Law's Coevolution

32 Pages Posted: 5 Apr 2019 Last revised: 6 Aug 2019

Date Written: April 2, 2019


One of most pervasive maxims of American jurisprudence is that law evolves. Applied metaphorically, it expresses the broad idea that law gradually adapts to its environment, unfolding in a linear and progressive manner through either human reason or social influence. Yet this belief has never been universal. Over a century ago, legendary jurist Oliver Wendell Holmes Jr. first argued that law does not evolve unilaterally and philosophically; it coevolves with everything in nature. Though Holmes’s obscure rebuttal was largely overlooked, it is particularly relevant today. In fact, his theory of legal coevolution is now confirmed by science. At the individual level, human beings possess a natural “legal” instinct that shapes their values, beliefs, and even their rationality. As people cooperate, this instinct foments prosocial impulses, social norm circles, and peer punishments. Because these proto-legal mechanisms are informal and localized, law emerges to coordinate, reconcile, and regulate them. Once entrenched, such interlocking “jurisystems” don’t remain stagnant but trigger a number of downward effects. Most immediately, they resolve human conflicts, relieve social stress, and reinforce social bonds. But they also shape our cultural memory, which eventually becomes embedded in our DNA. In this way, law is a bio-social component of a perpetual information exchange that constantly renews our sense of legality.

Keywords: General Jurisprudence, Legal Positivism, Legal Realism, Oliver Wendell Holmes, Complexity, Systems Science, Network Theory, Coevolution, Emergence, Coordination Dynamics, Epigenetics

JEL Classification: K40

Suggested Citation

Calnan, Alan, Law's Coevolution (April 2, 2019). Southwestern Law School Research Paper No. 2019/05. Available at SSRN: or

Alan Calnan (Contact Author)

Southwestern Law School ( email )

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