For norms also, the statement must be qualified. Norms are intentionally established, indeed as means of reducing externalities, and their benefits are ordinarily captured by those who are responsible for establishing them. But the capability of establishing and maintaining effective norms depends on properties of the social structure (such as closure) over which one actor does not have control yet are affected by one actor's action.

DEFINE: Clarifies the scope of 'norm' — intentional establishment aimed at reducing externalities — and the social-structural conditions (like closure) that determine whether such norms actually work.

Coleman, SocialCapitalCreation-1988, loc. 221