Varieties of Skepticism

Traditionally, philosophers have been skeptical that the imagination can justify beliefs about the actual world. After all, how could merely imagining something give you any reason to believe that it is true? However, within the past decade or so, a lively debate has emerged over whether the imagination can justify empirical belief and, if so, how. This paper provides a critical overview of the recent literature on the epistemology of imagination and points to avenues for future research.

What should we do when faced with powerful theoretical arguments that support a severe change in our personal beliefs and commitments? For example, what should new parents do when confronted by unanswered anti-natalist arguments, or two lovers vexed by social theory that apparently undermines love? On the one hand, it would be irrational to ignore theory just because it’s theory; good theory is evidence, after all. On the other hand, factoring in theory can be objectifying, or risks unraveling one's life, (...) fracturing one's identity or social relations. Sometimes, then, following the evidence where it apparently leads would mean not merely changing what we think but who we are. Some might say that there’s something right about the thought that theory can bear on what we ought to believe, it’s just that when we work with full beliefs, only then do we seriously risk having to substantially alter our doxastic economy when pressed by exceptional theoretical arguments. When we work with partial beliefs, however, this risk is greatly diminished. Others will say that we can advocate or champion revisionary positions whilst rationally retaining our pre-theoretical personal convictions. Still others will argue that we should adopt a Moorean posture towards the revisionary arguments. I argue that each response is inadequate, and argue instead that we are permitted to bracket certain kinds of theoretical evidence against our beliefs because of the personal and ethical risks born out of giving them serious consideration. In turn, some of philosophy's doxastic influence is constrained by its attendant ethical risks: the personal enjoys a partial insulation from the theoretical. I close by addressing what this means for practicing philosophers. (shrink)

Remarks in Wittgenstein’s On Certainty present a view according to which all knowledge rests on commitments to things we do not know. In his usual manner, Wittgenstein does not present a clearly defined set of premises designed to support this view. Instead, the reasons emerge along with the view through a series of often cryptic remarks. But this does not prevent us from critically assessing the position (or positions) one finds in the work. This paper attempts to do that in (...) the form of a philosophical dialogue. The challenges to Wittgenstein’s view raised here center on: the extent to which hinge commitments can plausibly be regarded as rules of a language-game rather than rationally assessable propositions, mutual support versus bottom up notions of justification, the subject and context relativity of hinge commitments, the difference between justification and persuasion, whether propositions of the form p is hinge are themselves hinge, and the general viability of Wittgenstein’s view as an alternative to epistemological skepticism and Moorean anti-skepticism. (shrink)

This is a draft translation of the first letter of G.E. Schulze's Aenesidemus. Comments and corrections welcome.

Outside the philosophy classroom, global skeptics – skeptics about all (purported) knowledge of the external world – are rare. But there are people who describe themselves as “skeptics” about various more specific domains, including self-professed “skeptics” about the reality of anthropogenic climate change. There is little to no philosophical literature that juxtaposes the climate change skeptic with the external world skeptic. While many “traditional” epistemologists assume that the external world skeptic poses a serious philosophical challenge in a way that the (...) climate change skeptic doesn’t, many “applied” or “social” epistemologists assume that there isn’t much to be learned from debates about the external world skeptic, finding her challenge to be distant from both common sense and real-world concerns. I try to show that both of these views are mistaken. The external world skeptic raises deep questions that are important for our everyday deliberation about what to believe, and there are significant structural parallels between the arguments for external world skepticism and those for at least a form of climate change skepticism that is idealized – but not too idealized! – from the views of flesh-and-blood climate change skeptics. As such, we have strong reasons to think in parallel about how to reply to both skeptics’ challenges. I thus finish by (briefly) considering how different widespread responses to the external world skeptic might or might not generalize happily to the climate change skeptic’s challenge. (shrink)

According to veridicalism, your beliefs about the existence of ordinary objects are typically true, and can constitute knowledge, even if you are in some global sceptical scenario. Even if you are a victim of Descartes’ demon, you can still know that there are tables, for example. Accordingly, even if you don’t know whether you are in some such scenario, you still know that there are tables. This refutes the standard sceptical argument. But does it solve the sceptical problem posed by (...) that argument? I argue that it does not, because we do not know substantively more about the external world according to veridicalism than we do according to the sceptical argument. Rather, veridicalism merely reformulates what little knowledge we have. I then draw some general conclusions about the nature of the sceptical problem, the formulation of the standard argument, and the significance of this for some other, non-veridicalist strategies. (shrink)

According to MODERATISM, perceptual justification requires that one independently takes for granted propositional hinges like <There is an external world>, <I am not a brain in a vat (BIV)>, and so on. This view faces the truth problem: to offer an account of truth for hinges that is not threatened by skepticism. Annalisa Coliva has tried to solve the truth problem by combining the claim that external world propositions have a substantive truth property like correspondence with the claim that hinges (...) have a deflationary truth property. I argue that the resulting view cannot offer a coherent characterization of ‘skeptical switch scenarios’ while providing an effective anti-skeptical strategy. In a more positive vein, I defend an approach that combines a correspondence conception of truth with epistemological disjunctivism. (shrink)

Many philosophers have been attracted to a restricted version of the principle of indifference in the case of self-locating belief. Roughly speaking, this principle states that, within any given possible world, one should be indifferent between different hypotheses concerning who one is within that possible world, so long as those hypotheses are compatible with one’s evidence. My first goal is to defend a more precise version of this principle. After responding to several existing criticisms of such a principle, I argue (...) that existing formulations of the principle are crucially ambiguous, and I go on to defend a particular disambiguation of the principle. According to the disambiguation I defend, how we should apply this restricted principle of indifference sensitively depends on our background metaphysical beliefs. My second goal is to apply this disambiguated principle to classical skeptical problems in epistemology. In particular, I argue that Eternalism threatens to lead us to external world skepticism, and Modal Realism threatens to lead us to inductive skepticism. (shrink)

In this Précis, I provide an overview of my Monograph Knowing and Checking: An Epistemological Investigation (Melchior 2019), which is subject to a book symposium organized by the University of Maribor. This volume in Acta Analytica contains contributions by Peter Baumann, Kelly Becker, Marian David, Nenad Miščević, Robert Weston Siscoe, and Danilo Šuster along with my replies.

This article develops a logical (or semantic) response to scepticism about the existence of an external world. Specifically, it is argued that any doubt about the existence of an external world can be proved to be false, but whatever appears to be doubt about the existence of an external world that _cannot_ be proved to be false is nonsense, insofar as it must rely on the assertion of something that is logically impossible. The article further suggests that both G. E. (...) Moore and Ludwig Wittgenstein worked towards the same solution but left their work unfinished. (shrink)

This is a critical notice of Christos Kyriacou and Kevin Wallbridge (eds.), Skeptical Invariantism Reconsidered. New York and London: Routledge, 2021. Pp. x + 324. ISBN 978-0-367-37018-3. It discusses in some detail contributions by Nevin Climenhaga, Christos Kyriacou, Michael Hannon, Kevin Wallbridge, Annalisa Coliva, and Genia Schönbaumsfeld.

The Cartesian arguments for external world skepticism are usually considered to be significant for at least two reasons: they seem to present genuine paradoxes and that providing an adequate response to these arguments would reveal something epistemically important about knowledge, justification, and/or our epistemic position to the world. Using only premises and reasoning the skeptic accepts, I will show that the most common Cartesian argument for external world skepticism leads to a previously unrecognized self-undermining dilemma: it either leads to a (...) reductio ad absurdum, or to avoid this reductio the skeptic must accept that this argument is epistemically idle—it does not provide any support for external world skepticism. Either way, this Cartesian argument cannot legitimately threaten or even call into question our beliefs about the external world. And thus, either way, this Cartesian argument for external world skepticism is not epistemically significant—it is not a genuine paradox and adequately responding to it need not reveal anything epistemically important. (shrink)

Various theorists contend that we may live in a computer simulation. David Chalmers in turn argues that the simulation hypothesis is a metaphysical hypothesis about the nature of our reality, rather than a sceptical scenario. We use recent work on consciousness to motivate new doubts about both sets of arguments. First, we argue that if either panpsychism or panqualityism is true, then the only way to live in a simulation may be as brains-in-vats, in which case it is unlikely that (...) we live in a simulation. We then argue that if panpsychism or panqualityism is true, then viable simulation hypotheses are substantially sceptical scenarios. We conclude that the nature of consciousness has wide-ranging implications for simulation arguments. (shrink)

In this paper, I argue that the ecological approach to perception provides resources to overcome the causal argument against disjunctivism. According to the causal argument, since the brain states that proximally cause the perceptual experience and the corresponding hallucinatory one can be of the same type, there would be no good reason to reject that the perceptual experience and the corresponding hallucinatory experience have fundamentally the same nature. Disjunctivism concerning the nature of the experience would then be false. I identify (...) three assumptions that support the causal argument: the indistinguishability assumption, the linearity assumption, and the duplication assumption. According to the ecological approach to disjunctivism, these assumptions should be rejected, opening up room for a version of disjunctivism that I call 'Ecological Disjunctivism'. Perceptual episodes are extended over time and are supervenient to the organism-environment system. They can be distinguished from the 'corresponding' hallucinations because the former results from a controlled process of attunement to the environment, whereas hallucinations are passive and insensible to the exploratory activities of the perceptual system. Finally, ecological disjunctivism, since it is immune to the causal argument, is more advantageous than negative and positive disjunctivism. (shrink)

In this paper, I offer reasons for thinking that two prominent sceptical arguments in the literature – the underdetermination-based sceptical argument and the closure-based sceptical argument – are less philosophically interesting than is commonly supposed. The underdetermination-based argument begs the question against a non-sceptic and can be dismissed with little fanfare. The closure-based argument, though perhaps not question-begging per se, does rest upon contentious assumptions that a non-sceptic is under no pressure to accept.

According to the idealist, facts about phenomenal experience determine facts about the physical world. Any such view must account for illusions: cases where there is a discrepancy between the physical world and our experiences of it. In this paper, I critique some recent idealist treatments of illusions before presenting my own preferred account. I then argue that, initial impressions notwithstanding, it is actually the realist who has difficulties properly accounting for illusions.

The paper defends Cartesian skepticism by an argument relying on internalism and infallibilism. It argues that this sort of skepticism gives the best explanation of our intuitions and ordinary epistemic practices.

Die klassische bikategoriale Ontologie von Substanzen und Akzidentien ist für die Festlegung der Strukturen menschlichen und tierischen Verhaltens nicht hinreichend, da die Umwelten dieses Verhaltens sich nicht in dieses klassische System einfügen. Wir bieten dementsprechend den Grundriß einer Theorie der besonderen Gebilde, die die Alltagswelten menschlicher und tierischer Verhalten konstituieren. Die Ausgangsüberlegung ist die folgende, Wir sind alle (Schau)spieler, und diese brauchen eine Bühne. Unsere Bühne ist die jeweilige Umwelt, in der wir leben und handeln. Der Terminus ‘Umwelt’ wird hierbei (...) in Analogie zu Husserls Begriff der Lebenswelt verwendet. Er bezeichnet dementsprechend einen strukturierten Teil der Welt, in den sich ein Lebewesen, z.B. ein Mensch, einpaßt. Die Umwelt ist, wenn man so will, demnach die Bühne, auf welcher sich unser Verhalten abspielt. Der Versuch, das Wesen solcher Umwelten ontologisch festzulegen, bringt allerdings ein schwieriges Problem mit sich - ein Problem so alt wie Platons Höhlengleichnis und so neu wie gegenwärtige Reflexionen amerikanischer Philosophen zur Metaphysik der virtuellen Realität und zum Gedankenexperiment des Gehirns im Tank. Es gibt nämlich in manchen Fällen grobe Inkonsistenzen zwischen (1) der Umwelt, wie wir sie uns gerade vorstellen, und (2) der Umwelt als Bestandteil der wirklichen Welt. Das Problem, zwischen diesen beiden Umweltklassen einen Ausgleich zu finden, wird im letzten Teil des Aufsatzes behandelt. (shrink)

Epistemological disjunctivism is a philosophical theory that has received special attention in the recent years. Particularly because it has been seen by many as a way of renewing discussions that range from the nature of justification of our daily beliefs to the possibility of unveiling the structure of the problem of radical skepticism and of responding to it. Duncan Pritchard is one of the authors who have offered a particular view of disjunctivism and ways of conceiving of disjunctivist treatments to (...) such questions. His work has as its main source of inspiration the seminal work of John McDowell. In this paper, I present a way of understanding the problem ofradicalskepticism and the mannerin which epistemological disjunctivism aimsto offer solutionsto it. In orderto do that, I present McDowell’s general proposal and discuss in which way his account differs from Pritchard’s own disjunctivism. At the end, I try to show how Pritchard’s approach tries to respond to radical skepticism not only by appealing to a disjunctivist reading of our epistemic position, but also by offering a revision of our structure of reasons. (shrink)

Cartesian arguments for global skepticism about the external world start from the premise that we cannot know that we are not in a Cartesian scenario such as an evil-demon scenario, and infer that because most of our empirical beliefs are false in such a scenario, these beliefs do not constitute knowledge. Veridicalist responses to global skepticism respond that arguments fail because in Cartesian scenarios, many or most of our empirical beliefs are true. Some veridicalist responses have been motivated using verificationism, (...) externalism, and coherentism. I argue that a more powerful veridicalist response to global skepticism can be motivated by structuralism, on which physical entities are understood as those that play a certain structural role. I develop the structuralist response and address objections. (shrink)

Here, I shall be examining the viability of a Moorean response to the Argument from Ignorance; i.e., one that tries to rebut the argument by denying its first premise that we cannot have knowledge that we are not BIVs. After first explicating the Argument from Ignorance in detail, I then go on to try and motivate this approach by critically examining two alternative approaches to dealing with radical scepticism: closure-denial, and attributer contextualism. Finding them wanting, I then turn to a (...) Moorean 'argument from knowledge', and diagnose why as it stands such an approach is ineffective, before going on to explore whether one can wed such an argument to an externalist framework in order to provide a more satisfying answer to the question of how one can know the denials of sceptical hypotheses, one that does not simply beg the question against the sceptic. Finding such a neo-Moorean approach to be initially promising, I then conclude by arguing that ultimately it winds up saving knowledge simpliciter only at the cost of losing rationally-grounded knowledge to the sceptic's grasp, and such a result is highly unpalatable. (shrink)

Duncan Pritchard recently proposed a Wittgensteinian solution to closure-based skepticism. According to Wittgenstein, all epistemic systems assume certain truths. The notions that we are not disembodied brains, that the Earth has existed for a long time and that one’s name is such-and-such all function as “hinge commitments.” Pritchard views a hinge commitment as a positive propositional attitude that is not a belief. Because closure principles concern only knowledge-apt beliefs, they do not apply to hinge commitments. Thus, from the fact that (...) a subject knows that he is sitting in a room, and the fact that the subject’s sitting in a room entails his bodily existence, it does not follow that the subject also knows that he is not an envatted brain. This paper rejects Pritchard’s non-belief reading of hinge commitments. I start by showing that the non-belief reading fails to solve the skeptical paradox because the reasons that Pritchard uses to support the non-belief reading do not exempt hinge propositions from closure principles. I then proceed to argue that the non-belief reading is false as it claims that hinge commitments, unlike ordinary beliefs, are rationally unresponsive—with the help of a scenario in which a subject’s experience is internally chaotic, we can safely conclude that the hinge commitment that one is not systematically mistaken about the world is equally responsive to one’s evidential situations. (shrink)

Some modern cosmological models predict the appearance of Boltzmann Brains: observers who randomly fluctuate out of a thermal bath rather than naturally evolving from a low-entropy Big Bang. A theory in which most observers are of the Boltzmann Brain type is generally thought to be unacceptable, although opinions differ. I argue that such theories are indeed unacceptable: the real problem is with fluctuations into observers who are locally identical to ordinary observers, and their existence cannot be swept under the rug (...) by a choice of probability distributions over observers. The issue is not that the existence of such observers is ruled out by data, but that the theories that predict them are cognitively unstable: they cannot simultaneously be true and justifiably believed. (shrink)

Going about our daily lives in an orderly manner requires us, once we are aware of them, to dismiss many metaphysical possibilities. We take it for granted that we are not brains in vats, or living in the Matrix, or in an extended dream. Call these things that we take for granted “anti-skeptical assumptions”. What should a reflective agent who believes these things think of these beliefs? For various reasons, it can seem that we do not have evidence for such (...) anti-skeptical assumptions. Are anti-skeptical assumptions, then, beliefs that one may rationally hold without evidence for them – indeed, even in the face of a positive judgment that one lacks evidence for them? I survey and criticize some prominent answers to this question, and then offer a positive view that blends externalism about evidence with a mild, qualified kind of pragmatism. The view I offer aims to do justice to the sense that anti-skeptical assumptions are evidentially groundless while also maintaining that one cannot rationally believe something that one judges oneself to lack sufficient evidence for. (shrink)

Radical skepticism relies on the hypothesis that one could be completely cut off from the external world. In this paper, I argue that this hypothesis can be rationally motivated by means of a conceivability argument. Subsequently, I submit that this conceivability argument does not furnish a good reason to believe that one could be completely cut off from the external world. To this end, I show that we cannot adequately conceive scenarios that verify the radical skeptical hypothesis. Attempts to do (...) so fall prey to one or another of three pitfalls: they end up incomplete, reveal a deep contradiction or recreate a non-skeptical hypothesis. I use these results to improve upon Pritchard’s recent attempt at undercutting radical skepticism. (shrink)

I will argue that cases of massive deception, such as New Evil Demon cases, as well as one-off cases of local deception present challenges to views according to which epistemic reasons, epistemic warrant, epistemic rationality or epistemic norms are factive. In doing so, I will argue is that proponents of a factive turn in epistemology should observe important distinctions between what are often simply referred to as ‘bad cases.’ Recognizing epistemologically significant differences between deception cases raises serious challenges for those (...) who deny a central role for non-factive aspects of epistemology. (shrink)

This paper reassesses the case against Evidential Externalism, the thesis that one's evidence fails to supervene on one's non-factive mental states, focusing on two objections to Externalism due by Nicholas Silins: the armchair access argument and the supervenience argument. It also examines Silins's attempt to undermine the force of one major source of motivation for Externalism, namely that the rival Internalist picture of evidence is implicated in some central arguments for scepticism. While Silins concludes that the case against Evidential Externalism (...) is surprisingly strong, reassessing the arguments supports the opposite conclusion; the objections to Externalism are weak, and for all Silins has shown it may well have unmatched advantages when it comes to resisting scepticism. (shrink)

The most prominent arguments for scepticism in modern epistemology employ closure principles of some kind. To begin my discussion of such arguments, consider Simple Knowledge Closure (SKC): (SKC) (Kxt[p] ∧ (p → q)) → Kxt[q].1 Assuming its truth for the time being, the sceptic can use (SKC) to reason from the two assumptions that, firstly, we don’t know ¬sh and that, secondly, op entails ¬sh to the conclusion that we don’t know op, where ‘op’ and ‘sh’ are shorthand for ‘ordinary (...) proposition’ and ‘sceptical hypothesis’ respectively. (SKC), however, fails for familiar reasons: since knowledge entails belief (KB), we can derive the falsity (F) from (SKC) by hypothetical syllogism, and thus reduce (SKC) to absurdity: (KB) Kxt[p] → Bxt[p]. (F) (Kxt[p] ∧ (p → q)) → Bxt[q]. (shrink)

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 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. (shrink)

Let us imagine an ideal ethical agent, i.e., an agent who (i) holds a certain ethical theory, (ii) has all factual knowledge needed for determining which action among those open to her is right and which is wrong, according to her theory, and who (iii) is ideally motivated to really do whatever her ethical theory demands her to do. If we grant that the notions of omniscience and ideal motivation both make sense, we may ask: Could there possibly be an (...) ideal utilitarian, that is, an ideal ethical agent whose ethical theory says that our only moral obligation consists in maximizing utility? I claim that an ideal agent cannot be utilitarian. My reasoning against ideal utilitarianism will parallel Putnam's famous argument against the brains in a vat. Putnam argues that an envatted brain cannot describe its own situation because its words do not refer to brains and vats; I argue that an ideal utilitarian cannot entertain or communicate the beliefs necessary to being a utilitarian. (shrink)

In this paper, I argue that, if transcendental arguments are to proceed from premises that are acceptable to the skeptic, the Transcendental Premise, according to which “X is a metaphysically necessary condition for the possibility of Y,” must be grounded in considerations of conceivability and possibility. More explicitly, the Transcendental Premise is based on what Szabó Gendler and Hawthorne call the “conceivability-possibility move.” This “inconceivability-impossibility” move, however, is a problematic argumentative move when advancing transcendental arguments for the following reasons. First, (...) from “S cannot conceive of P” it doesn’t necessarily follow that P is inconceivable. Second, from “P is inconceivable” it doesn’t necessarily follow that P is metaphysically impossible. Third, rather than block skeptical doubts, the conceivability-possibility move introduces skeptical doubts. For these reasons, transcendental arguments fail to deliver on their promise to overcome skeptical doubts. (shrink)

Within the framework of the epistemological debate on disagreement, this paper aims to examine the sceptical thesis that holds that, if it is impossible to rationally choose among two excluding positions, the only sensible or rational thing to do is to suspend judgement. The idea that ordinary life does not constitute the source of scepticism is presented, which rules out real disagreement between epistemic pairs as its foundation. Sceptical scenes differ ontologically from everyday scenes, without such ontological difference entailing an (...) epistemic difference, since epistemic practices do not vary from one sceptical scene to other types of scenes. (shrink)

Tim Button explores the relationship between words and world; between semantics and scepticism. -/- A certain kind of philosopher – the external realist – worries that appearances might be radically deceptive. For example, she allows that we might all be brains in vats, stimulated by an infernal machine. But anyone who entertains the possibility of radical deception must also entertain a further worry: that all of our thoughts are totally contentless. That worry is just incoherent. -/- We cannot, then, be (...) external realists, who worry about the possibility of radical deception. Equally, however, we cannot be internal realists, who reject all possibility of deception. We must position ourselves somewhere between internal realism and external realism, but we cannot hope to say exactly where. We must be realists, for what that is worth, and realists within limits. -/- In establishing these claims, The Limits of Realism critically explores and develops several themes from Hilary Putnam’s work: the model-theoretic arguments; the connection between truth and justification; the brain-in-vat argument; semantic externalism; and conceptual relativity. The book establishes the continued significance of these topics for all philosophers interested in mind, logic, language, or the possibility of metaphysics. (shrink)

Hilary Putnam’s BIV argument first occurred to him when ‘thinking about a theorem in modern logic, the “Skolem–Löwenheim Theorem”’ (Putnam 1981: 7). One of my aims in this paper is to explore the connection between the argument and the Theorem. But I also want to draw some further connections. In particular, I think that Putnam’s BIV argument provides us with an impressively versatile template for dealing with sceptical challenges. Indeed, this template allows us to unify some of Putnam’s most enduring (...) contributions to the realism/antirealism debate: his discussions of brains-in-vats, of Skolem’s Paradox, and of permutations. In all three cases, we have an argument which does not merely defeat the sceptic; it also shows us that we must reject some prima facie plausible philosophical picture. (shrink)

The problem of philosophical skepticism relates to the difficulty involved in underwriting the claim that we know anything of spatio-temporal reality. It is often claimed, in fact, that proper philosophical scrutiny reveals quite the opposite from what common sense suggests. Knowledge of external reality is thought to be even quite obviously denied to us as a result of the alleged fact that we all fail to know that certain skeptical scenarios do not obtain. A skeptical scenario is one in which (...) we have neurological occurrences just like any normal situation in which we actually perceive spatio-temporal objects, but where we are deceived in some sense as a result of the manipulation of our brains from some outside source. In this work I attempt to address the problem of philosophical skepticism by claiming that most of us are able to come to know plenty about external reality, since we can come to realize that a certain philosophical theory of perception is correct. The theory I have in mind is what I call a non-cognitive theory of perception. According to this view, perceptual experience is defined by continuous, sensitive behavioral interaction with spatio-temporal objects of the appropriate size, shape, hardness, speed, etc. Knowing that this theory of perception is correct is equivalent to knowing that we know plenty about external reality. This is ultimately because by knowing that a non-cognitive theory of perception is true, we know that any skeptical scenario must fail to obtain. The structure of the work proceeds by first discussing the significance of the problem of philosophical skepticism in some detail. Chapter 1 lays out how the problem does indeed forcefully arise if it is conceded that we fail to know that the skeptical scenarios fail to obtain. Chapter 2 develops the sort of view of our epistemological situation that falls out of accepting without qualification that the problem exists. Chapter 3 examines and criticizes certain popular responses to the skeptical problem. The main goal of these first three preliminary chapters is to indicate that once it is admitted that we fail to know that the skeptical scenarios fail to obtain, the problem of philosophical skepticism forcefully presents itself. Chapter 4, however, attacks the idea that we fail to know that the skeptical scenarios fail to obtain. In this chapter I argue that this idea is wedded to the position that a certain theory of perception is correct. The theory in question is what I call a conjunctive theory of veridical experience. According to this view, normal experience of spatio-temporal objects occurs when a subject has a certain perceptual experience, and that experience also happens to match up with and/or be satisfied by what is really the case. Only when a theory of this sort is assumed, I argue, is the claim that we fail to know that the skeptical scenarios fail to obtain found to be obvious. In chapter 5 I argue that, in fact, a non-cognitive theory, rather than a conjunctive theory, is the correct view to maintain. In the final chapter 6 I develop the epistemological position that falls out of accepting a non-cognitive theory. (shrink)

Michael WiIliams maintains that skepticism about the extemal worId is vitiated by a commitment to foundationalism and epistemological realism. (The latter is, approximately, the view that there is such a thing as knowledge of the extemal world in general, which the skeptic can take as a target). I argue that skepticism is not encumbered in the ways Williams supposes. What matters, first of all, is that we can’t perceive the difference between being in an ordinary environment and being in the (...) sort of situation the skeptic describes (e.g. having one’s brain manipulated by deceitful experimenters). This point can be upheld without embracing any substantial foundationalist tenet, such as the existence of basic beliefs, the availabiIity of something “given,” or the epistemic priority of experience. As to “epistemological realism,” I find that Williams has offered no principled way to distinguish between ordinary chaIIenges to knowledge and skeptical challenges which, supposedly, have no cIaim on our concem. (shrink)

Crispin Wright hat die bislang beste Rekonstruktion von Putnams Beweis gegen die skeptische Hypothese vom Gehirn im Tank vorgelegt. Aber selbst in Wrights Fassung hat der Beweis einen Mangel: Er wird mithilfe eines Prädikates wie z.B. "Tiger" geführt und funktioniert nur, wenn man sich darauf verlassen kann, dass es Tiger wirklich gibt. Aber die Skeptikerin bestreitet, über die Existenz von Tigern bescheid zu wissen. Das Problem lässt sich dadurch beheben, dass man den Beweis – statt mit dem extensionalen Begriff der (...) Referenz (wie bei Wright) – mit Intensionen führt. Zudem sollte der Beweis transzendental laufen, also einzig und allein auf den sprachlichen Voraussetzungen beruhen, die auch die Skeptikerin zur Formulierung ihrer Tank-Hypothese benötigt. -/- The best reconstruction of Putnam's brain-in-a-vat argument is due to Crispin Wright. But even Wright's version of the argument is not convincing. It employs predicates such as 'tiger' and reaches the conclusion only if we can rely upon the existence of tigers; and the skeptic disputes our knowledge regarding tigers. The problem is not insuperable: The argument must be run, not with the extensionalistic notion of reference (as in Wright's version), but with intensions. Furthermore, the argument should have a transcendental form; it should exclusively rely on conditions that are needed by the skeptic for formulating her own position. (shrink)

According to epistemic internalism, the only facts that determine the justificational status of a belief are facts about the subject’s own mental states, like beliefs and experiences. Externalists instead hold that certain external facts, such as facts about the world or the reliability of a belief-producing mechanism, affect a belief’s justificational status. Some internalists argue that considerations about evil demon victims and brains in vats provide excellent reason to reject externalism: because these subjects are placed in epistemically unfavorable settings, externalism (...) seems unable to account for the strong intuition that these subjects’ beliefs are nonetheless justified. I think these considerations do not at all help the internalist cause. I argue that by appealing to the anti-individualistic nature of perception, it can be shown that skeptical scenarios provide no reason to prefer internalism to externalism. (shrink)

This essay is concerned with solipsism, understood as the extreme sceptical view that I have no knowledge except of my subjective state. A less rough formulation of the view is mooted, inspired by a Quinean combination of naturalism and empiricism. An objection to the resultant position is then considered, based on Putnam’s argument that we are not brains in vats. This objection is first outlined, then pitted against a series of counter-objections. Eventually it is endorsed, but only at the price (...) of exposing the formulation of solipsism in question as not, after all, a satisfactory formulation. This leads to further speculation about the status of solipsism itself. Two of the possibilities that are considered are, firstly, that it is incoherent and, secondly, that it is inexpressible. (shrink)

Failure to recognize the "realistic" motivations for Putnam's commitment to internal realism has led to a widely shared misunderstanding of Putnam's arguments against metaphysical realism. Realist critics of these arguments frequently offer rebuttals that fail to confront his arguments. Simply put, Putnam's arguments --the brains in a vat argument as well as the model-theoretic argument -- are "reductios" that are intended to show that "metaphysical realism itself is not sufficiently realistic". If that claim can be substantiated then Putnam can go (...) on to argue that his own view is, by comparison, more realistic than metaphysical realism. (shrink)

This paper defends the legitimacy of semantical responses to certain skeptical challenges, with a particular focus on Putnam’s treatment of a particular version of Brain-in-Vat skepticism. It argues that while Putnam’s argument does not provide a general reply to Brain-in-Vat skepticism, the general approach it exemplifies is actually crucial in replying to other skeptical challenges that are otherwise hard to rebut.

Hillary Putnam has famously argued that we can know that we are not brains in a vat because the hypothesis that we are is self-refuting. While Putnam's argument has generated interest primarily as a novel response to skepticism, his original use of the brain in a vat scenario was meant to illustrate a point about the "mind/world relationship." In particular, he intended it to be part of an argument against the coherence of metaphysical realism, and thus to be part of (...) a defense of his conception of truth as idealized rational acceptability. Putnam's conclusions about the scenario are, however, actually out of line with central and plausible aspects of his own account of the relationship between our minds and the world. Reflections on semantics give us no compelling reason to suppose that claims like "I am a brain in a vat" could not turn out to be true. (shrink)

Are we perhaps in the "matrix", or anyway, victims of perfect and permanent computer simulation? No. The most convincing—and shortest—version of Putnam's argument against the possibility of our eternal envattment is due to Crispin Wright (1994). It avoids most of the misunderstandings that have been elicited by Putnam's original presentation of the argument in "Reason, Truth and History" (1981). But it is still open to the charge of question-begging. True enough, the premisses of the argument (disquotation and externalism) can be (...) formulated and defended without presupposing external objects whose existence appears doubtful in the light of the very skeptical scenario which Putnam wants to repudiate. However, the argument is only valid if we add an extra premiss as to the existence of some external objects. In order to avoid circularity, we should run the argument with external objects which must exist even if we are brains in a vat, e.g. with computers rather than with trees. As long as the skeptic is engaged in a discussion of the brain-in-a-vat scenario, she should neither deny the existence of computers nor the existence of causal relations; for if she does, she is in fact denying that we are brains in a vat. (shrink)

ABSTRACTThis article offers a novel sceptical argument that the sensitivity-contextualist must say is sound; moreover, she must say that the conclusion of this argument is true at ordinary standards. The view under scrutiny has it that in different contexts knowledge-attributing sentences express different propositions, propositions which differ in the stretch of worlds across which the subject is required to track the truth. I identify the underlying reason for the sceptical result and argue that it makes sensitivity-contextualism irremediably flawed. Contextualists, I (...) conclude, should abandon sensitivity for some other piece of epistemic machinery. (shrink)

It is received wisdom that the skeptic has a devastating line of argument in the following. You probably think, he says, that you know that you have hands. But if you knew that you had hands, then you would also know that you were not a brain in a vat, a brain suspended in fluid with electrodes feeding you perfectly coordinated impressions that are generated by a supercomputer, of a world that looks and moves just like this one. You would (...) know you weren’t in this state if you knew you had hands, since having hands implies you are no brain in a vat. You obviously don’t know you’re not a brain in a vat, though—you have no evidence that would distinguish that state from the normal one you think you’re in. Therefore, by modus tollens, you don’t know you have hands. At least, the skeptic has a devastating argument, it is thought, if we grant him closure of knowledge under known implication, which many of us are inclined to do: roughly, if you know p, and you know that p implies q, then you know q. (shrink)

According to veridicalism, your beliefs about the existence of ordinary objects are typically true, and can constitute knowledge, even if you are in some global sceptical scenario. Even if you are a victim of Descartes’ demon, you can still know that there are tables, for example. Accordingly, even if you don’t know whether you are in some such scenario, you still know that there are tables. This refutes the standard sceptical argument. But does it solve the sceptical problem posed by (...) that argument? I argue that it does not, because we do not know substantively more about the external world according to veridicalism than we do according to the sceptical argument. Rather, veridicalism merely reformulates what little knowledge we have. I then draw some general conclusions about the nature of the sceptical problem, the formulation of the standard argument, and the significance of this for some other, non-veridicalist strategies. (shrink)

The external world sceptic tells some familiar narratives involving massive deception. Perhaps we are brains in vats. Perhaps we are the victim of a deceitful demon. You know the drill. The sceptic proceeds by observing first that victims of such deceptions know nothing about their external environment and that second, since we cannot rule out being a victim of such deceptions our- selves, our own external world beliefs fail to attain the status of knowledge. Discussions of global external world scepticism (...) tend to focus on the second step, where a number of well-known lines of resistance have been offered. But there has been little attention to the first, seemingly innocuous step. That will be the focus of this paper. Part one – sections 1, 2, and 3 – will explain why these standard narratives are not convincing examples of cases where there is no knowledge of the external world. In part two – section 4 – we shall undertake a useful case study. David Lewis’s ‘Elusive Knowledge’ is often thought of as presenting an epistemological vision that is somewhat friendly to external world scepticism: as Lewis himself presents things, there are contexts where external world knowledge ascriptions are uniformly false, and where true knowledge ascriptions are limited to either axiomatic truths or truths about our inner life. We examine his discussion in the light of the preceding reflections and show that the framework he presents is not so concessionary to global external world scepticism after all. (shrink)