Working from within a rational-choice perspective he seeks to justify the inclusion of noninstrumental norms, in addition to rational choice, as a crucial mechanism required to explain social order. He delineates his argument by discussing a number of social activities that he feels are explicable by these mechanisms, including social institutions, bargaining, and collective action. Nuts and Bolts for the Social Sciences is intended as an introduction to and an illustration of the applicability of rational choice and noninstrumental norms as mechanisms of explanation. As such it requires evaluation along two dimensions. According to Elster, social norms are not explicable in terms of individual, rational adaptation to social situations, or individual maximization under constraints.
Norms are irreducible to rational choice.
While I agree with this contention, in my opinion Elster fails to understand, or at least to specify, when norms must be introduced into a rational-choice theory, and, more important, he fails to understand the consequences of their introduction for such a theory. In orthodox Arrow-Debreu general equilibrium models there is no need to postulate norms as a mechanism constituting social order. For example, workers receive the value of their marginal product as a wage, and this value is known to both employee and employer. Economically homogeneous workers receive equivalent wages, the value of equivalent marginal products. In equilibrium, a Pareto optimum is manifest.