In this paper, I will analyze the main elements that define the emergence of critical social thought in Peru in the twentieth century from the perspective of José Carlos Mariátegui (1894-1930). In his writings, an important tension can be perceived: that between the economic approach through which he examines the main issue in Peru - that of the large state and servitude stemming from land ownership - and the epistemic role that he assigns to the excluded sectors as capable of formulating new problems and solutions. I demonstrate that several factors must be considered to comprehend the complementarity between Mariátegui’s economic approach to the national reality and his advocacy for a form of radical democracy. We must thoroughly understand his quasi-pragmatist definition of “problem” and his approach to the economy as a form of life anchored in an ethical community. Furthermore, his defense of Marxism as a complex approach encompassing multiple research methodologies rather than as a set of dogmas should also be taken into account. Linked to these two elements is the importance that Mariátegui attaches to creating spaces for exchanging experiences aimed at complementing scientific work with the voices of those affected.