Cosmopolitans share the moral assumption that we have obligations and responsibilities to other people, near or distant. Today, those obligations and responsibilities are often connected with communication, but what is considered important for cosmopolitan communication differs between different thinkers. Given the centrality of communication in recent cosmopolitan theory and debate the purpose of this article is to examine assumptions about communication that are often taken for granted, and particularly the commonly held assumption that linguistic communication depends on shared or common languages. It is primarily Donald Davidson's philosophy of language that provides the framework for my examination. I argue that there are several reasons for reconstructing our understanding of the nature of language and communication, and that shared languages play a much more limited role in communication than many communication theorists, cosmopolitans and educators have imagined.