Competing norms and social evolution: Is the fittest norm efficient?

An influential theme in recent legal scholarship is that law is not as impo rtant as it appears. Social control, many scholars have noted, is often ach ieved through social norms-informal, decentralized systems of consensus and cooperation-rather than through law. This literature also displays a guard ed optimism that social evolutionary processes will tend to favor the adopt ion of efficient norms. Using concepts from evolutionary game theory, we de monstrate that efficient norms will prevail only in certain settings and no t in others: survival of the fittest does not imply survival of the efficie nt. In particular, we show that in many games of interest to legal scholars -games describing fundamental interactions in property, tort, and contract- evolutionary forces lead away from efficiency. We also describe how law rig hts this trend.