Fire and ice

Some say the world will end in fire,
Some say in ice.
From what I've tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.

Robert Frost, Fire and Ice (1920)

Jurisdynamics' series on complexity theory, which has pondered everything from disasters to global inequality to the very nature of law itself, has highlighted one of the fundamental divides among complex adaptive systems. As I discussed in Webs of Life, 89 Iowa L. Rev. 495, 550-51 (2004), not all systems exhibit the same resilience to exogenous shock. Neither natural, economic, nor legal systems can maximize productivity and stability at the same time. HOT systems exhibiting "highly optimized tolerance" maximize yield without incorporating safeguards against remote risks. The competing COLD strategy of "constrained optimization with limited deviations" sacrifices yield in order to hedge against a wider range of contingencies.

HOT strategies abound in ecology. Virulence in fungi, for instance, varies in direct proportion to the resistance of potential plant hosts. The resulting tradeoff between virulence and reproductive fitness reflects the ongoing arms race between a parasite's genes for virulence and a host's genes conferring resistance. The biosphere as a whole, perhaps the HOTtest system known, endures most crises (even if individual taxa fare poorly) but flirts with annihilation every time the planet collides with a large object such as the meteor that left the Chicxulub crater associated with the end of the Cretaceous.

By contrast, humans and their institutions tend to favor COLD systems. Law and economic policy, to name two of the most ambitious social systems, routine reflect a social judgment that "rank[s] other values higher than efficiency." INS v. Chadha, 462 U.S. 919, 959 (1983). This systematic tendency toward COLD risk-aversion, of course, is itself a product of HOT evolution over the course of humanity's natural history. For adaptation within complex human society, so it seems, ice seems as great as fire, and does suffice.