A discussion of why a strong doctrine of 'reason' may not be worth sustaining in the face of modern scientific speculation, and the difficulties this poses for scientific rationality, together with comments on the social understanding of religion, and why we might wish to transcend common sense.

There are two major puzzles in Hume’s epistemology. The first involves Hume’s fall into despair in the conclusion of Book One of the Treatise. When Hume reflects back upon the results of his research, he becomes so alarmed that he nearly throws his books and papers into the fire. Why did his investigations push him towards such intense skeptical sentiments? What dark discoveries did he make? The second puzzle concerns the way in which Hume emerges from this skeptical crisis and (...) proceeds with his investigations. Why the sudden change of heart? What accounts for the return of hope? Each of these puzzles represents a serious challenge to traditional approaches to Hume’s epistemology. A proper solution to them requires a careful examination of Hume’s claims about the untrustworthiness of our cognitive faculties as well as his strategy for improving their performance. (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)

A well known skeptical paradox rests on the claim that we lack warrant to believe that we are not brains in a vat (BIVs). The argument for that claim is the apparent impossibility of any evidence or argument that we are not BIVs. Many contemporary philosophers resist this argument by insisting that we have a sort of warrant for believing that we are not BIVs that does not require having any evidence or argument. I call this view ‘New Rationalism’. I (...) argue that New Rationalists are committed to there being some evidence or argument for believing that we are not BIVs anyway. Therefore, New Rationalism, since its appeal is that it purportedly avoids the problematic commitment to such evidence or argument, undermines its own appeal. We cannot avoid the difficult work of coming up with evidence or argument by positing some permissive sort of warrant. (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)

Davies and Wright have recently diagnosed the felt inadequacy of Moore’s response to the sceptic in terms of a failure of transmission of warrant. They argue that warrant fails to transmit across the following key inference: I have hands, if I have hands then I am not a BIV, so I am not a BIV, on the grounds that this inference cannot be used to rationally overcome doubt about its conclusion, and cannot strengthen one’s epistemic position with respect to the (...) conclusion. Here, for the sake of argument, I grant that the inference can neither rationally overcome doubt about its conclusion nor strengthen one’s epistemic position with respect to the conclusion, and examine whether, and in what way, this undermines.. (shrink)

E. J. Coffman defends Peter Klein’s work on epistemic closure against various objections that I raised in an earlier paper. In this paper, I respond to Coffman.

This is a response to a recent Philosophical Studies article by Bredo Johnsen, in which he makes a number of criticisms of Putnamian anti-skeptical arguments.

J.D. Collier sees Putnam as arguing (in the 'Brains in a Vat' chapter of [4]) that metaphysical realism is false.' He sees the argument as proceeding from the background assumption that metaphysical realism has the consequence that truth is 'radically non-epistemic', so that 'an [epistemically] ideal theory could be radically wrong about the world' [3, p. 413]. But, according to Collier, Putnam argues that 'an ideal theory satisfying all of our methodological and theoretical constraints cannot be false' [3, p. 413]. (...) Collier attempts to defend metaphysical realism against this Putnamian attack by distinguishing 'between our ability to state a theory and our ability to conceive its possibility' [3, p. 413]. I will show that this defence is unsuccessful. (shrink)

Massimo Dell'Utri (1990) provides a reconstruction of Hilary Putnam's argument (1981, chapter 1) to show that the hypothesis that we are brains in a vat is self-refuting. I will explain why the argument Dell'Utri offers us is, on the face of it, quite problematic. Then I will provide a way out of the difficulty.

In chapter 1 of Reason, Truth, and History, Hilary Putnam argues from some plausible assumptions about the nature of reference to the conclusion that it is not possible that all sentient creatures are brains in a vat. If this argument is successful, it seemingly refutes an updated form of Cartesian skepticism concerning knowledge of physical objects. In this paper, I will state what I take to be the most promising interpretation of Putnam's argument. My reconstructed argument differs from an argument (...) strongly suggested by Putnam's text. I will show that the latter argument obviously does not work. The more promising argument which I reconstruct on behalf of Putnam raises some interesting questions about the relation between the contents of one's beliefs and one's environment and about how this relation affects the evaluation of anti-skeptical arguments. I conclude that my reconstructed argument ultimately fails as a response to Cartesian skepticism: the argument engenders a skepticism about knowledge of meaning, or propositional content, which undercuts its anti-skeptical force. (shrink)

Machine generated contents note: Introduction; 1. Brains in a vat Anthony Brueckner; 2. Scepticism, objectivity, and brains in vats Gary Ebbs; 3. Ebbs on scepticism, objectivity, and brains in vats Anthony Brueckner; 4. The dialectical context of Putnam's argument that we are not brains in vats Gary Ebbs; 5. Trying to get outside your own skin Anthony Brueckner; 6. Can we take our words at face value? Gary Ebbs; 7. Is scepticism about self-knowledge incoherent? Anthony Brueckner; 8. Is scepticism about (...) self-knowledge coherent? Gary Ebbs; 9. The coherence of scepticism about self-knowledge Anthony Brueckner; 10. Why scepticism about self-knowledge is self-undermining Gary Ebbs; 11. Scepticism about self-knowledge redux Anthony Brueckner; 12. Self-knowledge in doubt Gary Ebbs; 13. Looking back Anthony Brueckner; Bibliography; Index. (shrink)

The Matrix presents a version of an old philosophical fable: the brain in a vat. A disembodied brain is floating in a vat, inside a scientist’s laboratory. The scientist has arranged that the brain will be stimulated with the same sort of inputs that a normal embodied brain receives. To do this, the brain is connected to a giant computer simulation of a world. The simulation determines which inputs the brain receives. When the brain produces outputs, these are fed back (...) into the simulation. The internal state of the brain is just like that of a normal brain, despite the fact that it lacks a body. From the brain’s point of view, things seem very much as they seem to you and me. (shrink)

In Reason, Truth, and History Hilary Putnam has presented an anti-skeptical argument purporting to prove that we are not brains in a vat. How exactly the argument goes is somewhat controversial. A number of competing "recon¬structions" have been proposed. They suffer from a defect which they share with what seems to be Putnam's own version of the argument. In this paper, I examine a very simple and rather natural reconstruction of the argument, one that does not employ any premises in (...) which a sentence, viz. the sentence 'I am a brain in a vat', is mentioned rather than used. In this respect my version of the argument is importantly different from what appears to be Putnam's own version. (shrink)

A few years back, I participated in the Spindell Conference in Memphis, and gave a paper, “How Can We Know That We’re Not Brains in Vats?” (available on-line at: http://pantheon.yale.edu/~kd47/Spindell.htm). The bulk of that paper concerned responses to skepticism. I pursued an unusually radical criticism of the often-criticized “Putnam-style” responses to skepticism. To put it rather enigmatically, I argued that such responses don’t work even if they work! And I compared such responses with the type of response I favor – (...) the “contextualist Moorean” response – to show how these latter responses are of a type that avoids the radical problems that plague Putnam-style responses. But in the final section of the paper, I turned briefly to a different, though related, issue, presenting my proposed solution to what’s often called the “McKinsey problem.”. (shrink)

This should be fairly close to the text of this paper as it appears in The Southern Journal of Philosophy 38 (2000), Spindel Conference Supplement: 121-148.

According to a typical skeptical hypothesis, the evidence of your senses has been massively deceptive. Venerable skeptical hypotheses include the hypotheses that you have been deceived by a powerful evil demon, that you are now having an incredibly detailed dream, and that you are a brain in a vat. It is obviously reasonable for you now to be confident that neither of the above hypotheses is true. Epistemologists have proposed many stories to explain why that is reasonable. One theory is (...) that those hypotheses are inherently much less plausible than the hypothesis that your senses are basically reliable. Another theory is that you currently don’t believe any of those hypotheses, and that you need no justification to continue in that disbelief, given that your current beliefs cohere properly. A third theory is that —given that your senses are working properly—your sensory experiences themselves justify you in believing propositions such as the proposition that you have hands. Neo is given very good evidence that some skeptical hypothesis is true. He rightly becomes doubtful that his senses are or have been trustworthy. In fact, he becomes confident of a particular hypothesis: that AI’s created the Matrix, etc. But this is just one of many types of hypotheses that might account for his experiences. These types include. (shrink)

One of the advantages of classical foundationalism was that it was thought to provide a refutation of skeptical worries, which raise the specter that our beliefs might be extensively mistaken. The most extreme versions of these worries are expressed in familiar thought experiments such as the brain-in-a-vat hypothesis, which imagines a world in which, unbeknownst to you, your brain is in a vat hooked up to equipment programmed to provide it with precisely the same visual, auditory, tactile, and other sensory (...) inputs that you have in this world. As a result, your opinions about your immediate environment are the same as they are in this world. You have the same beliefs about your recent activities, your current physical appearance, your present job, and so on, but in fact you are a brain in a vat tucked away in a corner of a laboratory. Thus, in the brain-in-a-vat world, your beliefs about these everyday matters are mistaken, and mistaken not just in detail, but deeply mistaken. (shrink)

Recent literature in epistemology has focused on the following argument for skepticism (SA): I know that I have two hands only if I know that I am not a handless brain in a vat. But I don't know I am not a handless brain in a vat. Therefore, I don't know that I have two hands. Part I of this article reviews two responses to skepticism that emerged in the 1980s and 1990s: sensitivity theories and attributor contextualism. Part II considers (...) the more recent ‘neo-Moorean’ response to skepticism and its development in ‘safety’ theories of knowledge. Part III argues that the skeptical argument set out in SA is not of central importance. Specifically, SA is parasitic on skeptical reasoning that is more powerful and more fundamental than that displayed by SA itself. Finally, Part IV reviews a Pyrrhonian argument for skepticism that is not well captured by SA, and considers a promising strategy for responding to it. (shrink)

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)

The problem of induction and the problem of Cartesian/brain-in-the-vat skepticism have much in common. Both are instances of a general problem of defeasible justification . I use the term "defeasible justification" to refer to a relation between a piece of evidence.

The brain-in-a-vat argument for skepticism is best formulated, not using the closure principle, but using the "Preference Principle," which states that in order to be justified in believing H on the basis of E, one must have grounds for preferring H over each alternative explanation of E. When the argument is formulated this way, Dretske's and Klein's responses to it fail. However, the strengthened argument can be refuted using a direct realist account of perception. For the direct realist, refuting the (...) BIV scenario is not a precondition on knowledge of the external world, and only the direct realist can give a non-circular account of how we know we're not brains in vats. (shrink)

This dissertation is a defense of moderate invariantism, the traditional epistemological position combining the following three theses: invariantism, according to which the word ‘know’ expresses the same content in every context of use; intellectualism, according to which whether one knows a certain proposition does not depend on one’s practical interests; and antiskepticism, according to which we really do know much of what we ordinarily take ourselves to know. Moderate invariantism needs defending because of seemingly powerful arguments for contextualism, the view (...) that, like ‘I’ and ‘now’, ‘know’ expresses different contents in different contexts. It has been argued that only contextualism can properly reply to skeptical arguments, and that only contextualism can account for our tendency to go from judging that a knowledge claim is true to judging that it is false in response to shifts in the context of use. Moderate invariantist replies to these arguments have largely failed. I propose new replies on behalf of moderate invariantism, while critiquing earlier, less successful attempts. Chapter one is introductory. In chapters two and three, I examine contextualist replies to skeptical arguments arising from radical skeptical hypotheses (such as the possibility that one is a brain in a vat) and from considerations involving lotteries. I argue that if contextualism can adequately respond to these arguments, then there are equally effective replies available to the moderate invariantist. In the next two chapters, I examine Stewart Cohen’s “Airport Case,” which elicits intuitions about knowledge claims that supposedly only contextualism can accommodate. In chapter four, I argue that none of the invariantist replies to the case that depend on denying the intuitions succeed; in chapter five, I accept the intuitions, but argue that contextualism does not follow from them. Finally, in chapter six, I evaluate two interesting invariantist critiques of contextualism; according to the first, contextualism collapses into the radical position that every English expression is context-sensitive; according to the second, ‘know’ fails a test for context-sensitivity involving indirect speech reports. (shrink)

Hilary 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.1 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.”2 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 argument has drawn a good deal of criticism already, but it will be argued here that these criticisms fail to capture the central problem with Putnam’s argument. Putnam’s conclusions about the self refuting character of the brain in a vat hypothesis, rather than simply being a consequence of his semantic externalism, will be shown to be actually out of line with central and plausible aspects of his own account of the relationship between our minds and the world. Reflections on intentionality and semantics ultimately give us no compelling reason to suppose that the beliefs expressed by claims like “I am a brain in a vat” could not be true,3 but (pace Putnam) this supports neither skepticism nor metaphysical realism. (shrink)

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)

"If a person can think of an F, then that person has come into causal contact with an F in the right way" is a premise in an obvious reconstruction of Putnam’s argument that we are not brains in vats. ’If a person can think of an F, then that person has come into causal contact with an F or with something at least as good as an F’ is the only controversial premise in Descartes’s argument for the existence of (...) God. Putnam’s principle entails Descartes’s, which suggests that we should enquire after better versions of Putnam’s proof. I present three variations and conclude that Putnam’s semantic theory does not have antisceptical consequences. In contrast, given Descartes’s cognitive situation, he was perfectly justified in accepting the soundness of his argument for the existence of God. (shrink)

Hilary Putnam has offered two arguments to show that we cannotbe brains in a vat, and one to show that our cognitive situationcannot be fully analogous to that of brains in a vat. The latterand one of the former are irreparably flawed by misapplicationsof, or mistaken inferences from, his semantic externalism; thethird yields only a simple logical truth. The metaphysical realismthat is Putnams ultimate target is perfectly consistent withsemantic externalism.

Skeptics try to persuade us of our ignorance with arguments like the following: 1. I don't know that I am not a handless brain-in-a-vat [BIV]. 2. If I don't know that I am not a handless BIV, then I don't know that I have hands. Therefore, 3. I don't know that I have hands. The BIV argument is valid, its premises are intuitively compelling, and yet, its conclusion strikes us as a absurd. Something has to go, but what? Contextualists contend (...) that an adequate solution to the skeptical problem must: (i) retain epistemic closure, (ii) explain the intuitive force of skeptical arguments by explaining why their premises initially seem so compelling, and (iii) account for the truth of our commonsense judgment that we do possess lots of ordinary knowledge. Contextualists maintain that the key to such a solution is recognizing that the semantic standards for 'knows' vary from context to context such that in skeptical contexts the skeptic's premises are true and so is her conclusion; but in ordinary contexts, her conclusion is false and so is her first premise. Despite its initial attractiveness, the contextualist solution comes at a significant cost, for contextualism has many counterintuitive results. After presenting the contextualist solution, I identify a number of these costs. I then offer a noncontextualist solution that meets the adequacy constraint identified above, while avoiding the costs associated with contextualism. Hence, one of the principal reasons offered for adopting a contextualist theory of knowledge -- its supposedly unique ability to adequately resolve the skeptical problem -- is undermined. (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)

Putnam argued in the first chapter of Reason, Truth and History that it is not epistemically possible that we are brains in a vat (of a certain sort). If his argument is correct, and can be extended in certain ways, then it seems that we can lay to rest the traditional skeptical worry that most of our beliefs about the external world are false. Putnam's argument that we know that we are not brains in a vat has two parts.

In early essays and in more recent work, Fred Dretske argues against the closure of perception, perceptual knowledge, and knowledge itself. In this essay I review his case and suggest that, in a useful sense, perception is closed, and that, while perceptual knowledge is not closed under entailment, perceptually based knowledge is closed, and so is knowledge itself. On my approach, which emphasizes the safe indication account of knowledge, we can both perceive, and know, that sceptical scenarios (such as being (...) a brain in a vat) do not hold. (shrink)

: Radical sceptical possibilities challenge the anti-realist view that truth consists in ideal rational acceptability. Putnam, as part of his defence of an anti-realist view, subjected the case of the brain in a vat to a semantic externalist treatment, which aimed to maintain the desired connection between truth and ideal rational acceptability. It is argued here that self-consciousness poses special problems for this externalist strategy. It is shown how, on a standard model of first-person reference, Putnam's brain in a vat (...) will be mistaken in its rational self-ascription of externalist predicates. The natural response, which employs an alternative model of first-person reference, is shown to have the equally realist consequence that there are enquiry-transcendent truths about the self. (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)

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)

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)

A sceptic confronts us and utters the following sentences: (1) "George does not know that he is not a brain-in-a-vat (BIV)." (2) "If George does not know that he is not a BIV, then George does not know that he has hands." (3) "So, George does not know that he has hands.".

This paper surveys attempts in the recent literature to offer a modal condition on knowledge as a way of resolving the problem of scepticism. In particular, safety-based and sensitivity-based theories of knowledge are considered in detail, along with the anti-sceptical prospects of an explicitly anti-luck epistemology.

Hilary Putnam deals in this book with some of the most fundamental persistent problems in philosophy: the nature of truth, knowledge and rationality. His aim is to break down the fixed categories of thought which have always appeared to define and constrain the permissible solutions to these problems.

From the mid-1980‘s to the early 2000‘s the wide-ranging resources of the concept we now call sensitivity , which Robert Nozick used to give an analysis of the concepts of knowledge and evidence , went largely unappreciated in epistemology. This was in part because these resources were upstaged by a glamorous implication the condition has for skepticism, and in part because of loss of faith in the project of giving a theory of knowledge at all, due to the failure time (...) and again to construct a theory without counterexamples. The sensitivity condition, or as Nozick called it the variation condition, which requires that were p to be false you wouldn‘t believe it, had its own apparent counterexamples. And while the implication of this condition for skepticism was elegant and principled – it is possible to know that there is a table in front of you without knowing you are not a brain in a vat – it had the price of denying closure of knowledge under known implication, that is, denying that knowing q and knowing that q implies p are together sufficient to make the belief in p that you have on that basis knowledge. (shrink)

The force of sceptical inquiries into out knowledge of other people is a paradigm of the force that philosophical views can have. Sceptical views arise out of philosophical inquiries that are identical in all major respects with inquiries that we employ in ordinary cases. These inquiries employ perfectly mundane methods of making and assessing claims to know. This paper tries to show that these inquiries are conducted in cases that lack certain contextual ingredients found in ordinary cases. The paper concludes (...) that these ordinary methods of inquiry, when employed in these limited cases, put us in a position in which we actually cannot know. Thus our ability to know will be a function of the added contextual elements that are found in ordinary cases. A second conclusion is that we come literally to observe bodily behaviour in the course of the sceptical inquiry; while in ordinary cases we observe pain-behaviour. (shrink)

That expressions should have their contents can seem paradigmatically contingent. But it can also seem a priori that expressions in one's own language should have their contents to the extent that instances of disquotation, such as "Socrates" refers to Socrates' and "cat" refers to cats', are trivially true. I attempt to reconcile these conflicting intuitions about meaningfulness by examining semantic and metasemantic details of linguistic reflexivity. I argue that instances of disquotation are contingent analytic in Kaplan's sense, and bring this (...) lesson to bear on semantic strategies for responding to skepticism, such as Putnam's Brains-in-a-Vat argument. (shrink)

There is a widespread belief among contemporary philosophers that skeptical hypotheses—such as that we are dreaming, or victims of an evil demon, or brains in a vat—cannot definitively be ruled out as false. This belief is ill-founded. In fact it is based on a failure to see that skeptical arguments beg the question. Such arguments assume that reality is not an immediate given of experience in order to prove that reality is not an immediate given of experience. This point is (...) explained and justified in detail. Conversely, however, the realist would beg the question in the opposite way if he tried to prove realism. The conclusion we should reach is that skepticism and realism are problems of immediacy and not of proof. They face us with a choice between alternatives that are not only radically different but also pretty much impregnable and irrelevant to each other. This choice is not arbitrary, for there are grounds to determine it. But the grounds are the immediate evidence and not the arguments. (shrink)

In this paper we offer an exegesis of Hilary Putnam’s classic argument against the brain-in-avat hypothesis offered in his Reason, truth and history (1981). In it, Putnam argues that we cannot be brains in a vat because the semantics of the situation make it incoherent for anyone to wonder whether they are a brain a vat. Putnam’s argument is that in order for ‘I am a brain in a vat’ to be true, the person uttering it would have to be (...) able to refer successfully to those things: the vat, and the envatted brain. Putnam thinks that reference can’t be secured without relevant kinds of causal relations, which, if envatted, the brain would lack, and so, it fails to be able to meaningfully utter ‘I am a brain in a vat’. We consider the implications of Putnam’s arguments for the traditional sceptic. In conclusion, we discuss the role of Putnam’s arguments against the brain in a vat hypothesis in his larger defense of his own internal realism against metaphysical realism. (shrink)

Skeptics claim that we know radically less than we think we do. For example, skeptics might claim that we have next to no knowledge of the past, the future, or other minds. Here we will consider the skeptical claim that we have next to no knowledge of the external world: the world of physical objects that we at least seem to perceive. One well-known argument in support of this claim appeals to the possibility of being a BIV: a brain in (...) a vat. According to the BIV Hypothesis, you are a mere BIV without a normal body. This of course means, among other things, that you don't have hands. The nerve endings of your brain are stimulated in a manner so sophisticated that the perfect illusion of a normal life is generated. Let's distinguish between the.. (shrink)

Suppose that a team of neurosurgeons and bioengineers were able to remove your brain from your body, suspend it in a life-sustaining vat of liquid nutrients, and connect its neurons and nerve terminals by wires to a supercomputer that would stimulate it with electrical impulses exactly like those it normally receives when embodied. According to this brain-in-a-vat thought experiment, your envatted brain and your embodied brain would have subjectively indistinguishable mental lives. For all you know—so one argument goes—you could be (...) such a brain in a vat right now.1 Daniel Dennett calls this sort of philosophical thought experiment an “intuition pump” (Dennett 1995). An intuition pump is designed to elicit certain intuitive convictions, but is not itself a proper argument: “intuition pumps are fine if they’re used correctly, but they can also be misused. They’re not arguments, they’re stories. Instead of having a conclusion, they pump an intuition. They get you to say ‘Aha! Oh, I get it!’ (Dennett 1995, p. 182). Philosophers have used the brain-in-a-vat story mainly to raise the problem of radical skepticism and to elicit various intuitions about meaning and knowledge (Putnam 1981). The basic intuition the story tries to pump is that the envatted brain, though fully conscious, has systematically false beliefs about the world, including itself. Some philosophers reject this intuition. They propose that the envatted brain’s beliefs are really about its artificial environment or that it.. (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)

Is matter real? Are persons real? Is time real? This Very Short Introduction discusses what, if anything, is "real" by looking at a variety of arguments from philosophy, physics, and cognitive science. The book shows that the question "what is real?" is not some esoteric puzzle that only philosophers ponder. Scientists also ask this question when they investigate whether candidates for the fundamental constituents of matter are actually "out there" or just a mere abstraction from a successful theory and cognitive (...) scientists ask it when trying to find out which set of the bewildering array of data processed by our brain could constitute the basis for the self. -/- Contents: -/- Introduction 1. What is real? Dreams and simulations 2. Is matter real? 3. Are persons real? 4. Is time real? Conclusion. (shrink)