Social justice is a key concept in the theory and practice of affirmative action. In India, social justice has come to serve as shorthand for affirmative action for disadvantaged groups, mainly lower castes. This paper provides a detailed analytical interpretation of social justice in a landmark legislative debate on quotas in India, namely the 1990 Mandal debate. It unpacks political rhetoric to reveal distinct conceptions of social justice, shows that claims for quotas for Other Backward Classes (OBCs) in the bureaucracy drew substantially on principles of social justice and democracy and argues that, despite appearances, several arguments for OBC representation in government jobs were compatible with the principle of merit. In doing so, the paper demonstrates that contrary to common opinion, political rhetoric deserves close attention. A reconstruction of political arguments over affirmative action advances understanding of some puzzling features of lower-caste politics in India. It also illuminates important questions in political theory debates on social justice.