Modern social orders are legitimized by the ideal of freedom. Most conceptions of this ideal are theorized against the backdrop of nature understood as governed by its own laws beyond the realm of the social. However, such an understanding of nature is now being challenged by the ‘Anthropocene’ hypothesis. This article investigates the consequences of this hypothesis for freedom as an ideal legitimizing social order. We begin by discussing the conception of legitimation, after which we examine three classical notions of freedom (developed by Hobbes, Kant, and Hegel), in light of the Anthropocene. Following our claim that these notions all have severe weaknesses in view of the Anthropocene, we argue that modern social orders are facing a new legitimation crisis. Such a crisis, we suggest, involves a ‘brutalization of social conflicts’, which under the conditions of the Anthropocene assumes the form of geo-social conflict.