Cartesian Skepticism

Enlightenment philosopher, René Descartes, set out to establish what could be known with certainty, untainted by a deceiving demon. With his method of doubt, he rejected all previous beliefs, allowing only those that survived rigorous scrutiny. In this essay, Leslie Allan examines whether Descartes's program of skeptical enquiry was successful in laying a firm foundation for our manifold beliefs. He subjects Descartes's conclusions to Descartes's own uncompromising methodology to determine whether Descartes escaped from a self-imposed radical skepticism.

Physicalism is the default position in science and in the philosophy of mind, but it should not be, I argue, because of two errors. By its epistemological error, physicalism tries to explain theoretically what is evident. Only what I experience in first person is certain, so pain does not need a theoretical explanation. Physics itself is based on first person perception, avoiding the epistemological error, and then physics can progress, even changing its own ontology. However, physicalism imposes the ontology of (...) physics on every science, and in physics everything is causal. By its ontological error, physicalism tries to explain causally what is intentional. And it happens that causality and intentionality are mutually exclusive, showing that the ontology of physics is insufficient wherever intentions are present. This ontological insufficiency prevents that physicalism can repeat the success of physics with any science where intentions play a rôle, and thus it is blocking the advance of both the social sciences and the philosophy of mind. To overcome this obstacle, I propose to go back to the essentials: we should consider again the transcendental problem raised by Descartes and its solutions by Hume and Kant. On top of this subjectivist solution, we should take advantage of Darwin and Turing, and we should extend our ontology beyond causality to include intentionality, and here my proposal is problem solving. Then you could join our Post-Kantian subjectivism and say with me: The world is not a huge machine, as physicalism proposes, but an enigmatic problem. (shrink)

In Meditation I, Descartes dismisses the possibility that he might be insane as a ground for doubting that the senses are a source of knowledge of the external world. In this paper, I argue that Descartes was justified in so doing, and draw some general epistemological conclusions from this result.

Descartes' demon is a deceiver: the demon makes things appear to you other than as they really are. However, as Descartes famously pointed out in the Second Meditation, not all knowledge is imperiled by this kind of deception. You still know you are a thinking thing. Perhaps, though, there is a more virulent demon in epistemic hell, one from which none of our knowledge is safe. Jonathan Schaffer thinks so. The "debasing demon" he imagines threatens knowledge not via the truth (...) condition on knowledge, but via the basing condition. This demon can cause any belief to seem like it's held on a good basis, when it's really held on a bad basis. Several recent critics grant Schaffer the possibility of such a debasing demon, and argue that the skeptical conclusion doesn't follow. By contrast, we argue that on any plausible account of the epistemic basing relation, the "debasing demon" is impossible. Our argument for why this is so gestures, more generally, to the importance of avoiding common traps by embracing mistaken assumptions about what it takes for a belief to be based on a reason. (shrink)

An overview of the import of disjunctivism to the problem of radical scepticism is offered. In particular, the disjunctivist account of perceptual experience is set out, along with the manner in which it intersects with related positions such as naïve realism and intentionalism, and it is shown how this account can be used to a motivate an anti-sceptical proposal. In addition, a variety of disjunctivism known as epistemological disjunctivism is described, and it is explained how this proposal offers a further (...) way of responding to radical scepticism. (shrink)

Pragmatic responses to skepticism have been overlooked in recent decades. This paper explores one such response by developing a character called the Pragmatic Skeptic. The Pragmatic Skeptic accepts skeptical arguments for the claim that we lack good evidence for our ordinary beliefs, and that they do not constitute knowledge. However, they do not think we should give up our beliefs in light of these skeptical conclusions. Rather, we should retain them, since we have good practical reasons for doing so. This (...) takes the sting out of skepticism: we can be skeptics, of a kind, without thereby succumbing to practical or intellectual disaster. I respond to objections, and compare the position of the Pragmatic Skeptic to views found in the work of (among others) David Hume, William James, David Lewis, Berislav Marusic, and Robert Pasnau. (shrink)

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.

O ceticismo é por vezes descartado como uma doutrina absurda e merecedora do seu lugar distante na antiguidade. Nada poderia ser menos correto. O ceticismo continua extremamente relevante para o pensamento filosófico e científico de hoje, servindo como um lembrete de que a sabedoria não é barata nem segura. Nesse texto, o meu objetivo principal é reproduzir o raciocínio das discussões clássicas sobre o ceticismo, mas de uma maneira coloquial e contemporânea. Após seguir as linhas de pensamento de Sexto Empírico, (...) René Descartes, e David Hume, eu vou extrair e identificar claramente as teses centrais que marcam as suas ideias. A minha intenção, porém, não é a de sugerir que as suas teses são auto-evidentes, ou incontestáveis, ou até hoje ainda incontestadas. Muito pelo contrário. A minha intenção é produzir um aperitivo ao debate e um convite a discussão. (shrink)

The lack of knowledge—as Timothy Williamson (2000) famously maintains—is ignorance. Radical sceptical arguments, at least in the tradition of Descartes, threaten universal ignorance. They do so by attempting to establish that we lack any knowledge, even if we can retain other kinds of epistemic standings, like epistemically justified belief. If understanding is a species of knowledge, then radical sceptical arguments threaten to rob us categorically of knowledge and understanding in one fell swoop by implying universal ignorance. If, however, understanding is (...) not a species of knowledge, then three questions arise: (i) is ignorance the lack of understanding, even if understanding is not a species of knowledge? (ii) If not, what kind of state of intellectual impoverishment best describes a lack of understanding? (iii) What would a radical sceptical argument look like that threatened that kind of intellectual impoverishment, even if not threatening ignorance? This paper answers each of these questions in turn. I conclude by showing how the answers developed to (i-iii) interface in an interesting way with Virtue Perspectivism as an anti-sceptical strategy. (shrink)

Jeder Mensch irrt – ausgenommen der Papst, wenn er Glaubenssätze verkündet. So jedenfalls befand einst das erste Vatikanische Konzil. Nun waren die Kardinäle, so bemerkt Keil frech, selbst keineswegs Träger der päpstlichen Unfehlbarkeit. »Woher wussten sie dann, dass der Papst unfehlbar ist?« Niemand weiß vorher, wann und wo er sich irren wird. Viele Philosophen haben daraus geschlossen, dass Menschen nichts wissen, sondern immer nur vermuten. Das ist aber ein Irrtum, den dieser kluge und kurzweilige Essay aufklärt.

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)

Let Entitlement Epistemology be the theory of knowledge which says that entitlement—a special kind of unearned warrant to accept or believe—can help us successfully address a range of sceptical arguments. Prominent versions of this theory urge that epistemology should not be concerned with knowledge (and similar externalist states) but rather with justification, warrant, and entitlement (at least insofar as these are conceived of as internalist states). Knowledge does not come first, half-way, or even last in epistemological theorising—rather, it ought to (...) come nowhere. The goal in what follows is two-fold: Firstly, to assess whether this extreme internalist version of Entitlement Epistemology is at all sustainable. (We shall find that it is not.) Secondly, to articulate a version of Entitlement Epistemology which arguably does much better. On the view to be explored, knowledge does not drop out of the epistemological picture: if we allow that there can be warrant for nothing, then there can be knowledge for nothing too. (shrink)

In the Refutation of Idealism, Kant aims to defeat the Cartesian radical skeptical hypothesis that empirical reality might not exist and we cannot have knowledge of it. Kant intends to demonstrate that conscious experience presupposes direct experience of empirical reality. This paper presents new challenges to the conclusions Kant reaches in the Refutation. Kant’s argument turns on the claim that the past must exist, and my challenges concern the possibility that there is no past.

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)

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)

Skeptical hypotheses such as the brain-in-a-vat hypothesis provide extremely poor explanations for our sensory experiences. Because these scenarios accommodate virtually any possible set of evidence, the probability of any given set of evidence on the skeptical scenario is near zero; hence, on Bayesian grounds, the scenario is not well supported by the evidence. By contrast, serious theories make reasonably specific predictions about the evidence and are then well supported when these predictions are satisfied.

According to Duncan Pritchard, there are two kinds of radical sceptical problem; the closure-based problem, and the underdetermination-based problem. He argues that distinguishing these two problems leads to a set of desiderata for an anti-sceptical response, and that the way to meet all of these desiderata is by supplementing a form of Wittgensteinian contextualism with disjunctivist views about factivity. I agree that an adequate response should meet most of the initial desiderata Pritchard puts forward, and that some version of Wittgensteinian (...) contextualism shows the most promise as a starting point for this, but I argue, contra Pritchard, that the addition of disjunctivism is unnecessary and potentially counter-productive. If we draw on lessons from Michael Williams's inferential contextualism then it is both possible, and preferable, to meet the most important of Pritchard's desiderata, undercutting both closure-based and underdetermination-based sceptical problems in a unified way, without the need to resort to disjunctivism. (shrink)

The epistemological problem of the external world asks: (1) “How is knowledge of the world possible given certain obstacles which make it look impossible?” This is a “how-possible?” question: it asks how something is possible given certain obstacles which make it look impossible (cf. Cassam 2007; Nozick 1981; Stroud 1984). Now consider the following question, which asks: (2) “How is a philosophically satisfying answer to (1) possible?” Scepticism is the thesis that knowledge of the world is impossible. It therefore represents (...) a negative answer to the first question. Meta-epistemological scepticism is the thesis that a satisfying philosophical explanation of how our knowledge of the world is possible is itself not possible. It therefore represents a negative answer to the second question. In this thesis, I explore the prospects of meta-epistemological scepticism. In particular, I structure the thesis around two master arguments from Stroud (1984, 2000, 2004, and 2009) for meta-epistemological scepticism. The first argument is what I call “Stroud’s puzzle”, and the second argument is “Stroud’s dilemma” (cf. Cassam 2009). I argue that Stroud’s puzzle fails to provide adequate support for meta-epistemological scepticism. However, I also argue that Stroud’s dilemma withstands serious objections (e.g., from Sosa 1994, Williams 1996, and Cassam 2009). In short, while Stroud’s puzzle fails to provide adequate support for meta-epistemological scepticism, Stroud’s dilemma does seem to provide adequate support for meta-epistemological scepticism. This thesis therefore represents a partial defence of meta-epistemological scepticism. Meta-epistemological scepticism is therefore a live option in epistemology. (shrink)

In this paper, I present and criticize a number of influential anti-skeptical strategies inspired by Wittgenstein’s remarks on ‘hinges’. Furthermore, I argue that, following Wittgen- stein’s analogy between ‘hinges’ and ‘rules of grammar’, we should be able to get rid of Cartesian skeptical scenarios as nonsensical, even if apparently intelligible, combinations of signs.

We revisit an important exchange on the problem of radical skepticism between Richard Rorty and Michael Williams. In his contribution to this exchange, Rorty defended the kind of transcendental approach to radical skepticism that is offered by Donald Davidson, in contrast to Williams’s Wittgenstein-inspired view. It is argued that the key to evaluating this debate is to understand the particular conception of the radical skeptical problem that is offered in influential work by Barry Stroud, a conception of the skeptical problem (...) which generates metaepistemological ramifications for anti-skeptical theories. In particular, we argue that, contra Williams, Rorty’s view that Davidson was offering a theoretical diagnosis of radical skepticism can be consistently maintained with his transcendental approach. (shrink)

The familiar Cartesian sceptical arguments all involve an explanation of our experiences. An account of the persuasive power of the sceptical arguments should explain why this is so. This supports a diagnosis of the error in Cartesian sceptical arguments according to which they mislead us into regarding our perceptual beliefs as if they were justified as inferences to the best explanation. I argue that they have instead a perceptual justification that does not involve inference to the best explanation and that (...) should not be put in doubt by the sceptical hypotheses. (shrink)

The relation of scepticism to infallibilism and fallibilism is a contested issue. In this paper I argue that Cartesian sceptical arguments, i.e. sceptical arguments resting on sceptical scenarios, are neither tied to infallibilism nor collapse into fallibilism. I interpret the distinction between scepticism and fallibilism as a scope distinction. According to fallibilism, each belief could be false, but according to scepticism all beliefs could be false at the same time. However, to put this distinction to work sceptical scenarios have to (...) be understood as ignorance-possibilities, not as error-possibilities. To show that scepticism is not tied to infallibilism I reject the principle of unrestricted relevance according to which any error- or ignorance-possibility whatsoever is relevant. Instead I argue that the sceptic should distinguish between local and global ignorance-possibilities. Global ignorance-possibilities are relevant even though not all ignorance-possibilities are relevant. The result is a refined version of the Cartesian sceptical argument that avoids two traps other versions do not avoid. (shrink)

The Neo-Moorean response to the radical skeptical challenge boldly maintains that we can know we’re not the victims of radical skeptical hypotheses; accordingly, our everyday knowledge that would otherwise be threatened by our inability to rule out such hypotheses stands unthreatened. Given the leverage such an approach has against the skeptic from the very start, the Neo-Moorean line is an especially popular one; as we shall see, though, it faces several commonly overlooked problems. An initial problem is that this particular (...) brand of anti-skeptical strategy is available only to a theory of knowledge that will compromise itself to especially weak epistemic standards—indeed, standards as weak as our epistemic grounds are for accepting the denials of skeptical hypotheses. With this said, the aim here is to investigate whether the Neo-Moorean line could be advanced against the skeptic in a way that wouldn’t require wholesale lowering of epistemic standards. Unfortunately, as we’ll see, Sosa’s (2007; 2009) view as well as what I argue to be the other two most plausible contender-views for maintaining a Neo-Moorean line—Greco’s and Pritchard’s—run (for similar reasons) into dead ends. The way forward, I’ll argue, is to take on board a unique variety of robust virtue epistemology accord­ing to which knowledge is thought to be situated a certain way within a gradient balance between ability and luck. (shrink)

Scepticism is sometimes expressed about whether there is any interesting problem of other minds. In this paper I set out a version of the conceptual problem of other minds which turns on the way in which mental occurrences are presented to the subject and situate it in relation to debates about our knowledge of other people's mental lives. The result is a distinctive problem in the philosophy of mind concerning our relation to other people.

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)

Descartes claims that God is both incomprehensible and yet clearly and distinctly understood. This paper argues that Descartes’s development of the contrast between comprehension and understanding makes the role of God in his epistemology more interesting than is commonly thought. Section one examines the historical context of sceptical arguments about the difficulty of knowing God. Descartes describes the recognition of our inability to comprehend God as itself a source of knowledge of him; section two aims to explain how recognizing limits (...) to our cognitive powers is supposed to yield knowledge of anything other than ourselves. Section three aims to give a partial account of the role that awareness of the limitations of our cognitive powers is supposed to play in anchoring our knowledge of other things, and to show how such an approach to knowledge could still contribute to the development of a response to scepticism in the contemporary context. (shrink)

Two stories have dominated the historiography of early modern philosophy: one in which a seventeenth century Age of Reason spawned the Enlightenment, and another in which a skeptical crisis cast a shadow over subsequent philosophy, resulting in ever narrower "limits to knowledge." I combine certain elements common to both into a third narrative, one that begins by taking seriously seventeenth-century conceptions of the topics and methods central to the rise of a "new" philosophy. In this revisionist story, differing approaches to (...) the central subject matter of early modern metaphysics--knowledge of substances through their essences and causal powers--arise as a result of disagreements about the powers of the human cognitive faculties. Methodological writings are seen as attempts to direct readers in the proper use of their cognitive faculties. The early modern rejection of the Aristotelian theory of cognition ranks equally in importance with rejection of Aristotelian doctrines about nature. Skepticism is more often than not a tool to be used in teaching the reader the proper use of the cognitive faculties, or indeed in convincing the reader of the existence or inexistence of certain cognitive faculties or powers. Instead of early modern "epistemology" or "theory of knowledge," one speaks, with seventeenth century writers, of theories of the cognitive faculties and their implications for the possibility of human knowledge. The early modern rejection of Aristotelian logic can then be seen as reflecting a negative assessment about the fit between syllogistic reasoning and logic as an art of reasoning or thinking which refines the use of the cognitive faculties. -/- Central to this new historiography is the story of the relation between the intellect and senses as cognitive faculties or powers. The development of philosophy from Descartes to Kant can be portrayed as a series of claims about the power of the intellect to know the essences of things, with resulting consequences for ontology and the foundations of natural philosophy. I illustrate this revised narrative by comparing three conceptions of the intellect in three philosophical settings, provided by several late scholastic Aristotelians, Descartes, and Locke. I have two aims: first, to exhibit the central role played by the conception of intellect or understanding in these authors, and, second, to locate their discussions of the cognitive faculties in relation to recent understandings of psychology, epistemology, logic, mind, and their relations. Early modern writings do not easily fit into the modern categories of epistemology and psychology; more generally, the early modern concern with the workings of mind does not coincide with recent conceptions of naturalism. These findings can help us to see problems with our current categories. (shrink)

During the 1630s Descartes recognized that he could not expect all legitimate claims in natural science to meet the standard of absolute certainty. The realization resulted from a change in his physics, which itself arose not through methodological reflections, but through developments in his substantive metaphysical doctrines. Descartes discovered the metaphysical foundations of his physics in 1629-30; as a consequence, the style of explanation employed in his physical writings changed. His early methodological conceptions, as preserved in the Rules and sketched (...) in Part Two of the Discourse, pertained primarily to his early work in optics. By the early 1630s, Descartes was concerned with new methodological problems pertaining to the postulation of micro-mechanisms. Recognition of the need to employ a method of hypothesis led him to lower the standard of certainty required of particular explanations in his mature physics. (shrink)

According to the reading offered here, Descartes' use of the meditative mode of writing was not a mere rhetorical device to win an audience accustomed to the spiritual retreat. His choice of the literary form of the spiritual exercise was consonant with, if not determined by, his theory of the mind and of the basis of human knowledge. Since Descartes' conception of knowledge implied the priority of the intellect over the senses, and indeed the priority of an intellect operating independently (...) of the senses, and since, in Descartes' view, the untutored individual was likely to be nearly wholly immersed in the senses, a procedure was needed for freeing the intellect from sensory domination so that the truth might be seen. Hence, the cognitive exercises of the Meditations, modeled not on the sense- and imagination-based exercises of Ignatius of Loyola, but on the Augustinian procedure of turning away from the senses and imagination to perceive the unpicturable with the fleshless eye of the mind. In accordance with this reading, the function of Descartes' skeptical arguments is not to introduce skepticism so that it can be defeated but to aid the meditator in withdrawing the mind from the senses in order to attend to truths of the pure intellect. These truths then offer the basis for a new natural philosophy, including a new theory of the senses. (shrink)

A concise review of skeptician in the Carterian model with a discussion of the reframing of the Cartesian paradigm by John McDowell in the 20th century.

The epistemological consequences of paradox are paradoxical. They can be usefully generated by telling a series of once-upon-a-time stories that make various philosophical points, starting out innocent and ending up, well, paradoxical. This is an introduction to my Live Skepticism, defended in Skepticism Comes Alive.