Article paru dans le Wall Street Journal du 17/11/2012 mais l'idée reste très générale et non pas cantonnée à la finance.
Learning to Love Volatility
Several years before the financial crisis descended on us, I put forward the concept of "black swans": large events that are both unexpected and highly consequential. We never see black swans coming, but when they do arrive, they profoundly shape our world: Think of World War I, 9/11, the Internet, the rise of Google.
In economic life and history more generally, just about everything of consequence comes from black swans; ordinary events have paltry effects in the long term. Still, through some mental bias, people think in hindsight that they "sort of" considered the possibility of such events; this gives them confidence in continuing to formulate predictions. But our tools for forecasting and risk measurement cannot begin to capture black swans. Indeed, our faith in these tools make it more likely that we will continue to take dangerous, uninformed risks.
Some made the mistake of thinking that I hoped to see us develop better methods for predicting black swans. Others asked if we should just give up and throw our hands in the air: If we could not measure the risks of potential blowups, what were we to do? The answer is simple: We should try to create institutions that won't fall apart when we encounter black swans—or that might even gain from these unexpected events.
Fragility is the quality of things that are vulnerable to volatility. Take the coffee cup on your desk: It wants peace and quiet because it incurs more harm than benefit from random events. The opposite of fragile, therefore, isn't robust or sturdy or resilient—things with these qualities are simply difficult to break.
To deal with black swans, we instead need things that gain from volatility, variability, stress and disorder. My (admittedly inelegant) term for this crucial quality is "antifragile." The only existing expression remotely close to the concept of antifragility is what we derivatives traders call "long gamma," to describe financial packages that benefit from market volatility. Crucially, both fragility and antifragility are measurable.
As a practical matter, emphasizing antifragility means that our private and public sectors should be able to thrive and improve in the face of disorder. By grasping the mechanisms of antifragility, we can make better decisions without the illusion of being able to predict the next big thing. We can navigate situations in which the unknown predominates and our understanding is limited.
Herewith are five policy rules that can help us to establish antifragility as a principle of our socioeconomic life.
Rule 1: Think of the economy as being more like a cat than a washing machine.
We are victims of the post-Enlightenment view that the world functions like a sophisticated machine, to be understood like a textbook engineering problem and run by wonks. In other words, like a home appliance, not like the human body. If this were so, our institutions would have no self-healing properties and would need someone to run and micromanage them, to protect their safety, because they cannot survive on their own.
By contrast, natural or organic systems are antifragile: They need some dose of disorder in order to develop. Deprive your bones of stress and they become brittle. This denial of the antifragility of living or complex systems is the costliest mistake that we have made in modern times. Stifling natural fluctuations masks real problems, causing the explosions to be both delayed and more intense when they do take place. As with the flammable material accumulating on the forest floor in the absence of forest fires, problems hide in the absence of stressors, and the resulting cumulative harm can take on tragic proportions.
And yet our economic policy makers have often aimed for maximum stability, even for eradicating the business cycle. "No more boom and bust," as voiced by the U.K. Labor leader Gordon Brown, was the policy pursued by Alan Greenspan in order to "smooth" things out, thus micromanaging us into the current chaos. Mr. Greenspan kept trying to iron out economic fluctuations by injecting cheap money into the system, which eventually led to monstrous hidden leverage and real-estate bubbles. On this front there is now at least a glimmer of hope, in the U.K. rather than the U.S., alas: Mervyn King, governor of the Bank of England, has advocated the idea that central banks should intervene only when an economy is truly sick and should otherwise defer action.
Promoting antifragility doesn't mean that government institutions should avoid intervention altogether. In fact, a key problem with overzealous intervention is that, by depleting resources, it often results in a failure to intervene in more urgent situations, like natural disasters. So in complex systems, we should limit government (and other) interventions to important matters: The state should be there for emergency-room surgery, not nanny-style maintenance and overmedication of the patient—and it should get better at the former.
In social policy, when we provide a safety net, it should be designed to help people take more entrepreneurial risks, not to turn them into dependents. This doesn't mean that we should be callous to the underprivileged. In the long run, bailing out people is less harmful to the system than bailing out firms; we should have policies now that minimize the possibility of being forced to bail out firms in the future, with the moral hazard this entails.
Rule 2: Favor businesses that benefit from their own mistakes, not those whose mistakes percolate into the system.
Some businesses and political systems respond to stress better than others. The airline industry is set up in such a way as to make travel safer after every plane crash. A tragedy leads to the thorough examination and elimination of the cause of the problem. The same thing happens in the restaurant industry, where the quality of your next meal depends on the failure rate in the business—what kills some makes others stronger. Without the high failure rate in the restaurant business, you would be eating Soviet-style cafeteria food for your next meal out.
These industries are antifragile: The collective enterprise benefits from the fragility of the individual components, so nothing fails in vain. These businesses have properties similar to evolution in the natural world, with a well-functioning mechanism to benefit from evolutionary pressures, one error at a time.
By contrast, every bank failure weakens the financial system, which in its current form is irremediably fragile: Errors end up becoming large and threatening. A reformed financial system would eliminate this domino effect, allowing no systemic risk from individual failures. A good starting point would be reducing the amount of debt and leverage in the economy and turning to equity financing. A firm with highly leveraged debt has no room for error; it has to be extremely good at predicting future revenues (and black swans). And when one leveraged firm fails to meet its obligations, other borrowers who need to renew their loans suffer as the chastened lenders lose their appetite to extend credit. So debt tends to make failures spread through the system.
A firm with equity financing can survive drops in income, however. Consider the abrupt deflation of the technology bubble during 2000. Because technology firms were relying on equity rather than debt, their failures didn't ripple out into the wider economy. Indeed, their failures helped to strengthen the technology sector.
Rule 3: Small is beautiful, but it is also efficient.
Experts in business and government are always talking about economies of scale. They say that increasing the size of projects and institutions brings costs savings. But the "efficient," when too large, isn't so efficient. Size produces visible benefits but also hidden risks; it increases exposure to the probability of large losses. Projects of $100 million seem rational, but they tend to have much higher percentage overruns than projects of, say, $10 million. Great size in itself, when it exceeds a certain threshold, produces fragility and can eradicate all the gains from economies of scale. To see how large things can be fragile, consider the difference between an elephant and a mouse: The former breaks a leg at the slightest fall, while the latter is unharmed by a drop several multiples of its height. This explains why we have so many more mice than elephants.
So we need to distribute decisions and projects across as many units as possible, which reinforces the system by spreading errors across a wider range of sources. In fact, I have argued that government decentralization would help to lower public deficits. A large part of these deficits comes from underestimating the costs of projects, and such underestimates are more severe in large, top-down governments. Compare the success of the bottom-up mechanism of canton-based decision making in Switzerland to the failures of authoritarian regimes in Soviet Russia and Baathist Iraq and Syria.
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Learning to Love Volatility
By NASSIM NICHOLAS TALEB
Several years before the financial crisis descended on us, I put forward the concept of "black swans": large events that are both unexpected and highly consequential. We never see black swans coming, but when they do arrive, they profoundly shape our world: Think of World War I, 9/11, the Internet, the rise of Google.
In economic life and history more generally, just about everything of consequence comes from black swans; ordinary events have paltry effects in the long term. Still, through some mental bias, people think in hindsight that they "sort of" considered the possibility of such events; this gives them confidence in continuing to formulate predictions. But our tools for forecasting and risk measurement cannot begin to capture black swans. Indeed, our faith in these tools make it more likely that we will continue to take dangerous, uninformed risks.
Some made the mistake of thinking that I hoped to see us develop better methods for predicting black swans. Others asked if we should just give up and throw our hands in the air: If we could not measure the risks of potential blowups, what were we to do? The answer is simple: We should try to create institutions that won't fall apart when we encounter black swans—or that might even gain from these unexpected events.
Fragility is the quality of things that are vulnerable to volatility. Take the coffee cup on your desk: It wants peace and quiet because it incurs more harm than benefit from random events. The opposite of fragile, therefore, isn't robust or sturdy or resilient—things with these qualities are simply difficult to break.
To deal with black swans, we instead need things that gain from volatility, variability, stress and disorder. My (admittedly inelegant) term for this crucial quality is "antifragile." The only existing expression remotely close to the concept of antifragility is what we derivatives traders call "long gamma," to describe financial packages that benefit from market volatility. Crucially, both fragility and antifragility are measurable.
As a practical matter, emphasizing antifragility means that our private and public sectors should be able to thrive and improve in the face of disorder. By grasping the mechanisms of antifragility, we can make better decisions without the illusion of being able to predict the next big thing. We can navigate situations in which the unknown predominates and our understanding is limited.
Herewith are five policy rules that can help us to establish antifragility as a principle of our socioeconomic life.
Rule 1: Think of the economy as being more like a cat than a washing machine.
We are victims of the post-Enlightenment view that the world functions like a sophisticated machine, to be understood like a textbook engineering problem and run by wonks. In other words, like a home appliance, not like the human body. If this were so, our institutions would have no self-healing properties and would need someone to run and micromanage them, to protect their safety, because they cannot survive on their own.
By contrast, natural or organic systems are antifragile: They need some dose of disorder in order to develop. Deprive your bones of stress and they become brittle. This denial of the antifragility of living or complex systems is the costliest mistake that we have made in modern times. Stifling natural fluctuations masks real problems, causing the explosions to be both delayed and more intense when they do take place. As with the flammable material accumulating on the forest floor in the absence of forest fires, problems hide in the absence of stressors, and the resulting cumulative harm can take on tragic proportions.
And yet our economic policy makers have often aimed for maximum stability, even for eradicating the business cycle. "No more boom and bust," as voiced by the U.K. Labor leader Gordon Brown, was the policy pursued by Alan Greenspan in order to "smooth" things out, thus micromanaging us into the current chaos. Mr. Greenspan kept trying to iron out economic fluctuations by injecting cheap money into the system, which eventually led to monstrous hidden leverage and real-estate bubbles. On this front there is now at least a glimmer of hope, in the U.K. rather than the U.S., alas: Mervyn King, governor of the Bank of England, has advocated the idea that central banks should intervene only when an economy is truly sick and should otherwise defer action.
Promoting antifragility doesn't mean that government institutions should avoid intervention altogether. In fact, a key problem with overzealous intervention is that, by depleting resources, it often results in a failure to intervene in more urgent situations, like natural disasters. So in complex systems, we should limit government (and other) interventions to important matters: The state should be there for emergency-room surgery, not nanny-style maintenance and overmedication of the patient—and it should get better at the former.
In social policy, when we provide a safety net, it should be designed to help people take more entrepreneurial risks, not to turn them into dependents. This doesn't mean that we should be callous to the underprivileged. In the long run, bailing out people is less harmful to the system than bailing out firms; we should have policies now that minimize the possibility of being forced to bail out firms in the future, with the moral hazard this entails.
Rule 2: Favor businesses that benefit from their own mistakes, not those whose mistakes percolate into the system.
Some businesses and political systems respond to stress better than others. The airline industry is set up in such a way as to make travel safer after every plane crash. A tragedy leads to the thorough examination and elimination of the cause of the problem. The same thing happens in the restaurant industry, where the quality of your next meal depends on the failure rate in the business—what kills some makes others stronger. Without the high failure rate in the restaurant business, you would be eating Soviet-style cafeteria food for your next meal out.
These industries are antifragile: The collective enterprise benefits from the fragility of the individual components, so nothing fails in vain. These businesses have properties similar to evolution in the natural world, with a well-functioning mechanism to benefit from evolutionary pressures, one error at a time.
By contrast, every bank failure weakens the financial system, which in its current form is irremediably fragile: Errors end up becoming large and threatening. A reformed financial system would eliminate this domino effect, allowing no systemic risk from individual failures. A good starting point would be reducing the amount of debt and leverage in the economy and turning to equity financing. A firm with highly leveraged debt has no room for error; it has to be extremely good at predicting future revenues (and black swans). And when one leveraged firm fails to meet its obligations, other borrowers who need to renew their loans suffer as the chastened lenders lose their appetite to extend credit. So debt tends to make failures spread through the system.
A firm with equity financing can survive drops in income, however. Consider the abrupt deflation of the technology bubble during 2000. Because technology firms were relying on equity rather than debt, their failures didn't ripple out into the wider economy. Indeed, their failures helped to strengthen the technology sector.
Rule 3: Small is beautiful, but it is also efficient.
Experts in business and government are always talking about economies of scale. They say that increasing the size of projects and institutions brings costs savings. But the "efficient," when too large, isn't so efficient. Size produces visible benefits but also hidden risks; it increases exposure to the probability of large losses. Projects of $100 million seem rational, but they tend to have much higher percentage overruns than projects of, say, $10 million. Great size in itself, when it exceeds a certain threshold, produces fragility and can eradicate all the gains from economies of scale. To see how large things can be fragile, consider the difference between an elephant and a mouse: The former breaks a leg at the slightest fall, while the latter is unharmed by a drop several multiples of its height. This explains why we have so many more mice than elephants.
So we need to distribute decisions and projects across as many units as possible, which reinforces the system by spreading errors across a wider range of sources. In fact, I have argued that government decentralization would help to lower public deficits. A large part of these deficits comes from underestimating the costs of projects, and such underestimates are more severe in large, top-down governments. Compare the success of the bottom-up mechanism of canton-based decision making in Switzerland to the failures of authoritarian regimes in Soviet Russia and Baathist Iraq and Syria.
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