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- Brian Weatherson (2007). The Bayesian and the Dogmatist. Proceedings of the Aristotelian Society 107 (1pt2):169-185.There is a lot of philosophically interesting work being done in the borderlands between traditional and formal epistemology. It is easy to think that this would all be one-way traffic. When we try to formalise a traditional theory, we see that its hidden assumptions are inconsistent or otherwise untenable. Or we see that the proponents of the theory had been conflating two concepts that careful formal work lets us distinguish. Either way, the formalist teaches the traditionalist a lesson about what the live epistemological options are. I want to argue, more or less by example, that the traffic here should be twoway. By thinking carefully about considerations that move traditional epistemologists, we can find grounds for questioning some presuppositions that many formal epistemologists make. To make this more concrete, I’m going to be looking at a Bayesian objection to a certain kind of dogmatism about justification. Several writers have urged that the incompatibility of dogmatism with a kind of Bayesianism is a reason to reject dogmatism.1 I rather think that it is reason to question the Bayesianism. To put the point slightly more carefully, there is a simple proof that dogmatism (of the kind I envisage) can’t be modelled using standard Bayesian modelling tools. Rather than conclude that dogmatism is therefore flawed, I conclude that we need better modelling tools. I’ll spend a fair bit of this paper on outlining a kind of model that (a) allows us to model dogmatic reasoning, (b) is motivated by the epistemological considerations that motivate dogmatism, and (c) helps with some familiar problems besetting the Bayesian. I’m going to work up to that problem somewhat indirectly. I’ll start with looking at the kind of sceptical argument that motivates dogmatism. I’ll then briefly rehearse the argument that shows dogmatism and Bayesianism are incompatible. Then in the bulk of the paper I’ll suggest a way of making Bayesian models more flexible so they are no longer incompatible with dogmatism..
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“Moorean Dogmatist” responses to external world skepticism endorse courses of reasoning that many people find objectionable. This paper seeks to locate this dissatisfaction in considerations about epistemic responsibility. I sketch a theory of immediate warrant and show how it can be combined with plausible “inferential internalist” demands arising from considerations of epistemic responsibility. The resulting view endorses immediate perceptual warrant but forbids the sort of reasoning that “Moorean Dogmatism” would allow. A surprising result is that Dogmatism’s commitment to immediate epistemic warrant isn’t enough to avoid certain standard arguments for skepticism about the external world.
What is the epistemological value of perceptual experience? In his recently influential paper, “The Skeptic and the Dogmatist”1, James Pryor develops a seemingly plausible answer to this question. Pryor’s answer comprises the following three theses: (F) “Our perceptual justification for beliefs about our surroundings is always defeasible – there are always possible improvements in our epistemic state which would no longer support those beliefs.” (517) (PK) “This justification that you get merely by having an experience as of p can sometimes suffice to give you knowledge that p is the case.” (520) (D) “When it perceptually seems to you as if p is the case, you have a kind of justification for believing p that does not presuppose or rest on your justification for anything else, which could be cited in argument (even an ampliative argument) for p. To have this justification for believing p, you need only have an experience that represents p as being the case. No further awareness or reflection or background beliefs are required.” (519) Let’s use the phrase “fallibilist dogmatism” to refer to the conjunction of (F), (PK), and (D).2 Pryor does not argue for either (F) or (PK) in his paper; he simply shares the widespread and plausible assumption that (F) and (PK) are both true. But the conjunction of (F) and (PK) implies that we can have knowledge on the basis of defeasible justification. And this view leads to paradox. Consider the following individually plausible but jointly incompatible statements.
In the past, few mainstream epistemologists have endorsed Bayesian epistemology, feeling that it fails to capture the complex structure of epistemic cognition. The defenders of Bayesian epistemology have tended to be probability theorists rather than epistemologists, and I have always suspected they were more attracted by its mathematical elegance than its epistemological realism. But recently Bayesian epistemology has gained a following among younger mainstream epistemologists. I think it is time to rehearse some of the simpler but still quite devastating objections to Bayesian epistemology. Most of these objections are familiar, but have never been adequately addressed by the Bayesians.
Many epistemologists hold that an agent can come to justifiably believe that p is true by seeing that it appears that p is true, without having any antecedent reason to believe that visual impressions are generally reliable. Certain reliabilists think this, at least if the agent’s vision is generally reliable. And it is a central tenet of dogmatism (as described by Pryor (2000) and Pryor (2004)) that this is possible. Against these positions it has been argued (e.g. by Cohen (2005) and White (2006)) that this violates some principles from probabilistic learning theory. To see the problem, let’s note what the dogmatist thinks we can learn by paying attention to how things appear. (The reliabilist says the same things, but we’ll focus on the dogmatist.) Suppose an agent receives an appearance that p, and comes to believe that p. Letting Ap be the proposition that it appears to the agent that p, and → be the material implication, we can say that the agent learns that p, and hence is in a position to infer Ap → p, once they receive the evidence Ap.1 This is surprising, because we can prove the following.
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"Dogmatism" is a term renovated by James Pryor [2000] to stand for a certain kind of neo-Moorean response to Scepticism and an associated conception of the architecture of basic perceptual warrant. Pryor runs the response only for (some kinds of) perceptual knowledge but here I will be concerned with its general structure and potential as a possible global anti-sceptical strategy. Something like it is arguably also present in recent writings of Burge 1 and Peacocke.2 If the global strategy could succeed, (...) it would pre-empt any role in the diagnosis and treatment of sceptical paradoxes for the kind of notion of entitlement (rational, non-evidential warrant) I have proposed elsewhere [Wright 2004]. But my overarching contention will be that Dogmatism is, generally and locally, too problematic a stance to be helpful in that project.
“Moorean Dogmatist” responses to external world skepticism endorse courses of reasoning that many people find objectionable. This paper seeks to locate this dissatisfaction in considerations about epistemic responsibility. I sketch a theory of immediate warrant and show how it can be combined with plausible “inferential internalist” demands arising from considerations of epistemic responsibility. The resulting view endorses immediate perceptual warrant but forbids the sort of reasoning that “Moorean Dogmatism” would allow. A surprising result is that Dogmatism’s commitment to immediate epistemic warrant isn’t enough to avoid certain standard arguments for skepticism about the external world.
I argue that its appearing to you that P does not provide justification for believing that P unless you have independent justification for the denial of skeptical alternatives – hypotheses incompatible with P but such that if they were true, it would still appear to you that P. Thus I challenge the popular view of ‘dogmatism,’ according to which for some contents P, you need only lack reason to suspect that skeptical alternatives are true, in order for an experience as of P to justify belief that P. I pursue three lines of objection to dogmatism, having to do with probabilistic reasoning, considerations of future or hypothetically available justification, and epistemic circularity. I briefly sketch a fall-back position which avoids the problems raised.
Open-minded people should endorse dogmatism because of its explanatory power. Dogmatism holds that, in the absence of defeaters, a seeming that P necessarily provides non-inferential justification for P. I show that dogmatism provides an intuitive explanation of four issues concerning non-inferential justification. It is particularly impressive that dogmatism can explain these issues because prominent epistemologists have argued that it can’t address at least two of them. Prominent epistemologists also object that dogmatism is absurdly permissive because it allows a seeming to provide justification even if the seeming was caused in some apparently inappropriate way. I conclude by disarming this objection.
Recently in epistemology a number of authors have mounted Bayesian objections to dogmatism. These objections depend on a Bayesian principle of evidential confirmation: Evidence E confirms hypothesis H just in case Pr(H|E) > Pr(H). I argue using Keynes’ and Knight’s distinction between risk and uncertainty that the Bayesian principle fails to accommodate the intuitive notion of having no reason to believe. Consider as an example an unfamiliar card game: at first, since you’re unfamiliar with the game, you assign credences based on the indifference principle. Later you learn how the game works and discover that the odds dictate you assign the very same credences. Examples like this show that if you initially have no reason to believe H, then intuitively E can give you reason to believe H even though Pr(H|E) ≤ Pr(H). I show that without the principle, the objections to dogmatism fail.
According to dogmatism, one may know a proposition by inferring it from a set of evidence even if one has no independent grounds for rejecting a skeptical hypothesis compatible with one’s evidence but incompatible with one’s conclusion. Despite its intuitive attractions, many philosophers have argued that dogmatism goes wrong because they have thought that it licenses Moorean reasoning — i.e., reasoning in which one uses the conclusion of an inference as a premise in an argument against a skeptical hypothesis that would undermine that very inference. In this paper I defend dogmatism against this line of thought. To begin with, I argue that the common assumption that uncontroversial Bayesian principles suffice to show that Moorean reasoning is not cogent is false: for all that Bayesianism says on the matter, Moorean reasoning might be perfectly fine. Nevertheless, Moorean reasoning does seem intuitively defective. As I argue, however, this does not provide grounds for an argument against dogmatism, because — contrary to what many philosophers have thought — dogmatism need not license Moorean reasoning. On the contrary, as I argue, dogmatism predicts that Moorean reasoning suffers from a clearly identifiable defect.
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