This paper discusses Habermas’s argument that justice requires solidarity as its ‘reverse side’, whereby the former provides the necessary global framework for establishing intersubjective solidarity whilst the latter constitutes an important precondition for igniting social and political change in the direction of social justice. In this paper I argue that such a paradigm of reciprocity might be fruitfully complemented by a less apparent yet substantial nexus: that between solidarity and perceived injustice, which I contend also triggers the emergence of solidarity. (...) Drawing from Arendt’s thematisation of solidarity as a principle that stems from human suffering and recent scholarship on transitional post-conflict justice, I analyse the negative and reactive aspect of solidarity and the role of negative emotions in its emergence. (shrink)