Chapter 8 is dedicated to analyze the conceptual foundations of Foucault’s archaeology of knowledge. This provides an insight into the preconceptual constitution of the “ground of depositivities” on which theories hold. Then, it discusses the criticism to it and Foucault’s answer to his critics. This led him to elaborate on the difference between “structures” and “discursive formations” and develop the different strategies needed for the reconstruction of the latter. As this chapter shows, Foucault’s perspective combines the two opposite currents, structuralism and phenomenology, to elaborate a particularly fruitful approach to intellectual history. Finally, it addresses the crucial point of how to account for epistemic mutations and what he calls its événementiel character.