Evolutionary Stable Strategies

The problem which is considered in this chapter is that of how the equilibria that have been calculated for games of security and struggles over property might emerge in a system of interaction where individuals follow some local optimization strategy, such as trial and error. This is important for two reasons. The first is that the models set out in the previous chapters depend on the assumption that agents can optimize globally and calculate their optimum strategies. Although these models are complete as descriptions of the equilibria that would be attained by optimizing agents, they do not address all the issues that are of concern in discussions of order and security. Where the games are straightforward, and the pay-offs sufficiently high, it might be expected that players would calculate the equilibria directly. Where things are more complicated it would take the players considerable effort and technical skill to calculate the optimum strategies. The second is that the assumption of global optimization may not be a completely adequate model of decision makers in the context of much of the discussion of spontaneous order. The implicit model that underlies much of this discussion seems to be of some sort of unplanned outcome. In this case it is of interest to investigate the consequences of treating individuals as following a local optimization rule. It might be the case, for example, that individuals use a trial and error approach.