Published online by Cambridge University Press: 27 December 2018
Interdisciplinary work in the law often starts and stops with the social sciences. To produce a complete understanding of how law, evolutionary game-theoretic insights must, however, supplement these more standard social scientific methods. To illustrate, this article critically examines The Force of Law by Frederick Schauer and The Expressive Powers of Law by Richard McAdams. Combining the methods of analytic jurisprudence and social psychology, Schauer clarifies the need for a philosophically respectable and empirically well-grounded account of the ubiquity of legal sanctions. Drawing primarily on economic and social psychological paradigms, McAdams highlights law's potential to alter human behavior through expressions that coordinate. Still, these contributions generate further puzzles about how law works, which can be addressed using evolutionary game-theoretic resources. Drawing on these resources, this article argues that legal sanctions are ubiquitous to law not only because they can motivate legal compliance, as Schauer suggests, but also because they provide the general evolutionary stability conditions for intrinsic legal motivation. In reaction to McAdams, this article argues that law's expressive powers can function to coordinate human behavior only because humans are naturally and culturally evolved to share a prior background agreement in forms of life. Evolutionary game-theoretic resources can thus be used to develop a unified framework from within which to understand some of the complex interrelationships between legal sanctions, intrinsic legal motivation, and law's coordinating power. Going forward, interdisciplinary studies of how law works should include greater syntheses of contemporary insights from evolutionary game theory.