In this article, I present a defence of conceptual plausibility, understood as an epistemic way to qualify concepts that situates them between the merely possible and the actual. To show that there is such a thing as conceptual plausibility, I rely on what seems to lie at the heart of many uses of the phrase ‘plausible concept’: explanatory fruitfulness. To make an effective case for the claim that conceptual plausibility is of philosophical interest, I present an argument based on the debate over the rationality of theistic belief and the concept of God. To show that conceptual plausibility is philosophically feasible, I first show that it cannot be reduced to propositional plausibility. Next, I offer a minimally precise characterization of conceptual plausibility; I approach this from a qualitative and comparative perspective as well. Finally, I show how these qualitative and comparative criteria of conceptual plausibility might be applied to the debate over the rationality of theistic belief and the concept of God.
