The Foundations of Capability Theory: Comparing Nussbaum and Gewirth

This paper is written from a perspective that is sympathetic to the basic idea of the capability approach. Our aim is to compare Martha Nussbaum’s capability theory of justice with Alan Gewirth’s moral theory, on two points: the selection and the justification of a list of central capabilities. On both counts, we contend that Nussbaum’s theory suffers from flaws that Gewirth’s theory may help to remedy. First, we argue that her notion of a (dignified) human life cannot fulfill the role of a normative criterion that Nussbaum wants it to play in selecting capabilities for her list. Second, we question whether Nussbaum’s method of justification is adequate, discussing both her earlier self-validating argumentative strategy and her more recent adherence to the device of an overlapping consensus. We conclude that both strategies fail to provide the capabilities theory with the firm foundation it requires. Next, we turn to Gewirth’s normative theory and discuss how it can repair these flaws. We show how his theory starts from a fundamental moral principle according to which all agents have rights to the protection of the necessary preconditions of their agency. Gewirth’s justification of this principle is then presented, using a version of a transcendental argument. Finally, we explicitly compare Nussbaum and Gewirth and briefly demonstrate what it would mean for Nussbaum to incorporate Gewirthian elements into her capabilities theory of justice.