The current reform of the research assessment system focuses on quality and qualitative assessment, and establishes a strong nexus between the two concepts. This article explores the definition of quality proposed in the Agreement on Reforming Research Assessment (ARRA) through an analysis of its principles and core commitments, and suggests that this definition is in line with the definition of Open Science provided in the UNESCO Recommendation on Open Science. Furthermore, a re-reading of The Conflict of the Faculties of Immanuel Kant is proposed to help understand the terms of the definition of Open Science and the link between the latter and research quality from a philosophical-political perspective. Finally, the article introduces a definition of quality in line with the ARRA, emphasising several aspects to be explored in its possible future developments.