Last week historian Bryan Ward-Perkins authored an interesting Financial Times op-ed in which he compared the present recession to the post-Roman Empire economy in the British Isles. Conditions then, needless to say, were "extremely bleak." Part of the reason for this, wrote Ward-Perkins, was that there was such a long way to fall from the advanced Roman economy. Going further, however, he explicitly links the collapse to the level of advancement--no matter what type of wings Icarus wears, he will always fail simply because he flew so high and close to the sun.
"Almost certainly the suddenness and the catastrophic scale of the crash were caused by the levels of sophistication and specialisation reached by the economy in Roman times. The Romano-British population had . . . relied on widespread markets to sustain their specialised production. When insecurity came in the fifth century, this impressive house of cards collapsed."
Well, there you go: an economy can only push Adam Smith so far. Apparent market sophistication--trade, division of labor--will eventually (and, seemingly, inexorably) become a weak structure, vulnerable to the slightest perturbation, upon which it will collapse:
"The more complex an economy is, the more fragile it is, and the more cataclysmic its disintegration can be."
That second clause seems pretty valid: the higher you fly the further you fall. But I think it's actually quite arguable, and the reason is because the first clause, Ward-Perkins' main point that complexity increases fragility, is wrong. It makes intuitive sense, of course, and the house of cards analogy misleadingly reinforces that intuition. The more cards you add, after all, the more fragile that house becomes; everyone knows that.
But a complex economy is not like a house of cards. Much of the complexity research over the last thirty years or so--however you may judge its worth en toto--has demonstrated the robustness of complex networks. And, as readers of Joseph Tainter know (I assume Ward-Perkins has read Tainter), there is little reason to think that a complex society like Imperial Rome, having weathered many different stresses over several centuries, should all of sudden turn to a house of cards because of the very complexity that made it strong in the first place.
To argue that complexity is equivalent to fragility requires you to increasingly argue backwards for why complexity turns from strength to weakness. The ultimate cause for the collapse of complex societies, as Tainter showed, is not their complexity. It may end up being a proximate cause or contributing factor, but not the ultimate reason. The reason, in Tainter's telling, is the marginal returns curve: at some point, a society's investment in complexity may yield diminishing marginal returns. When and if collapse does occur, moreover, it is not necessarily a bad thing; to be sure, it may bring all sorts of negative consequences. But, if the marginal returns hypothesis is correct, then the disintegration of a once-complex society into several simpler constituent parts should reset that curve and yield, once again, increasing marginal returns. People may be better off and, in many cases, actively choose to dissociate from complexity.
It's easy, of course, to argue too far in this vein and rely wholly on the supposed robustness of complex systems as a reason why they should perpetuate themselves. The reason complex systems persist and survive shocks is not their innate robustness; it is that they contain deep wells of potential adaptations (exaptations). It's also tempting to ascribe too much worth to complexity in and of itself. In social science and many of the natural sciences we continue to equate "complex" with "better," "simple" with "worse." The notion of progress up a ladder of complexity is seductive, and underlies the arguments of both avid proponents of complexity and those, like Ward-Perkins, who see the danger in too much sophistication.