As Olson explained, the interests that unite large groups are necessarily of the lowest-common-denominator variety. Therefore the concrete benefits of collective action to any individual are usually small compared with the costs — in time, effort and money — of participation. “Free-riding” is a constant threat — as the difficulties of collecting union dues illustrates. By contrast, small groups are good at collective action. It costs less to organize a few people around a narrow, but intensely felt, shared concern. For each member, the potential benefits of joint action are more likely to outweigh the costs, whether or not success comes at the larger society’s expense.