Why philosophize by telling stories? This paper focuses on some uses of narrative fiction in Jean-Jacques Rousseau’s works, and more specifically on its function in his political philosophy. By studying how fictions are inserted in argumentative writings, we attempt to show the benefits of using it: it makes the argument more tangible and affects the reader’s imagination to better convince him. In the case of political knowledge, fiction serves as a mediation between principles and experience. By showing political types and by promoting values, it provides a grid for interpreting reality. However, its effect is based on the commitment of readers, who, through the reading experience, constitute a sensitive community. Without this requirement, fiction fails to provide access to knowledge: that is its fragility.