William A. Callahan is professor of International Relations at the London School of Economics and Political Science. His publications include Sensible Politics: Visualizing International Relations (Oxford University Press, 2020). He also makes documentary films: ‘China Dreams’ was broadcast on KCET (Los Angeles) in 2015, ‘toilet adventures’ (2015) was shortlisted for a major award by the Arts and Humanities Research Council, and ‘Great Walls’ (2019) asks why we hate Trump’s wall and love the Great Wall of China.