In both Argentina and Brazil, the emergence of fiction was linked to a central contradiction. At the heart of fiction in nineteenth-century Argentina and Brazil there was a resistance to fiction. Fiction's defining trait was, precisely, its displaced use: in the impossibility of autonomous existence, its presence was highlighted by its forced absence; fiction became the negative condition of possibility of the written word both in the politically charged climate of national self-assertion following post-independence Argentina and in the early years of the Brazilian First Republic. As a result of this negative or residual formation, fiction --the non-authoritative discourse par excellence-- was both able and forced to engage with other --authoritative-- disocurses, such as those of philosophy, law, science, and political theory. At the same time, owing to its non-committal to pre-established categories of thought and theoretical frameworks, fiction was able to open up a discursive space from within which a crtical examination of both the authority and the legitimizing mechanisms of such discourses became possible. In this dissertation, I focus on the Brazilian and Argentine contexts to examine two key moments of the intersection of between fiction, aesthetics, and the theoretical triad of philosophy, law, and political theory, , tracing a critical genealogy in which the rise of autonomous fiction and discourses of authority are seen as mutually determinant. I begin, in Chapter 1, by analyzing the ambiguities surrounding two founding figures in the canon of each country: Domingo Faustino Sarmiento, in Argentina, and Euclides da Cunha, in Brazil. Not the least among these ambiguities is that, from the start, the discursive canon of which they occupy the center cannot be clearly defined. It is a canon that is both literary and socio-political, tellingly oscillating between the boundaries of the fictional and the non-fictional. Sarmiento and da Cunha, I contend, are located, each in their respective contexts, at a historical crossroad that offers a privileged glimpse into the mechanisms of formation of discursive authority. Writing at a time when received models and existent criteria proved insufficient and new ones were yet to be formed, they found themselves at a transitional moment in which the urgency of judgment was all the more pressing in light of the absence of criteria by which to judge. Examined from this perspective, new light is cast on the difficulty of generic classification which has marked the reception of Sarmiento's Facundo and da Cunha's Os Sertões to this day. I bring critical theory into dialogue with aesthetic theory and law studies to suggest that the aesthetic dimension in their works lies in the fact that in both texts we see a discourse at work in which the productive moment is emphasized over its doctrinary, legislative moment. In them, form, not yet crystallized into the formulas and formalities of categories and genres, is witnessed at its moment of formation, which is also the moment in which the authority of discourse, not yet having covered the tracks of its own genesis, reveals itself at its most fragile and contingent. It is the aesthetic dimension understood in this critical and productive relationship to pre-established categories of thought that I take up in the second and final part of the dissertation, encompassing Chapter 2 and 3, where I focus on the works of João Guimarães Rosa and Jorge Luis Borges, in Brazil and Argentina, respectively. In Chapter 2, dedicated to Rosa, I offer a reading of Grande Sertão: Veredas which emphasizes the book's allegorical dimension and the connection between allegory's interplay of identity and difference, presence and absence, with fiction's own modus operandi vis-à-vis the authoritative discourses of political and legal theory. I also offer a reading of a central episode in Grande Sertão: Veredas -- the trial of Zé Bebelo at the Sempre-Verde ranch-- in which fictional representation and political representation --the problematic history of political representation in Brazil-- are played against each other. In the final chapter, I examine the work of Jorge Luis Borges to show how fiction, understood as a discourse that does not conceal its moment of artifice, plays a mediating function between the production of authority and its legislating role, and in so doing opens up the possibility of a critical examination of its own validating assumptions and epistemic frameworks. I first examine how Borges problematizes the question of tradition and national identity through a discussion of his essay "El Escritor Argentino y la Tradición". In that essay, Borges offers as an alternative to a substantive national identity an identity that is relational and adjectival. This notion of an "adjectival identity"-- an identity that defines itself contextually, by means of the interplay of similarity and difference with all other identities, will guide Borges's own aesthetic project and his own insertion within the literary tradition with which he is, from the start, always already in dialogue. I then offer a close-reading of an essay and two fictional short stories of Borges's in which the genesis of authority is thematized - namely, Una vindicación del Falso Basílides, Los Teólogos, and Tres Versiones de Judas, in which the violent consolidation of the religious canon is set against the greater plausibility of heretic alternatives. I go on to examine how Borges's fictions find their counterpart in his essayistic work so as to constitute a coherent critique of philosophical authority. It is a critique in which the non-apodictic logic of fiction, by means of a semblance that mirrors the structural plausibility of philosophical discourse yet replaces philosophy's quest for the unity of truth with the forking paths of discursive possibility, denounces the contingency that underlies the categorical postulates of philosophy. To the extent that acknowledging the contingency of its own postulates poses a threat to the authority of a philosophical system, Borges's aesthetic critique of philosophical authority seems to suggest that philosophical logic ultimately resides on a fundamental denial, one in which what is at stake is precisely its categorical distinction from fictional discourse: the denial of its own moment of artifice.