The a priority of abduction

Abstract

Here we challenge the orthodoxy according to which abduction is an a posteriori mode of inference. We start by providing a case study illustrating how abduction can justify a philosophical claim not justifiable by empirical evidence alone. While many grant abduction's epistemic value, nearly all assume that abductive justification is a posteriori, on grounds that our belief in abduction's epistemic value depends on empirical evidence about how the world contingently is (e.g., parsimonious, or such that more parsimonious theories better track truth). Contra this assumption, we argue, first, that our belief in abduction's epistemic value is not and could not be justified a posteriori, and second, that attention to the roles experience plays in abductive justification supports taking abduction to be an a priori mode of inference. We close by highlighting how our strategy for establishing the a priority of abduction positively contrasts with strategies in Bonjour (In defense of pure reason. Cambridge University Press, New York, 1998), Swinburne (Epistemic justification. Claredon Press, Oxford, 2001), and Peacocke (The realm of reason. Oxford University Press, Oxford, 2004) aiming to establish the a priority of certain ampliative modes of inference or abductive principles.