1. AN UNCONTROVERSIAL EXPLANATORY PRINCIPLE IN INDIVIDUAL RATIONAL CHOICE THEORY: An individually rational agent A would not intentionally choose an act a, if there were an alternative act a' available to A that had better expected consequences (as evaluated by A). Therefore, the following is a VALID EXPLANATION of an agent A's choosing act a over act a': The expected consequences (as evaluated by A) of choosing act a were better than the expected consequences of act a', and A is individually rational.

2. THE ANALOGOUS SOCIAL CHOICE EXPLANATION IS FALLACIOUS! By analogy with the case of individually rational choice, it is natural, BUT FALLACIOUS, to suppose: A group G of individually rational agents A1, . . . , An would not intentionally choose acts a1 (chosen by A1), . . , an (chosen by An), if there were an alternative set of acts a'1, . . . , a'n, that would make everyone in the group better off (in their own estimation). This fallacious analogy, leads to the following INVALID EXPLANATION of A1, . . . , An's choice of a1, . . . , an over a'1, . . . , a'n: The expected consequences (as evaluated by A1, . . . , An) of choosing acts a1, . . . , an were better for every member of the group than the expected consequences (as evaluated by A1, . . . , An) of choosing acts a'1, . . . , a'n, and all members of the group are individually rational. Collective action problems illustrate this fallacy.