Normativity and Contrastive Explanation

My thesis concentrates on the distinction between pro tanto reasons and allthings-considered judgments, and their relation to normative justification. Negatively, it seeks to show that a prevailing kind of account of this relation should be rejected, namely that family of views which takes it that every reason has an associated weight, and the truth with respect to any issue is established by which set of reasons is weightiest. Through an examination of Ross’ doctrine of prima facie duties, this discussion also leads to a formulation of the central problem which any account of this relation must seek to solve. Positively, this thesis develops a new account of the relation between pro tanto reasons and all-things-considered judgements, based on the fundamental insight that a justification of normative propositions is identical to an explanation of their truth, were they to be true. I defend this identity claim, and seek to generate an account of justification from an account of explanation. Drawing on a deservedly popular ‘contrastive’ conception of explanation in the philosophy of science, I show how we can fruitfully think of justification as itself contrastive. Part of this is showing how the notion of a burden of explanation can shed light on the notion of a burden of justification, so a conception of justification emerges according to which a justification for a normative proposition consists in an solution to all those burdens of justification which it incurs. In turn, this feeds a conception of reasons, and their role in justification, alternative to that envisaged in a weighing model: pro tanto reasons determine the correct all-things-considered judgment insofar as they determine to what extent the truth of that judgement has an adequate explanation, such that the correct all-things-considered judgement is just that judgement whose truth would have a fully adequate explanation.