Minimal metaphysics in moral and political philosophy

Abstract The aim of this paper is to apply the methodology of minimal ontological commitments to moral and political philosophy. As minimal metaphysics in the philosophy of science endorses scientific realism, so we subscribe to moral realism, arguing that the presumption of liberty is the fundamental assumption defining a person. What needs to be justified then are restrictions to liberty and, in particular, the application of coercion upon persons. In examining knowledge claims about normative facts going beyond the presumption of liberty, such as, for instance, facts about a common good, we show that an ontological commitment to such normative facts is at odds with minimal metaphysics. We thus show how minimal metaphysics vindicates a Kantian deontological stance in moral and political philosophy: moral realism is limited to the obligations that follow from extending the presumption of liberty to all human beings in virtue of them being rational animals, hence to respect every person as an end in itself.