The project investigates the fundamental philosophical and ethical concepts that influenced Kauṭilya and their impact on the social and political realm as reflected in the treatise “Arthaśāstra” (1- 2nd cent. CE). It offers a new interpretation of the text in the context of its cultural background, i.e. investigating non-Brahminical (mainly Buddhist and Jain) philosophical elements in the earliest recensions of the text. These, and related issues, constitute a starting point of a thesis that Kauṭilya was not a political realist mainly concerned with power and motivated by self-interest, as occasionally insinuated in topic literature by the Machiavellian alignment. Instead, he was a thinker committed to the well-being of others and the harmonious function of a society. The main part inquires on how the implicated key mechanisms of practical reasoning and principled action support social justice. It offers a thorough analysis of the directives, which specifically ensure collective success (artha) of a cosmopolitan community. The subsequent part discusses ‘political authority’ in three central questions: - to what extent is political authority an independent pursuit? - to what extent is it impacted by external institutions and social realities? - how should the ruler address the potential contradictions between the rules of institutions and the rule of law? Last, I reassess two cases of the applications of social justice: the status of women and environmental measures.