Many important metaphysical arguments validly deduce an actuality from a possibility. For example: Because it is possible for me to exist in the absence of anything material, I am not my body. I argue that there is no reason to suppose that our capacity for modal judgment is equal to the task of determining whether the "possibility" premise of any of these arguments is true. I connect this thesis with Stephen Yablo's recent work on the epistemology of modal statements.

In these challenging pages, Unger argues for the extreme skeptical view that, not only can nothing ever be known, but no one can ever have any reason at all for anything. A consequence of this is that we cannot ever have any emotions about anything: no one can ever be happy or sad about anything. Finally, in this reduction to absurdity of virtually all our supposed thought, he argues that no one can ever believe, or even say, that anything is (...) the case. (shrink)

In this paper I argue that causal relations between objects are represented in visual experience, and contrast my argument and its conclusion with Michotte's results from the 1960's.

In lieu of an abstract, here is a brief excerpt of the content:Cartesian Skepticism from Bare PossibilityRobert WachbritIn making his case for skepticism, Peter Unger offers the following exotic case as one which “conforms to a familiar, if not often explicitly artic-ulated pattern or form” of skeptical reasoning: 1 imagine that there is an evil scientist who deceives subjects into falsely believing that there are rocks. Living in a world bereft of rocks, he induces belief in their existence using electrodes (...) implanted into the appropriate parts of the subjects’ brai ns, protoplasm, or systems through which he sends patterns of electrical impulses in accord with his deceptive designs. Unger then offers the following argument, which is supposed to instantiate the pattern or form of this kind of skeptical reasoning:If you know that there are rocks, then you can know that there is no such scientist doing this to you. But no one can ever know that there is no evil scientist who is, by means of electrodes, deceiving him into falsely believing there to be rocks. So... you never know that there are rocks. But of course we have chosen our person, and the matter of there being rocks, quite arbitrarily, and this argument... may be generalized to cover any external matter at all. From this, we may conclude... that nobody knows anything about the external world. 2After presenting this case and articulating its form, Unger claims that “this argument is the same in form as the ‘evil demon’ argument in Descartes’s [End Page 109] Meditations; it is but a more modern, scientific counter-part, with its domain of application confined to matters concerning the external world.” He then proceeds to describe Descartes’s argument as “the most compelling sceptical argument the phil osophical literature has to offer,” calling it in fact “the classical argument for scepticism.” 3These claims may seem a little bit surprising; for it is not obvious, even from the most careful attention to the text, that what is written about the evil demon in the First Meditation constitutes a skeptical argument at all, and the scholarly literature is generally, and perhaps surprisingly, quite confusing about just what is going on at the end of the First Meditation. Further, rather than being exceedingly compelling as Unger thinks, arguments of this form are not only assiduously avoided by Descarte s during his descent into skepticism but are in fact, as I shall argue with some help from Descartes, weak and considerably less compelling than the kind of skeptical challenges Descartes actually offers.My purpose in this paper, then, is to make two related points, one historical and the other philosophical. First, I will try to demonstrate, on the basis of both textual and critical evidence, that Descartes was not offering a (further and final) skeptica l argument when he invented his demon. I will try to exhibit some of the confusions in the scholarly literature about the text of the last three paragraphs of the First Meditation and, by so doing, support Gouhier’s position that the idea of the demon “ha s no metaphysical significance; it is purely a methodological artifice which permits doubt to continue....” 4 Second, I will show that embodied in Descartes’s rejection of this kind of skeptical reasoning is the very reason for its weakness, a weakness that should prevent it from being considered, as Unger considers it, the classical form of skeptical argument. The inventions of the First Meditation still exercise considerable hold on our philosophical imaginations. I hope to show that, at least as far as the demon is concerned, Descartes would have been surprised at some of the most conventional and entrenched scholarly interpretations given his use of it and not at all sympathetic to its employment in a skeptical argument. Lest the demon seem an old and tired subject of philosophical scrutiny, let me beg the reader’s indulgence by promising both a deeper than usual look into the text of the end of the First Meditation and some significant conclusions about Cartesian skepticism that are hardly commonplace and thus neither old nor tired. [End Page 110]I. The Textual EvidenceThe demon makes its first appearance in the last paragraph of the... (shrink)

Consider the skeptic about the external world. Let’s straightaway concede to such a skeptic that perception gives us no conclusive or certain knowledge about our surroundings. Our perceptual justification for beliefs about our surroundings is always defeasible—there are always possible improvements in our epistemic state which would no longer support those beliefs. Let’s also concede to the skeptic that it’s metaphysically possible for us to have all the experiences we’re now having while all those experiences are false. Some philosophers dispute (...) this, but I do not. The skeptic I want to consider goes beyond these familiar points to the much more radical conclusion that our perceptual experiences can’t give us any knowledge or even justification for believing that our surroundings are one way rather than another. (shrink)

One of the key supposed 'platitudes' of contemporary epistemology is the claim that knowledge excludes luck. One can see the attraction of such a claim, in that knowledge is something that one can take credit for - it is an achievement of sorts - and yet luck undermines genuine achievement. The problem, however, is that luck seems to be an all-pervasive feature of our epistemic enterprises, which tempts us to think that either scepticism is true and that we don't know (...) very much, or else that luck is compatible with knowledge after all. In this book, Duncan Pritchard argues that we do not need to choose between these two austere alternatives, since a closer examination of what is involved in the notion of epistemic luck reveals varieties of luck that are compatible with knowledge possession and varieties that aren't. Moreover, Pritchard shows that a more nuanced understanding of the relationship between luck and knowledge can cast light on many of the most central topics in contemporary epistemology. These topics include: the externalism/internalism distinction; virtue epistemology; the problem of scepticism; metaepistemological scepticism; modal epistemology; and the problem of moral luck. All epistemologists will need to come to terms with Pritchard's original and incisive contribution. (shrink)

The notion of conceivability has traditionally been regarded as crucial to an account of modal knowledge. Despite its importance to modal epistemology, there is no received explication of conceivability. One purpose of this paper is to argue that the notion is not fruitfully explicated in terms of the imagination. The most natural way of presenting a notion of conceivability qua imaginability is open to cogent criticism. In order to avoid such criticism, an advocate of the modal insightfulness of the imagination (...) must broaden the idea of what it is to be imaginable. I argue that this required broadening renders the imagination idle . Consequently, I distinguish two different accounts of the evidential basis of modal knowledge and present a more general argument that concludes that the very notion of conceivability should be eschewed in modal epistemology. (shrink)

David Lewis (1941-2001) was Class of 1943 University Professor of Philosophy at Princeton University. His contributions spanned philosophical logic, philosophy of language, philosophy of mind, philosophy of science, metaphysics, and epistemology. In On the Plurality of Worlds, he defended his challenging metaphysical position, "modal realism." He was also the author of the books Convention, Counterfactuals, Parts of Classes, and several volumes of collected papers.

I lay out the framework for my theory of sensory imagination in “Imagining as a guide to possibility.” Sensory imagining involves mental imagery , and crucially, in describing the content of imagining, I distinguish between qualitative content and assigned content. Qualitative content derives from the mental image itself; for visual imaginings, it is what is “pictured.” For example, visually imagine the Philadelphia Eagles defeating the Pittsburgh Steelers to win their first Super Bowl. You picture the greenness of the field and (...) the football’s brown oblong shape. Some of what you imagine isn’t explicitly pictured, however. That it is Sunday, that it is the Super Bowl: these facts are assigned. (shrink)

There is a long tradition in philosophy of using a priori methods to draw conclusions about what is possible and what is necessary, and often in turn to draw conclusions about matters of substantive metaphysics. Arguments like this typically have three steps: first an epistemic claim , from there to a modal claim , and from there to a metaphysical claim.

The paper begins with a clarification of the notions of intuition (and, in particular, modal intuition), modal error, conceivability, metaphysical possibility, and epistemic possibility. It is argued that two-dimensionalism is the wrong framework for modal epistemology and that a certain nonreductionist approach to the theory of concepts and propositions is required instead. Finally, there is an examination of moderate rationalism’s impact on modal arguments in the philosophy of mind -- for example, Yablo’s disembodiment argument and Chalmers’s zombie argument. A less (...) vulnerable style of modal argument is defended, which nevertheless wins the same anti-materialist conclusions sought by these other arguments. (shrink)

Dr Hart sets out to answer this question by showing that the issue is as much about the nature of causation as it is about the natures of mind and matter.

Kripkean examples of necessary a posteriori truths clearly provide a challenge to attempts to connect facts about possibility to facts about what people can conceive. The paper argues for a general principle connecting imaginability under certain special circumstances to possibility; it also discusses some of the issues raised by the resulting position.

Radical skepticism about the external implies that no belief about the external is even prima facie justified. A theoretical reply to skepticism has four stages. First, show which theories of epistemic justification support skeptical doubts (show which theories, given other reasonable assumptions, entail skepticism). Second, show which theories undermine skeptical doubts (show which theories, given other reasonable assumptions, do not support the skeptic’s conclusion). Third, show which of the latter theories (which non-skeptical theory) is correct, and in so doing show (...) that all of the rival theories of justification, skeptical and non-skeptical alike, are mistaken. Fourth, explain why skeptical doubts are sometimes (or sometimes merely seem) intuitive, and thereby accommodate skeptical doubts without capitulation. Michael Williams has pioneered the very idea of a theoretical reply. A theoretical diagnosis consists in just the first two stages. An adequate reply, which is correct at each stage, would rebut the skeptic entirely. Williams’ own reply, I argue, is inadequate. I offer in its place an exhaustive and accurate diagnosis of skepticism. I distinguish four kinds of skepticism and five theories of justification. I then show which theories do, and which theories do not, support which kinds of skepticism. (shrink)

This paper presents a partial analysis of perceptual knowledge, an analysis that will, I hope, lay a foundation for a general theory of knowing. Like an earlier theory I proposed, the envisaged theory would seek to explicate the concept of knowledge by reference to the causal processes that produce (or sustain) belief. Unlike the earlier theory, however, it would abandon the requirement that a knower's belief that p be causally connected with the fact, or state of affairs, that p.

This paper advances the thesis that we can justifiably believe philosophically interesting possibility statements. The first part of the paper critically discusses van Inwagens skeptical arguments while at the same time laying some of the foundation for a positive view. The second part of the paper advances a view of conceivability in terms of imaginability, where imaginging can be propositional, pictorial, or a combination of the two, and argues that conceivability can, and often does, provide us with justified beliefs of (...) what is metaphysically possible. The notion of scenarios is developed, as is an account of how filling out scenarios can uncover a defeater or, in many cases, strengthen the justification for the relevant possibility statement. (shrink)

I’m going to argue for a set of restricted skeptical results: roughly put, we don’t know that fire engines are red, we don’t know that we sometimes have pains in our lower backs, we don’t know that John Rawls was kind, and we don’t even know that we believe any of those truths. However, people unfamiliar with philosophy and cognitive science do know all those things. The skeptical argument is traditional in form: here’s a skeptical hypothesis; you can’t epistemically neutralize (...) it, you have to be able to neutralize it to know P; so you don’t know P. But the skeptical hypotheses I plug into it are “real, live” scientific-philosophical hypotheses often thought to be actually true, unlike any of the outrageous traditional skeptical hypotheses (e.g., ‘You’re a brain in a vat’). So I call the resulting skepticism Live Skepticism. Notably, the Live Skeptic’s argument goes through even if we adopt the clever anti-skeptical fixes thought up in recent years such as reliabilism, relevant alternatives theory, contextualism, and the rejection of epistemic closure. Furthermore, the scope of Live Skepticism is bizarre: although we don’t know the simple facts noted above, many of us do know that there are black holes and other amazing facts. (shrink)

It is a traditional empiricist doctrine that natural laws are universal truths. In order to overcome the obvious difficulties with this equation most empiricists qualify it by proposing to equate laws with universal truths that play a certain role, or have a certain function, within the larger scientific enterprise. This view is examined in detail and rejected; it fails to account for a variety of features that laws are acknowledged to have. An alternative view is advanced in which laws are (...) expressed by singular statements of fact describing the relationship between universal properties and magnitudes. (shrink)

I examine the conditions which hypotheses must satisfy if they are to be used to raise significant sceptical challenges. I argue that sceptical hypotheses do not have to be logically, metaphysically or epistemically possible: they need only to depict scenarios subjectively indistinguishable from the actual world and to show how subjects can believe what they do while not having knowledge. I also argue that sceptical challenges can be raised against a priori beliefs, even if those beliefs are necessarily true. I (...) hope to broaden our conception of the legitimate kinds of sceptical challenges which can be raised. (shrink)

_Naming and Necessity_ has had a great and increasing influence. It redirected philosophical attention to neglected questions of natural and metaphysical necessity and to the connections between these and theories of naming, and of identity. This seminal work, to which today's thriving essentialist metaphysics largely owes its impetus, is here reissued in a newly corrected form with a new preface by the author. If there is such a thing as essential reading in metaphysics, or in philosophy of language, this is (...) it. (shrink)

In discussions of perception and its relation to knowledge, it is common to distinguish what one comes to believe on the basis of perception from the distinctively perceptual basis of one's belief. The distinction can be drawn in terms of propositional contents: there are the contents that a perceiver comes to believe on the basis of her perception, on the one hand; and there are the contents properly attributed to perception itself, on the other. Consider the content.

"This is a marvelous book, full of subtle, thoughtful, and original argument.

A transcript of three lectures, given at Princeton University in 1970, which deals with (inter alia) debates concerning proper names in the philosophy of language.

Evidentialism is a view about the conditions under which a person is epistemically justified in having a particular doxastic attitude toward a proposition. Evidentialism holds that the justified attitudes are determined entirely by the person's evidence. This is the traditional view of justification. It is now widely opposed. The essays included in this volume develop and defend the tradition. Evidentialism has many assets. In addition to providing an intuitively plausible account of epistemic justification, it helps to resolve the problem of (...) the criterion, helps to disentangle epistemic and ethical evaluations, and illuminates the relationship between epistemic evaluations of beliefs and the evaluation of the methods used to form beliefs. These issues are all addressed in the essays presented here. External world skepticism poses the classic problem for an epistemological theory. The final essay in this volume argues that evidentialism is uniquely well qualified to make sense of skepticism and to respond to its challenge. Evidentialism is a version of epistemic internalism. Recent epistemology has included many attacks on internalism and has seen the development of numerous externalist theories. The essays included here respond to those attacks and raise objections to externalist theories, especially the principal rival, reliabilism. Internalism generally has been criticized for having unacceptable deontological implications, for failing to connect epistemic justification to truth, and for failing to provide an adequate account of what makes basic beliefs justified. Each of these charges is answered in these essays. The collection includes two previously unpublished essays and new afterwords to five of the reprinted essays; it will be the definitive resource on evidentialism for all epistemologists. (shrink)

Introduction -- Part I: The classical problems of epistemology -- Descartes's epistemology -- The concept of knowledge -- The problem of induction -- A priori justification and knowledge -- Immediate experience -- Knowledge of the external world -- Some further epistemological issues : other minds, testimony, and memory -- Part II: Contemporary responses to the cartesian epistemological program -- Introduction to part II -- Foundationalism and coherentism -- Internalism and externalism -- Quine and naturalized epistemology -- Knowledge and skepticism.

This book, first published in 2000, is about the nature of skeptical arguments and their role in philosophical inquiry. John Greco delineates three main theses: that a number of historically prominent skeptical arguments make no obvious mistake, and therefore cannot be easily dismissed; that the analysis of skeptical arguments is philosophically useful and important, and should therefore have a central place in the methodology of philosophy; and that taking skeptical arguments seriously requires us to adopt an externalist, reliabilist epistemology. Greco (...) argues that the importance of skeptical arguments is methodological. It is further argued that taking skeptical arguments seriously requires us to adopt a version of 'virtue epistemology', or a theory of knowledge that makes intellectual virtue central in the analysis of knowledge. The above methodology has consequences for moral and religious epistemology; in particular, a theory of moral perception is defended. (shrink)