During the attacks that have affected France and many other countries since 2015, social media have been spaces where one can obtain live information, organise solidarity actions and express one’s emotions. But they have also been arenas for the formation of counter-publics, producing and disseminating forms of discourse in opposition to the ‘dominant political and media discourse’. In this chapter, Romain Badouard shows how these alternative arenas preserve a certain radical pluralism of opinions and argues against the temptation to confuse them with other forms of reaction characterised by a desire to manipulate public opinion or to legitimise the use of physical violence.