ABSTRACT
Almost a century and a half ago, Charles Darwin (1871: 166) argued that natural selection would support the evolution of social behavior, since there would be selection between competing groups as well as selection between competing individuals within groups. In competition between groups, groups in which individuals cared something about what was good for the group, not only about what was good for themselves, would be favored. For biologists, claims of this sort went very much out of fashion after Williams’s (1966) classic critique of group selection. This was not because there is something wrong with Darwin’s claim that between-group selection would favor some measure of social motivation. The argument that between-group as well as within-group selection must occur has never been in dispute. No competent biologist doubts it, nor that such selection would favor grouporiented rather than self-interested behavior where the two conflict. The counterargument is rather that the intermittent between-group advantage to social motivation would be swamped by the routine within-group advantage to self-interest. In the language of economics, the argument leaves open the possibility that the result will be a corner solution, or something very close to it.
