This paper argues for the conjunctive thesis of naïve realism and phenomenal intentionalism about perceptual experiences. Naïve realism holds that the phenomenology of veridical perceptual experience is constituted by environmental objects that the subject perceives. Phenomenal intentionalism about perceptual experience states that perceptual experience has intentionality in virtue of its phenomenology. I first argue that naïve realism is not incompatible with phenomenal intentionalism. I then argue that phenomenal intentionalists can handle two objections to it by adopting naïve realism: the first (...) objection is that phenomenal intentionalism cannot explain how a veridical perceptual experience is directed at a particular object rather than any other object of the same kind. The second objection is that phenomenal intentionalism cannot explain how a perceptual experience is directed at a type of external object rather than other types of objects without appealing to a resemblance relation between a perceptual experience and an external object, which is considered to be problematic. (shrink)

Disjunctivism about sensory experience is frequently put forward in defence of a particular conception of perception and perceptual experience known as naïve realism. In this paper, I present an argument against naïve realism that proceeds through a rejection of disjunctivism. If the naïve realist must also be a disjunctivist about the phenomenal nature of experience, then naïve realism should be abandoned.

I argue that the possibility of non-perceptual experience need not compel a naïve realist to adopt a disjunctive conception of experience. Instead, they can maintain that the nature of perceptual and hallucinatory experience is the same, while still claiming that perceptual experience is presentational of the objects of perception. On such a view the difference between perceptual and non-perceptual experience will lie in the nature of the objects that are so presented. I will defend a view according to which in (...) non-perceptual experience one is presented with mere universals, while in perceptual experience one is presented with the instantiation of a universal by a particular. This is to adopt disjunctivism about the objects of experience, about that which is apparently present in experience. (shrink)

Brains, it has recently been argued, are essentially prediction machines. They are bundles of cells that support perception and action by constantly attempting to match incoming sensory inputs with top-down expectations or predictions. This is achieved using a hierarchical generative model that aims to minimize prediction error within a bidirectional cascade of cortical processing. Such accounts offer a unifying model of perception and action, illuminate the functional role of attention, and may neatly capture the special contribution of cortical processing to (...) adaptive success. This target article critically examines this approach, concluding that it offers the best clue yet to the shape of a unified science of mind and action. Sections 1 and 2 lay out the key elements and implications of the approach. Section 3 explores a variety of pitfalls and challenges, spanning the evidential, the methodological, and the more properly conceptual. The paper ends (sections 4 and 5) by asking how such approaches might impact our more general vision of mind, experience, and agency. (shrink)

John Campbell investigates how consciousness of the world explains our ability to think about the world; how our ability to think about objects we can see depends on our capacity for conscious visual attention to those things. He illuminates classical problems about thought, reference, and experience by looking at the underlying psychological mechanisms on which conscious attention depends.

We perceive a world of mind-independent macroscopic material objects such as stones, tables, trees, and animals. Our experience is the joint upshot of the way these things are and our route through them, along with the various relevant circumstances of perception; and it depends on the normal operation of our perceptual systems. How should we characterise our perceptual experience so as to respect its basis and explain its role in grounding empirical thought and knowledge? I offered an answer to this (...) question in Perception and its objects. Here I aim to clarify some of my central arguments and to develop and defend the position further in the light of subsequent critical discussion. (shrink)

Physical objects are such things as stones, tables, trees, people and other animals: the persisting macroscopic constituents of the world we live in. therefore expresses a commonsense commitment to physical realism: the persisting macroscopic constituents of the world we live in exist, and are as they are, quite independently of anyone.

Perceptions are externally-directed—they present us with a mind-independent reality, and thus contribute to our abilities to think about this reality, and to know what is objectively the case. But perceptions are also internally-dependent—their phenomenologies depend on the neuro-computational properties of the subject. A good theory of perception must account for both these facts. But naive realism has been criticized for failing to accommodate internal-dependence. This paper evaluates and responds to this criticism. It first argues that a certain version of naive (...) realism, often called “selectionism”, does indeed struggle with internal-dependence. It then develops an alternate version of naive realism which does not. This alternate version, inspired by an idea of Martin’s, accommodates the internal-dependence of perceptions by recognizing the role that the subject’s neuro-computational properties play in shaping perceptual phenomenology. At the same time, it retains the distinctive naive realist account of the external-directedness of perceptions. (shrink)

What are hallucinations? A common view in the philosophical literature is that hallucinations are degenerate kinds of perceptual experience. I argue instead that hallucinations are degenerate kinds of sensory imagination. As well as providing a good account of many actual cases of hallucination, the view that hallucination is a kind of imagination represents a promising account of hallucination from the perspective of a disjunctivist theory of perception like naïve realism. This is because it provides a way of giving a positive (...) characterisation of hallucination—rather than characterising hallucinations in negative, relational, terms as mental events that are subjectively indistinguishable from veridical perceptual experiences. (shrink)

A natural starting point for theories of perceptual states is ordinary perception, in which a subject is successfully related to her mind-independent surroundings. Correspondingly, the simplest theory of perceptual states models all such states on perception. Typically, this simple, common-factor relational view of perceptual states has received a perfunctory dismissal on the grounds that hallucinations are nonperceptual. But I argue that the nonperceptual view of hallucinations has been accepted too quickly. I consider three observations thought to support the view, and (...) argue that all three are dealt with equally well by an alternative view, illusionism, on which hallucinations do involve perception. Since this is so, adopting a common-factor relational view of all perceptual states remains a tenable option. (shrink)

This chapter starts by restating the causal-hallucinatory argument against naive realism. This argument depends on the possibility of “philosophers' hallucinations.” It draws attention to the role of what the chapter refers to as the nonarbitrariness of philosophers' hallucinations in supporting this argument. The chapter then discusses three attempts to refute the argument. Two of them, those associated with John McDowell and with Michael Martin, are explicitly forms of disjunctivism. The third, exemplified by Mark Johnston, has, the chapter claims, disjunctivist features. (...) None of these responses to the argument is plausible. (shrink)

An overview of the philosophy and psychology of hallucination and its relevance to the philosophy of perception.

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. (shrink)

The aim of this paper is to argue that the phenomenal similarity between perceiving and visualizing can be explained by the similarity between the structure of the content of these two different mental states. And this puts important constraints on how we should think about perceptual content and the content of mental imagery.

The Bayesian brain hypothesis provides an attractive unifying framework for perception, cognition, and action. We argue that the framework can also usefully integrate interoception, the sense of the internal physiological condition of the body. Our model of entails a new view of emotion as interoceptive inference and may account for a range of psychiatric disorders of selfhood.

I raise a problem for common-factor theories of experience concerning the demonstrative thoughts we form on the basis of experience. Building on an insight of Paul Snowdon 1992, I argue that in order to demonstratively refer to an item via conscious awareness of a distinct intermediary the subject must have some understanding that she is aware of a distinct intermediary. This becomes an issue for common-factor theories insofar as it is also widely accepted that the general, pre-philosophical or ‘naïve’ view (...) of experience does not accept that in normal perceptual cases one is consciously aware of non-environmental (inner, mental) features. I argue then that the standard common-factor view of experience should be committed to attributing quite widespread referential errors or failures amongst the general, nonphilosophical populace – which seems an unattractively radical commitment. After clarifying the various assumptions I am making about experience and demonstrative thoughts, I consider a number of possible responses on behalf of the common-factor theorist. I finish by arguing that my argument should apply to any common-factor theory, not just avowedly ‘indirect' theories. (shrink)

A number of philosophers have argued in favour of the Dependency Thesis: if a subject sensorily imagines an F then he or she sensorily imagines from the inside perceptually experiencing an F in the imaginary world. They claim that it explains certain important features of imaginative experience, in brief: the fact that it is perspectival, the fact that it does not involve presentation of sensory qualities and the fact that mental images can serve a number of different imaginings. I argue (...) that the Dependency Thesis is false and that, in any event, it does not have the explanatory credentials claimed for it. Some of the features of imaginative experience are incorrectly specified, namely the absence of presentation of sensory qualities. With a more precise idea of what we need to explain, I argue that the explanation should proceed by noting that imagination and perception have phenomenally similar contents and that this is to be explained in terms of the similar kinds of representations in play. I trace the consequences of my discussion for disjunctivist theories of perception, Berkeleian Idealism and the characterisation of knowing what an experience is like. (shrink)

When we see an object, we also represent those parts of it that are not visible. The question is how we represent them: this is the problem of amodal perception. I will consider three possible accounts: (a) we see them, (b) we have non-perceptual beliefs about them and (c) we have immediate perceptual access to them, and point out that all of these views face both empirical and conceptual objections. I suggest and defend a fourth account, according to which we (...) represent the occluded parts of perceived objects by means of mental imagery. This conclusion could be thought of as a (weak) version of the Strawsonian dictum, according to which “imagination is a necessary ingredient of perception itself”. (shrink)

This paper sets out a novel response to the ‘screening off problem’ for naïve realism. The aim is to resist the claim (which many naïve realists accept) that the kind of experience involved in hallucinating also occurs during perception, by arguing that there are causal constraints that must be met if an hallucinatory experience is to occur that are never met in perceptual cases. Notably, given this response, it turns out that, contra current orthodoxy, naïve realists need not adopt any (...) particular view about the psychological nature of hallucinatory experience to handle the screening off problem. Consequently, room opens up for naïve realists to endorse whatever theory of hallucinatory experience seems to best capture the distinctive nature of such episodes. (shrink)

Disjunctivists maintain that perceptual experiences and hallucinatory experiences are distinct kinds of event with different metaphysical natures. Moreover, given their view about the nature of perceptual cases, disjunctivists must deny that the perceptual kind of experience can occur during hallucination. However, it is widely held that disjunctivists must grant the converse claim, to the effect that the hallucinatory kind of experience occurs even during perception. This paper challenges that thought. As we will see, the argument for thinking that the hallucinatory (...) kind of experience is present even in cases of perception depends on prior acceptance of a ‘non-demanding’ conception of hallucination, on which all it takes to produce an hallucinatory experience is to induce in the subject the right kind of neurological condition. On the view developed here, by contrast, there are substantive causal conditions, going beyond the mere occurrence of the right kind of neurological state, that must be met if an experience of the hallucinatory kind is to occur. By drawing on this view, I argue, disjunctivists can deny that the kind of experience involved in hallucination ever occurs during perception. This then allows disjunctivists to avoid certain important problems they would otherwise face. It also leaves them with considerably more freedom when it comes to theorising about the nature of hallucinatory experience. (shrink)

A common objection to sense-datum theories of perception is that they cannot give an adequate account of the fact that introspection indicates that our sensory experiences are directed on, or are about, the mind-independent entities in the world around us, that our sense experience is transparent to the world. In this paper I point out that the main force of this claim is to point out an explanatory challenge to sense-datum theories.

The disjunctive theory of perception claims that we should understand statements about how things appear to a perceiver to be equivalent to statements of a disjunction that either one is perceiving such and such or one is suffering an illusion (or hallucination); and that such statements are not to be viewed as introducing a report of a distinctive mental event or state common to these various disjoint situations. When Michael Hinton first introduced the idea, he suggested that the burden of (...) proof or disproof lay with his opponent, that what was needed was to show that our talk of how things look or appear to one.. (shrink)

Much of the discussion of Naive Realism about veridical experience has focused on a consequence of adopting it—namely, disjunctivism about perceptual experience. However, the motivations for being a Naive Realist in the first place have received relatively little attention in the literature. In this paper, I will elaborate and defend the claim that Naive Realism provides the best account of the phenomenal character of veridical experience.

Many philosophers are skeptical about disjunctivism —a theory of perceptual experience which holds roughly that a situation in which I see a banana that is as it appears to me to be and one in which I have a hallucination as of a banana are mentally completely different. Often this skepticism is rooted in the suspicion that such a view cannot adequately account for the bad case—in particular, that such a view cannot explain why what it’s like to have a (...) hallucination can be exactly like what it’s like to have a veridical experience, that it cannot explain why the hallucination I have in the bad case is subjectively indistinguishable from the kind of experience I have in the good case, and that it cannot offer a viable account of the nature of hallucination. -/- In this paper, I argue that a proper formulation of disjunctivism can avoid these objections. Disjunctivism should be formulated as the weakest claim required to preserve its primary motivation, viz., Naïve Realism—the view that veridical experience fundamentally consists in the subject perceiving entities in her environment. And the weakest claim required to preserve Naïve Realism allows for many sorts of commonalities across the good and hallucinatory cases, commonalities that can be marshaled in responding to the objections. Most importantly, disjunctivism properly formulated is compatible with “positive” accounts of the nature of hallucination. (shrink)

This paper examines the relationship between perceiving and imagining on the basis of predictive processing models in neuroscience. Contrary to the received view in philosophy of mind, which holds that perceiving and imagining are essentially distinct, these models depict perceiving and imagining as deeply unified and overlapping. It is argued that there are two mutually exclusive implications of taking perception and imagination to be fundamentally unified. The view defended is what I dub the ecological–enactive view given that it does not (...) succumb to internalism about the mind-world relation, and allows one to keep a version of the received view in play. (shrink)

Recently representationalists have cited a phenomenon known as the transparency of experience in arguments against the qualia theory. Representationalists take transparency to support their theory and to work against the qualia theory. In this paper I argue that representationalist assessment of the philosophical importance of transparency is incorrect. The true beneficiary of transparency is another theory, naïve realism. Transparency militates against qualia and the representationalist theory of experience. I describe the transparency phenomenon, and I use my description to argue for (...) naïve realism and against representationalism and the qualia theory. I also examine the relationship between phenomenological study and phenomenal character, and discuss the results in connection with the argument from hallucination. (shrink)

As standardly conceived, an illusion is an experience of an object o appearing F where o is not in fact F. Paradigm examples of color illusion, however, do not fit this pattern. A diagnosis of this uncovers different sense of appearance talk that is the basis of a dilemma for the standard conception. The dilemma is only a challenge. But if the challenge cannot be met, then any conception of experience, such as representationalism, that is committed to the standard conception (...) is false. Perhaps surprisingly, naïve realism provides a better account of color illusion.An apparence ymaad by som Magyk. Chaucer. (shrink)

Like dreaming, hallucination has been a formative trope for modern philosophy. The vivid, often tragic, breakdown in the mind’s apparent capacity to disclose reality has long served to support a paradoxical philosophical picture of sensory experience. This picture, which of late has shaped the paradigmatic empirical understanding the senses, displays sensory acts as already complete without the external world; complete in that the direct objects even of veridical sensory acts do not transcend what we could anyway hallucinate. Hallucination is thus (...) the mother of Representationalism, which insists that it is mental intermediaries that make other.. (shrink)

[John Hawthorne] We examine some well-known disjunctivist projects in the philosophy of perception, mainly in a critical vein. Our discussion is divided into four parts. Following some introductory remarks, we examine in part two the link between object-dependent contents and disjunctivism. In part three, we explore the disjunctivist's use of discriminability facts as a basis for understanding experience. In part four, we examine an interesting argument for disjunctivism that has been offered by Michael Martin. /// [Scott Sturgeon] The paper aims (...) to do five things: sketch the backbone of disjunctivism about visual experience, explore the view of our title, defend a version of that view from two objections, press two more objections of my own, and sketch a more radical variety of disjunctivism which avoids much of the bother. (shrink)

Recent debates between representational and relational theories of perceptual experience sometimes fail to clarify in what respect the two views differ. In this essay, I explain that the relational view rejects two related claims endorsed by most representationalists: the claim that perceptual experiences can be erroneous, and the claim that having the same representational content is what explains the indiscriminability of veridical perceptions and phenomenally matching illusions or hallucinations. I then show how the relational view can claim that errors associated (...) with perception should be explained in terms of false judgments, and develop a theory of illusions based on the idea that appearances are properties of objects in the surrounding environment. I provide an account of why appearances are sometimes misleading, and conclude by showing how the availability of this view undermines one of the most common ways of motivating representationalist theories of perception. (shrink)

Naive realists hold that experience is to be understood in terms of an intimate perceptual relation between a subject and aspects of the world, relative to a certain standpoint. Those aspects of the world themselves shape the contours of consciousness. But blurriness is an aspect of some of our experiences that does not seem to come from the world. I argue that this constitutes a significant challenge to some forms of naive realism. But I also argue that there is a (...) robust form of naive realism which is unfazed by the blurriness of some of our experiences, even when that blurriness is understood as a subjective modification of consciousness. (shrink)

Visual experiences seem to exhibit phenomenological particularity: when you look at some object, it – that particular object – looks some way to you. But experiences exhibit generality too: when you look at a distinct but qualitatively identical object, things seem the same to you as they did in seeing the first object. Naïve realist accounts of visual experience have often been thought to have a problem with each of these observations. It has been claimed that naïve realist views cannot (...) account for the generality of visual experiences, and that the naïve realist explanation of particularity has unacceptable implications for self- knowledge: the knowledge we have of the character of our own experiences. We argue in this paper that neither claim is correct: naïve realism can explain the generality of experiences, and the naïve realist explanation of particularity raises no problems for our self-knowledge. (shrink)

Cognitive Penetration holds that cognitive states and processes, specifically propositional attitudes (e.g., beliefs), sometimes directly impact features of perceptual experiences (e.g., the coloring of an object). In contrast, more traditional views hold that propositional attitudes do not directly impact perceptual experiences, but rather are only involved in interpreting or judging these experiences. Understandably, Cognitive Penetration is controversial and has been criticized on both theoretical and empirical grounds. I focus on defending it from the latter kind of objection and in doing (...) so, highlight important features of Cognitive Penetration mechanisms and effects. I first sketch promising criteria for Cognitive Penetration and then address widespread Replication and Demonstration worries about purported instances of it. Next, I present one of the most compelling Cognitive Penetration studies and address specific objections against it and others. I demonstrate that each of these objections misunderstands important features of either Cognitive Penetration mechanisms or the specific studies to which they are applied. Ultimately, I conclude that multiple key studies are not undermined by these objections and con- tinue to provide support for Cognitive Penetration. Correcting these misunderstandings bolsters empirical support for Cognitive Penetration and contributes to a better understand- ing of the mechanisms involved in perceptual processing. (shrink)

Cognitive Penetration holds that cognitive states and processes, specifically propositional attitudes (e.g., beliefs), sometimes directly impact features of perceptual experiences (e.g., the coloring of an object). In contrast, more traditional views hold that propositional attitudes do not directly impact perceptual experiences, but rather are only involved in interpreting or judging these experiences. Understandably, Cognitive Penetration is controversial and has been criticized on both theoretical and empirical grounds. I focus on defending it from the latter kind of objection and in doing (...) so, highlight important features of Cognitive Penetration mechanisms and effects. I first sketch promising criteria for Cognitive Penetration and then address widespread Replication and Demonstration worries about purported instances of it. Next, I present one of the most compelling Cognitive Penetration studies and address specific objections against it and others. I demonstrate that each of these objections misunderstands important features of either Cognitive Penetration mechanisms or the specific studies to which they are applied. Ultimately, I conclude that multiple key studies are not undermined by these objections and continue to provide support for Cognitive Penetration. Correcting these misunderstandings bolsters empirical support for Cognitive Penetration and contributes to a better understanding of the mechanisms involved in perceptual processing. (shrink)

To imagine is to form a mental representation that does not aim at things as they actually, presently, and subjectively are. One can use imagination to represent possibilities other than the actual, to represent times other than the present, and to represent perspectives other than one’s own. Unlike perceiving and believing, imagining something does not require one to consider that something to be the case. Unlike desiring or anticipating, imagining something does not require one to wish or expect that something (...) to be the case. // -/- Imagination is involved in a wide variety of human activities, and has been explored from a wide range of philosophical perspectives. Philosophers of mind have examined imagination’s role in mindreading and in pretense. Philosophical aestheticians have examined imagination’s role in creating and in engaging with different types of artworks. Epistemologists have examined imagination’s role in theoretical thought experiments and in practical decision-making. Philosophers of language have examined imagination’s role in irony and metaphor. // -/- Because of the breadth of the topic, this entry focuses exclusively on contemporary discussions of imagination in the Anglo-American philosophical tradition. (shrink)

I consider a new, non-disjunctive strategy for ‘relational’ or ‘naïve realist’ theories to respond to arguments from ‘perfect’ (causally matching) hallucinations. The strategy, in a nutshell, is to treat such hypothetical cases as instances of perception rather than hallucination. After clarifying the form and dialectic of such arguments, I consider three objections to the strategy. I provide answers to the first two objections but concede that the third — based on the possibility of ‘chaotic’ (uncaused) perfect hallucinations — cannot obviously (...) be dealt with by the proposed strategy. However, such ‘chaotic’ scenarios are also problematic for standard representational accounts of experience. Thus I conclude that perfect hallucinations pose no more of a threat to the relational theory than to its main representational rival. (shrink)

Naïve realism, often overlooked among philosophical theories of perception, has in recent years attracted a surge of interest. Broadly speaking, the central commitment of naïve realism is that mind-independent objects are essential to the fundamental analysis of perceptual experience. Since the claims of naïve realism concern the essential metaphysical structure of conscious perception, its truth or falsity is of central importance to a wide range of topics, including the explanation of semantic reference and representational content, the nature of phenomenal consciousness, (...) and the basis of perceptual justification and knowledge. One of the greatest difficulties surrounding discussions of naïve realism, however, has been lack of clarity concerning exactly what affirming or denying it entails. In particular, it is sometimes unclear how naïve realism is related to the claim that perceptual experience is in some sense direct or unmediated, and also to what extent the view is compatible with another widely discussed thesis in the philosophy of perception, the claim that perceptual experiences are states with representational content. In this essay, I discuss how recent work on these issues helps to clarify both the central commitments of naïve realism, as well as its relation to representationalist theories of perception. Along the way, I will attempt to shed light on the different ways in which each approach tries to address the various theoretical challenges facing a philosophical theory of perception, and also to assess the prospects for views that attempts to combine features of each approach. (shrink)

This paper sketches an account that explains the elusive subjective quality of 'enduring substantiality' of the phenomenal self. It integrates a recent predictive processing account of the self by Chris Letheby and Philip Gerrans with key ideas of Michael Graziano's attention schema theory of consciousness. Similarly to the attention schema theory, the present account posits an internal model of ongoing attentional processing that supports attentional control. In terms of predictive processing, it is a dynamic model of precision estimates that represents (...) the salience of features, objects, and internal and external processes. The apparent substantiality of the self is then explained by a structural feature of this salience model: it binds different dimensions of salience by representations of higher-order dimensions of salience. The result of this salience binding is a phenomenally transparent 'salience object', which is represented as a cause of widespread changes in precision estimates, and results in a form of epistemic self-control. Phenomenologically, this goes along with the experience of the self as an attentional agent, and in this way creates the origin of our consciously experienced first-person perspective: I attend, I am. (shrink)

The phenomenal particularity thesis says that if a mind-independent particular is consciously perceived in a given perception, that particular is among the constituents of the perception’s phenomenology. Martin, Campbell, Gomes and French and others defend this thesis. Against them are Mehta, Montague, Schellenberg and others, who have produced strong arguments that the phenomenal particularity thesis is false. Unfortunately, neither side has persuaded the other, and it seems that the debate between them is now at an impasse. This paper aims to (...) break through this impasse. It argues that we have reached the impasse because two distinct conceptions of phenomenology—a “narrow” conception and a “broad” conception—are compatible with our what-it-is-like characterizations of phenomenology. It also suggests that each of these two conceptions has its own theoretical value and use. Therefore, the paper recommends a pluralistic position, on which we acknowledge that there are two kinds of phenomenology: narrow phenomenology and broad phenomenology. The phenomenal particularity thesis is true only with respect to the latter. (shrink)

This paper has two aims. The first is to use contemporary discussions of naïve realist theories of perception to offer an interpretation of Merleau-Ponty’s theory of perception. The second is to use consideration of Merleau-Ponty’s theory of perception to outline a distinctive version of a naïve realist theory of perception. In a Merleau-Pontian spirit, these two aims are inter-dependent.

Hallucination is a big deal in contemporary philosophy of perception. The main reason for this is that the way hallucination is treated marks an important stance in one of the most hotly contested debates in this subdiscipline: the debate between 'relationalists' and 'representationalists'. I argue that if we take hallucinations to be a form of mental imagery, then we have a very straightforward way of arguing against disjunctivism: if hallucination is a form of mental imagery and if mental imagery and (...) perception have some substantive common denominator, then a fortiori, perception and hallucination will also have a substantive common denominator. (shrink)