The exegesis of a famous work in social and political philosophy may be made interesting by explaining the problem that engaged its author. It may be made doubly interesting by applying the philosophy to a contemporary issue. That two-fold agenda, when successfully addressed, may also demonstrate the lasting value of the work and that the problem that it sought to investigate is in some sense perennial. This paper pursues such an agenda by supplying an exegesis of Karl Popper’s famous work (...) on social and political philosophy: The Open Society and Its Enemies. It uses a recently published collection of Popper’s previously unpublished or uncollected papers on social and political philosophy to elucidate the work’s themes, contents and problem situation. It also applies its central ideas to a contemporary issue: the referendum on so-called ‘Brexit’, held on 23rd June 2016, to decide whether the United Kingdom ought to remain a member of the European Union. The exegesis that is thereby supplied offers a third outcome of contemporary interest: an unqualified philosophical defence of ‘Brexit’. (shrink)