historians, political theorists, anthropologists and the public
have tended to think about the political process in seasonal, cyclical
terms. From Polybius to Paul Kennedy, from ancient Rome to imperial
Britain, we discern a rhythm to history. Great powers, like great
men, are born, rise, reign and then gradually wane. No matter whether
civilizations decline culturally, economically or ecologically,
their downfalls are protracted.
In the same
way, the challenges that face the United States are often represented
as slow-burning. It is the steady march of demographics – which
is driving up the ratio of retirees to workers – not bad policy
that condemns the public finances of the United States to sink deeper
into the red. It is the inexorable growth of China’s economy, not
American stagnation, that will make the gross domestic product of
the People’s Republic larger than that of the United States by 2027.
As for climate
change, the day of reckoning could be as much as a century away.
These threats seem very remote compared with the time frame for
the deployment of U.S. soldiers to Afghanistan, in which the unit
of account is months, not years, much less decades.
But what if
history is not cyclical and slow-moving but arrhythmic – at times
almost stationary but also capable of accelerating suddenly, like
a sports car? What if collapse does not arrive over a number of
centuries but comes suddenly, like a thief in the night?
are complex systems, made up of a very large number of interacting
components that are asymmetrically organized, which means their
construction more resembles a termite hill than an Egyptian pyramid.
They operate somewhere between order and disorder. Such systems
can appear to operate quite stably for some time; they seem to be
in equilibrium but are, in fact, constantly adapting. But there
comes a moment when complex systems "go critical." A very
small trigger can set off a "phase transition" from a
benign equilibrium to a crisis – a single grain of sand causes
a whole pile to collapse.
Not long after
such crises happen, historians arrive on the scene. They are the
scholars who specialize in the study of "fat tail" events
– the low-frequency, high-impact historical moments, the ones
that are by definition outside the norm and that therefore inhabit
the "tails" of probability distributions – such as
wars, revolutions, financial crashes and imperial collapses. But
historians often misunderstand complexity in decoding these events.
They are trained to explain calamity in terms of long-term causes,
often dating back decades. This is what Nassim Taleb rightly condemned
in "The Black Swan" as "the narrative fallacy."
most of the fat-tail phenomena that historians study are not the
climaxes of prolonged and deterministic story lines; instead, they
represent perturbations, and sometimes the complete breakdowns,
of complex systems.
complexity, it is helpful to examine how natural scientists use
the concept. Think of the spontaneous organization of termites,
which allows them to construct complex hills and nests, or the fractal
geometry of water molecules as they form intricate snowflakes. Human
intelligence itself is a complex system, a product of the interaction
of billions of neurons in the central nervous system.