An Argument for External World Skepticism from the Appearance/Reality Distinction Moti Mizrahi St. John's University motimizra@gmail.com Abstract In this paper, I argue that arguments from skeptical hypotheses for external world skepticism derive their support from a skeptical argument from the distinction between appearance and reality. This skeptical argument from the appearance/reality distinction gives the external world skeptic her conclusion (i.e., that S doesn't know that p) without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments. If this is correct, then this skeptical argument from the appearance/reality distinction poses a new skeptical challenge that cannot be resolved by denying skeptical hypotheses or knowledge closure. Keywords appearance/reality distinction; contextualism; external world skepticism; knowledge closure; skeptical hypotheses 1. Introduction Arguments from skeptical hypotheses for external world skepticism 1 begin by taking any proposition about the external world, p, which, if known, implies that the negation of some skeptical hypothesis is also known, and then concluding that one does not know that p, since one does not know the negation of the skeptical hypothesis. 2 For example: SA Let o be some ordinary proposition about the external world, such as that I have two hands, and let h be a proposition describing some skeptical hypothesis, such as that I am a handless brain in a vat. 1. I know that o only if I know that ¬h. 2. But I don't know that ¬h. 1 Dodd (2012, 338) calls external world skepticism "Cartesian skepticism about knowledge, the view that we don't know many things about the external world, e.g., that I have hands" (emphasis in original). 2 For a skeptical argument that does not proceed from a skeptical hypothesis, see Unger (1971). Cf. Douven and Olders (2008). 2 Therefore, 3. I don't know that o (Greco 2007, 625). Likewise, according to Anthony Brueckner: The skeptical argument, in a nutshell, runs as follows. Choose some external-world proposition that I claim to know, say H = I have hands. By the principle that knowledge is closed under known entailment, if I know H, then I know ~SK = I am not a handless brain in a vat. My evidence does not enable me to know ~SK (Brueckner 2011, 296). 3 As John Greco (2007, 625) notes, the "argument [namely, SA] generalizes," i.e., it applies to any proposition about the external world. In addition to the Brain-In-a-Vat (BIV) hypothesis, made popular by Hilary Putman (1981) (cf. Brueckner 1986), 4 other skeptical hypotheses include Descartes' evil demon or evil genius hypothesis (see, e.g., Vogel 1990 and Schaffer 2010), the dream hypothesis (see, e.g., Brown 2009 and Wilson 2012) and The Matrix (Irwin 2002). 5 In what follows, I argue that arguments from skeptical hypotheses for external world skepticism, like SA, derive their support from a skeptical argument from the distinction between appearance and reality. This skeptical argument from the appearance/reality distinction gives the external world skeptic her conclusion (i.e., S doesn't know that p) without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments. If this is correct, then this skeptical argument from the appearance/reality distinction poses a new skeptical challenge that cannot be resolved by denying skeptical hypotheses or knowledge closure. Here is how I plan to proceed. In Section 2, I will sketch an argument from the appearance/reality distinction for external world skepticism. In Section 3, I will discuss the ways in which this skeptical argument differs from three skeptical arguments that superficially resemble it. In Section 4, I will explain why this skeptical argument poses a skeptical challenge that is different from that posed by arguments from skeptical hypotheses, like SA. In Section 5, I will consider two strategies for replying to the skeptical argument from the appearance/reality distinction and their shortcomings. 2. A Skeptical Argument from the Appearance/Reality Distinction To see why arguments from skeptical hypotheses for external world skepticism like SA derive their support from a skeptical argument from the distinction between appearance and reality, consider premise (2) in SA. Let o be the proposition that I have two hands and let h be the BIV 3 See also Pritchard (2014, 214) and Moretti (2014, 381) on "the underdetermination argument for global external world scepticism according to which we cannot know any contingent proposition h about our environment because any sensory evidence for h equally justifies some sceptical scenario sh alternative to h (e.g., the Cartesian demon scenario or the brain-in-a-vat scenario)." 4 See also Avnur (2011) on BIV and the New Rationalism. 5 See also Hazlett (2006) on justification for "hinge propositions." Cf. Brueckner (2007). On whether skepticism can be tested scientifically, see Walker (2004). 3 hypothesis. If BIV were true, would o be false? Yes; if I am a BIV, then I do not have hands. Why, then, premise (2) is false? Well, if I were a BIV, everything would appear just the same. In other words, if I were a BIV, it would appear to me as though o were true. And if I were not a BIV, it would still appear to me as though o were true. That is to say, whether I am a BIV or not, it would appear to me as though o were true. That is why I do not know that I am not a BIV. The same goes for any skeptical hypothesis. 6 If this is correct, then support for premise (2) in SA comes from an argument like the following: (2.1) S knows that ¬h only if S can distinguish between it being the case that h and it appearing to S that h. (2.2) It is not the case that S can distinguish between it being the case that h and it appearing to S that h. Therefore, (2.3) S doesn't know that ¬h. This argument in support of premise (2) in SA is based on "the distinction between 'appearance' and 'reality', between what things seem to be and what they are" (Russell 2008, 10). 7 It is generally acknowledged that it might appear or seem to S that p even if it is not the case that p. For example: (S1) It seems that the pencil in the glass of water is broken. But it is not broken, as is evident when it is taken out of the glass. To see that the appearance/reality distinction, and hence the failure to distinguish between it being the case that p and it appearing to S that p, applies to sensory modalities other than vision, consider the following: (S2) It seems that the water in the bucket is warm. But the water is not warm. The water feels warm to my touch because my hand was in cold water before I put it into this bucket. (S3) It seems to me that this lemon is sweet. But the lemon is not sweet. It simply tastes sweet because I just had some miracle fruits before I ate this lemon. With this understanding of the appearance/reality distinction in hand, it becomes clear that premise (2.1) effectively says that distinguishing between appearance (i.e., that it appears to S as if p) and reality (i.e., that p) is a necessary condition for knowledge about the external world. If p and the appearance as if p are indistinguishable to S, then S doesn't know that p. To see why, consider the case of the pencil in a glass of water. It appears as if the pencil is broken. But this is 6 Cf. Melchior (2014) on skepticism and sensitivity. 7 See also Rescher (2010) on the appearance/reality distinction, although Rescher (2010, 17) thinks that "the salient lesson of acknowledging a potential discrepancy between Reality and Appearance is emphatically not that skepticism is true and that secure knowledge is unavailable." 4 a mere appearance. In reality, the pencil is not broken. To find out the truth about this state of affairs, I cannot rely simply on appearances. If I were to rely on appearances alone, I would believe falsely that the pencil is broken. To further illustrate premise (2.1), consider the analogy known as Plato's Cave (The Republic, Books Six and Seven): Seated prisoners, chained so that they cannot move their heads, stare at a cave wall on which are projected images. These images are cast from carved figures illuminated by a fire and carried by people on a parapet above and behind the prisoners. A prisoner is loosed from his chains. First he sees the carved images and the fire. Then he is led out of the cave into 'real' world. Blinded by the light of the sun, he cannot look at the trees, rocks and animals around him, but instead looks at the shadows and reflections (in water) cast by those objects. As he becomes acclimatized, he turns his gaze to those objects and finally, fully acclimatized, he looks to the source of illumination, the sun itself (Silverman 2012). In Plato's Cave, everything is not as it seems. All that the prisoners in Plato's Cave see is appearances-mere images or shadows-not reality. For example, when the released prisoner comes back to Plato's Cave, his shadow on the cave's wall appears to the prisoners as black. But this is a mere appearance. The prisoner himself is not a black shadow. The point, then, is that, in Plato's Cave, things are not as they appear. As long as one is in Plato's Cave, one cannot distinguish between appearance and reality, for things would appear exactly the same to one, either way. Now, let h be a proposition describing Plato's Cave. Can S distinguish between h and the appearance as if h? No; because, whether h obtains or not, everything would appear to S exactly the same. Now, let p be the proposition that the returning prisoner is shadowy black. If h (= Plato's Cave) were true, would p (= the returning prisoner is shadowy black) be true? No; because if S is in Plato's Cave, then S is merely looking at a shadow, not the returning prisoner. Hence, to know that p, S must be able to distinguish between p and the appearance as if p. How can S tell whether p is a mere appearance or p is really the case? In order to distinguish between appearance and reality, there must be some way to examine p independently of the appearance as if p. If S is in Plato's Cave, however, then there is no way to examine p independently of the appearance as if p, for all that S has epistemic access to in Plato's Cave is appearances. To sum up, then, at the core of arguments for external world skepticism from skeptical hypotheses, such as SA, is a premise to the effect that S knows that p only if that p is the case and the appearance as if p is the case are distinguishable to S, since, if any skeptical hypothesis obtains, then p is false contrary to appearances. If distinguishing between appearance and reality is indeed a necessary condition for knowledge about the external world, as I have argued, then the following argument from the appearance/reality distinction for external world skepticism can be made: AR Let p be some everyday proposition about the external world, such as "I have two hands." 5 (3.1) S knows that p only if it being the case that p and it appearing to S that p are distinguishable to S. (3.2) It is not the case that it being the case that p and it appearing to S that p are distinguishable to S. Therefore, (3.3) S doesn't know that p. Accordingly, AR is a skeptical argument that gives the external world skeptic her conclusion (i.e., S doesn't know that p) without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments. 3. How AR Differs from Three Other Skeptical Arguments There are three skeptical arguments discussed in the literature on external world skepticism that some might think bear some resemblance to AR. For this reason, it is worth noting the differences between AR and these skeptical arguments. These skeptical arguments are the following:  the "no good inference" argument (Greco 2000, 86);  a skeptical argument from the indistinguishability principle (Vogel 1997, 15);  a skeptical argument from the underdetermination principle (Pritchard, forthcoming, Ch. 2 §1). According to the "no good inference" argument, there can be no knowledge about the external world because "knowledge [about the external world] requires good inferences" (Greco 2000, 104) but "there is no good inference from how things appear to how things are" (Greco 2000, 86). Like AR, then, Greco's "no good inference" argument appeals to the appearance/reality distinction. Unlike AR, however, Greco's "no good inference" argument asserts that good inferences (specifically, some good inference between "it appears as if p" and "p") are a necessary condition for knowledge about the external world, whereas AR asserts that distinguishing between appearance and reality is a necessary condition for knowledge about the external world. According to AR, then, there can be no knowledge about the external world, not because there is no good inference from "it appears to S that p" to "p", but because there is no way to distinguish between how things appear and how things are, whether any way of distinguishing between appearance and reality, if there is one, involves inference or not. In other words, on both Greco's "no good inference" argument and AR, knowledge about the external world cannot be had because a necessary condition for such knowledge cannot be fulfilled. However, on Greco's "no good inference" argument, the necessary condition is one of inferring p from the appearance as if p, whereas on AR the necessary condition is one of distinguishing between p and the appearance as if p. 6 According to the indistinguishability principle, "if x and y are indistinguishable to you, then you can't know by perception that (you are confronted with) x and not y" (Vogel 1997, 15; emphasis in original). As Vogel explains (1997, 16), "the variable 'y' [...] range[s] over all merely possible entities (or, perhaps, merely possible states of affairs)" (emphasis in original). To make a skeptical argument from the indistinguishability principle, Vogel provides the following skeptical scenario: [The skeptic will argue that] being in Homer's presence and being in the presence of a suitably rigged computer are indistinguishable to you, just as the presence of Homer and the presence of Rex [who are identical twins] are. Hence, you don't know by perception that you are in the presence of Homer instead of the computer. Then, unless your belief that you are in Homer's presence is shored up in some other way, the skeptic's full conclusion will follow: you don't know you are in Homer's presence at all (Vogel 1997, 15; emphasis in original). As I understand it, then, the skeptical argument from the indistinguishability principle involves an appeal to skeptical hypotheses, such as the skeptical scenario quoted above, given that y ranges over possible states of affairs, which include skeptical hypotheses like BIV. In other words, the "skeptic holds that we have no reason at all for believing that we aren't victims of massive sensory deception" (Vogel 1997, 18; emphasis in original). In AR, on the other hand, there are no appeals (explicit or implicit) to skeptical hypotheses or massive sensory deceptions. Instead, AR proceeds from the premise that S must be able to distinguish between some proposition about the external world, p, being true and it appearing to S as if p is true in order to know that p is indeed true. Hence, as far as AR is concerned, the only variables that matter are variables that range over everyday propositions about the external world (and epistemic subjects, of course), not propositions about possible state of affairs, skeptical hypotheses, or massive sensory deceptions. Such everyday propositions about the external world are supposed to be the sort of propositions the non-skeptic thinks we can know. All of this is not to say that one argument is better than another. The indistinguishability argument and AR are simply different ways of raising skeptical doubts. Likewise, the third argument, namely, Pritchard's skeptical argument from the underdetermination principle, is another way of raising skeptical doubts. According to the underdetermination principle, "If S knows that p and q describe incompatible scenarios, and yet S lacks a rational basis for preferring p over q, then S lacks knowledge that p" (Pritchard, forthcoming, Ch. 2 §1). With the underdetermination principle, Pritchard argues, the skeptical challenge can be stated in the form of an inconsistent triad as follows: The Inconsistent Radical Sceptical Triad** (I**) One does not have better rational support for believing an everyday proposition than for believing that one is the victim of an inconsistent radical sceptical hypothesis. (II**) The underdetermination principle. (III**) One has widespread everyday knowledge (Pritchard, forthcoming, Ch. 2 §1). 7 As I understand it, then, the skeptical argument from the underdetermination principle involves an appeal to skeptical hypotheses, such as BIV, given that p and q range over not only everyday propositions about the external world but also skeptical scenarios. Indeed, Pritchard gives BIV as an example of a scenario that is incompatible with everyday propositions about the external world, such as the proposition that I am seated at my desk. But again, as far as AR goes, there are no appeals (explicit or implicit) to skeptical scenarios. Rather, AR proceeds from the premise that S must be able to distinguish between some proposition about the external world, p, being true and it appearing to S as if p is true in order to know that p is indeed true. Hence, as far as AR is concerned, the only variables that matter are variables that range over everyday propositions about the external world, which are the sort of propositions the non-skeptic thinks we can know, not propositions about skeptical possibilities. If AR gives the external world skeptic her conclusion (i.e., that S doesn't know that p) without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments, as I have argued, then it presents a new skeptical challenge that cannot be resolved by denying skeptical hypotheses or knowledge closure. In the next section, then, I explain why AR poses a skeptical challenge that is different from the challenge posed by skeptical arguments like SA. 4. Why AR Poses a New Skeptical Challenge To appreciate the new skeptical challenge posed by AR, we need to understand the ways in which AR differs from SA. In this section, then, I discuss two key respects in which AR differs from SA. To understand these two key respects in which AR differs from SA, and thus presents a new skeptical challenge, we need to keep in mind that a crucial premise in SA is based on an argument like AR. As we have seen, premise (2) in SA is based on an argument like the modus tollens argument from premises (2.1) and (2.2) to conclusion (2.3), which, like AR, is an appeal to the appearance/reality distinction. That is, premise (2) in SA is plausible because things would appear exactly the same to S whether h obtains or not. In other words, whether h obtains or not, it would still appear to S as though o were the case, and thus S cannot distinguish between o and the appearance as if o, which is why S does not know that o. If this is correct, then SA employs a premise, namely, premise (2), which derives its support from an appeal to the appearance/reality distinction, i.e., from an argument like AR. Now, the first key difference between AR and SA is that, unlike SA, AR involves no appeals to skeptical hypotheses. Unlike in SA, appeals to skeptical hypotheses are redundant as far as AR in concerned. For, whether any skeptical hypothesis obtains or not, it is often the case that distinguishing between p and the appearance as if p cannot be done by relying merely on the way things appear to one, as (S1), (S2), and (S3) illustrate. If this is correct, then there is a skeptical argument, namely, AR, which gives the external world skeptic her conclusion (i.e., that S doesn't know that p) without appealing to skeptical hypotheses. Since AR gives the external world skeptic her conclusion (i.e., S doesn't know that p) without appealing to skeptical hypotheses, a contextualist response to skepticism is ineffective as far as resolving the skeptical challenge posed by AR is concerned. According to Keith DeRose 8 (2004, 22-41), for instance, denials of skeptical hypotheses are strong in most contexts. Since AR makes no appeals to skeptical hypotheses, however, denying skeptical hypotheses does not help resolve the skeptical challenge posed by AR. Some might think that there could be contexts in which denials of (3.1) are strong in DeRose's sense. DeRose characterizes knowledge in terms of "strong enough true belief." On DeRose's account, "the strength of S's belief that p is inversely proportional to the closeness of the nearest world where either [p is the case and S disbelieves that p] or [p is not the case and S believes that p] obtain" (Cogburn and Roland 2012, 240). Accordingly, for DeRose, "my belief that I have hands is strong enough to count as knowledge because the closest worlds where I have hands and don't believe that I have hands, or where I lack hands and believe I have hands, are far distant from the actual world" (Cogburn and Roland 2012, 240). Accordingly, given that possible worlds in which skeptical hypotheses obtain are not considered as near as possible worlds in which they do not, a contextualist can argue that denials of skeptical hypotheses are strong in most contexts. As DeRose (1995, 42) puts it, when "the conservational air has cleared," and normal standards of epistemic appraisal are restored, one can safely reject radical skeptical hypotheses. (Cf. Pritchard forthcoming, Ch. 2 §4.) As far as AR is concerned, however, this move will not do for the same reason that it is ineffective as a response to Pritchard's underdetermination-based Inconsistent Radical Skeptical Triad. Just as the underdetermination-based skeptical paradox makes no appeals to epistemic standards, "but rather turns on a perfectly general thesis about the inadequacy of the rational support available to us for our everyday beliefs" (Pritchard, forthcoming, Ch. 2 §4), AR makes no appeals to epistemic standards, but rather turns on our general inability to distinguish between mere appearances and reality. Moreover, as I have argued above, AR doesn't even turn on appels to skeptical hypotheses. Unlike skeptical hypotheses, which are logical, or even metaphysical, possibilities that obtain in possible worlds that are taken to be quite distant from the actual world, mistaking mere appearances for reality is a physical possibility. For this reason, even if denials of radical skeptical hypotheses are strong in most contexts, it is not the case that denials of (3.1) are strong in most contexts, since it is taken to be true in the actual world that we often fail to distinguish between how things appear to be and how they actually are. The second key difference between AR and SA is that, unlike SA, AR does not presuppose any closure principles. Contrary to Brueckner's (2011, 296) reconstruction of the skeptical argument for external world skepticism, there is no need to appeal to the principle that knowledge is closed under known entailment as far as AR in concerned. 8 This is so because AR proceeds from the premise that distinguishing between p and the appearance as if p is a necessary condition for knowledge about the external world rather than a logical consequence of knowing that p. 9 To see this, consider the first premise in Brueckner's version of SA, namely, "if I know H, then I know ~SK" (Brueckner 2011, 296). The antecedent, i.e., "I know that H" is 8 See also Atkins and Nance (2014, 36) who say that "Contemporary discussions of skepticism often frame the skeptic's argument around an instance of the closure principle." They go on to argue that the closure argument for external world skepticism is defective. 9 On knowledge closure, see Hales (1995). On closure and skepticism, see White (1991). Cf. Almeida (2012, 197) who argues that the "skeptic can make do with principles that are weaker than the familiar closure principles." 9 supposed to entail "I know that ~SK" by the principle that knowledge is closed under known entailment. Since it is not the case that I know that ~SK, it follows that I don't know that H. In AR, however, there is no need to assume that knowledge is closed under known entailment. In AR, "it being the case that p and it appearing to S that p are distinguishable to S" is not construed as an entailment of "S knows that p". Rather, "it being the case that p and it appearing to S that p are distinguishable to S" is construed as a necessary condition for knowing that p. 10 In other words, AR proceeds from the assumption that being able to distinguish between it being the case that p and it appearing to S as if p is a necessary condition for knowledge about the external world, not from the assumption that there is any entailment between "S knows that p" and "it being the case that p and it appearing to S that p are distinguishable to S". If this is correct, then, contrary to Duncan Pritchard (2005, 37) who says that "the core radical sceptical arguments all pivot upon the principle that the epistemic operator is closed under known entailments," 11 we have an argument for external world skepticism, namely AR, that does not rely on such a principle. That is to say, there is a skeptical argument, namely, AR, which gives the external world skeptic her conclusion (i.e., S doesn't know that p) without assuming that knowledge is closed under known entailments. Since AR gives the external world skeptic her conclusion (i.e., S doesn't know that p) without assuming that knowledge is closed under known entailments, rejecting knowledge closure is an ineffective move as far as resolving the skeptical challenge posed by AR is concerned. For many epistemologists, "Rejecting knowledge closure is [...] the key to resolving skepticism" (Luper 2012). 12 If the aforementioned considerations are correct, however, then there is an argument for external world skepticism, namely AR, which does not rely on the principle that knowledge is closed under known entailment. Clearly, then, denying knowledge closure will not help meet the skeptical challenge posed by AR. In the next section, I consider two strategies for replying to AR and their shortcomings. 5. Can the Skeptical Challenge Posed by AR be Resolved? I have argued that arguments from skeptical hypotheses for external world skepticism derive their support from a skeptical argument from the appearance/reality distinction. This skeptical argument from the appearance/reality distinction, namely, AR, gives the external world skeptic her conclusion (i.e., that S doesn't know that p) without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments. Insofar as it does not appeal to skeptical hypotheses and does not presuppose knowledge closure, AR poses a new skeptical challenge that cannot be resolved by denying skeptical hypotheses or knowledge closure. So how can the skeptical challenge posed by AR be resolved? In this section, I discuss two potential strategies for addressing the skeptical challenge posed by AR. The first is to reject the appearance/reality distinction altogether. The second is to 10 On negating skeptical hypotheses as a necessary condition for having justified beliefs about the external world, see Silins (2008). Cf. Kotzen (2012). 11 Though cf. Pritchard (forthcoming). 12 See, for example, Nozick (1981, 243-244) and Dretske (2003, 105-118) and (2005, 13-26). Cf. Hawthorne (2005). 10 reject premise (3.1), according to which distinguishing between mere appearances and reality is a necessary condition for knowledge about the external world. I think that both strategies fall short of addressing the skeptical challenge posed by AR. If I am right, then it is not clear how to respond to the skeptical challenge posed by AR, and so more work needs to be done to meet this new skeptical challenge. Let's begin with the first strategy, namely, rejecting the appearance/reality distinction. Dorit Bar-On considers rejecting the appearance/reality distinction as far as content skepticism and self-knowledge are concerned when she writes: As regards ordinary self-knowledge, what this means is that, if we want to adhere to the idea that we possess an especially secure and privileged kind of knowledge of our present states of mind, we must either reject the appearance/reality distinction as it applies to one's own mind or reject the recognitional conception of ordinary self-knowledge (BarOn 2012, 197; emphasis in original). Bar-On (2012, 197) rejects the first disjunct, i.e., denying the appearance/reality distinction, since she does "not see how we can have an objectivist view of mentality while denying that it is possible for things in the mental realm to be different from the way they appear to anyone, including oneself" (emphasis in original). Likewise, if knowledge is factive, then it is difficult to see how we can deny the possibility that things could be different from the way they appear. For, as Timothy Williamson (2000, 40) puts it, "factive mental states are important to us as states whose essence includes a matching between mind and world, and knowing is important to us as the most general factive stative attitude" (emphasis added). So that leaves the second disjunct, i.e., denying that knowledge about the external world requires recognizing that things are as they appear to one, which is the second strategy I have mentioned above. But this move, which amounts to rejecting premise (3.1) of AR, is problematic as well. If knowledge is a factive stative mental state whose "essence includes a matching between mind and world" (Williamson 2000, 40), then knowing that p is true is a matter of knowing that there is such a match. That, in turn, requires access to p independently of S's appearance as if p. That is, knowing that p requires considering the appearance as if p and p independently and recognizing that they match. But there is no way to access p independently of the appearance that p. Our access to the external world is always appearance-mediated. 13 There is no way to access p that is unmediated by appearances in order to determine that it matches the appearance that p. If this is correct, then there is no way to distinguish between p and the appearance as if p. But if p and the appearance as if p are indistinguishable to S, and distinguishing between the two is a necessary condition for knowledge about the external world, then it follows that there can be no knowledge of the external world. If the aforementioned strategies, namely, rejecting the appearance/reality distinction and rejecting (3.1), fall short of resolving the skeptical challenge posed by AR, as I have argued, then it is not clear how to respond to the skeptical challenge posed by AR, and thus more work needs 13 See, for example, Greco (2000, 32). Note that this is not a question of direct versus indirect realism about perception. Even direct realists, like Huemer (2001, 81), accept that "we cannot perceive external objects without having perceptual experiences that represent them." 11 to be done to meet this new skeptical challenge. But the important lesson, I submit, is that our efforts to resolve the skeptical challenge should be focused on the appearance/reality distinction rather than skeptical hypotheses or closure principles. 6. Conclusion In this paper, I have argued that arguments from skeptical hypotheses for external world skepticism derive their support from a skeptical argument from the distinction between appearance and reality. This skeptical argument from the appearance/reality distinction, namely, AR, gives the external world skeptic her conclusion (i.e., that S doesn't know that p) without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments. Insofar as it does not appeal to skeptical hypotheses and does not presuppose knowledge closure, AR poses a new skeptical challenge that cannot be resolved by denying skeptical hypotheses or knowledge closure. The upshot of AR, I submit, is that skeptical challenges can be raised without appealing to skeptical hypotheses or closure principles. If this is correct, then we have been looking for answers to the challenge posed by external world skepticism in the wrong places. 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