This lecture presents the main topics of debate on linguistic justice in academic literature. What are the principles of territoriality and personality? What language policies should be introduced following those principles? How does linguistic justice relate to social justice? What are the the most powerful arguments for effectively defending the linguistic rights of ethnic minorities? Do majorities also have rights and duties? What is a fair language policy for migrants? Is English as a world language an advantage or disadvantage for linguistic diversity? Can languages have rights?

To address these questions a dialogue is needed between various disciplines, including political philosophy and sociolinguistics, but also some subdisciplines of economics and law. And, of course, also interlinguistics and esperantology. The lecture could easily become a whole course. With that in mind, the authors and theories are explained in more detail. Using geographically (and historically) diverse examples possible relationships between linguistic justice and language conflicts are discussed. In view of recent developments, such as the success of the Esperanto course in Duolingo, it is discussed to what extent these may influence analyses of linguistic justice and the future role of Esperanto in the global language system. It is hoped that after (active) listening and participation the audience will be able to explain to anyone what linguistic justice is about. This may become one of the Esperanto movement's strongest and most effective arguments in the future.