The history of knowledge is today often presented as an expansion of the history of science. This article argues that it has a greater ambition. The definition of the history of knowledge urges us to ask new questions about epistemic hierarchies and the role of ignorance in their historical development. These issues allow the field not only to become more freestanding but also to contribute to building the expertise required by the challenges of the twenty-first century. This article presents a programmatic outline of a future history of ignorance, reflecting on historiographical challenges and indicating novel avenues for research.