How can we explain that the publication of The Sorrows of Young Werther triggered a wave of suicides among European readers, or that the release of The Birth of a Nation resurrected a dying Ku Klux Klan? If fiction sometimes influences reality, is it not because reality itself is, at least in part, fictional in nature? The central issue of this project is the performativity of illusory representations. On the one hand, it implies questioning the propensity of human beings to delude themselves and to tell (themselves) stories, that is to say, to make up fictions at the same time as they perceive and describe what they call "reality". On the other hand, the omnipresence of these illusory representations implies that we also study their real effects on human thought and behaviour, based on the mere fact that they are believed and disseminated. In this way, I intend to develop a new philosophical anthropology, that of the homo fabulator. I will focus specifically on the seeds of this philosophical anthropology of homo fabulator, during the second nineteenth century, which saw the emergence of a new representation of the world, of man and of his place in it, confirming the decline of metaphysics and the rise of the human sciences. These disciplines, which intersect and whose representatives dialogue and debate, quote and translate each others, thus contribute to highlighting the place of fabulation in the functioning of the psyche and of human societies. At the Institut des textes et manuscrits modernes (ITEM), I will use genetic criticism, which is implemented in an interdisciplinary manner, to study the phenomena of the circulation of ideas and the translation of texts (central to the University Research School Translitterae, of which ITEM is a part) that preside over the development of a rich intellectual and philosophical debate in late 19th century Europe. The digital humanities will complete this approach and will allow me to master and unify a vast corpus in order to show the profound coherence of this pivotal moment in the history of ideas. The originality of my approach lies in a triple reversal. 1) Historical, through the attention I give to the second nineteenth century. This attention is opposed to both the overly exacerbated focus on hyper actuality, which blinds us to the processes that made it possible, and to the overwhelming weight of German idealism of the early 19th century in the history of philosophy, which obscures the decisive importance of the following decades. 2) Disciplinary, through the interdisciplinary approach I propose to adopt in studying the many academic fields claiming the status of human sciences. The pronounced empirical orientation of these disciplines contributes to forging a completely new image of human nature and its faculties of knowledge, which accompanies and ratifies the decline of the illusory representations previously conveyed by religion and metaphysics. 3) Philosophical, insofar as the upheaval which, in the wake of the Kantian revolution, crystallised in the second half of the 19th century, saw the radical questioning of what had been the object of the whole history of philosophy: the quest for truth, in favour of an investigation into the conditions of possibility of illusion, henceforth conceived as primary. The unifying philosophical theory that I propose, based on an interdisciplinary approach, will thus endeavour to offer the archaeology of an epistemological regime that is dominant today by situating it in the intellectual context of its emergence. The proper understanding of our modernity in crisis and of the relationship that human beings have with the world around them is at stake.