This paper attempts to give new life to a conception of the rights to equality and non-discrimination —often misleadingly called ‘formal’ and currently less fashionable— built around irrationality in the distribution of a benefit. To be clear, this is both a conception of ‘substantive inequality’ and discrimination. First, the paper outlines the philosophical picture of practical reason which underpins the conception. It then moves to substance, in particular the central notion of equal moral status Then, relying on argumentation theory, it shows how the conception can be extracted from the language of equality and discrimination provisions. Finally, it argues that, compared with other conceptions of equality and discrimination, this one is particularly suited for judicial decision-making: it is (1) grounded in a standard account of action and responsibility (2) simple and down-to-earth and (3) institutionally legitimate. This explains its persisting presence in many jurisdictions.