Abstract: Ordinary people tend to be realists regarding perceptual experience, that is, they take perceiving the environment as a direct, unmediated, straightforward access to a mindindependent reality. Not so for (ordinary) philosophers. The empiricist influence on the philosophy of perception, in analytic philosophy at least, made the problem of perception synonymous with the view that realism is untenable. Admitting the problem (and trying to offer a view on it) is tantamount to rejecting ordinary people’s implicit realist assumptions as naive. So what exactly is the problem? We can approach it via one of the central arguments against realism – the argument from hallucination. The argument is intended as a proof that in ordinary, veridical cases of perception, perceivers do not have an unmediated perceptual access to the world. There are many versions of it; I propose the following1: 1. Hallucinations that are subjectively indistinguishable from veridical perceptions are possible. 2. If two subjective states are indistinguishable, then they have a common nature. 3. The contents of hallucinations are mental images, not concrete external objects. 4. Therefore, the contents of veridical perceptions are mental images rather than concrete external objects. The key move is, I believe, from the fact that hallucinations that are subjectively indistinguishable from cases of veridical perception are possible to an alleged common element, factor, or nature, in the form of a mental state, in the two cases – that is, premise 2. Disjunctivism, at its core, can be taken as simply denying this move, and arguing that all that follows from the premise stating the possibility of hallucinations that are subjectively indistinguishable from cases veridical perception is that there is a broader category, that of “experience as of...”, which encompasses both cases..

Abstract: The question how to account for illusion has had a prominent role in shaping theories of perception throughout the history of philosophy. Prevailing philosophical wisdom today has it that phenomena of illusion force us to choose between the following two options. First, reject altogether the early modern empiricist idea that the core subjective character of perceptual experience is to be given simply by citing the object presented in that experience. Instead we must characterize perceptual experience entirely in terms of its representational content. Second, retain the early modern idea that the core subjective character of experience is simply constituted by the identity of its direct objects, but admit that these must be mind-dependent entities, distinct from the mind-independent physical objects we all know and love. I argue here that the early modern empiricists had an indispensable insight. The idea that the core subjective character of perceptual experience is to be given simply by citing the object presented in that experience is more fundamental than any appeal to perceptual content, and can account for illusion, and indeed hallucination, without resorting to the problematic postulation of any such mind-dependent objects.

Abstract: This contribution explores the psychological basis of illusion and the feeling of what is real in relation to a process theory (microgenesis) of mind/brain states. The varieties of illusion and the alterations in the feeling of realness are illustrated in cases of clinical pathology, as well as in everyday life. The basis of illusion does not rest in a comparison of appearance to reality nor in the relation of image to object, since these are antecedent and consequent phases in the same mental state. The study of pathological illusions and hallucinations shows that the feeling of realness in an object depends on its coherence within and across perceptual modalities. Illusion is shown to be not the taking of the phenomenal for the real, but the overlooking of the real in the phenomenal, since all things exist, i.e. are real, as categories of intrinsic relations in the unique mode of their conception. Finally, the implications of the account are discussed in relation to moral conduct, self-realization, acceptance, and the will to enjoy a world of 'brain-born' mental phenomena

Abstract: It is a common tactic, going back to the beginnings of religion and philosophy, to presume that we are enveloped in a world of untruth and illusion, thereby fueling our movement toward truth. In more modern times, Descartes demonstrates this process clearly with his Meditations. This work extends the Cartesian skeptical position by challenging the concept of illusion itself, asking those who have ever called something ‘an illusion’ to question the meaning of these assertions. This broader skepticism partially annihilates itself without completely collapsing under the weight of self-contradiction.

Abstract: The 'content view', in slogan form, is 'Perceptual experiences have representational content'. I explain why the content view should be reformulated to remove any reference to 'experiences'. I then argue, against Bill Brewer, Charles Travis and others, that the content view is true. One corollary of the discussion is that the content of perception is relatively thin (confined, in the visual case, to roughly the output of 'mid-level' vision). Finally, I argue (briefly) that the opponents of the content view are partially vindicated, because perceptual error is due to false belief

Abstract: The subjective character of a given experience leaves open the question of its precise status. If it looks to a subject K as if there is an object of a kind F in front of him, the experience he is having could be veridical, or hallucinatory. Advocates of the Causal Theory of perception (whom I shall call

Abstract: One central fact about hallucinations is that they may be subjectively indistinguishable from perceptions. Indeed, it has been argued by M. G. F. Martin and others that the hallucinatory experiences concerned cannot — and need not — be characterised in any more positive general terms. This epistemic conception of hallucinations has been advocated as the best choice for proponents of experiential (or ‘na¨ıve realist’) disjunctivism — the view that perceptions and hallucinations differ essentially in their introspectible subjective characters. In this chapater, I aim to formulate and defend an intentional alternative to experiential disjunctivism called experiential intentionalism. This view does not only enjoy some advantages over its rival, but also can hold on to the epistemic conception of perception-like hallucinations. First of all, I try to spell out in a bit more detail in which sense hallucinations may be subjectively indistinguishable from perceptions, and why this leads us to erroneously judge them to be perceptions (cf. sections I–III and VIII). Then, I raise three challenges each for experiential disjunctivism and its orthodox intentionalist counterparts (cf. sections IV and V), notably in respect of the need to explicate why a perception-like hallucination still makes the same judgements reasonable from the subject’s perspective as the corresponding perceptions. And, finally, I propose my alternative both to experiential disjunctivism and to orthodox intentionalism. Experiential intentionalism takes perceptions and perception-like hallucinations to share a common character partly to be spelled out in intentional — and, hence, normative — terms (cf. sections VI and VII). The central thought is that the hallucinations concerned are intentionally — and erroneously — presented to us as perceptual relations to the world. I aim to show that the resulting view can meet all six challenges (cf. sections VI–VIII). I end..

Abstract: When philosophers speak or write about hallucinations, they usually have perceptual (or ’true’) hallucinations in mind - that is, hallucinations which the subject mistakes for genuine perceptions and which have the same impact on his mental lives as the latter.1 One reason for this is the fact that philosophers tend to address the topic of hallucination, not for its own sake, but only in the context of some wider issues. Thus, when they are discussing hallucinations, they are primarily interested in other topics, such a how - or whether - we are able to acquire knowledge about the external world, in which sense our mental states are directed at objects and properties, how best to account for what our experiences are subjectively like, which features suffice for something to count as a conscious experience, and so on. Especially the epistemic question, but also the connected issues in the philosophy of mind, lead them first of all to the phenomenon of genuine perception. For perceptions are precisely those mental episodes which point us to, and bring us into contact with, the world; and they also constitute the paradigm examples of conscious episodes with a distinctive phenomenal character. Hallucinations, on the other hand, do neither. Instead, they become relevant for the epistemic and related considerations only in so far as they give rise to sceptical scenarios and cast doubt on the common-sense (or naive) conception of the nature of perceptual experiences. And, in both cases, only those hallucinations matter which are indistinguishable from genuine perceptions with respect to their content and character.2 In the cognitive sciences (broadly understood as ranging from, say, neuroscience to developmental or evolutionary psychology), by contrast, hallucinations are much more prominent objects of study, and moreover objects of study in their own right. From the perspective of empirical investigations of the brain and mind - whether they utilise neuroimaging, observe behaviour, or examine verbal reports - hallucinations simply form one class of mental phenomena among many, all of which are ultimately in the same need of being studied and accounted for as part of our attempt to come to a full understanding of how our psychology works and is neurally realised..

Abstract: Finding disjunctivist versions of direct realism unexplanatory, Mark Johnston [(2004). Philosophical Studies, 120, 113–183] offers a non-disjunctive version of direct realism in its place and gives a defense of this view from the problem of hallucination. I will attempt to clarify the view that he presents and then argue that, once clarified, it either does not escape the problem of hallucination or does not look much like direct realism

Abstract: Recent neural models clarify many properties of mental imagery as part of the process whereby bottom-up visual information is influenced by top-down expectations, and how these expectations control visual attention. Volitional signals can transform modulatory top-down signals into supra-threshold imagery. Visual hallucinations can occur when the normal control of these volitional signals is lost

Abstract: Philosophers of mind have recently sought to establish a theoret- ical use for nonconceptual content. Although there is disagreement about what nonconceptual content is supposed to be, this much is clear. A state with nonconceptual content is mental. Hence, while one may deny that refrigerators and messy rooms have conceptual capacities, their states, as physical and not mental, do not have nonconceptual content. A state with nonconceptual content is also intentional, which is to say that it represents a feature of the world for a subject. It may be tempting to think of qualitative states as having nonconceptual content since they can be experienced by indi- viduals independently of their possession of the requisite concepts, e.g. someone could experience pains, itches or tingles without possessing the concept pain, itch or tingle. But on such a view, one would have to assume that qualitative states are representational since mental states cannot be candidates for nonconceptuality unless they have intentional properties.2

Abstract: Michael Martin aims to affirm a certain pattern of first-person thinking by advocating disjunctivism, a theory of perceptual experience which combines naive realism with the epistemic conception of hallucination. In this paper I argue that we can affirm the pattern of thinking in question without the epistemic conception of hallucination. The first part of my paper explains the link that Martin draws between the first-person thinking and the epistemic conception of hallucination. The second part of my paper explains how we can achieve Martin’s ambition without Martin’s theory. One resource that I enlist for this purpose is a naive-realist friendly conception of first-person access to experience. The metaphysical theory that I enlist is a form of naive realism that endorses an intentionalist or representationalist “common-factor” approach to veridical and hallucinatory experience. The third part of my paper briefly develops this theory.

Abstract: Inspired by the writings of J. M. Hinton (1967a, 1967b, 1973), but ushered into the mainstream by Paul Snowdon (1980–1, 1990–1), John McDowell (1982, 1986), and M. G. F. Martin (2002, 2004, 2006), disjunctivism is currently discussed, advocated, and opposed in the philosophy of perception, the theory of knowledge, the theory of practical reason, and the philosophy of action. But what is disjunctivism?

Abstract: Cultural differences in the perception of geometric illusions. Science 139: 769- 71. Shepard, RN 1 99o. Mind sights. New York: Freeman & Co. ...

Abstract: Stoffregen & Bardy (S&B) make the point that the statement “I am moving” made by subjects in a “swinging room” cannot be explained as an illusion of motion, and there is thus no perceptual illusion. In this they are correct. There is in fact motion, but of the environment. We argue that the subjects misinterpret this because the information to the visual system is ambiguous and also deceiving

Abstract: Audrey … lives in a noisy environment and so has never experienced silence. Audrey … wants to experience silence and so constructs a soundproof chamber. When she enters the chamber, Audrey learns something: what it is like to hear silence. … Audrey is introspecting an absence of auditory sensations while perceiving an absence of sound … an auditory gap that originates through healthy hearing of an external state of silence. (271)

Abstract: How should the Na¨ıve Realist who eschews representational percep- tual content account for illusions? Bill Brewer has recently proposed that illusions should be treated solely in terms of post-experiential misjudgement

Abstract: The psychological concept of illusion is defined as a process involving an interaction of logical and empirical considerations. Common usage suggests that an illusion is a discrepancy between one's awareness and some stimulus. Following preliminary definitions of classes of stimuli, five definitions of illusion are considered, based upon the possible discrepancies between awareness and a stimulus. It is found that each of these definitions fails to make important distinctions, even to the point of equating all illusory and perceptual phenomena. This dilemma is resolved by redefining illusion without reference to truth or falsity, but relative to the functioning of a given perceptual system under different conditions. The definition accepted as best is 'a discrepancy between one's perceptions of an object or event observed under different conditions'. Conditions may differ in terms of stimulus exposure, stimulus context, or experiental context. The philosophical and psychological implications are discussed of accepting a definition of illusion not based on a discrepancy between awareness and a stimulus

Abstract: Early formulations of disjunctivism about perception refused to give any positive account of the nature of hallucination, beyond the uncontroversial fact that they can in some sense seem to the same to the subject as veridical perceptions. Recently, some disjunctivists have attempt to account for hallucination in purely epistemic terms, by developing detailed account of what it is for a hallucinaton to be indiscriminable from a veridical perception. In this paper I argue that the prospects for purely epistemic treatments of hallucinations are dim, and that this undermines the case for disjunctivism

Abstract: Phenomenal character is determined by representational content, which both hallucinatory and veridical experiences can share. But in the case of veridical experience, unlike hallucination, the external objects of experience literally have the properties one is aware of in experience. The representationalist can accept the common factor assumption without having to introduce sensory intermediaries between the mind and the world, thus securing a form of direct realism

Abstract: A comprehensive theory of the structure and cognitive function of the human imagination, and its relationship to perceptual experience, is developed, largely through a critique of the account propounded in Colin McGinn's Mindsight. McGinn eschews the highly deflationary (and unilluminating) views of imagination common amongst analytical philosophers, but fails to develop his own account satisfactorily because (owing to a scientifically outmoded understanding of visual perception) he draws an excessively sharp, qualitative distinction between imagination and perception (following Wittgenstein, Sartre, and others), and because of his fatally flawed, empirically ungrounded conception of hallucination. In fact, however, an understanding of perception informed by modern visual science will enable us to unify our accounts of perception, mental imagery, dreaming, hallucination, creativity, and other aspects of imagination within a single coherent theoretical framework

Abstract: My purpose is to take a close look at the nature of visual content. I discuss the view that visual experiences have only existential contents, the view that visual experiences have either singular or gappy contents, and the view that visual experiences have multiple contents. I also consider a proposal about visual content inspired by Kaplan's well known theory of indexicals. I draw out some consequences of my discussion for the thesis of intentionalism with respect to the phenomenal character of visual experience

Abstract: Perhaps the greatest challenge to an existential phenomenological account of perception is that posed by the argument from illusions. Recent developments in research on the behaviour of subjects suffering from illusions together with some seminal ideas found in Merleau-Ponty''s writings enable us to develop and corroborate an account of the phenomenon of illusions, one, which unlike the empiricist account, does not undermine our conviction that in perception we reach the things themselves. The traditional argument from illusions derives its force from an uncritical assumption that the process of experience takes place in time conceived as an infinite series of distinct moments. Once this assumption has been bracketed we are able to recognise the paradoxical truth that in the disillusion something can become that which it has always been and can cease to be that which it has never been. Furthermore, through a reflection on our experience of others overcoming their illusions, and on psychological evidence, we are able to show that there is nothing to suggest that this description of the disillusion is a description of a private or subjective event