Abstract

Hume and Kant destroyed the belief in the apriori de re, i.e. the rationalist’s doctrine of direct awareness of necessary facts about the nature of being. Later on, analytical philosophy told us that there are only two general classes of statements, synthetics a posteriori and analytics a priori. Quine eventually rejected the a priori in general and advanced a radical empiricism. However, both moderate and radical empiricism has recently been challenged by realistic minded philosophers. They have argued that ontological topics such as the nature of properties, laws or causation remain strongly undetermined by semantic ascent and Quinean ontological commitment, and announced an ontological turn. Are not ontological or metaphysical explanations a priori explanations? Despite his preferred talk in terms of a posteriori realism and inference of the best explanation, Armstrong’s defence of universals looks very much like an apriori one. Others, such as Barry Smith, explicitly defend that there are synthetic propositions a priori de re. I believe in both: Kant was right in claiming that an understanding of what metaphysics can teach us is dependent upon a clear concept of the synthetic a priori, but—against Kant— synthetics a priori de re are legitimate. In this paper I will defend synthetics a priori de re. However, I will reject the rationalist’s appeal to direct awareness of necessary facts as well as undeniableness or infallibility as necessary conditions for a prioris. Instead I will claim that all synthetics a priori express hypothetical truths.