We have several intuitive paradigms of defeating evidence. For example, let E be the fact that Ernie tells me that the notorious pet Precious is a bird. This supports the premise F, that Precious can fly. However, Orna gives me *opposing* evidence. She says that Precious is a dog. Alternatively, defeating evidence might not oppose Ernie's testimony in that direct way. There might be other ways for it to weaken the support that Ernie's testimony gives me for believing F, without (...) the new evidence itself intuitively constituting reasons to believe one way or the other about Precious's flight ability. An example: Ursula tells me that Ernie has no idea what Precious's species is; he's just guessing. She may not herself want to or be in a position to weigh in about Precious's real species or flight ability. I call defeating evidence of this sort *undermining evidence. (shrink)

Although several important methodologies implicitly assume the truth of epistemic conservatism, the view that holding a belief confers some measure of justification on the belief, recent criticisms have led some to conclude that epistemic conservatism is an implausible view. That conclusion is mistaken. In this article, I propose a new formulation of epistemic conservatism that is not susceptible to the criticisms leveled at earlier formulations of epistemic conservatism. In addition to withstanding these criticisms, this formulation of epistemic conservatism has several (...) benefits. First, this formulation has the benefits of earlier formulations of epistemic conservatism, that is to say it makes sense of our intuitions about justification in regard to both memory beliefs and beliefs for which we have forgotten our evidence. Second, it provides a good way of responding to the skeptic’s challenge concerning the possibility of possessing knowledge of the external world posed by the Alternative Hypotheses argument. Third, it provides responses to both forms of a new skeptical problem plaguing basic knowledge structure theories, the Problem of Easy Knowledge formulated by Stewart Cohen. I argue that given the many benefits of this formulation of epistemic conservatism and the fact that it is not vulnerable to the criticisms that undermine earlier formulations of epistemic conservatism, this formulation of epistemic conservatism is a plausible view to maintain. (shrink)

While such epistemic rules as 'If you perceive that X, you ought to believe that X' and 'If you have outstanding testimony that X, you ought to believe that X' seem to be getting at important truths, it is easy to think of cases in which they come into conflict. To avoid classifying such cases as dilemmas, one can hold either that epistemic rules have built-in unless-clauses listing the circumstances under which they don't apply, or, alternatively, that epistemic rules are (...) contributory. This paper explores both responses from a formal perspective, drawing on a simple defeasible logic framework. (shrink)

Nick Bostrom’s recently patched ‘‘simulation argument’’ (Bostrom in Philos Q 53:243–255, 2003; Bos- trom and Kulczycki in Analysis 71:54–61, 2011) purports to demonstrate the probability that we ‘‘live’’ now in an ‘‘ancestor simulation’’—that is as a simulation of a period prior to that in which a civilization more advanced than our own—‘‘post-human’’—becomes able to simulate such a state of affairs as ours. As such simulations under consid- eration resemble ‘‘brains in vats’’ (BIVs) and may appear open to similar objections, the (...) paper begins by reviewing objections to BIV-type proposals, specifically those due a presumed mad envatter. In counter example, we explore the motivating rationale behind current work in the development of psychologically realistic social simula- tions. Further concerns about rendering human cognition in a computational medium are confronted through review of current dynamic systems models of cognitive agency. In these models, aspects of the human condition are repro- duced that may in other forms be considered incomputable, i.e., political voice, predictive planning, and consciousness. The paper then argues that simulations afford a unique potential to secure a post-human future, and may be nec- essary for a pre-post-human civilization like our own to achieve and to maintain a post-human situation. Long-s- tanding philosophical interest in tools of this nature for Aristotle’s ‘‘statesman’’ and more recently for E.O. Wilson in the 1990s is observed. Self-extinction-level threats from State and individual levels of organization are compared, and a likely dependence on large-scale psychologically realistic simulations to get past self-extinction-level threats is projected. In the end, Bostrom’s basic argument for the conviction that we exist now in a simulation is reaffirmed. (shrink)

The aim of this paper is to analyse and develop how scepticism becomes an intelligible question starting from requirements that epistemologists themselves aim to endorse. We argue for and defend the idea that the root of scepticism is the underdetermination principle by articulating its specificitya respectable epistemic principle and by defending it against objections in current literature. This engagement offers a novel understanding of underdetermination-based scepticism. While most anti-sceptical approaches challenge scepticism by understanding it as postulating uneliminated scenarios of mass (...) deception, or as endorsing unnatural epistemic requirements, we argue here that both contentions are mistaken. Underdetermination-based scepticism targets our beliefs by issuing a genuine question about the rational support they enjoy. If we cannot establish that the sources of our beliefs provide them the required epistemic merit and authority, they lack non-arbitrary grounds. This has a sizable impact on what constitutes a satisfactory anti-sceptical strategy. Strategies that merely focus on the scenario-based aspect of scepticism, or on the truth-functional evaluation of our beliefs, are shown to miss the mark of the sceptical threat. The proposed analysis ultimately provides a shift in perspective concerning the character and reach of philosophical doubt. (shrink)

Epistemologists understand radical skepticism as arising from two principles: Closure and Underdetermination. Both possess intuitive prima facie support for their endorsement. Understanding how they engender skepticism is crucial for any reasonable anti-skeptical attempt. The contemporary discussion has focused on elucidating the relationship between them to ascertain whether they establish distinct skeptical questions and which of the two constitutes the ultimately fundamental threat. Major contributions to this debate are due to Brueckner, Cohen, and Pritchard. This contribution aims at defending Brueckner’s contention (...) that underdetermination expresses the fundamental skeptical threat and that the closure-based argument can ultimately be reduced to it, at least concerning skeptical contexts. This will be achieved by undermining Cohen’s objections to Brueckner on both counts. Cohen’s argument endorses a picture of evidential underdetermination, which, while apt for non-skeptical contexts, cannot be applied to radical skepticism. A comparison with a case of scientific underdetermination is developed to argue for this idea. Our argument is then applied to the principle equivalence issue and to objections against it. It is then shown how this analysis possesses a distinctive effect on our understanding of the skeptical threat and the assessment of successful anti-skeptical strategies. (shrink)

Many philosophers now argue that the doubts of the philosophical sceptic are unnatural ones, in that they are not forced on us by considerations that any reasonable person would have to accept as compelling but only arise if one has already accepted certain controversial theoretical commitments. In this article I defend the naturalness of philosophical scepticism against such criticisms. After defining "global ontological scepticism," I examine the work of a number of anti-sceptical philosophers—Michael Huemer, Michael Williams, and John McDowell. Although (...) McDowell does move the debate to a deeper level by interpreting scepticism as a challenge to the very possibility of the mind's apprehending reality by being in a rational rather than a merely causal relation to it, none of them succeeds in showing that global ontological scepticism is, in the relevant sense, unnatural. This is not to say that the sceptic is correct; simply that it has not been shown that we can reasonably dismiss the sceptical questions and thereby evade the need to engage seriously with the sceptical arguments. (shrink)

Many philosophers now argue that the doubts of the philosophical sceptic are unnatural ones, in that they are not forced on us by considerations that any reasonable person would have to accept as compelling but only arise if one has already accepted certain controversial theoretical commitments. In this article I defend the naturalness of philosophical scepticism against such criticisms. After defining “global ontological scepticism,” I examine the work of a number of anti‐sceptical philosophers—Michael Huemer, Michael Williams, and John McDowell. Although (...) McDowell does move the debate to a deeper level by interpreting scepticism as a challenge to the very possibility of the mind's apprehending reality by being in a rational rather than a merely causal relation to it, none of them succeeds in showing that global ontological scepticism is, in the relevant sense, unnatural. This is not to say that the sceptic is correct; simply that it has not been shown that we can reasonably dismiss the sceptical questions and thereby evade the need to engage seriously with the sceptical arguments. (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)

This paper provides a reinterpretation of some of the most influential skeptical arguments, Agrippa’s trilemma, meta-regress arguments, and Cartesian external world skepticism. These skeptical arguments are reasonably regarded as unsound arguments about the extent of our knowledge. However, reinterpretations of these arguments tell us something significant about the preconditions and limits of persuasive argumentation. These results contribute to the ongoing debates about the nature and resolvability of deep disagreement. The variety of skeptical arguments shows that we must distinguish different types (...) of deep disagreement. Moreover, the reinterpretation of skeptical arguments elucidates that deep disagreement cannot be resolved via argumentation. (shrink)

The first step in responding to the challenge of external world skepticism is to get clear on the structure of the skeptic’s argument. The most prominent varieties of skeptical arguments either rely on closure principles or underdetermination principles. The relationship between these two sorts of arguments is contentious. Some argue that these arguments can independently motivate skepticism. Others argue that they are really equivalent. I argue that although these two arguments are distinct, their independence is not as obvious as some (...) have thought. The fact that these arguments are not equivalent is important because skeptical arguments that appeal to underdetermination principles cannot be refuted by simply denying closure. So, the strategy for responding to skepticism offered by Nozick/Dretske does not seem an adequate solution. (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.

Moore’s paradox supports the principle of “metacoherence”, i.e., that if one categorically believes that P, one is committed to accepting that one knows that P. The principle raises puzzles about how, when one has justification for P, one also has justification for the claim that one knows P. I reject a skeptical answer as well as a bootstrapping answer, and I suggest that we typically have independent justification for the claim that we know P.

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.

In “Compassionate Phenomenal Conservatism” (2007), “Phenomenal Conservatism and the Internalist Intuition” (2006), and Skepticism and the Veil of Perception (2001), Michael Huemer endorses the principle of phenomenal conservatism, according to which appearances or seemings constitute a fundamental source of (defeasible) justification for belief. He claims that those who deny phenomenal conservatism, including classical foundationalists, are in a self-defeating position, for their views cannot be both true and justified; that classical foundationalists have difficulty accommodating false introspective beliefs; and that phenomenal conservatism (...) is most faithful to the central internalist intuition. I argue that Huemer’s self-defeat argument fails, that classical foundationalism is able to accommodate fallible introspective beliefs, and that classical foundationalism captures a relatively clear internalist intuition. I also show that the motivation for phenomenal conservatism is less than clear. (shrink)

In a recent paper McCain (2012) argues that weak predictivism creates an important challenge for external world scepticism. McCain regards weak predictivism as uncontroversial and assumes the thesis within his argument. There is a sense in which the predictivist literature supports his conviction that weak predictivism is uncontroversial. This absence of controversy, however, is a product of significant plasticity within the thesis, which renders McCain’s argument worryingly vague. For McCain’s argument to work he either needs a stronger version of weak (...) predictivism than has been defended within the literature, or must commit to a more precise formulation of the thesis and argue that weak predictivism, so understood, creates the challenge to scepticism that he hopes to achieve. The difficulty with the former is that weak predictivism is not uncontroversial in the respect that McCain’s argument would require. I consider the prospects of saving McCain’s argument by committing to a particular version of weak predictivism, but find them unpromising for several reasons. (shrink)

The purpose of this paper is to get clear on how we should think about Mooreanism. I will argue that Mooreanism is best understood as a metaphilosophical response to skepticism rather than a particular position on specialized debates in first-order epistemology. This ecumenical understanding of Mooreanism implies that a broad array of epistemologists is free to be Moorean. In Sect. 2 I discuss several non-Moorean responses to skepticism. In Sect. 3 I provide an exposition of Mooreanism itself. In Sect. 4 (...) I show that most epistemologists are free to be Mooreans. This is important for the following reason: to the extent that we want a non-concessive reply to the skeptic – rather than a reply that is partially or potentially concessive – we should be highly attracted to Mooreanism. (shrink)

The epistemological problem of the external world asks: (1) “How is knowledge of the external 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?” Skepticism is the thesis that knowledge of the external world is impossible. It (...) therefore represents a negative answer to the first question. Meta-epistemological skepticism is the thesis that a satisfying philosophical explanation of how our knowledge of the external world is possible is itself impossible. It therefore represents a negative answer to the second question. In this thesis, I explore the prospects of meta-epistemological skepticism. In particular, I structure the thesis around two master arguments from for meta-epistemological skepticism. The first argument is that skepticism represents a kind of paradox which requires dispensing with a plausible principle or belief, or even 'platitude', which means that there's no philosophically satisfying response to the paradox (see, e.g., Stroud 1984), and the second argument is “Stroud’s dilemma” (cf. Cassam 2009), that either we explain how external world knowledge is possible by reference to what external world knowledge we have, thereby failing to answer the philosophical question adequately, or else we don't, but then we succumb to first-order skepticism. I argue that the first argument fails to provide adequate support for meta-epistemological skepticism. However, the second argument, Stroud’s dilemma, is plausible and withstands serious objections (e.g., from Sosa 1994, Williams 1996, and Cassam 2009). In short, while the worry emerging out of the 'skeptical paradox' view fails to adequately support meta-epistemological skepticism, Stroud’s dilemma succeeds. Fortunately, it doesn't show that we lack external world knowledge; we rather just can't explain, philosophically, how it's possible. We may have first-order knowledge without understanding how it's possible. This thesis therefore represents a partial defense of meta-epistemological skepticism. Meta-epistemological skepticism is a live option in epistemology. (shrink)

What if your peers tell you that you should disregard your perceptions? Worse, what if your peers tell you to disregard the testimony of your peers? How should we respond if we get evidence that seems to undermine our epistemic rules? Several philosophers have argued that some epistemic rules are indefeasible. I will argue that all epistemic rules are defeasible. The result is a kind of epistemic particularism, according to which there are no simple rules connecting descriptive and normative facts. (...) I will argue that this type of particularism is more plausible in epistemology than in ethics. The result is an unwieldy and possibly infinitely long epistemic rule — an Uber-rule. I will argue that the Uber-rule applies to all agents, but is still defeasible — one may get misleading evidence against it and rationally lower one’s credence in it. (shrink)

Pritchard argues that epistemological disjunctivism seems plainly false at first sight, but if it were right, it would represent the “holy grail of epistemology” (1), a view that allows us “to have our cake and eat it too” (3). This prospect motivates Pritchard to develop and defend an account that prima facie might seem simply false. It is disputable whether ED really seems plainly false at first sight or whether this intuition is based on a particular philosophical tradition. However, in (...) this paper I will not discuss whether ED is actually true. Rather, I will investigate whether, if true, it has the advantages over rival accounts that Pritchard claims. (shrink)