I am a historian of ideas. My work encompasses the sweep of Western history from the ancient world to the present day, and is attuned to developments on both sides of the Atlantic. But the fulcrum of my research and writing has been Western Europe in the long eighteenth century, the so-called age of Enlightenment. This is a period that I and other scholars see as a critical age of articulation between the ancient and the modern, the old and the new, and thus a fertile period for investigating concepts and debates that have played a crucial role in shaping the modern world.

In order to fully appreciate the novelty and continuity of such concepts and debates—whether these be human equality, the place of happiness in human expectations; the evaluation of creativity, intelligence, and genius; the origins of conservatism; or the religious response to modernity—it helps to take a long view. In part for this reason, I am a proponentwith my colleague David Armitage of a form of long-range intellectual history that we call a “history in ideas.” We use the term to distinguish it from an older history of ideas that was often idealist in its assumptions about historical causality and change; needlessly constricted in its belief that high culture alone was the privileged site for the investigation of governing concepts; and insensitive to the role played by indigenous contexts and social practices in shaping ideas and their reception.

While seeking to correct for these deficiencies, a new history in ideas aims to recover a sense of the perspective afforded by the intellectual longue-durée, attending to continuity and commonality, as well as to departure and difference. Self-consciously interdisciplinary and eclectic, this approach to the past operates on the assumption that ideas are promiscuous, and so seeks to follow them across a wide range of fields and domains. My own work draws on literature and religion, art history and the history of science, politics, philosophy, psychology, and economics among other disciplines, to follow ideas wherever they might lead. In keeping with the conviction that the humanities are the patrimony of humanity, and not the sole possession of any single profession or group, my work also strives to present its findings in a style that is broadly accessible, aiming to entertain as well as instruct. Finally, though I am a historian, and so write above all about men and women in the past, I do so always with an ear to what their thoughts, ideas, and experiences have to say to us in the present.

My current and future work is focused on the history of ideas about equality; on the global history of happiness, for which I am editing a forthcoming volume for Routledge with the historians of emotions Katie Barclay and Peter Stearns; and working on a short book on the history of lighting and illumination in the appropriately named Age of Enlightenment, for which I will spend the winter and spring of 2024 as a fellow at the Davis Center at Princeton.