An overview of the new evil demon problem.

Disjunctivism, as a theory of visual experience, claims that the mental states involved in a “good case” experience of veridical perception and a “bad case” experience of hallucination differ, even in those cases in which the two experiences are indistinguishable for their subject. Consider the veridical perception of a bar stool and an indistinguishable hallucination; both of these experiences might be classed together as experiences (as) of a bar stool or experiences of seeming to see a bar stool. This might (...) lead us to think that the experiences we undergo in the two cases must be of the same kind, the difference being that the former, but not the latter, is connected to the world in the right kind of way. Such a conjecture has been called a “highest common factor” or “common kind” assumption. At heart, disjunctivism consists in the rejection of this assumption. According the disjunctivist, veridical experiences and hallucinations do not share a common component. There are a host of interesting questions surrounding disjunctivism including: What is involved in the claims that good case and bad case experiences differ? Why might one might want to be a disjunctivist? What kinds of claims can the disjunctivist make about hallucination and illusion? These questions, and problems for the thesis, will be discussed as we proceed. (shrink)

Naive realism is one of the oldest theories of perception. To a first approximation, naive realism is the view that perception is a direct relation between a subject and an object. Many historical philosophers (from Locke to Russell) argued that naive realism must be rejected on the grounds that hallucinations are perceptual experiences without an object. Contemporary philosophers have resurrected the theory by insisting that genuine cases of perception have a different structure or a different metaphysical status than non-genuine ones. (...) This version of naive realism has come to be known as ‘disjunctivism’. Epistemological disjunctivism and disjunctivism about phenomenal belief, or what I shall call ‘Epistemological disjunctivism’, have also gained popularity in recent years. More recently disjunctivist accounts of bodily movements, abilities and reasons for action have entered the philosophical scene. This entry focuses on the contemporary debate about disjunctivism: its characterization, its motivation and its potential shortcomings. (shrink)

Disjunctivists hold that perceiving external objects is fundamentally different from any experiential state that is not a perception. In fact, roughly speaking, disjunctivists say that they have nothing in common. Suppose that it appears to someone as though she perceives something. Disjunctivists say that there are two disparate sorts of facts that could make this true. Either she is genuinely perceiving something, or she is in an experiential state of merely apparent perception. An apparent perception is fundamentally unlike a perception. (...) Disjunctivists differ in what they say the fundamental difference is. We’ll get to some of that shortly. First I’ll say where I’m headed here. (shrink)

Twin-earth thought experiments, standardly construed, support the externalist doctrine that the content of propositional attitudes involving natural-kind terms supervenes upon properties external to those who entertain them. But this doctrine in conjunction with a common view of self-knowledge might have the intolerable consequence that substantial propositions concerning the environment could be knowable a priori. Since both doctrines, externalism and privileged self-knowledge, appear independently plausible, there is then a paradox facing the attempt to hold them concurrently. I shall argue, however, that (...) externalist claims about the dependence of content on environmental factors presuppose certain theses about the semantics of natural-kind terms that, if sound, would make those claims eligible for empirical justification instead. In fact, that is the only interpretation of their epistemic status that could square with the standard conclusion from twin-earth cases. Furthermore, it can be shown to solve the paradox of externalism and self-knowledge in a more doxastically conservative way--accommodating precisely each of the well-accepted intuitions about knowledge, closure and the individuation of content given up by available competitors. (shrink)

Part 1 argues that, despite rhetorical appearances, McDowell accepts a standard version of epistemic externalism. Moreover, epistemic externalism plays an important role in McDowell’s response to skepticism. Part 2 argues that, contra McDowell, epistemic externalism is necessary for rejecting skepticism, and content externalism is not sufficient for rejecting skepticism.