Recently, Ernest Sosa (2007) has proposed two novel solutions to the problem of dream skepticism. In the present paper, I argue that Sosa’s first solution falls prey to what I will refer to as the conditionality problem, i.e., the problem of only establishing a conditional—in this case, if x, then I am awake, x being a placeholder for a condition incompatible with dreaming—in a context where it also needs to be established that we can know that the antecedent (...) holds, and as such can infer the consequent, i.e., I am awake. Sosa’s second solution, in terms of so-called reflective knowledge, is shown to land him in the dilemma of either facing yet another conditionality problem, or violating an internalist constraint that he explicitly grants the skeptic with respect to what kind of factors can be legitimately invoked in our account of how we may know the relevant antecedent. For these reasons, I conclude that Sosa has not solved the problem of dream skepticism. (shrink)

Ernest Sosa has proposed two different ways to respond to dreaming skepticism. In this paper I argue that Sosa's first response —which centers on holding that we have no beliefs in dreams— does not appear to be successful against either the hyperbolic or the realistic dreaming skeptic. I also argue that his second attempt to respond to the dreaming skeptic by arguing that perceptual knowledge indeed counts as what he calls "animal knowledge", may succeed but requires (...) us to perform what appears to be some radical surgery on the concept of knowledge; a radical surgery that, as I show, is probably unnecessary to avoid dreaming skepticism. Finally, I sketch some independent considerations why I think that the hyperbolic skeptic's dreaming argument is not acceptable. Ernesto Sosa propone dos maneras de responder al escéptico del sueño. En este ensayo argumento que su primera propuesta, según la cual no tenemos creencias en los sueños, no parece ser una buena respuesta en contra de ninguno de los escepticismos del sueño, de los cuales distingo dos tipos: el hiperbólico y el realista. También argumento que su segunda propuesta para responder al escéptico del sueño, en la que argumenta que el conocimiento perceptual sí cuenta como conocimiento animal, quizá resulte exitosa; sin embargo, ésta requiere llevar a cabo una cirugía radical en el concepto de conocimiento; una cirugía que, como muestro, es probablemente innecesaria para evitar el escepticismo del sueño. Finalmente bosquejo algunas razones independientes por las cuales considero que el argumento del escéptico hiperbólico del sueño no es aceptable. (shrink)

The problem of dream skepticism – i.e., the problem of what can justify one’s belief that they are not dreaming – is one of the most famous problems in philosophy. I propose a way of responding to the problem which is available if one subscribes to the theory that the sensory experiences that we have in dreams consist of images (as opposed to false percepts). The response exploits a particular feature of imagination, viz., that it is not possible (...) to simultaneously have two separate imagistic experiences in the same modality. (shrink)

Based on the distinction drawn by James Conant between Cartesian skepticism and Kantian skepticism, I intend to show that Wittgenstein’s remarks on dreaming should not be understood as a direct attack on the former, as commonly held, but as an indirect attack on it, for Wittgenstein approaches Descartes’ dreaming hypothesis by changing the very problematic at stake. Wittgenstein’s attack on skepticism takes one step back from a question about how to distinguish between dreaming that (...) one is experiencing something and actually experiencing it, for this attack focuses on the linguistic conditions of the possibility of something that the Cartesian problematic takes for granted, that is, the very possibility of saying “I am dreaming.” I also intend to show that Wittgenstein’s remarks on dreaming should be read in light of his claim that skepticism is nonsensical put forward in the Tractatus logico-philosophicus as well in his last writings. More specifically, I intend to show that the words “I am dreaming” are nonsensical in the same sense as the alleged proposition “There are physical objects” and the expression of doubt about the existence of physical objects or the external world. (shrink)

I offer a novel reading in this dissertation of René Descartes’s (1596–1650) skepticism in his work Meditations on First Philosophy (1641–1642). I specifically aim to answer the following problem: How is Descartes’s skepticism to be read in accordance with the rest of his philosophy? This problem can be divided into two more general questions in Descartes scholarship: How is skepticism utilized in the Meditations, and what are its intentions and relation to the preceding philosophical tradition? -/- I (...) approach the topic from both a historical and a text-based analysis, combining textual and contextual research. I examine Descartes’s skepticism against two main traditions in the historical analysis: philosophical skepticism and Aristotelian Scholasticism. I argue that skepticism in the Meditations is intended to oppose and upheave both Scholasticism and skepticism. The intended results of the work are not merely epistemological but also metaphysical and even ethical. Furthermore, these ambitions cannot be neatly distinguished but merge into each other. -/- The third historical context against which the skeptical meditations are examined is the literary genre of meditative exercises, particularly from the 1500–1600’s, which, while religiously and spiritually oriented, likewise provided the practitioner with an enlightened understanding of self-knowledge and their cognitive place in the world on the way to closer spiritual proximity to God. I argue by this reading that the skepticism of the Meditations is an attentive, meditational cognitive exercise that is not merely instrumental and methodological but is to have a genuine and serious (psychologically real) effect on our thinking. The skeptical meditation is not simply a theoretical thought experiment but is to be seriously practiced as a transformative process of reorienting one’s cognitive framework to discover truth, certainty, and a way to a happy, tranquil, and virtuous life. -/- I offer a close reading in the textual analysis of the first three meditations of the Meditations. I argue that the meditative skepticism employed in the work does not reject the previous beliefs but suspends judgment on them, withdrawing assent until further evidence can be found. I introduce a new term into Descartes scholarship in this analysis, based on the terminology of ancient skepticism: Cartesian epochē (gr. epochē, suspension, withdrawal). Instead of rejecting previous beliefs or assenting to the probably false, the skeptical procedure of the Meditations is argued to emulate in important ways the suspension of judgment on equally balanced reasons in ancient Pyrrhonian skepticism. Novel interpretations are presented along the way of the will’s freedom, of the First Meditation’s skeptical scenarios, of the cogito, and of the vindication of metaphysical certainty, as well as a clarification of the Cartesian Circle problem. -/- Reinterpreting the relation of Descartes’s skepticism to the preceding historical and literary traditions leads to a new look at the skeptical method itself. Presenting a new interpretation of skepticism in the Meditations leads at the same time to a new look at its relation to the historical context. The two research questions are, then, intrinsically tied together. -/- My focus in the study is on the Meditations, but I also reference and discuss Descartes’s other philosophical works, as well as his correspondence, when necessary. (shrink)

J. L. Austin’s attitude towards traditional epistemological problems was largely negative. They arise and are maintained, he charged, by “sleight of hand,” “wile,” “concealed motives,” “seductive fallacies,” fixation on a handful of “jejune examples” and a host of small errors, misinterpretations, and mistakes about matters of fact (1962: 3- 6, 1979: 87). As these charges indicate, he did not offer a general critical theory of traditional epistemological theorizing or of the intellectual motivations that lead to it. Instead, he subjected individual (...) arguments to piecemeal criticism, patiently showing how things go awry in conception, motivation, argumentation, and plain fact. The work was incremental, but the goal was radical: to reduce large edifices to rubble. As he put it regarding certain sense datum theories, “the right policy is to go back to a much earlier stage, and to dismantle the whole doctrine before it gets off the ground” (1962: 142). It is often said that Austin’s criticisms were linguistic, but this is only partly right. While he occasionally charges traditional epistemologists with misusing crucial words and relying on unregulated and inadequately motivated technical terms, he also charges them with factual errors and with distorting or misunderstanding the procedures involved in epistemically evaluating people’s claims and beliefs. For this reason, it is best to see Austin as criticizing traditional epistemological puzzles and projects from the point of view of our ordinary lives (including our best scientific theories and practices). He starts with a commitment to our ordinary ways of using words, our ordinary convictions about.. (shrink)

Explore's al-Ghazāli's skeptical methodology in Deliverance from Error.

In this paper I aim to elucidate Wittgenstein’s claim that the so-called dream argument is senseless. Unlike other interpreters, who understand the sentence “I am dreaming” as contradictory or self-defeating, I intend to elucidate in what sense one should understand it as senseless or, more precisely, as nonsensical. In this sense, I propose to understand the above-mentioned claim in light of Wittgenstein’s criticism of skepticism from the _Tractatus logico-philosophicus_ to his last writings. I intend to show that the (...) words “I am dreaming” are nonsensical in the same sense as the alleged proposition “There are physical objects” or the expression of doubt about the existence of external objects. (shrink)

Sextus Empiricus offers an underappreciated and under-discussed version of dream-based skepticism. Most philosophers interested in dreams and skepticism focus on the question of how you know you are not currently dreaming. Sextus points out that our waking experiences and dreams often conflict. And, the challenge goes, what reason do you have to trust the one over the other? This question presupposes that dreams and waking experiences are distinguishable. Thus the kinds of responses typically offered against dream-based (...) class='Hi'>skepticism do not apply. And if we accept an idea upheld by one camp in the contemporary debate over the epistemology of disagreement, Sextus’ challenge is difficult to answer. A G.E. Moore-inspired response to the problem is also proposed and explored. It is argued that Sextus’ version of the problem reveals a certain limitation in that sort of approach to skeptical problems. (shrink)

Having fascinated some of the greatest philosophers from the earliest times, dreaming figures importantly in the history of philosophy, as in Plato’s Theaetetus, Augustine’s Confessions, and, perhaps most famously, Descartes’s Mediations. By far the greatest philosophical focus on dreaming has been epistemic: Socrates suggests to Theaetetus that since he cannot tell whether he is dreaming, he cannot trust his senses to know contingent facts about the world around him. And a similar worry drives Descartes’s radical doubt in (...) the First Meditation. We might think that dream skepticism is, among the radical Cartesian skeptical scenarios, a particularly worrying one, since dreams, unlike evil demons, are a commonplace of everyday life. (shrink)

A 1% skeptic is someone who has about a 99% credence in non-skeptical realism and about a 1% credence in the disjunction of all radically skeptical scenarios combined. The first half of this essay defends the epistemic rationality of 1% skepticism, appealing to dream skepticism, simulation skepticism, cosmological skepticism, and wildcard skepticism. The second half of the essay explores the practical behavioral consequences of 1% skepticism, arguing that 1% skepticism need not be behaviorally (...) inert. (shrink)

This paper appeals to the phenomenon of dreaming to provide a novel defense against arguments from evil. The thrust of the argument is as follows: when we wake up after a nightmare we are often filled entirely with relief, and do not consider ourselves to have actually suffered very much at all; and since it is epistemically possible that this whole life is simply a dream, it follows that it is epistemically possible that in reality there is very little (...) suffering. This epistemic possibility decisively undermines a key premise of both logical and evidential arguments from evil. (shrink)

A 1% skeptic is someone who has about a 99% credence in non-skeptical realism and about a 1% credence that some radically skeptical scenario obtains. The first half of this essay defends the epistemic rationality of 1% skepticism, endorsing modest versions of dream skepticism, simulation skepticism, cosmological skepticism, and wildcard skepticism. The second half of the essay explores the practical behavioral consequences of 1% skepticism.

Putnam’s semantic argument against the BIV hypothesis and Sosa’s argument against dream skepticism based on the imagination model of dreaming share some important structural features. In both cases the skeptical option is supposed to be excluded because preconditions of its intelligibility are not fulfilled (affirmation and belief in the dream scenario, thought and reference in the BIV scenario). Putnam’s reasoning is usually interpreted differently, as a classic case of deception, but this feature is not essential. I propose to (...) interpret BIV’s utterances as cases of reference failure best captured by truth-value gaps. Both anti-skeptical strategies are then vulnerable to the same type of objections (how do we know what state we are in or how do we know what kind of language do we speak). (shrink)

Modern-day heirs of the Cartesian revolution have been fascinated by the thought that one could utilize certain hypotheses – that one is dreaming, deceived by an evil demon, or a brain in a vat – to argue at one fell swoop that one does not know, is not justified in believing, or ought not believe most if not all of what one currently believes about the world. A good part of the interest and mystique of these discussions arises from (...) the contention that the seeds of such arguments lie in our ordinary epistemic practices, so that external world skepticism can arise “from within”. But is this contention correct? I doubt it. Taking skepticism seriously requires that we address this question head on. To do so, I will approach skeptical arguments from a certain vantage point. I will try to stand, as far as possible, with both feet squarely in ordinary life. I will start out with all of our ordinary commitments about what is the case, about what we know or have reason to believe, about when someone knows, is justified, or has good reason to believe something, and about how one should proceed in deciding what to believe. My question, then, will be this. From within that vantage point can I somehow be moved in a reasonable way to accept the conclusion that I know far less about the world around me than I thought, or that epistemically speaking, I really ought not believe much of what I have believed about the world around me? In order for such movement to take place, I will have to find reason from within my ordinary standpoint to discount or reject much of what I ordinarily accept. And of course, that reason will have to come from some.. (shrink)

This book argues that external world skepticism is false for straightforward reasons. To make this case it develops and defends a neglected methodological approach involving a distinctive process of first-person reflection. We begin within the practices, procedures, and commitments of ordinary life and science. We then seek some reason to think skepticism true, carefully scrutinizing all the most important arguments. Finding no reason to think it true and decisive reasons to think it false, we reject it. As the (...) book shows, this is a fully satisfactory refutation. No epistemological theorizing is needed. The book begins by exploring and defending this method in seminal works of G. E. Moore and J. L. Austin. Turning to contemporary epistemology, it asks why we shouldn't appeal to considerations about the world when responding to skeptical argumentation. No good reason is found, despite exploration of a wide range of central issues in recent epistemology. To the contrary, perfectly ordinary examples indicate that it is correct to reject the skeptical scenarios - the dreaming worry, Descartes' evil demon, the brain-in-a-vat - by appealing to things we know about the world. Likewise, considerations about sensory perception do not provide any reason to think our evidence excludes considerations about the world. Along the way, methodological lessons are drawn from consideration of the most important skeptical arguments in the contemporary literature. The book concludes by defending the satisfactoriness of its approach. What emerges is a new understanding of what philosophical illumination might look like in relation to core epistemological issues. (shrink)

The dream argument and its role in Cartesian doubt continue to engage commentators. As recent scholarship shows, a consensus has yet to be attained. In what follows I attempt to resolve the current debate by offering an account of the dream doubt which captures Descartes’s rhetorical strategy in Meditation I. A faithful reading of the text, I propose to show, reveals that the dream doubt is not entertained seriously nor is it proposed merely for the sake of methodological skepticism. (...) It is rather an integral part of a dogmatic intrusion of Cartesian science at a pivotal point in the critique of prescientific experience. After presenting the proposed interpretation, I examine the accounts offered in the current scholarship. (shrink)

One of the most important and perennially debated philosophical questions is whether we can have knowledge of the external world. Butchvarov here considers whether and how skepticism with regard to such knowledge can be refuted or at least answered. He argues that only a direct realist view of perception has any hope of providing a compelling response to the skeptic and introduces the radical innovation that the direct object of perceptual, and even dreaming and hallucinatory, experience is always (...) a material object, but not necessarily one that actually exists. This leads him to a metaphysics in which reality is ultimately constructed by human decisions out of objects that are ontologically more basic but which cannot be said in themselves to be either real or unreal. (shrink)

Abstract: Ernest Sosa has recently articulated an insightful response to skepticism and, in particular, to the dream argument. The response relies on two independent moves. First, Sosa offers the imagination model of dreaming according to which no assertions are ever made in dreams and no beliefs are involved there. As a result, it is possible to distinguish dreaming from being awake, and the dream argument is blocked. Second, Sosa develops a virtue epistemology according to which in appropriately (...) normal conditions our perceptual beliefs will be apt. Hence, in these conditions, we will have at least animal knowledge, and the conclusion of the dream argument is undermined. In this article, I examine various moves that the skeptic can make to resist Sosa's challenge, and I contrast the proposal to a neo-Pyrrhonian stance. In the end, there is surprisingly little disagreement about the status of ordinary perceptual beliefs in the two stances. (shrink)

Jennifer Windt’s Dreaming is an enormously rich and thorough book, developing illuminating connections between dreaming, the methodology of psychology, and various philosophical subfields. I’ll focus on two epistemological threads that run through the book. The first has to do with the status of certain assumptions about dreams. Windt argues that the assumptions that dreams involve experiences, and that dream reports are reliable — are methodologically necessary default assumptions, akin to Wittgensteinian hinge propositions. I’ll suggest that Windt is quietly (...) pre-supposing some sceptical assumptions, and that recent literature in epistemic externalism may bear in important ways on her arguments. The second thread involves the perennial sceptical worry that dreaming threatens ordinary knowledge. I’ll suggest again that Windt makes tacit sceptical assumptions one may wish to resist. (shrink)

Although Descartes presents himself as an adversary of skepticism, in contemporary epistemology he is celebrated much more for his presentation of the skeptical problem than for his efforts to solve it. The ‘Cartesian skepticism’ of the evil genius argument remains a Standard starting point for current discussions, a starting point that is seen to provide such a powerful challenge to knowledge that while one as much as contemplates such arguments one loses the right to ascribe knowledge to anyone. (...) Even Descartes's less radical skeptical arguments are still widely credited as having tremendous force: Barry Stroud, for example, argues at length that no satisfactory response has yet been given to the dream argument of the First Meditation. The Cartesian response to skepticism, on the other hand, is not nearly so warmly received. In the current literature on skepticism one does not find much resistance to Stroud's assessment of the Cartesian response to skepticism as utterly unpromising, nor to his diagnosis of its central fault: the Cartesian response depends on a series of theological claims that Descartes does not show to be plausible, let alone true. (shrink)

This paper compares the relative merits of perceptual beliefs and introspective beliefs in the context of dream arguments for skepticism. It is argued that introspective beliefs are not epistemically privileged over perceptual beliefs.

Zhuangzi’s Butterfly Dream story can be read as a skeptical response to the Cartesian Cogito, ergo sum solution, for it presents I exist as fundamentally unprovable, on the grounds that the notion about “I” that it is guaranteed to refer to something existing, which Descartes seems to assume, is unwarranted. The modern anti-skepticism of Hilary Putnam employs a different strategy, which seeks to derive the existence of the world not from some “indubitable” truth such as the existence of myself (...) , but from the meaning of some particular assertion I make. In this paper, I argue, however, that Putnam’s argument fails to deliver on the promise of showing the self-refuting nature of the skeptical hypothesis, as it relies on a double use of “I”, a fallacy of equivocation, reflecting an unsolved tension between the argument’s general premise, which is rather Zhuangzian in spirit, and his unwitting adoption of that unwarranted notion about “I”. I try to show further that the skepticism in Zhuangzi’s Butterfly Dream not only can be used to refute the proofs of the existence of the empirical I , but also is effective against accounts concerning the existence of the transcendental I. (shrink)

_ Source: _Volume 7, Issue 3, pp 147 - 172 The Indian Buddhist philosopher Vasubandhu has seldom been considered in conjunction with the problem of external-world skepticism despite the fact that his text, _Twenty Verses_, presents arguments from ignorance based on dreams. In this article, an epistemological phenomenalist interpretation of Vasubandhu is supported in opposition to a metaphysical idealist interpretation. On either interpretation, Vasubandhu gives an invitation to the problem of external-world skepticism, although his final conclusion is closer (...) to skepticism on the epistemological phenomenalist interpretation. The article ends with reflections on what light Vasubandhu might shed on the issue of whether skepticism is a natural problem in epistemology as well as why, despite Vasubandhu, the skeptical problem was not a central issue in the later Indian tradition. (shrink)

The skeptical Dream argument appeals to the possibility of dreaming. The skeptic holds that states of being awake are subjectively indistinguishable from possible dream states and that this means that we do not know that we are awake. This, the skeptic then claims, means that we have to accept that we do not have external world knowledge.It is natural to assume that there must be a connection between the Dream argument and epistemic internalism, the view that a belief is (...) justified for a given person if and only if the person has cognitive access to all the factors that are needed for the belief to be justified. The problem, the skeptic thinks, is that in order for my belief that I am awake to be justified I have to have cognitive access to something that establishes that I am awake. But according to the skeptic, even if I am awake, this is not something I have cognitive access to. However, the more precise connections between internalism and the skeptical argument are not so clear. (shrink)

The skeptical Dream argument appeals to the possibility of dreaming. The skeptic holds that states of being awake are subjectively indistinguishable from possible dream states and that this means that we do not know that we are awake. This, the skeptic then claims, means that we have to accept that we do not have external world knowledge.It is natural to assume that there must be a connection between the Dream argument and epistemic internalism, the view that a belief is (...) justified for a given person if and only if the person has cognitive access to all the factors that are needed for the belief to be justified. The problem, the skeptic thinks, is that in order for my belief that I am awake to be justified I have to have cognitive access to something that establishes that I am awake. But according to the skeptic, even if I am awake, this is not something I have cognitive access to. However, the more precise connections between internalism and the skeptical argument are not so clear. (shrink)

Ernest Sosa has argued that the solution to dream scepticism lies in an understanding of dreams as imaginative experiences – when we dream, on this suggestion, we do not believe the contents of our dreams, but rather imagine them. Sosa rebuts scepticism thus: dreams don’t cause false beliefs, so my beliefs cannot be false, having been caused by dreams. I argue that, even assuming that Sosa is correct about the nature of dreaming, belief in wakefulness on these grounds is (...) epistemically irresponsible. The proper upshot of the imagination model, I suggest, is to recharacterize the way we think about dream scepticism: the sceptical threat is not, after all, that we have false beliefs. So even though dreams don’t involve false beliefs, they still pose a sceptical threat, which I elaborate. (shrink)

The classical Indian school called Nyāya (literally “logic” or “right reasoning”), is arguably the leading anti-skeptical tradition within all of Indian philosophy. Defending a realist metaphysics and an epistemology of “knowledge sources” (pramāṇa), its responses to skepticism are often appropriated by other schools of thought. This paper examines its responses to skeptical arguments from dreams, from “the three times,” from justificatory regress, and over the problem of induction.

Modern-day heirs of the Cartesian revolution have been fascinated by the thought that one could utilize certain hypotheses – that one is dreaming, deceived by an evil demon, or a brain in a vat – to argue at one fell swoop that one does not know, is not justified in believing, or ought not believe most if not all of what one currently believes about the world. A good part of the interest and mystique of these discussions arises from (...) the contention that the seeds of such arguments lie in our ordinary epistemic practices, so that external world skepticism can arise “from within”. But is this contention correct? I doubt it. Taking skepticism seriously requires that we address this question head on. To do so, I will approach skeptical arguments from a certain vantage point. I will try to stand, as far as possible, with both feet squarely in ordinary life. I will start out with all of our ordinary commitments about what is the case, about what we know or have reason to believe, about when someone knows, is justified, or has good reason to believe something, and about how one should proceed in deciding what to believe. My question, then, will be this. From within that vantage point can I somehow be moved in a reasonable way to accept the conclusion that I know far less about the world around me than I thought, or that epistemically speaking, I really ought not believe much of what I have believed about the world around me? In order for such movement to take place, I will have to find reason from within my ordinary standpoint to discount or reject much of what I ordinarily accept. And of course, that reason will have to come from some.. (shrink)

The relationship between Vietnam and China could be captured in the Chinese expression of “同床异梦”, which means lying on the same bed but having different dreams. The two countries share certain cultural and political similarities but also diverge vastly in their national interests. This paper adds to the extant literature on this topic by analyzing the element of trust/mistrust in their interactions in trade-investment, tourism, and defense-security. The analysis shows how the relationship is increasingly interdependent but is equally fragile due (...) to the lack of trust on both sides. The mistrust or even distrust of Chinese subjects run deep within the Vietnamese mindset, from the skepticism of Chinese investment, Chinese tourists, discrimination against ethnic Chinese, to the caution against Chinese aggression in the South China Sea. The paper forecasts that, despite the deep-seated differences and occasional mistrust, going forward, neither side would risk damaging the status quo even when tensions peak. (shrink)

The paper deals with Wittgenstein’s treatment of radical skepticism. He holds from his earliest work to his last that skepticism is senseless and therefore no rebuttal, such as G.E. Moore offered, is necessary.

I argue that Cartesian skepticism about the external world leads to a vicious regress of skeptical attitudes, the only principled and unproblematic response to which requires refraining from taking the very first skeptical step.

According to "skepticism about the external world", one cannot know whether there are any things that have these two characteristics: they exist, or occur, at, or come from, some place, and they might have existed even had no one been conscious of them. In attempting to show that one cannot know whether or not there are any such things, the skeptic appeals to the alleged fact that one cannot rule out various possibilities, e.g., the possibility that one is (...) class='Hi'>dreaming. But, if one cannot rule out these possibilities, then how can one even have any grounds for believing that there are such things? I show how certain attempts to explain how one can have such grounds cannot succeed, and I offer an alternative that does succeed. This alternative depends upon a certain analysis of the notion of sensory experience. After providing that analysis, and showing how, by appeal to it, we can explain not only how it is possible to have grounds for believing that there are external things, but how it is possible to know that there are, I explain why it is that philosophers have failed to appreciate the possibility of providing such an explanation. In offering this explanation, I also explain why it is that skepticism about the external world, as well as various other philosophical doctrines, is subject to what I call "instability". (shrink)