Social capital is associated with considerable benefits for individuals and communities. Because some social capital is non-excludable, people may be disinclined to undertake activities that will create it. This is especially likely when the norm of self-interest is prominent. In addition, given the birds of a feather phenomenon, social capital appears to thrive in homogenous networks, and to languish in the face of diversity. I argue that social capital meets the criteria of a moral concept and that treating it as such can address these vulnerabilities. In particular, as a moral principle, social capital would be more demanding than mere self-interest and the moral requirement of universality would trigger a duty to act impartially with respect to networks. Since market interactions can create social capital, and social capital is a moral good, market interactions are in part constitutive of the good. I also argue that global social capital is important for both global well-being and sustainable globalization. Given the benefits of social capital, including it in the choice architecture as a moral principle will be worth the investment. Copyright Springer-Verlag 2012
