Though historically important, the notion of tacit consent plays little role in contemporary discussions of political legitimacy. The idea, in fact, is often dismissed as obviously implausible. The ambition of this paper is to challenge this assumption and show that tacit consent can become a key ingredient in a theory of legitimacy. Instead of defining tacit consent through residence (where, according to John Locke or Plato's Socrates, staying in the country amounts to tacitly consenting to its system of rule), the (...) paper explores a different strategy, delimiting tacit consent as an absence of active dissent. The basic idea starts from the fact that widespread anti-government protests and demonstrations always carry a potent delegitimating force. Political legitimacy is therefore never permanent and unchangeable, regardless of the nature of the regime, and can be undermined at all times by active dissent from the population. Having established the relationship between dissent and delegitimation of political power, even the inverted, stronger claim is defended: the absence of active dissent (i.e., tacit consent) can, under certain circumstances, serve to legitimize political power. The paper sets up and defends several conditions that need to be met for the right normative mandate to be created by the population tacitly accepting the existing power arrangements. If those are fulfilled (especially when full freedom of expression and information is granted), tacit consent can become a vital element of political legitimacy. (shrink)