In defence of dogmatism Luca Moretti Aberdeen University l.moretti@abdn.ac.uk final draft ABSTRACT According to Jim Pryor's dogmatism, when you have an experience with content p, you often have prima facie justification for believing p that doesn't rest on your independent justification for believing any proposition. Although dogmatism has an intuitive appeal and seems to have an antisceptical bite, it has been targeted by various objections. This paper principally aims to answer the objections by Roger White according to which dogmatism is inconsistent with the Bayesian account of how evidence affects our rational credences. If this were true, the rational acceptability of dogmatism would be seriously questionable. I respond that these objections don't get off the ground because they assume that our experiences and our introspective beliefs that we have experiences have the same evidential force, whereas the dogmatist is uncommitted to this assumption. I also consider the question whether dogmatism has an antisceptical bite. I suggest that the answer turns on whether or not the Bayesian can determine the priors of hypotheses and conjectures on the grounds of their extra-empirical virtues. If the Bayesian can do so, the thesis that dogmatism has an antisceptical bite is probably false. Keywords: dogmatism, Bayesianism, perceptual scepticism, perceptual justification, immediate justification, explanationism, Pryor, White, Silins. 1. Introduction Pryor (2000) has introduced an interesting epistemological position called dogmatism according to which, roughly: When it perceptually seems to you as if p is the case, you have [prima facie] justification for believing p that does not presuppose or rest on your justification for anything else... 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)1 1 Similar positions have been proposed by, among others, Pollock (1986) and Huemer (2001). 2 For instance, if you experience as if this is a hand, you acquire prima facie justification for believing that this is a hand even if you have no independent justification for believing that no sceptical scenario is instantiated or that your perception is reliable.2 Although Pryor's position might strike one as natural and intuitive, it has laid itself open to criticism of a different kind. This paper principally aims to answer the Bayesian objections by White (2006). These objections purport to show that dogmatism is inconsistent with the Bayesian account of how evidence rationally affects our credences. If this were true, the rational acceptability of dogmatism would be at risk. I respond that White's objections don't get off the ground because they assume that our experiences and our introspective beliefs that we have experiences have the same evidential force, whereas the dogmatist is uncommitted to this assumption. I also consider the question whether dogmatism has an antisceptical bite, as Pryor contends. I suggest that the answer turns on whether or not the Bayesian can determine her prior credences by appealing to extraempirical evidence, which is controversial. If the Bayesian can do so, the thesis that dogmatism has an antisceptical punch is probably false. This is the paper's structure: §2 introduces dogmatism. §3 illustrates apparent merits of dogmatism. §4 reviews White's objections. §5 explains why dogmatism is not inconsistent with Bayesianism. §6 suggests that if the Bayesian can use extra-empirical evidence to determine her prior credences, dogmatism has probably no antisceptical bite. §7 draws the conclusions. 2. Dogmatism The dogmatist endorses the popular view in contemporary philosophy of mind that apparent perceptions or experiences are not just occurrences of sense data but mental states provided with propositional contents.3 These contents are about, not the subjective character of our experiences, but observable things in the world. Since these contents represent the world accurately or 2 My paper attempts to adhere to the original picture of dogmatism presented in Pryor (2000 and 2004), which I find plausible. 3 Many philosophers nowadays maintain that experiences have representational contents, but not just everyone identifies these contents with propositional contents. See Siegel (2011) for an overview. 3 inaccurately, experiences have conditions of accuracy. According to the dogmatist, believing p and experiencing as if p are two independent ways to entertain the same content p; hence experiences are not beliefs, though both of them have contents.4 Other mental states have contents – e.g. hopes and desires. These states also represent the world in virtue of their contents, but hopes and desires aren't experiences because their content is hoped or desired rather than experienced. Experiences and beliefs have it in common that they both represent assertively: when they represent that p, they do so in a way that purports to show how the world actually is (cf. Pryor 2005: 187-188). This doesn't happen with hopes and desires. Pryor (2000) characterises dogmatism as follows: [For any content of experience p,] whenever you have an experience of p's being the case, you thereby have immediate (prima facie) justification for believing p. (532) Pryor (2000: 533-534 and 2005: 183) implicitly recognises that this characterisation is inaccurate. It looks implausible that whenever a subject S experiences as if p, S has justification for believing p. S's having justification for believing p requires for instance S to be able to entertain the belief that p. But S might be unable to do this in certain cases. Thus, in order to enable S to have justification for p, further conditions additional to S's mere experiencing as if p ought to be fulfilled. Pryor would seem to assume that these additional conditions are often satisfied in everyday life. Therefore, a more accurate characterization of dogmatism is the following: (DG) For any content of experience p, your experience as if p can (and will often) give you immediate prima facie justification for believing p. Let us dissect DG. The dogmatist endorses an internalist notion of epistemic justification5 (cf. Pryor 2000: 542, note 9) and focuses on propositional justification6 (cf. Pryor 2000: 521). To characterise the notion of immediate justification let us first clarify the notion of mediate 4 One can experience as if p without believing p – for example when one knows one is having an optical illusion. 5 According to the internalist, if p is justified for a subject, all factors that make p justified for her are recognisable by the subject by mere reflection or are identifiable with some of the subject's mental states. Dogmatism satisfies the first condition at least. 6 A subject has propositional justification for believing p if, whether or not she believes p or believe p for the right reason, it would be epistemically appropriate for her to believe p. 4 justification.7 One has mediate justification for believing a proposition p if and only if one has justification for believing p and at least part of this justification it is based on independent justification of whatever (non-zero) degree one has for some proposition. Saying that one's justification for p is based on one's independent justification for some proposition is saying, for Pryor, that the first justification is constituted by or exists in virtue of the second justification. Suppose you look at the battery status indicator of your laptop, which reads '0%'. You have justification for believing that (P) the indicator reads '0%'. Your justification for P, together with your justification for other propositions (e.g. propositions about the function of the indicator and the components of your computer), gives you justification for believing that (Q) your laptop's battery is flat. In this case it seems correct to say that your justification for Q exists in virtue of, among other things, your independent justification for P. Thus your justification for Q is mediate. One has immediate justification for believing a proposition p if and only if one has justification for believing p and no part of this justification is based on one's independent justification of whatever (non-zero) degree for any proposition. Suppose you have justification for believing that (P) you are in pain, and that you have it because you feel pain. In this case your justification for believing P exists in virtue of, among other things, your feeling. But no part of this justification seems to exist in virtue of independent justification you have for believing any proposition. Thus your pain gives you immediate justification for P (cf. Pryor 2005: 182-183). Pain has presumably no representational content. The dogmatist contends that mental states with content can also supply immediate justification. For instance: An experience as if there being hands seems to justify one in believing there are hands in a perfectly straightforward and immediate way. (Pryor 2000: 536) For the dogmatist this example generalises: any experience with content p is able to provide prima facie immediate justification for believing p. The dogmatist denies that experiences can justify their contents because experiences are in turn justified. An introspective belief about an experience (i.e. 7 See Pryor (2005) and Siegel and Silins (forthcoming) for more detailed presentations of these two notions. 5 one's belief that one has a given experience) can be justified, but it seems to make no sense to say that an experience can in itself be epistemically justified (cf. Pryor 2005: 189). Pryor maintains that experiences can justify their contents because of their distinctive phenomenology that makes them represent their contents assertively. He describes this phenomenology as 'the feeling of seeming to ascertain that a given proposition is true' (Pryor 2004: 357. Cf. also Pryor 2000: 547, note 37). According to the dogmatist, the phenomenology of seeming to ascertain that p is true can provide the subject with a defeasible reason – and thus a defeasible justification – for taking p as true. The dogmatist doesn't claim that any proposition justified by experience is immediately justified by it. In the example about the laptop, the justification for believing that (Q) my laptop's battery is flat comes in part from my experiencing something. But in that case my experiencing cannot have Q as its content. As it is very implausible that I can literally experience as if my laptop's battery is flat. Accordingly, the dogmatist wouldn't say that Q can be immediately justified by my experience. The propositions that I can literally experience to be true are – for the dogmatist – the contents of my experiences. Pryor leaves it largely indeterminate what propositions qualify as contents of one's experience,8 though he includes among them those about elementary and familiar material objects, such as the proposition that there is a red cube or that there is a hand. According to DG, we can have immediate prima facie justification for believing the contents of our experiences, whichever propositions they turn out to be (cf. Pryor 2000: 538-539 and 2004: 357). Immediate perceptual justification comes as prima facie justification because it can be defeated by additional evidence possessed by the subject (cf. Pryor 2000: 545, note 28). Whether immediate perceptual justification is also all things considered justification depends on what other evidence the subject possesses and on whether or not this evidence acts as a defeater. Different sorts of things count as defeaters. Perceptual justification for believing p can be defeated – for instance – by evidence in favour of ~p (where '~' is logical negation), by evidence that p's truth is, in the relevant 8 For a survey of the different options see Siegel (2011). 6 circumstances, not ascertainable by perception, by evidence that one's senses are malfunctioning, and so on (cf. Pryor 2000: 534). 3. Apparent merits of dogmatism Dogmatism looks attractive and plausible for various motives. To begin with, DG seems to match everyday epistemic practices. In ordinary circumstances we might have more or less explicit beliefs about, say, the reliability of our faculties, but our reasons for holding many of our ordinary perceptual beliefs don't seem to include the reasons we have for these additional beliefs. Instead we seem to entertain many of our perceptual beliefs just because of how things appear to us to be. Imagine for instance you have the experience as if an apple is on the table. In that case you would normally answer the question 'Why do you have any reason for believing that there is an apple on the table?' by simply saying 'Because I see it'. The answer 'Because I see it and I have reasons to believe that my faculties are reliable' would appear quite unnatural. Dogmatism also forms the basis for modest foundationalism (that makes no claim of infallibility, certainty, or self-evidence for the foundations). For it sheds light on how propositions can be prima facie justified directly by experience without inference from other independently justified propositions (cf. Pryor 2005: 184-192). Finally, dogmatism would seem to offer a response to perceptual scepticism. Since I will attempt an appraisal of the antisceptical consequences of Pryor's position in §6, let me now describe this response in some detail. The sceptic typically appeals to non-perceiving alternatives. Suppose you have perceptual justification for believing p. An essential characteristic of any non-perceiving alternative sh to p is that your perceptual justification for p would be defeated if you had reason to believe that sh is true (cf. Pryor 2000: 527). There are at least two types of non-perceiving alternatives: those incompatible and those compatible with p. Suppose P says that there is an apple before you, SH1 says that you are a disembodied soul in an immaterial world having the hallucination of an apple before you produced by a demon, and that SH2 says that a computer linked to your brain makes you 7 experience as if there is an apple before you. If you had reason to believe that SH1 or SH2 is true, you would distrust your experience as if P as a ground for believing P. Note that while SH1 rules out P, SH2 doesn't. So SH1 is incompatible with P whereas SH2 compatible with it. A popular argument for perceptual scepticism runs as follows (cf. Pryor 2000: 524-532 and Schiffer 2004: 161-165): (1) For any proposition p, you can acquire justification for believing p from your experience only if you have independent justification for believing that no non-perceiving alternative sh to p is true (i.e. for believing ~sh for any relevant sh). (2) You cannot possess such independent justification. Therefore: (3) You cannot acquire justification for believing any p from your experience. This argument is logically valid but its premises can be questioned. The dogmatist uses DG to reject or discredit (1). The dogmatist argues that if DG is true, (1) is false or very implausible when p stands for a content of experience (in Pryor's sense). Note that DG and (1) look at first blush compatible. In brief DG entails that you can acquire justification for believing p form your experiencing as if p even if your justification for p is not based on any independent justification for believing any proposition. We saw before that in order for you to possess this immediate justification for p, some necessary conditions additional to your experiencing as if p should be fulfilled. These conditions may require you to have independent justification for some proposition – this is not forbidden by DG if this justification is no basis for your justification for p (I'll give some example in §5). In apparent agreement with this, (1) doesn't say that the independent justification for ~sh necessary for your perceptual justification for p is a basis of that perceptual justification. Pryor (2000: 545, note 33) contends that, in spite of this apparent harmony, DG undercuts the most natural line of reasoning that the sceptic can use to support (1). This line of reasoning says that you need independent justification for ~sh just because your perceptual justification for p needs to be based on your independent justification for ~sh. But if DG is true, this reasoning is fallacious because you can have perceptual justification for p that is not based on your independent justification for ~sh. If DG is true, it is open to the sceptic to try to defend (1) by other means. The 8 sceptic should explain why your having independent justification for ~sh is necessary but not basing for your having perceptual justification for p. But it is difficult to imagine how the sceptic could motivate this claim. Suppose the dogmatist has succeeded in rejecting (1) by adducing DG. The dogmatist could then press the sceptic once again by arguing that even if we don't possess default justification for disbelieving any non-perceiving alternative, we can have perceptual justification for disbelieving some of them. Consider any non-perceiving alternative sh incompatible with p. You know that p entails ~sh, and justification is presumably closed under known entailment. Therefore, if you acquire immediate prima facie justification for believing p from your experience as if p, that justification must flow to ~sh through the entailment. Hence you will acquire prima facie justification for disbelieving sh too (cf. Pryor 2004: 361-362). 4. White's objections Dogmatism has caught the attention of philosophers but also prompted their criticism.9 Siegel and Silins (forthcoming) have suggested lines of reply to many of these objections. My article specifically focuses on the objections raised in White (2006) aiming to show that dogmatism is inconsistent with the Bayesian account of how evidence rationally affects our credences. The Bayesian assumes that degrees of rational belief – or credences – obey the probability calculus and conceives of both hypotheses and evidence as propositions believed with a given degree of strength. Thanks to its intuitive appeal, ductility and a list of penetrating analyses, Bayesianism is tremendously influential in today's epistemology. If dogmatism were proven to be incompatible with Bayesianism, many would conclude that dogmatism has to go to the wall. In any case this clash would generate a philosophical puzzle with no easy solution. White formulates his objections synchronically. However, as these objections appear to be about epistemic processes, to make my analysis as accurate as possible I prefer to re-formulate them 9 See for instance Schiffer (2004), White (2006), Wright (2007) and Siegel and Silins (forthcoming). 9 diachronically. Let Cr be a rational subject S's credence function, and let Cre be S's credence function updated upon S's learning that e is true. I take the updating procedure to be standard conditionalisation, according to which Cre(p) = Cr(p|e) and Cre(e) = 1. This says that for any propositions p and e on which Cr is defined, as S learns e, S's credence in p equates to the conditional credence in p given e that S had before learning e, and S's credence in e becomes the highest possible. White assumes that the degree of epistemic justification for believing a proposition p that one has in a given situation and the degree of credence in p that one should rationally have in the same situation coincide or are very closely related to one another. This assumption is very intuitive, so I won't question it. From this assumption White infers that, in general, one acquires some justification for believing a proposition p from evidence e if and only if one's credence in p should increase upon one's learning e.10 Suppose now that: E = 'It appears to me that this is a hand'. P = 'This is a hand'. SH = 'This is a fake-hand'. A fake-hand is everything that is not a hand but cannot be visually distinguished from a hand. 'Examples of fake-hands include perfect plastic replicas of hands, and moving projected holograms of hands' (White 2006: 528). Thus SH stands for any hypothesis incompatible with P that entails E or makes E highly probable. This is White's first objection. It is very plausible that CrP(E) ≅ CrSH(E) ≅ 1 – i.e. my credence in E should be close to certainty when the truth of P or the truth of SH is given to me. Furthermore, since I shouldn't in general expect to have the experience of a hand, Cr(E) << 1 – i.e. my prior credence in E should be far from certainty. Thus CrP(E) > Cr(E) and CrSH(E) > Cr(E). It is easy to prove that the first inequality entails that CrE(P) > Cr(P), and the second that CrE(SH) > Cr(SH). 10 The only if direction of this biconditional is controversial (cf. Wright 2011 and Moretti and Piazza 2013). I don't want to press this objection here because it would distract us from more serious difficulties of White's arguments. 10 This indicates that when I learn E, I acquire some justification for both P and SH. It can be shown that CrE(SH) > Cr(SH) entails that CrE(~SH) < Cr(~SH). This indicates that when I learn E, my justification for ~SH decreases. Thus it seems that when I experience as if this is a hand, I cannot acquire justification for ~SH. White concludes from this – in contradiction with Pryor's contention – that if I have perceptual justification for P, this justification cannot transmit from P to P's logical consequence ~SH (cf. White 2006: 532-533). This is White's second objection. (Although White's second objection follows from his first, the second objection is actually his central objection because it directly targets DG.) It can be proven that since ~SH logically follows from P, CrE(P) ≤ CrE(~SH). We saw before that CrE(~SH) < Cr(~SH). These two formulae trivially entail that CrE(P) < Cr(~SH). This means that 'its appearing to me that this is a hand can render me justifiably confident that it is a hand, only if I am already confident that it is not a fake-hand' (White 2006: 534). White assumes here that when Pryor speaks of justification for a proposition p, he speaks of justification for being confident that p, which is – it seems to me – roughly the same as justification for fully believing p. This reading of Pryor's views actually matches many of his claims.11 Hence I will not question this interpretation. We can model justification for full belief as sufficiently high rational credence: one has justification for fully believing p just in case one's credence in p should rationally exceed a given value t, presumably very high and close to 1. CrE(P) < Cr(~SH) entails that CrE(P) > t only if Cr(~SH) > t. Thus it seems that unless I already have justification for fully believing ~SH, when I experience as if P I cannot acquire justification for fully believing P. White appears to take this upshot to show that, when epistemic justification is analysed in Bayesian terms, my experience as if P cannot give me immediate justification for believing P. This clashes with DG.12 To highlight the intuitive plausibility of the conclusions of his arguments, White outlines two thought experiments involving again P, E and ~SH (cf. White 2006: 535-537). In these thought 11 At least in Pryor (2000) and (2005). 12 Schiffer (2004) puts forward a criticism of dogmatism that (insofar as I understand it) is similar to this objection. 11 experiments it would be hardly questionable – according to White – that my experiencing as if P lessens my justification for ~SH. For it would be hardly questionable that CrE(~SH) < Cr(~SH). As we have seen, this inequality constitutes a crucial step in the articulation of White's both objections. For the sake of completeness let me briefly describe the first of these thought experiments. Suppose I'm put to sleep while you write on three cards the following instructions:13 Card-A: Chop off my hands and replace them with fake ones. Card-B: Leave my hands alone. Card-C: Chop off my hands and leave the stumps. You put the three cards in a hat. You randomly pick one card and stolidly carry out the instructions. When I'm awake and I lift an arm, (E) it appears to me that this is a hand. Since I know the random procedure with the cards you intended to follow, before learning E my degree of credence in ~SH should be 2/3. But after learning E, my degree of credence in ~SH should drop to 1/2. For now I know that you didn't pick Card-C, but I also know that you could have picked Card-A just as easily as Card-B. So CrE(~SH) < Cr(~SH).14 White's Bayesian objections seem to aim to question dogmatism – prominently DG – and the dogmatist's responses to the perceptual sceptic at once. For the sake of clarity I prefer to divorce these two challenges. In the next section I will investigate whether dogmatism and Bayesianism are actually inconsistent. In the subsequent section I will investigate whether dogmatism has actually an antisceptical bite. 5. Dogmatism and Bayesianism are not inconsistent White's objections have impressed many epistemologists and led some to respond. For instance, Pryor (manuscript), Weatherson (2007) and Kung (2010) all suggest ways to revise the Bayesian 13 In White's original example you are put to sleep and I write the instructions on the cards. For reasons of stylistic coherence with the rest of my paper I have swapped you with me. 14 White's second thought experiment is similar but based on statistical claims: e.g. the percentages of living people who are missing one hand and have a plastic replica or a stump. 12 framework to accommodate the intuitions of the dogmatist.15 In contrast with revisionary responses of this type, Silins (2007) argues that White hasn't actually shown that DG and Bayesianism are incompatible. Although I agree on this conclusion, I'm not satisfied with Silins's argument.16 Before articulating my own argument – which I believe is more compelling – let me explain the reasons of my discontent with Silins's. Recall that the salient formal result of White's second objection is given by the following inequality: CrE(P) < Cr(~SH). White takes – or seems to take – this formula to contradict DG. Silins (2007: 131) responds that this inequality doesn't establish that my having independent justification for believing ~SH is a condition necessary and basing for my acquiring perceptual justification for P. White's inequality can at best establish – according to Silins – that my having independent justification for believing ~SH is a condition necessary for my acquiring perceptual justification for believing P. Since DG doesn't disallow conditions for perceptual justification that are necessary but not basing, White's inequality doesn't contradict DG. To bolster his response, Silins gives examples of other conditions for perceptual justification that appear necessary but not basing (cf. Silins 2007: 131-132). Let us consider two of them. Take the conceptually true proposition that (Q) a hand is a hand. I always have justification for believing Q if I possess the concepts required to entertain Q. Note that my learning E gives me justification for believing that (P) this is a hand only if I have the concepts required to entertain P, which include – presumably – the very concepts required to entertain Q. Consequently, whenever my experience gives me justification for believing P, I also have independent justification for believing Q. My having independent justification for Q is thus a necessary condition for my having perceptual justification for P but it doesn't look like a basing condition for it. For instance, no part of my perceptual justification for P seems to exist in 15 All these proposals aim at a formal vindication of the thesis that when I learn E, my degree of justification for ~SH increases. To achieve this, Pryor (insofar as I understand him) replaces the standard credence function with an original superadditive credence function, Weatherson switches to imprecise probabilities and introduces a non-standard conditionalisation procedure, Kung re-interprets the standard notion of incremental confirmation to the effect that a proposition e can confirm a proposition p even if Cr(p|e) ≤ Cr(p). 16 Also note that Silins (2007: §3.2) concedes that White's first objection goes through. It will shortly be apparent that I disagree. 13 virtue of, among other things, my independent justification for believing Q. Consider now the contingent proposition that (Q*) I exist. Presumably, whenever I have perceptual justification for believing P, I also have a cogito-style independent justification for believing Q*. In this case too my having independent justification for Q* is a necessary condition for my having perceptual justification for P but it doesn't appear to be a basing condition for it. Silins's response to White is ingenious but it seems to me to be fairly questionable. Compare the following two propositions: (B1) If I have justification for believing P when I learn E, I have it on the basis of, among other things, my independent justification for Q (or Q*). (B2) If I have some degree of justification for P when I learn E, I have it on the basis of, among other things, my higher degree of independent justification for ~SH. If B2 is true, my having a higher degree of independent justification for ~SH is a condition necessary and basing for my having some degree of perceptual justification for P. I agree with Silins that B1 is blatantly false. Yet B2 doesn't look false when examined in light of White's inequality according to which CrE(P) < Cr(~SH). Quite the reverse, once it is granted that degrees of justification are intimately related to degrees of rational credence, the claim that If I have some degree of justification for P when I learn E, this justification exists in virtue of, among other things, my higher degree of independent justification for ~SH would seem to be the most natural explanation of why CrE(P) < Cr(~SH). (Or, at any rate, many epistemologists would claim so.) Thus White's inequality would seem to give us a reason to accept B2 through an inference to the best explanation.17 B2 entails that my having a degree of 17 It is worth stressing that Silins (2007) gives no explanation (or no good explanation) of how it can be the case that CrE(P) < Cr(~SH) if my having a higher degree of independent justification for ~SH is a condition only necessary but not basing for my having some degree of perceptual justification for P. In particular, the interesting philosophical view that Silins outlines in his paper – called rationalist liberalism – entails that my having independent justification for believing ~SH (note: not higher independent justification for ~SH) is a condition necessary but not basing for my having perceptual justification for believing P (cf. Silins 2007: 132-133). (In a nutshell this views says that: (1) E gives me immediate justification for believing P; (2) I can have justification for believing P from E only if I have no reason to suspect that SH is true; (3) if I have no reason to suspect that SH is true, I'm entitled to believe ~SH – i.e. I have independent justification for believing ~SH.) Since rationalist liberalism leaves it indeterminate whether my necessary but not basing independent justification for ~SH must be higher or lower than or equal to my perceptual justification for P, I don't see how the truth of this view could constitute an explanation (or at least a good explanation) of White's inequality. One could take the inability of rationalist liberalism to explain this neat inequality to be evidence against it. Silins's rationalist liberalism has been independently criticised by Kotzen (2012). 14 independent justification sufficiently high to sustain full belief in ~SH is a condition necessary and basing for my having a degree of perceptual justification sufficiently high to sustain full belief in P. This claim would seem to be incompatible with DG because it seems to entail that my experience as if P cannot give me immediate justification for believing P. For these reasons I don't find Silins's response to White convincing. I suspect that many epistemologists will share my concerns. Rather than attempting to improve on Silins's case, let me present a completely different argument for the claim that dogmatism and Bayesianism are compatible that appears to me to be less moot and more straightforward. White (2006) relies on a formal model in which empirical evidence is a believed proposition about an experience – i.e. one's introspective belief that one has a given experience. Thus empirical evidence turns out to be a content believed. In contrast, we saw that for the dogmatist empirical evidence is a content experienced rather than believed. The basic source of difficulties for both of White's objections is that they presuppose a notion of perceptual evidence that is not the one distinctive of dogmatism. Consequently, these objections are incapable of striking the dogmatist's notion of perceptual justification. Let me now expand on this response. We have seen that for the Bayesian Cre(p) refers the degree of credence in p that a subject should rationally have when she learns e – i.e. when she comes to believe e to the highest possible degree. Accordingly, CrE(P), CrE(SH) and CrE(~SH), in White's objections, refer to the degrees of credence in respectively P, SH and ~SH that I should have when I come to believe E to the highest possible degree, where E is proposition that it appears to me that P. To model the dogmatist's notion of perceptual justification one should use a different formalism capable of symbolising the credence in P, SH and ~SH that I should have when I experience as if P.18 White's model is thus misrepresentative in two senses: (1) it replaces the content P with the different content E and (2) it replaces an experience with a belief. Since the expressions CrE(P), CrE(SH) and CrE(~SH) don't refer to the credence in P, SH and ~SH that I should have when I experience as if P, the conclusions 18 Note that I'm not denying that there is an intimate link between experience-based justification and rational credence. What I'm simply suggesting is that the notion of rational credence intimately related to the notion of experience-based justification cannot adequately be modelled by a Bayesian credence function. 15 of White's arguments cannot affect – at least directly – the dogmatist's theses about perceptual justification.19 One might try to reformulate White's objections by replacing E with P itself. This would help cope with problem (1) but not with problem (2). For CrE(P), CrE(SH) and CrE(~SH) will turn into CrP(P), CrP(SH) and CrP(~SH), which refer to the degrees credence in P, SH and ~SH that I should have when I come to believe P to the highest possible degree. One might contend that since experiencing as if P and coming to believe P have similar evidential consequences for the subject, the second can be taken to be a close surrogate for the first. Whether or not this is in general correct, coming to believe P to the highest possible degree doesn't seem to be a close surrogate for experiencing as if P. An important difference is that while one's experiencing as if P is compatible with one's rationally doubting P, one's coming to rationally believe P to the highest possible degree is not. A more crucial problem with replacing E with P is that this operation would make the resulting re-formulations of White's objections inconclusive. These re-formulations would go through only if it turned out that my learning P should lessen (or at least should not boost) my credence in ~SH. For this would parallel the crucial proposition in White's both objection that my learning E should lessen my credence in ~SH. Yet note that since P entails ~SH and Cr(P) > 0, it follows that CrP(~SH) = 1. Since I shouldn't be just certain that ~SH, Cr(~SH) < 1. Hence CrP(~SH) > Cr(~SH). Thus the result is that my learning P should boost my credence in ~SH. One might suggest replacing E with P while using Jeffrey conditionalisation instead of standard conditionalisation. Jeffrey conditionalisation enables a rational subject S to update her credence function on the grounds of uncertain evidence – i.e. on the grounds of a mere change of her credence in an evidential proposition that may not coincide with S's coming to believe that proposition to the highest possible degree. Suppose Crold is S's credence function before S's 19 This problem affects White's objections independently of their synchronic or diachronic formulation. In White's original synchronic formulation CrE(P), CrE(SH) and CrE(~SH) are replaced by the conditional credences Cr(P|E), Cr(SH|E) and Cr(~SH|E), which refer to the credence in P, SH and ~SH that I should rationally have if I believed E to the highest possible degree. Thus, again, P is replaced with E and an experience is replaced with a belief. 16 acquiring evidence y, and Crnew is S's credence function upon her acquiring evidence y. Let x be any proposition on which Crold is defined. On Jeffrey conditionalisation, Crnew(x) = Crnew(y) Crold(x|y) + Crnew(~y) Crold(x|~y). This says that S's credence in x upon S's changing her credence in y is equal to the sum of two things: the product of S's new credence in y by S's conditional credence in x given y before S's changing her credence in y, and the product of S's new credence in ~y by S's conditional credence in x given ~y before S's changing her credence in y. Switching to Jeffrey conditionalisation would enable me to update my credence function on the basis of a mere increase in my credence in P (which wouldn't coincide with my becoming certain that P). One might insist that a mere increase in my credence in P is a close surrogate for my experiencing as if P. However this suggestion is also doomed to fail, for the resulting re-formulations of White's objections are inconclusive. These re-formulations would go through only if my acquiring uncertain evidence P should lessen (or at least should not boost) my credence in ~SH. But this turns out to be false. For on Jeffrey conditionalisation it holds true that if (i) Crnew(P) > Crold(P) and (ii) Crold(~SH|P) > Crold(~SH), then (iii) Crnew(~SH) > Crold(~SH). Since the suggestion we are inspecting here is to the effect that my credence in P raises, (i) is satisfied. Furthermore, P entails ~SH and Crold(P) > 0, thus Crold(~SH|P) = 1. As I shouldn't be certain that ~SH, Crold(~SH) < 1. Thus Crold(~SH|P) > Crold(~SH). So (ii) is satisfied too. Hence (iii) is true: my acquiring uncertain evidence P should boost my credence in ~SH. One might contend that White's original objections hit dogmatism indirectly because, even though experiences are not beliefs about experiences, experiences and correlated introspective beliefs have the same evidential force. The contention would precisely be this: since my introspective belief that (E) I experience as if P lessens my justification for ~SH, my sole experience as if P should also lessen my justification for ~SH. White appears to endorse this view.20 For instance, White (2006: 535) assumes that if I have the experience as if P together with the introspective belief that E, the strength of my justification for ~SH should be identical to the 20 And so does Silins (2007: 120, note 17). 17 strength of my justification for ~SH depending on my sole belief that E. This means that – as we have seen – the strength of my justification for ~SH should decrease. (I agree with White on this point. I'll return to it shortly.) White then suggests that: If the rational response to its appearing that [P] this is a hand, when I also believe that [E] it appears that this is a hand, is to decrease my confidence that [~SH] it is not a fake-hand,21 then surely this is the rational response to the same experience [as if P] when I do not even consider how things appear to me. (2006: 535) Thus, for White, my experience as if P alone should lessen my justification for ~SH, exactly as my belief that E does. If White's suggestion is correct, the dogmatist can be targeted by two informal objections that parallel White's formal arguments. First, suppose my experience as if P raises my justification for P so that I have prima facie justification for believing P. As this experience doesn't boost my justification for ~SH, my justification for P cannot transmit to ~SH. Second, since I know that P entails ~SH and justification is closed under known entailment, I can have prima facie justification for P when I experience as if P only if I have justification for ~SH. But my experience as if P can make me acquire no justification for ~SH. Thus I can have prima facie justification for believing P when I experience as if P only if I have independent justification for believing ~SH. One might find it intuitive that experiences and correlated introspective beliefs have the same or similar evidential force. However our intuitions about this matter seem to depend crucially on the conception of perceptual evidence we presuppose. If one adopts the dogmatist conception, one will naturally conclude that experiences and correlated introspective beliefs can have very dissimilar evidential force. Consider again E and P. Note that the content of the belief that E (the proposition that it appears to me that this is a hand) and the content of the experience as if P (the proposition that this is a hand) do not stand in the same logical relation with SH (the proposition that this is a fake-hand). Consequently, believing E and experiencing as if P will not have – presumably – the same evidential consequences for SH. As I know that SH entails E or makes E highly probable, it is intuitive that my learning E should boost my justification for SH and thus lessen my justification for 21 White's original passage omits 'not' and literally reads 'it is a fake-hand'. This is certainly a typo. 18 ~SH. On the other hand, as I know that P is logically incompatible with SH, it is very counterintuitive that my experience as if P – in which it seems to me to ascertain that P – should boost my justification for SH. The dogmatist is not committed to this odd claim. She will make the more plausible claim that, since I know P to be incompatible with SH, my experience as if P will lessen my justification for SH and thus boost my justification for ~SH. This claim doesn't conflict with Bayesian principles because the evidence here is an experience and not a belief. Bayesianism has – so to speak – no jurisdiction over this epistemic transaction. If my experience as if P alone boosts my justification for ~SH, the informal objections to dogmatism don't take off the ground. To complete my response to White's arguments let me now focus on a last epistemological issue that will also prove relevant for the topic of the next section. The dogmatist can surely generalise the thesis that my experience as if P and my belief that E have divergent evidential force with respect to ~SH to other epistemic subjects and propositions. Consider any content of experience p (in Pryor's sense) of any subject S capable of entertaining beliefs about her own experiences. The dogmatist can contend that the evidential force of S's experience as if p with regard to a proposition x and the evidential force of S's belief that (e) S experiences as if p with regard to the same proposition x need not coincide and may diverge. If this is true, an important question is how the evidential force of S's experience as if p and the evidential force of S's belief that e should work together to determine S's justification for x. It appears intuitively true that when the strength of the justification that S's belief that e supplies for a proposition x can be determined by S, the justification that S's mere experience as if p supplies for x becomes irrelevant for S's epistemic status with regard to x. We can express the same epistemological thesis by saying that the evidential import that S's mere experience as if p has for x will be overruled by the evidential import that S's belief that e has for x whenever the latter import can be determined by S. Note that when the evidential import that S's experience as if p has for x is overruled by the evidential import that S's belief that e has for x, the degree of S's all things considered justification for x (i.e. the justification for x that S possesses when she has both the 19 experience as if p and the belief that e) will trivially coincide with the degree of S's justification for x based on S's belief that e. To sense the intuitive plausibility of the above epistemological considerations, let us consider this simple thought experiment. Suppose I face a randomly chosen wall in a square room. Since my eyes are shut, I cannot see the colour of the wall. I'm reliably told, however, that the room has two white walls and two red walls. One of the white walls is illuminated by a hidden red light, so that it would appear to me to be red, but the other three walls are illuminated by natural light. Let us stipulate that: R = 'The wall is red'. B = 'It appears to me that the wall is red'. SH* = 'The wall is white but looks red because it is illuminated by a hidden red light'. It is easy to determine the strength of my prior justification for R, B and ~SH* (i.e. before I open my eyes). Given my background information, I should assume that Cr(R) = 1/2, Cr(B) ≅ 3/4 and Cr(~SH*) = 3/4. Since the threshold for justification for full belief is presumably very high and near to 1, I don't have prior justification for fully believing R or ~SH*. Given my background information, it is also easy to determine the strength of the justification that I would have for R and ~SH* if I believed B. Since Cr(R) = 1/2, Cr(B) ≅ 3/4 and Cr(~SH*) = 3/4, considering that Cr(B|R) ≅ 1 and Cr(B|~SH*) ≅ 2/3, it follows through Bayes theorem22 that Cr(R|B) ≅ Cr(~SH*|B) ≅ 2/3. By conditionalising, CrB(R) ≅ CrB(~SH*) ≅ 2/3. Thus, even if I came to believe B, I would not have justification for fully believing R or ~SH*. Note that Cr(~SH*) = 3/4 > CrB(~SH*) ≅ 2/3. This indicates that if I believed B, my justification for ~SH* would actually drop, in accordance with White's first objection. Now imagine I open my eyes and I experience as if R. Suppose I acquire prima facie immediate justification for fully believing R. Since my experience gives me the feeling of verifying just R, which is incompatible with SH*, I will lower my justification for SH* and thus boost my 22 According to which Cr(R|B) = Cr(R) Cr(B|R) / Cr(B) and Cr(~SH*|B) = Cr(~SH*) Cr(B|~SH*) / Cr(B). 20 justification for ~SH*. In particular, since I have prima facie justification for fully believing R and I know that R entails ~SH*, I will acquire via transmission from R prima facie justification for fully believing ~SH* too. Yet suppose that after experiencing as if R, I reflect on my mental states and come to believe B. Since I can know the strength of the justification that this belief gives me for R and ~SH*, my experience as if R will cease to be evidentially relevant for R and ~SH*. And my all things considered justification for R and ~SH* will be determined by the above Bayesian inferences. Accordingly, I will not possess all things considered justification for fully believing R or ~SH*. Let me outline another thought experiment that will hopefully persuade the reader still unconvinced that the evidential force of my experience as if R should be overruled by the evidential force of my belief that B if the latter force is determinable. Suppose an oracle, who I know to be virtually infallible, has just told me that I will have the experience as if R at t. Thus now I already believe B23 (suppose my confidence in B is as strong as if I were already at t and had that experience). Also imagine that now I have sufficient information to determine the justification that my believing B gives me for R and ~SH*. Suppose that then, at t, I experience as if R. It is strongly intuitive that my justification for R and ~SH* should not change at t. Since I can determine the strength of the justification that my belief that B gives me for R and ~SH*, this justification overrules the justification that my sole experiencing as if R gives me for R and ~SH*. As we saw in §4, White contends that his thought experiment about playing cards offers a clear example of the fact that my experiencing as if P (the proposition that this is a hand) lowers my justification for ~SH (the proposition that it is not the case that this is not a fake-hand). I'm now in the position to suggest a response to this contention on the dogmatist's behalf.24 The dogmatist can argue as follows: White's thought experiment shows at best that my experience as if P and my introspective belief (E) that I have that experience together lower my justification for ~SH. White's 23 To prevent misunderstandings let's make the implicit temporal references in B, R and ~SH* explicit. Thus B = 'It appears to me at t that the wall is red at t', R = 'The wall is red at t', and ~SH* = 'At t the wall is white but looks red because it is illuminated by a hidden red light'. 24 White's second, statistical example can be "defused" by the dogmatist in a similar way. 21 thought experiment does not show, however, that my sole experience as if P lowers (or even doesn't change) my justification for ~SH. White's thought experiment could in fact be described as proceeding along the following three contiguous stages: at t0, before lifting my arm, I don't have justification for fully believing P or ~SH. At t1 I lift my arm and have the experience as if P. This experience makes me acquire prima facie justification for fully believing P and, via epistemic transmission, for fully believing ~SH. At t2 I reflect on my experience and come to believe E. My all things considered justification for ~SH comes now to coincide with the justification that my belief that E bestows on ~SH, which is lower than my prima facie justification for it at t2 and even than my initial justification for ~SH at t0. Thus the justification that decreases in White's thought experiment is my all things considered justification for ~SH. But this doesn't happen to my prima facie justification for ~SH, resting on my sole experience as if P, which instead increases. One might be puzzled by the claim that there are evidential transactions like those described by the dogmatist that, as I have argued in this section, are inexplicable in Bayesian terms. Why are there epistemic transactions of this sort if, as we have seen, the subject S should override their results as S reflects on her evidence and successfully applies Bayesian reasoning? The dogmatist can respond that we often attribute perceptually justified beliefs to beings incapable of reflecting on their experiences (such as small children and perhaps animals). If there existed no evidential transactions independent of introspective beliefs, we couldn't easily make these attributions. The dogmatist could add that there may be cases in which even if S can reflect on her own perceptual evidence, S has insufficient background information to be able to draw Bayesian inferences. In these situations S cannot override the results of her non-Bayesian transactions, so S should stick to these results. (I return to this in the next section.) Let us consider our outcomes so far: we saw that White's Bayesian arguments can directly hit neither the dogmatist's thesis DG according to which my experiencing as if p can (and will often) give me prima facie justification for believing p that is not based on independent justification for ~sh, nor the dogmatist's thesis that this justification for p (if available) transmits to ~sh across the 22 entailment. We saw, furthermore, that White's contention that the Bayesian arguments indirectly strike the above two theses can be rejected by the dogmatist without questioning Bayesian methodology. We can conclude that White has not shown that dogmatism and Bayesianism are incompatible. 6. Does dogmatism have an antisceptical bite? Despite the above positive result, one could still argue that dogmatism doesn't have the antisceptical punch that Pryor maintains it has. A simple argument for this conclusion is the following: consider any rational subject S capable like most of us of introspection, and any possible content p of S's experience. The dogmatist can claim that S's experience as if p can (and will often) give S immediate prima facie justification for believing p and, via transmission, prima facie justification for believing ~sh (where sh is any non-perceiving alternative to p incompatible with p). The dogmatist should concede, however, that upon having the experience as if p, S should introspect herself and come to entertain the belief that (e) she has that experience. For this process would give S further evidence relevant for her appraisal of p and ~sh.25 Suppose then that S entertains the belief that e. As a consequence, the evidential force of S's sole experience as if p for p and ~sh will be overruled by the evidential force of that introspective belief of S. Thus whether or not S has justification for believing p and ~sh will actually depend on the support that S's belief that e supplies for p and ~sh, whereas the support that S's experience as if p offers for p and ~sh will prove irrelevant for it. The result is that whether or not perceptual scepticism can be rebutted depends on whether or not the mediate justification produced by S's introspective beliefs suffice to sustain S's beliefs about her environment, but it clearly does not depend on any immediate justification that S's experiences could produce. This shows that dogmatism has no real antisceptical punch for subjects like us capable of introspection. 25 Refraining from doing so would make S epistemically irresponsible. 23 Can the dogmatist resist this conclusion? I'm unable to settle this question here, as this would require a thorough investigation that I cannot carry out in the remainder of this paper. To contribute to the discussion on this issue I can only make two related suggestions. First, a rejoinder to the above argument seems to follow quite naturally from an assumption about the general setting of the debate on perceptual scepticism made by some advocates of dogmatism. Second, this assumption would prove false, and the rejoinder ineffective, if the controversial thesis that we can determine our prior credences in hypotheses and conjectures by inspecting their extra-empirical virtues turned out to be true. Thus whether or not dogmatism has an antisceptical bite seems to depend on the truth of this controversial thesis. Let us start with my first suggestion. Pryor (manuscript) and Kung (2010) appear persuaded that: (U) When we engage in discussion with the perceptual sceptic we should take the epistemic subject S to possess no default evidence for any non-perceiving alternative sh or its negation ~sh.26 For example, Pryor (manuscript) states that the situations in which dogmatism is meant to apply to respond to the perceptual sceptic – so, presumably, the typical situations adduced by the perceptual sceptic – are those in which the epistemic subjects can conceive of some non-perceiving alternative sh 'but are wholly uninformed about it' (5, my emphasis). Kung (2010) describes the same situations as those in which 'the subject has no [default] reason to believe any skeptical alternative [sh] to p' (7), where 'to have no reason to believe that sh ... is to possess no considerations in favor of either sh or ~sh'27 (2, edited). Unfortunately neither Pryor nor Kung has provided an explicit defence of U. Both of them concede that S could in principle acquire default evidence for sh or ~sh on the grounds of her knowledge of the chance or objective probability of sh (cf. Pryor, manuscript: §6 and Kung 2010: 5-6). They seem to assume, however, that when perceptual scepticism is the object of discussion, 26 Weatherson (2007) might also accept U though I'm not completely sure. 27 For Kung (2010) a reason for sh is 'some cognitively accessible state that counts in favor of sh. It does not have to count very strongly in favor of sh; the reason may be far from strong enough to justify you in believing that sh' (2, edited). 24 we cannot take S to know the objective probabilities of sh. This assumption is very plausible if this knowledge is meant to come from perceptual evidence. Suppose we allowed S to know the objective probability of sh from, say, the relative frequency of the instantiations of the hypotheses of the same type as sh, where these instantiations are known by perception. Since the sceptic just claims that we cannot perceptually know anything, this would presumably beg the question against the sceptic. More generally, any explanation of S's having default evidence for sh or ~sh resting on the presupposition that S has perceptual knowledge would be an easy target of the objection that it begs the question against the sceptic. Let us suppose for the moment that U is correct. To defuse the argument against the antisceptical bite of dogmatism outlined at the beginning of this section, the dogmatist should infer from U – saying that S has no default evidence for sh or ~sh – that S has no way to set Cr(sh) and Cr(~sh), i.e. her prior credences in sh and ~sh. Bayesian objectivists and subjectivists28 are very likely to raise objections. The objectivist may contend that if S has no evidence for sh or ~sh, S is bound to determine Cr(sh) and Cr(~sh) by using some version of the principle of indifference.29 The subjectivist will contend, alternatively, that S is rationally entitled to set Cr(sh) and Cr(~sh) as she likes provided that these two values are probabilistically coherent (and perhaps satisfy some minimal formal constraint).30 The dogmatist can retort by questioning the adequacy of both objectivism and subjectivism when Bayesianism is specifically used to model – like in the present context – epistemic justification. The Bayesian formalism can model the notion of epistemic justification only if the rationality displayed by the credences referred to in its formulae is specifically epistemic (rather than, say, practical or moral). There is today wide agreement – at least among epistemologists sympathetic to internalism – that credences are epistemically rational only if 28 For these varieties see Weisberg (2011). 29 A basic formulation of it says that given a countable set of mutually exclusive and exhaustive hypotheses, if S's evidence doesn't favour some hypotheses over the others, S should distribute equally her credence over all of them. As sh and ~sh are mutually exclusive and exhaustive and S's all evidence cannot discriminate between them, S's credence in either hypothesis should be 1/2. Notoriously, the principle of indifference appears to entail incoherent results. White (2010) has attempted a defence of it. See however Dodd (2013)'s rejoinder. 30 For instance some require Cr to be regular – i.e. to assign 0 and 1 only to respectively contradictions and tautologies. 25 they are suitably supported by evidence (cf. Kelly 2003). The dogmatist should insist that if S sets Cr(sh) and Cr(~sh) in accordance with objectivism or subjectivism in the envisaged situation of lack of evidence, S's prior credences in sh and ~sh would fail to be epistemically rational. It would be implausible that Bayesian formulae could model S's epistemic justification in that case.31 Once the Bayesian objectivist's and the subjectivist's objections have been set aside, the dogmatist can conclude that since Cr(~sh) cannot be determined, Cre(~sh) cannot be determined.32 And that since Cre(~sh) cannot be determined and p entails ~sh so that Cre(p) ≤ Cre(~sh), Cre(p) cannot be determined either. Consequently, if upon experiencing as if p, S forms the introspective belief that e, this belief will have for S no determinable evidential consequences regarding p and ~sh (at least via Bayesian reasoning). Hence S's belief that e will have no determinable evidential consequences for p and ~sh capable of overruling the evidential consequences that S's sole experience as if p has for p and ~sh. If this experience gives S prima facie justification for believing p33 and, via transmission, for believing ~sh, S should hold to this justification as all things considered justification. This seems to show that dogmatism has an antisceptical bite after all. 31 One might perhaps think of other ways to determine Cr(sh) and Cr(~sh) in absence of evidence. Wright (2004 and 2007) for instance contends that even though we have no default evidence for sh or ~sh, we are rationally entitled to accept or trust ~sh. It is unclear however if degrees of acceptance or trust qualify as degree of credence. Furthermore it is quite controversial whether the rationality of Wright's entitlement is genuinely epistemic rather than only pragmatic (cf. Jenkins 2007 and Pritchard 2005). 32 This is why: by definition of conditional credence Cr(~sh|e) = Cr(~sh & e)/Cr(e) with Cr(e) > 0. It follows from the probability calculus that Cr(~sh & e) ≤ Cr(~sh). As Cr(~sh) cannot be determined, Cr(~sh & e) cannot be determined. Thus Cr(~sh & e)/Cr(e) and Cr(~sh|e) cannot be determined. Since Cre(~sh) = Cr(~sh|e), Cre(~sh) cannot be determined either. The same result obtains if conditional credences are taken to be primitive. Suppose T is a tautology. It seems very plausible that if Cr(~sk) cannot be determined, then Cr(~sh|T) cannot be determined. Even if conditional credences are primitive, it holds true that Cr(~sh|e) = Cr(~sh|e & T) = Cr(~sh & e|T)/Cr(e|T) with Cr(e|T) > 0. Furthermore, Cr(~sh & e|T) ≤ Cr(~sh|T). Since Cr(~sh|T) cannot be determined, Cr(~sh & e|T) cannot be determined. So Cr(~sh & e|T)/Cr(e|T) cannot be determined, and neither Cr(~sh|e &T) nor Cr(~sh|e) can be determined. Thus, again, Cre(~sh) cannot be determined. Note that I'm presupposing that Cre(e) = 1; so I use standard conditionalisation. One might insist that Cre(e) should be < 1 and that, consequently, I should use Jeffrey conditionalisation. This would substantially change nothing. On Jeffrey conditionalisation Crnew(~sh) = Crnew(e) Crold(~sh|e) + Crnew(~e) Crold(~sh|~e). Since neither Crold(~sh|e) nor Crold(~sh|~e) can be determined, Crnew(~sh) cannot be determined. The reader can verify that nothing would substantially change if conditional credences were taken to be primitive. 33 The sceptic might attempt to retort as follows: as S cannot determine Cr(p), S cannot determine her degree of default (or independent) justification for p, with the consequence that S's experience as if p cannot give S immediate justification for believing p. But the chances of success of this retort look very dim. If there is anything like immediate perceptual justification for believing p, this justification is by definition not based on any degree of independent justification for any proposition, thus not even on any degree of independent justification for p itself. To make her point, the sceptic should argue that a condition necessary but not basing for S's having immediate perceptual justification for believing p is S's having some degree of independent justification for p. I don't see how the sceptic could substantiate this claim. If immediate perceptual justification could be analysed in Bayesian terms, the sceptic might contend that a 26 Let us turn to my second suggestion. Many epistemologists will probably find U moot or at least suspect. A reason to think so is the following: when we engage in discussion with the perceptual sceptic, it looks question begging to presuppose that we have default evidence for sh or ~sh rooted in perception. It doesn't look question begging, however, to presuppose that we possess default evidence for sh or ~sh rooted in something other than perception. In particular, some philosophers contend that extra-empirical virtues of hypotheses and theories have evidential force. They typically concentrate on explanatory power, considered to be the most comprehensive and fundamental theoretical extra-empirical virtue (see mainly Lycan 2002). A few of these authors champion Bayesianism and suggest that if we have no other source of evidence, we can in principle determine our prior credence in any hypothesis by inspecting its explanatory power. The guiding intuition is that our subjective ascriptions of prior probabilities should mirror our assessments of explanatory power to the effect that hypotheses with higher explanatory power will get higher priors whereas hypotheses with lower explanatory power will get lower priors.34 Proposals of broadly this type have been put forward by, among others, Okasha (2000), McGrew (2003) and Lipton (2004). It is fair to say that both the thesis that explanatory power is a source of evidence and the thesis that evidence coming from explanatory power can be exploited to determine our prior credences are still hotly debated in the literature and appear quite controversial. (For an overview on the state of the discussion see Douven 2011.) Nonetheless, if these theses turned out to be true, U should be rejected. For we should take the epistemic subject S referred to in U to possess at least in principle extra-empirical evidence for determining Cr(sh)35 and thus Cr(~sh),36 for any nonperceiving alternative sh conceivable by her. If this were the case, the argument against the thesis necessary condition for S's determining Cre(p) is S's being able to determine Cr(p) and insist that this condition is not basing. Yet, as I argued in the former section, it is very dubious that immediate perceptual justification can be analysed in Bayesian terms. 34 Although it is admittedly difficult to provide an analysis of the notion of explanatory power, it is uncontroversial that we can very often establish, on an intuitive basis, that a hypothesis does explain the evidence or that it explains it better or worse than other hypotheses. 35 In the same way we should take S to have evidence for determining the correlated Cr(p). 36 Considering that Cr(~sh) = 1 – Cr(sh). 27 that dogmatism has an antisceptical bite outlined at the start of this section would probably go through. 7. Conclusions Dogmatism is an epistemological view worthy of attention and safeguarding: dogmatism makes sense of ordinary epistemic practices and attributions of perceptually warranted beliefs; it also seems to provide the basis for moderate foundationalism. In this paper I have argued that dogmatism is not incompatible with Bayesianism, as White contends. For dogmatism and Bayesianism are meant to account for different types of epistemic justification. Some epistemologists claim that dogmatism has an antisceptical punch. I have given non-conclusive reasons to doubt that this is true. I have suggested that the question of the antisceptical bite of dogmatism is entangled with the question of the evidential force of explanatory power, which is still hotly debated in current epistemology. Acknowledgments I'm very grateful to Catrin Campbell-Moore, Lorenzo Casini, Richard Dawid, Dylan Dodd, AnnaMaria Eder, Filippo Ferrari, Stephan Hartmann, Elisabetta Lalumera, Tommaso Piazza, Soroush Rafiee-Rad, Karim Thebault, Lars Weisbrod, Elia Zardini and a reviewer of this Journal for important comments and criticism upon drafts of this paper. Part of my research was supported by a Visiting Fellowship from the Tilburg Centre for Logic and Philosophy of Science and a Carnegie Grant from the Carnegie Trust for the Universities of Scotland. The final draft of this paper was written at the Munich Center for Mathematical Philosophy (MCMP). I thank the MCMP for hosting me and for providing a stimulating atmosphere to conduct this research. 28 References Dodd, D. (2013). 'Roger White's argument against imprecise credences'. British Journal for the Philosophy of Science 64: 69-77. Douven, I. (2011). 'Abduction'. In E. N. Zalta (ed.) The Stanford Encyclopedia of Philosophy. URL = <http://plato.stanford.edu/archives/spr2011/entries/abduction/>. Huemer, M. (2001). Skepticism and the Veil of Perception. NY: Rowman & Littlefield. Jenkins, C. (2007). 'Entitlement and Rationality'. Synthese 157: 25-45. Kelly, T. (2003). 'Epistemic Rationality as Instrumental Rationality: A Critique'. Philosophy and Phenomenological Research 66: 612640. 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