With this monograph on Kant and the problem of language, Raphaël Ehrsam develops a well-argued reconstruction of the architectonic place of language in Kant’s philosophy. The author terms his argument “genetic thesis”. On Ehrsam’s genetic thesis, in Kant’s philosophy the mastery of linguistic competences is indispensable to the acquisition of a priori theoretical and practical cognitions. The material of the book can be divided into three parts. In the first part (Introduction and Chapter One), Ehrsam frames the subject by outlining his thesis and foregrounding Kant’s notions of acquisition and epigenesis. In the second part (Chapters Two - Five), he then articulates his thesis by reconstructing the functions played by specific linguistic instances in Kant’s theoretical and practical philosophy. The third part (Chapter Six) is devoted to sketching Kant’s thoughts on how the human being, both as an individual and a species, acquires linguistic competences.