We are deeply imbued with the idea that modernity lies in the channelling of passions through reason, either by taking into account universal norms or by the composition of well-understood interests. Their resurgence in contemporary conflicts, with its procession of extreme violence, shows that it is not so. As globalisation is calling into question the coherence of the national state, as weapons, especially atomic weapons, are changing the nature of war, inter-state conflicts are giving way to civil wars, terrorism and the rise of social violence. Is this unleashing of passions at the root of the current upheavals, or is it the cause of them? To grasp the dynamics of our complex and changing world, we need to understand both the analysis of war and peace and our categories of political philosophy. In this way, we will understand the role played by passions, their circulation, their interaction, their balance and imbalance, not only in the outbreak of conflicts but also in their possible overcoming. It is the whole problem of politics to think about the possible coexistence between citizens, allies and adversaries within a common global order.