Is realism in political theory compatible with utopianism? This article shows that it is, by reconstructing a highly restrictive realist approach to political theory for guiding legislation and public policy, drawn from the work of Adam Smith, and showing how it can accommodate Piketty’s utopian proposal for a global tax on capital. This shows not only that realism and utopianism are compatible; but how realist and utopian political theory can be carried out in concrete cases. This moves debates to more (...) interesting questions of which forms of utopianism are permissible within which forms of realism; contributes to moving the contemporary realism debates from a Methodenstreit to questions of how it can and ought to be done; and contributes to an important contemporary debate about the permissibility of utopian proposals for political and economic reform in general and Piketty’s proposed global tax on capital in particular. (shrink)