Cosmopolitanism – the view that moral concern, and consequently moral duties, are not limited by borders – seems to justify colonialism with a ‘civilizing’ mission, because it supports the enforcement of moral norms universally, with no distinctions between territories, and settler colonialism, because it promotes ideas like common ownership of the Earth and open borders. I argue that existing attempts to defend cosmopolitanism from this worry fail, and that instead the cosmopolitan should embrace a cosmopolitan instrumentalist defence. According to cosmopolitan (...) instrumentalism, colonialism is wrong (when it is wrong) for instrumental reasons: it has all sorts of terrible effects. There is nothing per se wrong with colonialism itself, so cosmopolitanism need not worry about licencing it in principle. There is much that is wrong with colonialism in practice, so cosmopolitanism can easily condemn colonialism as egregiously wrong, although it cannot condemn it as per se or necessarily wrong. (shrink)