Spiritualism designates a philosophy that lays claim to the separation of mind and body and the ontological and epistemological primacy of the former. In France, it is associated with the names of Victor Cousin and René Descartes, or more precisely with what Cousin made of Descartes as the founding father of a brittle rational psychology, closed off from the positive sciences, and as a critic in respect to the empiricist legacy of the idéologues. Moreover, by considering merely the end result, severed from its polemical genesis, we are prevented from understanding how the category of experience constituted a crucial question for spiritualism itself. Through returning to the origin of these discussions in the 1826 preface to Cousin’s Fragments philosophiques, this essay pursues a threefold path: to show (1) that the public birth of Cousinian spiritualism coincides with the affirmation of applying the experimental method, issuing from Bacon, to the study of facts of consciousness; (2) that Cousin’s later evolution follows a process of radicalization—that is, in this context, of ontologization and of reduction; and (3) that by recovering this genesis, we can distinguish many forms of spiritualisms committed to the experimental method, both in alliance with the early Cousin and against the later Cousin. In this way, we can rediscover the interwoven philosophical links, lost in the process of institutionalization, between metaphysical demands and empiricist concerns, or between “French” philosophy and the legacy of Condillac.