Brenton Tarrant, the white supremacist terrorist who killed at least 50 Muslims in New Zealand, titled his manifesto, released shortly before the attack, The Great Replacement. The title recalls the work of French far-right author Renaud Camus, whose ideas have been eagerly taken up by Alain Finkielkraut, and in the manifesto, France looms large as the sight of Tarrant's turn to white supremacy. In this article, Frédéric Debomy castigates the influence of Alain Finkielkraut in France and the power of ideas on political action.