In recent years, several philosophers have argued that the a priori/a posteriori distinction is a legitimate distinction but does not carve at the epistemological joints and is theoretically unimportant. In this paper, I do two main things. First, I respond to the most prominent recent challenge to the significance of the a priori/a posteriori distinction – the central argument in Williamson (2013). Second, I discuss the question of what the theoretical significance of the a priori/a posteriori distinction is. -/- I (...) first present the a priori/a posteriori distinction as it is typically developed. I then turn to Williamson’s challenge to the significance of the distinction. Williamson points out that we often use the same cognitive mechanisms in coming to have a priori and a posteriori knowledge. So how could it be, asks Williamson, that there is a “deep epistemological difference” between the two? In response to this challenge, I argue that there is an important disanalogy between Williamson’s central example of a case of a priori knowledge and his central example of a case of a posteriori knowledge. Although the beliefs in the two cases are formed in similar ways, the ways in which their justification can be defeated are different. This suggests that there is an important epistemological difference between the two cases, one that cannot be captured in terms of the cognitive mechanisms used to form the beliefs. -/- Although Williamson’s argument is unsuccessful, there remains the question of just what the theoretical significance of the a priori/a posteriori distinction is. I argue that the point of the distinction is not to enable us to represent some joint in nature, but rather to help us to identify epistemological problem cases. We understand – more-or-less – the epistemology of simple perceptual knowledge. The epistemology of non-perceptual knowledge is far less clear. The purpose of labeling a case of knowledge as a priori is to claim that its epistemology should not be assimilated to the epistemology of perception. Instead, it is something of a puzzle case. -/- This proposal has an important implication. There are several ways in which a case of knowledge can be different from a simple case of perceptual knowledge. Two differences are perhaps the most important: (i) the justification of the belief does not involve phenomenality, and (ii) the belief does not stand in a causal relation to what the belief is about. When beliefs about some subject matter fit either (i) or (ii), an epistemological puzzle arises. So there is more than one kind of epistemological puzzle to solve. This suggests that there is an important theoretical role for (at least) two distinctions in the ballpark of the traditional a priori/a posteriori distinction. (shrink)

Many Bayesians such as White and Silins have argued that Moorean reasoning is defective because it is a case where probabilistic support fails to transmit across the relevant entailment. In this paper, I argue against their claim. On the Bayesian argument, a skeptical hypothesis is that you are a brain in a vat that appears to have hands. To disclose the defect in Moorean reasoning, the Bayesian argument is supposed to show that its appearing to you as if you have (...) hands does not increase the probability of a non-skeptical hypothesis such that you are not a brain in a vat. But what their argument really shows is rather a trivial fact that acquiring theses handlike experiences eliminates the possibility of not having these experiences, and so your having these experiences lowers the probability of the disjunctive claim that you are not a brain in a vat or it does not appear as if you have hands. Along these lines, I argue that what the Bayesian proof establishes has nothing to do with the defect in Moorean reasoning. (shrink)

This paper explores the problems that are raised by a certain traditional sceptical paradox. The conclusion will be that the most challenging problem raised by this paradox does not primarily concern the justification of beliefs; it concerns the justification of belief-forming practices. This conclusion is supported by showing that if we can solve the sceptical problem for belief-forming practices, then it will be a relatively straightforward matter to solve the problem that concerns the justification of beliefs.

On the assumption that we may learn from our elders and betters, this paper approaches some fundamental questions in perceptual epistemology through a dispute between McDowell and Wright about external world scepticism.