The Problems of Philosophy is a 1912 book by Bertrand Russell, in which Russell attempts to create a brief and accessible guide to the problems of philosophy. Focusing on problems he believes will provoke positive and constructive discussion, Russell concentrates on knowledge rather than metaphysics: If it is uncertain that external objects exist, how can we then have knowledge of them but by probability. There is no reason to doubt the existence of external objects simply because of sense data. Russell (...) guides the reader through his famous 1910 distinction between knowledge by acquaintance and knowledge by description and introduces important theories of Plato, Aristotle, René Descartes, David Hume, John Locke, Immanuel Kant, Georg Wilhelm Friedrich Hegel and others to lay the foundation for philosophical inquiry by general readers and scholars alike. "In the following pages I have confined myself in the main to those problems of philosophy in regard to which I thought it possible to say something positive and constructive, since merely negative criticism seemed out of place. For this reason, theory of knowledge occupies a larger space than metaphysics in the present volume, and some topics much discussed by philosophers are treated very briefly, if at all. (shrink)

Bertrand Russell was one of the greatest logicians since Aristotle, and one of the most important philosophers of the past two hundred years. As we approach the 125th anniversary of the Nobel laureate's birth, his works continue to spark debate, resounding with unmatched timeliness and power. The Problems of Philosophy, one of the most popular works in Russell's prolific collection of writings, has become core reading in philosophy. Clear and accessible, this little book is an intelligible and stimulating guide to (...) those problems of philosophy which often mistakenly lead to its status as too lofty and abstruse for the lay mind. Focusing on problems he believes will provoke positive and constructive discussion, Russell concentrates on knowledge rather than metaphysics, steering the reader through his famous 1910 distinction between "knowledge by acquaintance and knowledge by description," and introducing important theories of Descartes, Kant, Hegel, Hume, Locke, Plato, and others to lay the foundation for philosophical inquiry by general readers and scholars alike.With a new introduction by John Perry, this valuable work is a perfect introduction to the field and will continue to stimulate philosophical discussion as it has done for nearly forty years. (shrink)

Immensely intelligible, thought-provoking guide by Nobel prize-winner considers such topics as the distinction between appearance and reality, the existence and nature of matter, idealism, inductive logic, intuitive knowledge, many other subjects. For students and general readers, there is no finer introduction to philosophy than this informative, affordable and highly readable edition that is "concise, free from technical terms, and perfectly clear to the general reader with no prior knowledge of the subject."—The Booklist of the American Library Association.

Knowledge and its Limits presents a systematic new conception of knowledge as a kind of mental stage sensitive to the knower's environment. It makes a major contribution to the debate between externalist and internalist philosophies of mind, and breaks radically with the epistemological tradition of analyzing knowledge in terms of true belief. The theory casts new light on such philosophical problems as scepticism, evidence, probability and assertion, realism and anti-realism, and the limits of what can be known. The arguments are (...) illustrated by rigorous models based on epistemic logic and probability theory. The result is a new way of doing epistemology and a notable contribution to the philosophy of mind. (shrink)

According to an influential contextualist solution to skepticism advanced by Keith DeRose, denials of skeptical hypotheses are, in most contexts, strong yet insensitive. The strength of such denials allows for knowledge of them, thus undermining skepticism, while the insensitivity of such denials explains our intuition that we do not know them. In this paper we argue that, under some well-motivated conditions, a negated skeptical hypothesis is strong only if it is sensitive. We also consider how a natural response on behalf (...) of DeRose appears to be equally available to his primary rival (viz., the sensitivity theorist). (shrink)

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

The question whether epistemological concepts are closed under deduction is an important one since many skeptical arguments depend on closure. Such skepticism can be avoided if closure is not true of knowledge (or justification). This response to skepticism is rejected by Peter Klein and others. Klein argues that closure is true, and that far from providing the skeptic with a powerful weapon for undermining our knowledge, it provides a tool for attacking the skeptic directly. This paper examines various arguments in (...) favor of closure and Klein's attempted use of closure to refute skepticism. Such a refutation of skepticism is mistaken. But the closure principle is in any case false, so the skepticism that depends on it is undermined. The appeal of the closure principle derives from a failure to recognize an important feature of our epistemological concepts, namely, their context relativity. (shrink)

John Greco’s Putting Skeptics in Their Place is an important book. Greco persuasively argues that the best skeptical arguments cannot be easily dismissed and should not be ignored. These arguments cannot be easily dismissed because they defend important conclusions and make no obvious mistake. The arguments should not be ignored because their proper analysis reveals much about central philosophical notions such as knowledge and evidence. While defending these conclusions Greco offers sophisticated metaepistemological and metaphilosophical reflections. Philosophers properly attending to the (...) strongest skeptical arguments will, according to Greco, find themselves heading in the direction of a virtue-based version of reliabilism. Greco defends this general type of theory and outlines the major components of his preferred version of the theory. Greco stops short of defending a fully precise account of knowledge, but he offers a spirited defense of his claim that such a theory should fall somewhere in the family of virtue-based reliabilist theories, a type of theory that Greco calls “agent reliabilism.” Greco concludes with a brief discussion of moral and religious epistemology in which he applies some of the insights gained in his exploration and defense of agent reliabilism. (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)

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)

What knowledge is imperilled by sceptical doubt? That is, what range of beliefs may be called into doubt by sceptical nightmares like the Cartesian demon hypothesis? It is generally thought that demons have limited powers, perhaps only threatening a posteriori knowledge of the external world, but at any rate not threatening principles like the cogito. I will argue that there is a demon – the debasing demon – with unlimited powers, which threatens universal doubt. Rather than deceiving us with falsities, (...) the debasing demon would allow us true beliefs, but only as guesses. (shrink)

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.

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)

I focus on a key argument for global external world scepticism resting on the underdetermination thesis: the argument according to which we cannot know any proposition about our physical environment because sense evidence for it equally justifies some sceptical alternative (e.g. the Cartesian demon conjecture). I contend that the underdetermination argument can go through only if the controversial thesis that conceivability is per se a source of evidence for metaphysical possibility is true. I also suggest a reason to doubt that (...) conceivability is per se a source of evidence for metaphysical possibility, and thus to doubt the underdetermination argument. (shrink)

Keith DeRose’s solution to the skeptical problem is based on his indirect sensitivity account. Sensitivity is not a necessary condition for any kind of knowledge, as direct sensitivity accounts claim, but the insensitivity of our beliefs that the skeptical hypotheses are false explains why we tend to judge that we do not know them. The orthodox objection line against any kind of sensitivity account of knowledge is to present instances of insensitive beliefs that we still judge to constitute knowledge. This (...) objection line offers counter-examples against the claim of direct sensitivity accounts that sensitivity is necessary for any kind of knowledge. These examples raise an easy problem for indirect sensitivity accounts that claim that there is only a tendency to judge that insensitive beliefs do not constitute knowledge, which still applies to our beliefs that the skeptical hypotheses are false. However, a careful analysis reveals that some of our beliefs that the skeptical hypotheses are false are sensitive; nevertheless, we still judge that we do not know them. Therefore, the fact that some of our beliefs that the skeptical hypotheses are false are insensitive cannot explain why we tend to judge that we do not know them. Hence, indirect sensitivity accounts cannot fulfill their purpose of explaining our intuitions about skepticism. This is the hard problem for indirect sensitivity accounts. (shrink)

Nico Silins has proposed and defended a form of Liberalism about perception that, he thinks, is a good compromise between the Dogmatism of Jim Pryor and others, and the Conservatism of Roger White, Crispin Wright, and others. In particular, Silins argues that his theory can explain why having justification to believe the negation of skeptical hypotheses is a necessary condition for having justification to believe ordinary propositions, even though (contra the Conservative) the latter is not had in virtue of the (...) former. I argue that Silins's explanation is unsuccessful, and hence that we should prefer either White/Wright-style Conservatism (which can explain this necessary condition) or Pryor-style Dogmatism (which denies that this is a necessary condition). (shrink)

This book develops and defends a version of direct realism: the thesis that perception gives us direct awareness, and non-inferential knowledge, of the external..

I defend the view that there is a privileged class of propositions – that there is an external world, among other such 'hinge propositions'– that possess a special epistemic status: justified belief in these propositions is not defeated unless one has sufficient reason to believe their negation. Two arguments are given for this conclusion. Finally, three proposals are offered as morals of the preceding story: first, our justification for hinge propositions must be understood as defeatable, second, antiskeptics must explain our (...) knowledge in the face of 'actual world' skepticism (like dreaming skepticism) as much as in the face of the usual sort (like brain-in-vat skepticism), and, finally, our justification for hinge propositions is basic (i.e. non-inferential). (shrink)

This paper evaluates a number of closure principles (for both knowledge and justification) that have appeared in the literature. Counterexamples are presented to all but one of these principles, which is conceded to be true but trivially so. It is argued that a consequence of the failure of these closure principles is that certain projects of doxastic logic are doomed, and that doxastic logic is of dubious merit for epistemologists interested in actual knowers in the actual world.

The second major thesis of the book follows closely on the first: that the analysis of skeptical arguments is philosophically useful and important, and should therefore have a central role in the methodology of philosophy, and especially in the methodology of epistemology. A close analysis of skeptical arguments highlights our pre-theoretically plausible, but ultimately mistaken, assumptions about the nature of knowledge and evidence. Skeptical arguments are powerful just because their assumptions are so plausible pre-theoretically. But the arguments show us where (...) those assumptions lead, and thereby force us to rethink those assumptions. On this view, skeptical arguments constitute theoretical problems rather than practical problems. There is no “practical” or “existential” problem of skepticism. Rather, skeptical arguments show us that we need to rethink our assumptions about knowledge and evidence, and replace them with something better. (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)

It is nowadays taken for granted that the core radical sceptical arguments all pivot upon the principle that the epistemic operator in question is 'closed' under known entailments. Accordingly, the standard anti-sceptical project now involves either denying closure or retaining closure by amending how one understands other elements of the sceptical argument. However, there are epistemic principles available to the sceptic which are logically weaker than closure but achieve the same result. Accordingly the contemporary debate fails to engage with the (...) sceptical problem in its strongest form. (shrink)

Unger (1974/2000) presents an argument for skepticism that significantly differs from the more traditional arguments for skepticism. The argument is based on two premises, to wit, that knowledge would entitle the knower to absolute certainty, and that an attitude of absolute certainty is always inadmissible from an epistemic viewpoint. The present paper scrutinizes the arguments that Unger provides in support of these premises and shows that none of them is tenable. It thus concludes that Unger's argument for skepticism fails to (...) threaten the possibility of knowledge. (shrink)

Cartesian skepticism about epistemic justification (‘skepticism’) is the view that many of our beliefs about the external world – e.g., my current belief that I have hands – aren’t justified. I examine the two most influential arguments for skepticism – the Closure Argument and the Underdetermination Argument – from an evidentialist perspective. For both arguments it is clear which premise the anti-skeptic must deny. The Closure Argument, I argue, is the better argument in that its key premise is weaker than (...) the Underdetermination Argument’s key premise. However, it’s also likely that the motivation for accepting both key premises is exactly the same. So there may be a sense in which both arguments provide exactly the same motivation for skepticism. Then I argue that if I I’m right about what the motivation for accepting the arguments’ key premises is, then neither argument succeeds in providing a good reason to accept skepticism. I conclude by explaining why I think epistemologists are right to expend a lot of time and effort on refuting these arguments, even if neither argument provides any motivation for skepticism. (shrink)

Those of us who have followed Fred Dretske’s lead with regard to epistemic closure and its impact on skepticism have been half-wrong for the last four decades. But those who have opposed our Dretskean stance, contextualists in particular, have been just wrong. We have been half-right. Dretske rightly claimed that epistemic status is not closed under logical implication. Unlike the Dretskean cases, the new counterexamples to closure offered here render every form of contextualist pro-closure maneuvering useless. But there is a (...) way of going wrong under Dretske’s lead. As the paper argues, Cartesian skepticism thrives on closure failure in a way that is yet to be acknowledged in the literature. The skeptic can make do with principles which are weaker than the familiar closure principles. But I will further claim that this is only a momentary reprieve for the skeptic. As it turns out, one of the weaker principles on which a skeptical modus tollens must rest can be shown false. (shrink)

Michael Williams and Crispin Wright have claimed that we are epistemically justified in believing hinge propositions, such as there is an external world. In a recent paper Allan Hazlett puts forward an argument that purports to elucidate the source of such justification. This paper reconstructs Hazlett's argument and offers a criticism of it.

In this paper, I will clarify Jonathan Schaffer's; debasing scepticism, highlighting its logical structure. 1 In many current discussions of scepticism, its scope is limited to propositions about the external world which, if known at all, are known a posteriori. The standard sceptical set-up goes as follows. The sceptic specifies a sceptical hypothesis, or counterpossibility, that is incompatible with the external-world propositions that I claim to know. The hypothesis – e.g. that I am a brain in a vat – is (...) claimed by the sceptic to be within the realm of metaphysical possibility. The sceptical argument, in a nutshell, runs as follows. Choose some external-world proposition that I claim to know, say H = I have hands. By the principle that knowledge is closed under known entailment, if I know H, then I know ∼SK = I am not a handless brain in a vat. My evidence does not enable me to know ∼SK. Hence I …. (shrink)

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)

In my remarks, I discuss Sosa's attempt to deal with the sceptical threat posed by dreaming. Sosa explores two replies to the problem of dreaming scepticism. First, he argues that, on the imagination model of dreaming, dreaming does not threaten the safety of our beliefs. Second, he argues that knowledge does not require safety, but a weaker condition which is not threatened by dreaming skepticism. I raise questions about both elements of his reply.

A well known skeptical paradox rests on the claim that we lack warrant to believe that we are not brains in a vat. 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)

Contemporary discussions of skepticism often frame the skeptic's argument around an instance of the closure principle. Roughly, the closure principle states that if a subject knows p, and knows that p entails q, then the subject knows q. The main contention of this paper is that the closure argument for skepticism is defective. We explore several possible classifications of the defect. The closure argument might plausibly be classified as begging the question, as exhibiting transmission failure, or as structurally inefficient. Interestingly, (...) perhaps, each of these has been proposed as the correct classification of Moore's proof of an external world. (shrink)

Those of us who have followed Fred Dretske's lead with regard to epistemic closure and its impact on skepticism have been half-wrong for the last four decades. But those who have opposed our Dretskean stance, contextualists in particular, have been just wrong. We have been half-right. Dretske rightly claimed that epistemic status is not closed under logical implication. Unlike the Dretskean cases, the new counterexamples to closure offered here render every form of contextualist pro-closure maneuvering useless. But there is a (...) way of going wrong under Dretske's lead. As the paper argues, Cartesian skepticism thrives on closure failure in a way that is yet to be acknowledged in the literature. The skeptic can make do with principles which are weaker than the familiar closure principles. But I will further claim that this is only a momentary reprieve for the skeptic. As it turns out, one of the weaker principles on which a skeptical modus tollens must rest can be shown false. (shrink)

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.

Reality vs. appearance -- How truth thought "agrees" with reality -- Cognitive access to reality -- Problems of fallibilism -- Scientific realism -- The rationale of realism.

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)

Most of us think we can always enlarge our knowledge base by accepting things that are entailed by (or logically implied by) things we know. The set of things we know is closed under entailment (or under deduction or logical implication), which means that we know that a given claim is true upon recognizing, and accepting thereby, that it follows from what we know. However, some theorists deny that knowledge is closed under entailment, and the issue remains controversial. The arguments (...) against closure include the following. (shrink)