Stability-Induced Fragility

Stability-Induced Fragility

Compare a bank employee whose income is steady until a job loss with a taxi driver whose income varies daily. Their risks differ even if the employee’s income looks more stable. Taleb makes a similar comparison between centralized government and a messy municipally led confederation: the second may be stable in the long run because of some dose of volatility.

A scientific argument showing how tight controls backfire and cause blowups was made by James Clerk Maxwell of electromagnetic theory fame. “Governors” are contraptions meant to control the speed of steam engines by compensating for abrupt variations. They aimed at stabilizing the engines, and they apparently did, but they paradoxically sometimes brought about capricious behavior and crashes. Light control works; close control leads to overreaction, sometimes causing the machinery to break into pieces. In a famous paper “On Governors,” published in 1867, Maxwell modeled the behavior and showed mathematically that tightly controlling the speed of engines leads to instability.

It is remarkable how Maxwell’s neat mathematical derivations and the dangers of tight control can be generalized across domains and help debunk pseudo-stabilization and hidden long-term fragility.1 In the markets, fixing prices, or, equivalently, eliminating speculators, the so-called “noise traders”—and the moderate volatility that they bring—provide an illusion of stability, with periods of calm punctuated with large jumps. Because players are unused to volatility, the slightest price variation will then be attributed to insider information, or to changes in the state of the system, and will cause panics. When a currency never varies, a slight, very slight move makes people believe that the world is ending. Injecting some confusion stabilizes the system.

Indeed, confusing people a little bit is beneficial—it is good for you and good for them. For an application of the point in daily life, imagine someone extremely punctual and predictable who comes home at exactly six o’clock every day for fifteen years. You can use his arrival to set your watch. The fellow will cause his family anxiety if he is barely a few minutes late. Someone with a slightly more volatile—hence unpredictable—schedule, with, say, a half-hour variation, won’t do so.

Variations also act as purges. Small forest fires periodically cleanse the system of the most flammable material, so this does not have the opportunity to accumulate. Systematically preventing forest fires from taking place “to be safe” makes the big one much worse. For similar reasons, stability is not good for the economy: firms become very weak during long periods of steady prosperity devoid of setbacks, and hidden vulnerabilities accumulate silently under the surface—so delaying crises is not a very good idea. Likewise, absence of fluctuations in the market causes hidden risks to accumulate with impunity. The longer one goes without a market trauma, the worse the damage when commotion occurs.

This adverse effect of stability is straightforward to model scientifically, but when I became a trader, I was told of a heuristic used by veterans, and only old seasoned veterans: when a market reaches a “new low,” that is, drops to a level not seen in a long time, there is “a lot of blood” to come, with people rushing to the exit. Some people unused to losing shekels will be experiencing a large loss and will incur distress. If such a low market level has not been seen in years, say two years, it will be called “a two-year low” and will cause more damage than a one-year low. Tellingly, they call it a “cleanup,” getting the “weak hands” out of the way. A “weak hand” is clearly someone who is fragile but doesn’t know it and is lulled by a false sense of security. When many such weak hands rush to the door, they collectively cause crashes. In Taleb’s account, a volatile market provides a more frequent “cleanup” of risks. That mechanism does not guarantee that a market will avoid a collapse.

Fluctuat nec mergitur (fluctuates, or floats, but does not sink) goes the Latin saying.