Philosophical arguments regarding academic freedom can sometimes appear removed from the real conflicts playing out in contemporary universities. This paper focusses on a set of issues at the front line of these conflicts, namely, questions regarding sex, gender and gender identity. We document the ways in which the work of academics has been affected by political activism around these questions and, drawing on our respective disciplinary expertise as a sociologist and a philosopher, elucidate the costs of curtailing discussion on fundamental demographic and conceptual categories. We discuss some philosophical work that addresses the conceptual distinction between academic freedom and free speech and explore how these notions are intertwined in significant ways in universities. Our discussion elucidates and emphasises the educational costs of curtailing academic freedom.