This article attempts to establish an epistemological diagnosis of the contemporary phenomenon of the development of conspiracy theories. It begins with a critique of two approaches to understanding this phenomenon. The “hyper-critical” approach consists in arguing that the development of conspiracy theories demonstrates a lack of "critical thinking", and therefore recommends as a solution that we teach students not to believe in anything without having verified its truthfulness themselves. Jean-Baptiste Guillon replies that this “epistemic individualist” strategy is ineffective, even counterproductive, because a study of conspiracy discourse reveals that belief in conspiracy theories is emboldened by individualist rhetoric. The second approach rejected by the author consists in denying the existence of any problematic phenomenon related to “conspiracy theories”. This approach is primarily based on the difficulty of precisely defining what constitutes a “conspiracy mindset”. The author responds by defining this mindset as an exacerbation of epistemic individualism, i.e., the inability to distinguish between reliable and unreliable sources.