In this chapter, while acknowledging an important and famous early influence of Renouvier on James’s notions of belief and free will, the author documents a major and growing disagreement in their exchanges. The author argues that this disagreement is by no means a peripheral matter, since it involves James’s assessment of Renouvier’s neo-Kantianism. After having presented the core of Renouvier’s main influence in the section “Free Will’s Champion, Kantian Style,” the author gives a brief survey of James’s presence in the Critique Philosophique in the section “James’s Contributions,” and deals, in the following sections, with James’s early criticisms of Renouvier on philosophical method (the section “Methods and Categories”), on the perception of space and time (the section ”Unbounded Spaces”) and on consciousness (the section ”The Stream of Thought”). In order to accomplish this, the author focuses on a more limited period than James’ career as a whole : the author follows him from the early writings to the mid-1880s—that is, precisely to the point where James and Renouvier’s philosophical itineraries begin to diverge. The author’s larger goal is to illustrate how the Critique Philosophique was at first a hospitable publication for the young James, but also how, from the end of this period on, important disputes emerged, in particular over consciousness, which gave rise to a paradoxical situation : the very organ that contributed to make James known turned out to be at odds with several of his most important theses, before the publication of the Principles, and even more before Pragmatism.