The diplomatic success of international solidarity nongovernmental organizations (IS-NGOs) can to some extent be explained by their use of a form of persuasive communication or lobbying. The effectiveness of these organizations should not conceal their real lack of power, i.e., their inability to change either the behavior of citizens or the mindset that serves as the basis of the actions of international institutions. As we shall attempt to show, these phenomena are connected: the condition of the effectiveness of IS-NGO diplomatic communication is, in fact, that it takes part in a vision of communication that focuses on persuasion and mutual intelligibility. Yet this approach itself serves to reinforce stereotypes and perpetuates an international approach borrowed from colonialism. In this sense, IS-NGO diplomatic communication cannot be seen as helping to build the world of solidarity they themselves advocate. This is why a paradigm shift is needed: the epistemological model of (persuasive and mutually intelligible) communication needs to be abandoned in favor of a model based on incommunication.