Online research in philosophy

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.

Particularism renders the options for a sound moral epistemology few and the prospects dim. One leading approach treats basic knowledge of particular cases as derivable from an a priori moral principle and a posteriori knowledge of the contingent non-moral facts to which the principle applies. Particularists must forgo this approach because it requires principles. Yet a purely a posteriori moral epistemology is also implausible, especially when combined with particularism. Particularists such as Jonathan Dancy are thus led to the view that our basic moral knowledge is a priori knowledge of contingent moral facts. We argue that this epistemology is unsound. While some cases of a priori knowledge of (even deeply) contingent facts may be defensible, they are not sufficient for particularist purposes. Moreover, neither Dancy’s appeal to the distinction between positive and negative dependence nor his discussion of intuitive examples provides sufficient support for this epistemology.

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.

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

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.

Williamson (1986) presents a troublesome example of the contingent a priori ; troublesome, because it does not involve indexicals, and hence cannot be defused via the usual two-dimensional strategies. Here I explore how the example works, via an examination of crucial belief-forming method M, partly in response to Hawthorne (2002) and the questions there raised for 'hyperreliable' belief-forming methods. I suggest that, when used to form a belief, M does its special work through creating a verifying state of affairs which guarantees the truth of the belief thus formed. This creative link can be said to account for the knowledge-conferring status of M. But it also provides us with a way to defuse the purported example of the contingent a priori . The knowledge at issue is only a priori in virtue of this creative link, an importantly different epistemic achievement from standard cases of a priori knowledge. One important moral to be drawn is that the a priori / a posteriori distinction does not appear to be slicing the epistemological beast at its joints.

Suppose that it is necessary that if one believes that the F is F if any unique thing is, one believes of the F, if there is one, that it is F if any unique thing is. I argue that it follows (in all but a few cases) that it is also necessary that if one knows a priori that the F is F if any unique thing is, one knows a priori of the F, if there is one, that it is F if any unique thing is. I claim that because of this, a priori knowledge of de re propositions, including contingent de re propositions, is a relatively common phenomenon. However, because attributions of belief and knowledge are context-sensitive, the question whether it possible to know a priori of a given object that it is F if anything is will typically have different answers in different contexts.

By introducing a name 'one meter' and stipulating that it refers to the length of stick S, the stipulator appears to be in a position to gain immediate (and arguably a priori) knowledge of a mind- and language-independent fact-the fact that the length of stick S is one meter. It appears that other users of the name can gain this knowledge only through empirical enquiry. I argue that this presents a paradox. After clarifying the nature of the paradox, I offer a solution by arguing that, contrary to appearances, other users of 'one meter' implicitly knew that the length of stick S is one meter before learning the name, as did the stipulator prior to introducing the name. There is some distinct knowledge that other users of the name can only gain empirically, but the stipulator cannot gain this knowledge without empirical enquiry either.

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.

Kripke maintains that one who stipulatively introduces the term ‘one meter’ as a rigid designator for the length of a certain stick s at time t is in a position to know a priori that if s exists at t then the length of s at t is one meter. Some (e.g., Soames 2003) have objected to this alleged instance of the contingent a priori on the grounds that the stipulator's knowledge would have to be based in part on substantive metalinguistic knowledge. I examine Soames's argument for the a posteriority of the relevant metalinguistic knowledge, and I argue that its main premise is false.