  In essence, the theories that Olson’s argument demolished were all grounded in a fallacy of composition. We commit this fallacy whenever we suppose the characteristics of a group or set are the characteristics of the members of the group or set or vice versa. In the theories that fail Olson’s test the fact that it would be in the collective interest of some group to have a particular result, even counting the costs of providing the result, is turned into the assumption that it would be in the interest of each individual in the group to bear the individual costs of contributing to the group’s collective provision. If the group has an interest in contributing to provision of its good, then individual members are (sometimes wrongly) assumed to have an interest in contributing. Sometimes, this assumption is merely shorthand for the recognition that all the members of a group are of the same mind on some issue. For example, a group of anti-war marchers are of one mind with respect to the issue that gets them marching. There might be many who are along for the entertainment, to join a friend or spouse, or even to spy on the marchers, but the modal motivation of the individuals in the group might well be the motivation summarily attributed to the group. But very often the move from individual to group intentions or vice versa is wrong.