Online research in philosophy

This paper presents two different kinds a priori entitlements and argues that both are necessary to account for scientific knowledge. On the one hand, there are formal a priori entitlements whose existence is grounded in conditions on concept possession. On the other hand, there are material a priori entitlements that an agent accrues in virtue of practical reasoning. The discussion aims to reconcile the strengths of Christopher Peacocke’s and Michael Friedman’s recent work on the a priori, while overcoming the weaknesses of their respective proposals.

The terms "a priori" and "a posteriori" refer primarily to how or on what basis a proposition might be known. A proposition is knowable a priori if it is knowable independently of experience. A proposition is knowable a posteriori if it is knowable on the basis of experience. The a priori/a posteriori distinction is epistemological and should not be confused with the metaphysical distinction between the necessary and the contingent or the semantical or logical distinction between the analytic and the synthetic. Two aspects of the a priori/a posteriori distinction require clarification: the conception of experience on which the distinction turns; and the sense in which a priori knowledge is independent of such experience. The latter gives rise to important questions regarding the positive basis of a priori knowledge.

(K1) All knowledge of necessary propositions is a priori. (K2) All propositions known a priori are necessary. (K3) All knowledge of analytic propositions is a priori; and (K4) Some propositions known a priori are synthetic.

Inspired by two-dimensional modal logic, some have sought to provide analyses of the notion of the contingent a priori which identify the a priori with truths which have a necessary diagonal. I argue that these analyses fail insofar as they miss the crucial epistemic aspect of the a priori. Augmenting these analyses with specifically epistemic accounts might be possible, but the interest would then reside in these epistemic accounts of the a priori and not in the formal models.

In this paper I will offer a novel understanding of a priori knowledge. My claim is that the sharp distinction that is usually made between a priori and a posteriori knowledge is groundless. It will be argued that a plausible understanding of a priori and a posteriori knowledge has to acknowledge that they are in a constant bootstrapping relationship. It is also crucial that we distinguish between a priori propositions that hold in the actual world and merely possible, non-actual a priori propositions, as we will see when considering cases like Euclidean geometry. Furthermore, contrary to what Kripke seems to suggest, a priori knowledge is intimately connected with metaphysical modality, indeed, grounded in it. The task of a priori reasoning, according to this account, is to delimit the space of metaphysically possible worlds in order for us to be able to determine what is actual.

In what follows, I argue that Hume works with a notion of the a priori that, though unfamiliar today, was standard in the seventeenth and eighteenth centuries. On this notion of the a priori, to know (consider, prove) something a priori is to know (consider, prove) it from the grounds that make it true. I will refer to this as the "from-grounds" notion of the a priori, and to the now-familiar and dominant notion—on which to know something a priori is to know it with a justification that is independent of experience—as the "non-empirical" notion.Hume holds, as a substantive thesis, that one knows something a priori, where 'a priori' is understood in the from-grounds sense, only if one knows it independently of ..

The distinction between a priori and a posteriori knowledge has been the subject of an enormous amount of discussion, but the literature is biased against recognizing the intimate relationship between these forms of knowledge. For instance, it seems to be almost impossible to find a sample of pure a priori or a posteriori knowledge. In this paper, it will be suggested that distinguishing between a priori and a posteriori is more problematic than is often suggested, and that a priori and a posteriori resources are in fact used in parallel. We will define this relationship between a priori and a posteriori knowledge as the bootstrapping relationship. As we will see, this relationship gives us reasons to seek for an altogether novel definition of a priori and a posteriori knowledge. Specifically, we will have to analyse the relationship between a priori knowledge and a priori reasoning , and it will be suggested that the latter serves as a more promising starting point for the analysis of aprioricity. We will also analyse a number of examples from the natural sciences and consider the role of a priori reasoning in these examples. The focus of this paper is the analysis of the concepts of a priori and a posteriori knowledge rather than the epistemic domain of a posteriori and a priori justification.

The book sets out to analyse the notion of a priori justification and of a priori knowledge.

I argue that you can have a priori knowledge of propositions that neither are nor appear necessarily true. You can know a priori contingent propositions that you recognize as such. This overturns a standard view in contemporary epistemology and the traditional view of the a priori, which restrict a priori knowledge to necessary truths, or at least to truths that appear necessary.