and the internet. They were all produced by tinkering and none of them ended up doing what their inventors intended them to do. All were black swans. The big hope for the world is that, as we tinker, we have a capacity for choosing the best outcomes.

"We have the ability to identify our mistakes eventually better than average; that's what saves us." We choose the iPod over the Walkman. Medicine improved exponentially when the tinkering barber surgeons took over from the high theorists. They just went with what worked, irrespective of why it worked. Our sense of the good tinker is not infallible, but it might be just enough to turn away from the apocalypse that now threatens Extremistan.

He also wants to see diplomats dying of cirrhosis of the liver. It means they're talking and drinking and not going to war. Parties are among the great good things in Taleb's world.

And you and me? Well, the good investment strategy is to put 90% of your money in the safest possible government securities and the remaining 10% in a large number of high-risk ventures. This insulates you from bad black swans and exposes you to the possibility of good ones. Your smallest investment could go "convex" – explode – and make you rich. High-tech companies are the best. The downside risk is low if you get in at the start and the upside very high. Banks are the worst – all the risk is downside. Don't be tempted to play the stock market – "If people knew the risks they'd never invest."

There's much more to Taleb's view of the world than that. He is reluctant to talk about matters of human nature, ethics or any of the traditional concerns of philosophy because he says he hasn't read enough. But, when pressed, he comes alive.

"You have to worry about things you can do something about. I worry about people not being there and I want to make them aware." We should be mistrustful of knowledge. It is bad for us. Give a bookie 10 pieces of information about a race and he'll pick his horses. Give him 50 and his picks will be no better, but he will, fatally, be more confident.

We should be ecologically conservative – global warming may or may not be happening but why pollute the planet? – and probablistically conservative. The latter, however, has its limits. Nobody, not even Taleb, can live the sceptical life all the time – "It's an art, it's hard work." So he doesn't worry about crossing the road and doesn't lock his front door – "I can't start getting paranoid about that stuff." His wife locks it, however.

He believes in aristocratic – though not, he insists, elitist – values: elegance of manner and mind, grace under pressure, which is why you must shave before being executed. He believes in the Mediterranean way of talking and listening. One piece of advice he gives everybody is: go to lots of parties and listen, you might learn something by exposing yourself to black swans.

I ask him what he thinks are the primary human virtues, and eventually he comes up with magnanimity – punish your enemies but don't bear grudges; compassion – fairness always trumps efficiency; courage – very few people have this; and tenacity – tinker until it works for you.

"Let's be human the way we are human. Homo sum – I am a man. Don't accept any Olympian view of man and you will do better in society."

Above all, accept randomness. Accept that the world is opaque, majestically unknown and unknowable. From its depths emerge the black swans that can destroy us or make us free. Right now they're killing us, so remember to shave. But we can tinker our way out of it. It's what we do best. Listen to Taleb, an ancient figure, one of the great Mediterranean minds, when he says: "You find peace by coming to terms with what you don't know." Oh, and watch those carbs

Taleb's top life tips

1 Scepticism is effortful and costly. It is better to be sceptical about matters of large consequences, and be imperfect, foolish and human in the small and the aesthetic.

2 Go to parties. You can't even start to know what you may find on the envelope of serendipity. If you suffer from agoraphobia, send colleagues.

3 It's not a good idea to take a forecast from someone wearing a tie. If possible, tease people who take themselves and their knowledge too seriously.

4 Wear your best for your execution and stand dignified. Your last recourse against randomness is how you act — if you can't control outcomes, you can control the elegance of your behaviour. You will always have the last word.

5 Don't disturb complicated systems that have been around for a very long time. We don't understand their logic. Don't pollute the planet. Leave it the way we found it, regardless of scientific 'evidence'.

6 Learn to fail with pride — and do so fast and cleanly. Maximise trial and error — by mastering the error part.

7 Avoid losers. If you hear someone use the words 'impossible', 'never', 'too difficult' too often, drop him or her from your social network. Never take 'no' for an answer (conversely, take most 'yeses' as 'most probably').

8 Don't read newspapers for the news (just for the gossip and, of course, profiles of authors). The best filter to know if the news matters is if you hear it in cafes, restaurants... or (again) parties.

9 Hard work will get you a professorship or a BMW. You need both work and luck for a Booker, a Nobel or a private jet.

10 Answer e-mails from junior people before more senior ones. Junior people have further to go and tend to remember who slighted them.

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