Gary Hatfield

This chapter considers philosophical problems concerning non-human (and sometimes human) animals, including their metaphysical, physical, and moral status, their origin, what makes them alive, their functional organization, and the basis of their sensitive and cognitive capacities. I proceed by assuming what most of Descartes’s followers and interpreters have held: that Descartes proposed that animals lack sentience, feeling, and genuinely cognitive representations of things. (Some scholars interpret Descartes differently, denying that he excluded sentience, feeling, and representation from animals, and I consider the evidence for these interpretations as well.) Given that Descartes denied any sort of soul to animals, his other philosophical commitments entailed that he must explain the vital and sensitive powers of non-human animals through purely material causes. Indeed, he welcomed this task, for he was engaged in the larger project of providing purely mechanistic explanations for all natural phenomena of the material world. Animal bodies form functional unities that are adapted to environmental circumstances. In his new physics, Descartes sought to discover or hypothesize material mechanisms that would explain the physiological and behavioral capacities of animals, including how they maintain themselves by seeking food and drink, reproduce themselves, and modify their behavior to fit current circumstances. Metaphysically, his new perspective raised the problem of accounting for the functional unity of the animal body considered as a purely material construction, devoid of an active, organizing power such as the sensitive soul. Descartes’s project becomes even more challenging if we ask whence come such mechanisms that are capable of performing the functions of living things. Officially, Descartes endorsed the accepted theological orthodoxy, that God designed and created the bodily mechanisms of humans and animals. However, in his natural philosophy he set himself the task of explaining the origin of animals as part of the natural development of the universe out of an original chaotic soup of material particles. Within this naturalistic perspective, he must explain how, through purely material processes, the functionally organized bodies of living things (plants and animals) could be produced from non-living matter. Without a designing creator, how do animal bodies arise that are capable of digesting food, growing, reproducing, and performing the behaviors needed to preserve life and health?

This paper examines Helmholtz's attempt to use empirical psychology to refute certain of Kant's epistemological positions. Particularly, Helmholtz believed that his work in the psychology of visual perception showed Kant's doctrine of the a priori character of spatial intuition to be in error. Some of Helmholtz's arguments are effective, but this effectiveness derives from his arguments to show the possibility of obtaining evidence that the structure of physical space is non-Euclidean, and these arguments do not depend on his theory of vision. Helmholtz's general attempt to provide an empirical account of the "inferences" of perception is regarded as a failure.

Descartes entitled the Sixth Meditation "The existence of material things, and the real distinction between mind and body." But these topics take up only two paragraphs, about one-third of the way into the Sixth Meditation (which is the longest of the six). The other topics in the Meditation partly pertain to the cognitive faculties that a seeker after knowledge must employ: senses, imagination, and intellect. They also concern the mind–body relation: not only is it to be shown that mind and body are distinct, but also that they are “closely joined” together. The joining of mind to body contributes to explanations of the cognitive faculties, for such a joining is, in Descartes’ view, necessary for the operation of sense and imagination, whereas the exercise of the intellect in the pursuit of metaphysical results -- as in his argument for mind–body distinctness -- takes place without the mind interacting with the body. But this still doesn't account for the most sustained discussion in the Sixth Meditation, which concerns the role of the senses in informing us about the world around us. While the trustworthiness of the senses has been under suspicion up to this point in the Meditations, now the senses are rehabilitated. They can serve to acquaint us with the world of bodies, for the purposes of empirical investigation serving natural philosophy but, more usually, for the practical purpose of informing us of potential benefits and harms in our immediate environment. In this regard, Descartes considers the ways in the senses might be subject to local errors or might, if used inappropriately, draw us into systematic error. But the previous results of the Meditations now offer the means for avoiding such systematic error, and the reflections of the Sixth Meditation can guide us toward practical uses of the senses in ways that reduce error. In the end, the senses are found to be trustworthy for the guidance of action, and this trustworthiness extends even to a qualitative experience such as color, which helps us to discriminate among the bodies that we see.

This chapter examines the Helmholtz's changing conceptions of the relation between scientific cognition (the thought processes of the investigator) and artistic cognition. It begins with two case studies: Helmholtz's application of sensory physiology and psychology respectively to music and to painting. Consideration of these concrete cases leads to Helmholtz's account of the methodology of aesthetics, and specifically to his formulation of the distinction between the *Geisteswissenschaften* and *Naturwissenschaften*. It then examines the development of his comparative account of the thought processes of artist and scientist. This development parallels the development of his psychological theory of judgment into his famous theory of unconscious inference. The latter development exemplifies his classical "aesthetics of science."

The philosophers René Descartes (1596–1650), Nicolas Malebranche (1638–1715), Benedict Spinoza (1632–77), and Gottfried Wilhelm Leibniz (1646–1716) are grouped together as rationalists because they held that human beings possess a faculty of reason that produces knowledge independently of the senses. In this regard, they contrast with empiricist philosophers, such as John Locke and David Hume, who believed that all knowledge arises from the senses. The rationalists contended that proper use of reason would yield the first principles of metaphysics, the most basic science of all. Metaphysics was also called “first philosophy,” and it took as its subject matter nothing less than the basic properties and principles of everything. For our purposes, it is important to note that the rationalists believed that metaphysics could provide foundations for specialized disciplines, including ethics and physics, and also medicine and other applied subjects. The rationalists and their followers developed theoretical positions of ambitious intellectual scope, ranging from metaphysical conclusions about the existence and nature of God to detailed theories of physical and physiological processes. Although they put great store in the faculty of reason for establishing overarching principles, they looked to observation and experience to provide data and evidence for their detailed theories. They took special interest in the metaphysics and physics of the human organism, and this led them to psychological topics concerning the characteristics and principles of animal behavior, the process of sense perception, the passions, and emotions, and appetites, the cognitive operations of the mind (including attention and understanding), and the relation between mental phenomena and bodily processes in the brain and sense organs. The various rationalists, but especially Descartes, made original contributions to these topics. After considering the character of psychology as a discipline in the seventeenth century, we will examine these contributions in turn.

Recent Cartesian scholarship postulates two Descartes, separating Descartes into a scientist and a metaphysician. The purpose varies, but one has been to show that the metaphysical Descartes, of the Meditations, is less genuine than the scientific Descartes. Accordingly, discussion of God and the soul, the evil demon, and the non-deceiving God were elements of rhetorical strategy to please theologians, not of serious philosophical argumentation. I agree in finding two Descartes, but the two I identify are not scientist and philosopher, but practitioner and methodologist of the mathematical sciences on the one hand, and metaphysician of a new, general science of nature on the other. This chapter examines the transition to the second Descartes, and especially the metaphysical turn. It proposes that although Descartes' doubt was methodological and he felt no serious threat from skepticism and absolute certainty was not his primary goal. Rather, the doubt was used to reform the intellect, or to teach the use of the pure intellect (and to obtain certainty in that domain). Further, Descartes' metaphysics was primarily in the service of his natural philosophy (where in the main he did not claim absolute certainty). He did not talk about God and the soul in order to fool the theologians. His discussion of the relation between God and human reason was part of a metaphysical strategy in which, through his doctrine on the eternal truths, he separated knowledge of the first principles of natural philosophy (gained by the natural light) from theological cognition (through the light of grace), thereby seeking to render his metaphysics distinct from the proper domain of theology.

The term “perceptual constancy” was used by the Gestalt theorists in the early part of the twentieth century (e.g., Koffka 1935, 34, 90) to refer to the tendency of perception to remain invariant over changes of viewing distance, viewing angle, and conditions of illumination. This tendency toward constancy is remarkable: every change in the viewing distance, position, and illumination is necessarily accompanied by a change in the local proximal (retinal) stimulation, and yet perception remains relatively stable. The tendency toward perceptual constancy encouraged the Gestalt theorists to look beyond local proximal stimulation in grounding their theories of perception. In the ensuing decades, much has been learned about the constancies. Evidence for this assertion may be found in the contributions to the current volume as well as in earlier volumes (e.g., Epstein 1977; Walsh and Kulikowsky 1998). These advances notwithstanding, significant questions remain open. Our aim here is to note some advances and specify some open questions.

Psychology considered as a natural science began as Aristotelian "physics" or "natural philosophy" of the soul. C. Wolff placed psychology under metaphysics, coordinate with cosmology. Scottish thinkers placed it within moral philosophy, but distinguished its "physical" laws from properly moral laws (for guiding conduct). Several Germans sought to establish an autonomous empirical psychology as a branch of natural science. British and French visual theorists developed mathematically precise theories of size and distance perception; they created instruments to test these theories and to measure visual phenomena such as the duration of visual impressions. These investigators typically were dualists who included mental phenomena within nature.

It seems intuitively obvious that metameric matching of color samples entails a loss of information, for spectrophotometrically diverse materials appear the same. This intuition implicitly relies on a conception of the function of color vision and on a related conception of how color samples should be individuated. It assumes that the function of color vision is to distinguish among spectral energy distributions, and that color samples should be individuated by their physical properties. I challenge these assumptions by articulating a different conception of the function of color vision, according to which color vision serves to partition object surfaces into discrimination classes.

Some experiments in perceptual psychology measure perceivers’ phenomenal experiences of objects versus their cognitive assessments of object properties. Analyzing such experiments, this article responds to Pizlo’s claim that much work on shape constancy before 1985 confused problems of shape ambiguity with problems of shape constancy. Pizlo fails to grasp the logic of experimental designs directed toward phenomenal aspects of shape constancy. In the domain of size perception, Granrud’s studies of size constancy in children and adults distinguish phenomenal from cognitive factors

This chapter deals with Immanuel Kant's remarks on touch and vision in the context of his pragmatic anthropology, by considering his views of the scope, aims, and methods of that fledgling discipline. Kant supports his discussion with appeals to observation and experience that form a kind of everyday phenomenology of sensory experience. The chapter considers Kant's notion of the relation between the pragmatic and the theoretical, including his remarks that a pragmatic anthropology does not present theoretical or scholastic knowledge but focuses on worldly knowledge. Kant derived the framework for his discussion of the five external senses from his lectures on metaphysics, especially those on empirical psychology. In both empirical psychology and anthropology he categorizes the senses into those that are comparatively objective and those that are comparatively subjective: the objective senses provide more cognition, and provide occasion for reflection, but the subjective senses have more sensation than reflection.

Seeing happens effortlessly and yet is endlessly complex. Among the most fascinating aspects of visual perception is its stability and constancy. As we shift our gaze or move about the world, the light projected onto the retinas is constantly changing. Yet the surrounding objects appear stable in their properties. Psychologists have long been interested in the constancies. They have asked questions such as: How good is constancy? Is constancy a fact about how things look, or is it a product of our beliefs and judgments about how things look? How can the contents of visual experience be studied experimentally? Philosophers have long been interested in characterizing visual experience and have become widely interested in the constancies more recently. As psychologists and philosophers have interacted, new questions have arisen: If experience is not as of retinal stimulation (proximal mode), but does not always exhibit constancy (or at least not in all respects), how shall we describe this intermediate state? Also, should we regard any departure from constancy as a failure of the visual system, or might it be a reasonable or adaptive response? In what circumstances is seeing highly conditioned by cognitive factors such as background assumptions, and in what circumstances not? Our volume focuses on size constancy and color constancy. It considers methodologies for studying conscious visual perception, efforts to describe visual experience in relation to constancy, what it means that constancy is not always perfect, and the conceptual resources needed for explaining visual experience.

The chapter advances two theses involving Descartes and the mind. The first concerns Descartes' conception of mental faculties, particularly the intellect. As I read the _Meditations_, a fundamental aim of that work is to make the reader aware of the deliverances of the pure intellect, perhaps for the first time. Descartes' project is to alter the reader's Aristotelian beliefs about the faculty of the intellect and its relation to the senses, while at the same time coaxing her to use the pure intellect to perceive the first truths of metaphysics. His anti-Aristotelian understanding of the power of pure intellect undergirds his attempted revolution in metaphysics and physics. The second thesis pertains to Descartes' naturalism about the mind. Descartes typically is seen as having excluded mind from nature, thereby deanimating (literally, "de-souling") the physical world and making it safe for a full-scale mechanistic physics. This attitude effectively makes the mind into "a convenient receptacle for the chips and whittlings of science, rather than a possible object of scientific knowledge" (E. A. Burtt). In contrast, I argue that Descartes included (at least some functions and states of) mind as part of nature, that despite his dualism he continued an established tradition of treating the operations of the senses as open to empirical investigation, and that in virtue of his dualism he initiated a new line of thought leading to the search for specifically psychophysical laws, that is, laws linking non-mental bodily states to states of mind. The precise senses in which Descartes did and did not include *mind* under the rubric *nature* is problematic; but he did use language suggesting that even the intellect is a natural constituent of the human being, as when he ascribed intellectual cognitions to "the natural light."

Review of: Stephen Gaukroger: The Collapse of Mechanism and the Rise of Sensibility: Science and the Shaping of Modernity, 1680-1760. Oxford: Clarendon, 2010, pp. ix+505. £47.00 (hb). ISBN 9780199594931. This volume is the second of a projected six-volume work on the shaping of modern cognitive values through the emergence of a scientific culture, a phenomenon that Gaukroger takes to be specific to the West. The volume ranges from Newton’s initial publications on optics to the French Enlightenment and the publication of the <i>Encyclopédie</i> of Diderot and d’Alembert. During this period, the unity within natural philosophy, secured by the view that matter theory should underlie all natural philosophy, is challenged, as is the unity between natural philosophy and physico-theology, the latter unity being the primary source of the cultural legitimacy that had allowed natural philosophy to flourish. The first type of unity was sundered as Newtonian natural philosophy disavowed the requirement that mechanics be united with a microscopic corpuscularian basis. Further, during this period, scientific (or natural philosophical) values first came to dominate the cognitive values of an entire culture, largely through the <i>persona</i> of the <i>philosophe</i> as the embodiment of reason, albeit a sensibilized reason arising from the new non-mechanistic natural philosophy of the mid-eighteenth century and no longer tied to physico-theology. The book does a better job charting the trend toward disunity than it does charting the rise of sensibility.

Shape and slant judgments of rotated or frontoparallel ellipses were elicited from three groups of 10 subjects. A masking stimulus was introduced to control processing time. Backward masking trials were presented with interstimulus intervals of 0, 25, and 50 msec, Reduction of processing time altered shape judgments in the direction of projective shape and slant judgments in the direction of frontoparallelness. This finding is consistent with the shape-slant invariance hypothesis. In order to study the effects of processing load, one group of subjects was given prior knowledge of the kind of judgment to be made on each trial, one group had no prior knowledge, and a third group made both judgments on each trial. The effects of the processing load manipulation were interpreted in terms of the role of attention in perceptual encoding. Consistent with previous findings, allocation of attention did not affect perceptual encoding.

The theory of knowledge in early twentieth-century Anglo American philosophy was oriented toward phenomenally described cognition. There was a healthy respect for the mind-body problem, which meant that phenomena in both the mental and physical domains were taken seriously. Bertrand Russell's developing position on sense-data and momentary particulars drew upon, and ultimately became like, the neutral monism of Ernst Mach and William James. Due to a more recent behaviorist and physicalist inspired "fear of the mental", this development has been down-played in historical work on early analytic philosophy. Such neglect assumes that the "linguistic turn" is a proper and permanent effect of twentieth-century philosophy, an assumption that distorts early analytic historiography, and begs a substantive philosophical question about thought and cognition.

The chapter focuses on attributions of the transparency of thought to early modern figures, most notably Descartes. Many recent philosophers assume that Descartes believed the mind to be “transparent”: since all mental states are conscious, we are therefore aware of them all, and indeed incorrigibly know them all. Descartes, and Berkeley too, do make statements that seem to endorse both aspects of the transparency theses (awareness of all mental states; incorrigibility). However, they also make systematic theoretical statements that directly countenance “unnoticed” thoughts or mental states, that is, thoughts or mental states of which the subject is unaware and has no knowledge. Descartes, having identified the essence of mind with thought or representation, distinguishes bare states of mind from states of which we have reflective awareness, thereby providing a theoretical tool for understanding both his seeming endorsement of transparency and his actual denial of it: Descartes distinguished between a basic perceptual state, or a basic awareness, and reflectively conscious states that involve explicit noticing and cognizing on the part of the subject. Leibniz (as is better known) directly endorsed a similar distinction between bare perception and reflective consciousness, using the term “perception” for the first and “apperception” for the second. In these cases, bare perceptions are not transparently available to the subject, and so in fact the subject does not have knowledge, hence does not have incorrigible knowledge, of all its occurrent mental states. This chapter gives evidence to support these claims; elaborates the complex psychology of the subject found in Descartes and other early moderns; and notes some ways in which these early moderns contributed to the genesis of the modern subject. Finally, it compares McDowell’s conception of the Cartesian mind with the conceptions of mind found in the writings of Descartes, Berkeley, and Leibniz, finding that his characterization caricatures the positions of early modern philosophers. McDowell's characterization has four elements: consciousness as essence of mind; intentionality as exclusively mental; the veil of perception; and the transparency of mind. Only the second point, about intentionality, fully fits Descartes. As a consequence of his own misdirection, McDowell misses the actual basis of his difficulty in connecting mind with world, which arises from a point of agreement between him and Descartes: the removal of intentionality from material sensory systems. But whereas Descartes could relocate (nonconceptual) sensory intentionality in mental states, McDowell is left to account for it with his overly cognitivized scheme of perceptual content as exclusively conceptual. (Paper first given at the European Society for Early Modern Philosophy, 2007.)

It is difficult to evaluate the role of activity - of force or of that which has causal efficacy - in Descartes’ natural philosophy. On the one hand, Descartes claims to include in his natural philosophy only that which can be described geometrically, which amounts to matter (extended substance) in motion (where this motion is described kinematically).’ Yet on the other hand, rigorous adherence to a purely geometrical description of matter in motion would make it difficult to account for the interactions among the particles that constitute Descartes’ universe, since the notions of extension and kinematical motion do not in themselves imply any causal agency. There is, after all, no reason to expect that a particle whose single essence is extension, even if we suppose it to be moving, should impart motion to another particle, while conversely, there is no reason to expect a resting particle to hinder the motion of an impinging one. Descartes' hankering for an austere ontology of matter in motion is in danger of excluding causal agency (force, conceived dynmically) from matter. To the modern reader it may seem obvious that Descartes did not get himself into such a fix, since matter in motion so readily reminds us of kinetic energy or of some more primitive notion of force. Yet by no means is it obvious that Descartes attributed causal efficacy to matter in motion per se. Serious scholars have held opposite positions on this issue. Westfall, Gabbey, and others’ have argued that although on the metaphysical plane Descartes attempted to eliminate force from his mechanical universe, nonetheless ‘force is a real feature’ of his mechanical world. The thrust of this view is that Descartes conceived of force as ‘the capacity of a body in motion to act’, by means of impact, upon other bodies. An opposing interpretation, defended here, is that Descartes did in fact deny causal agency to moving matter per se, restricting agency to immaterial substances such as the human mind, angels, and God. The intention of this interpretation is not to de-emphasize the role of matter in motion in Descartes’ explanation of nature, but rather to stress the fact that Descartes did not conceive of this moving matter dynamically. Reprinted in Descartes, ed. by J. Cottingham, Oxford Readings in Philosophy (Oxford: Oxford University Press, 1998), 281–310.

The chapter begins with a sketch of the empirical, theoretical, and philosophical background to nineteenth-century theories of perception, focusing on visual perception. It then considers German sensory physiology and psychology in the nineteenth century and its reception. This section gives special attention to: assumptions about nerve–sensation relations; spatial perception; the question of whether there is a two-dimensional representation in visual experience; psychophysics; size constancy; and theories of colour perception. The chapter then offers a brief look at the interaction between perceptual theory and philosophical issues in epistemology and the metaphysics of mind in Britain and America, focusing on: the notion of a muscle sense; the problem of the external world; and forms of perceptual realism. It ends with an overview of psychological theories of perception in the early twentieth century and the Gestalt reaction, culminating with J. J. Gibson.

Descartes understood the subject matter of physics (or natural philosophy) to encompass the whole of nature, including living things. It therefore comprised not only nonvital phenomena, including those we would now denominate as physical, chemical, minerological, magnetic, and atmospheric; it also extended to the world of plants and animals, including the human animal (with the exception of those aspects of the human mind that Descartes assigned to solely to thinking substance: pure intellect and will). Descartes wrote extensively on physiology and on the physiology and psychology of the senses. This chapter examines the notions of *physiology* and *psychology* in medical and natural philosophical works of Descartes' day; follows his efforts to bring physiology into his mechanistic idiom; considers the relation between physiology of the animal machine and psychological functions that yield functionally appropriate behavior; goes into his physiology and psychology of vision; and elaborates the tension in Descartes' works between his metaphysically supported micro-corpuscularism and his discussion of the animal machine as an organic unity comprising various functionally and teleologically characterized systems. The chapter draws on Descartes' works in both metaphysics and natural philosophy, including his Treatise on Man (originally published as L'Homme, 1664).

Visual space can be distinguished from physical space. The first is found in visual experience, while the second is defined independently of perception. Theorists have wondered about the relation between the two. Some investigators have concluded that visual space is non-Euclidean, and that it does not have a single metric structure. Here it is argued that visual space exhibits contraction in all three dimensions with increasing distance from the observer, that experienced features of this contraction are not the same as would be the experience of a perspective projection onto a fronto-parallel plane, and that such contraction is consistent with size constancy. These properties of visual space are different from those that would be predicted if spatial perception resulted from the successful solution of the inverse problem. They are consistent with the notion that optical constraints have been internalized. More generally, they are also consistent with the notion that visual spatial structures bear a resemblance relation to physical spatial structures. This notion supports a type of representational relation that is distinct from mere causal correspondence. The reticence of some philosophers and psychologists to discuss the structure of phenomenal space is diagnosed in terms of the simple materialism and the functionalism of the 1970s and 1980s

As the word “optics” was understood from antiquity into and beyond the early modern period, it did not mean simply the physics and geometry of light, but meant the “theory of vision” and included what we should now call physiological and psychological aspects. From antiquity, these aspects were subject to geometrical analysis. Accordingly, the geometry of visual experience has long been an object of investigation. This chapter examines accounts of size and distance perception in antiquity (Euclid and Ptolemy) and the Middle Ages (Ibn al-Haytham), before turning to "natural geometry" in Kepler and Descartes. It finds a purely mechanical realization of natural geometry in Descartes (primarily in his L'Homme, 1664), in which he conceives states of the visual system as varying in accordance with distance, much as his geometrical compasses vary their spatial relations in accordance with geometrical proportions. This reading challenges the notion that a two-dimensional sensation (without three-dimensional phenomenality) was universally accepted prior to the nineteenth century by positing a direct psychophysiological account of the experience of distance in Descartes. It thereby challenges the interpretations of Descartes on natural geometry of George Berkeley, Nancy Maull, Margaret Wilson, Erwin Panofsky, and Jonathan Crary.

The concept of representation has become almost inextricably bound to the concept of symbol systems. the concepts is nowhere more prevalent than in descriptions of "internal representations." These representations are thought to occur in an internal symbol system that allows the brain to store and use information. In this paper we explore a different approach to understanding psychological processes, one that retains a commitment to representations and computations but that is not based on the idea that information must be stored and manipulated in symbol systems. In particular, we suggest that the notion of a symbol system as currently understood construes psychological processes in terms of a specific type of computational system, in which a control function "reads," "interprets," and manipulates discrete entities called "symbols." We argue that other types of computational systems may provide a more appropriate characterization of psychological processes. One implication of our argument is the need to consider the constraints placed on computational theories in psychology by the nature of the computing device itself, the human brain. Perhaps surprisingly, this implication leads us to the conclusion that a "functionalist" conception of psychological processes (discussed below) does not entail that physiology is irrelevant to psychology, as has been maintained by prominent adherents of the symbol-systems approach.

This paper develops an appearance view of perception (focusing on vision). When we see an object, we see it by having it appear some way to us. We see the object, not the appearance; but we see the object via the appearance. The appearance is subjectively conditioned: aspects of it depend on attributes of the subject. We mentally have the appearance and can reflect on it as an appearance. But in the primary instance, of veridical perception, it is the object that we focus on and experience. I contrast this view with naive realism (sometimes called disjunctivism) (Brewer, Campbell, Noe) and with intentionalist or representationalist views, which I call the physical content view (Dretske, Tye, Crane, Hill, Burge). I agree with these views in rejecting sense-data intermediaries and in affirming direct perception, but I argue that direct perception occurs via appearances, making mine a critical direct realism. The other views attempt to explain the spatial content of perception (shape, size, distance) entirely through the physical properties of objects and their physical relation to the perceiver (viewing position). I argue instead that there are ineliminably subjective aspects of normal spatial perception, which are systematically manifested as a lack of full phenomenal constancy. This systematic underconstancy can’t be accounted for at all by a consistent naive realism; for the physical content view, it requires that most of our ordinary perception is classified as illusory, violating the spirit of that view. Accepting phenomenal underconstancy as pervasive, I suggest that our ability to perceive the mind-independent properties of objects depends on developed conceptual abilities. In the final section, I compare my appearance view with the adverbialism of Chisholm and the critical direct realism of Roy Wood Sellars.

Descartes is widely regarded to be the father of modern philosophy and his Meditations is among the most important philosophical texts ever written. _The Routledge Guidebook to Descartes’ Meditations_ introduces the major themes in Descartes’ great book and acts as a companion for reading this key work, examining: The context of Descartes’ work and the background to his writing; Each separate part of the text in relation to its goals, meanings and impact; The reception the book received when first seen by the world; The relevance of Descartes’ work to modern philosophy, it’s legacy and influence. With further reading included throughout, this text follows Descartes’ original work closely, making it essential reading for all students of philosophy, and all those wishing to get to grips with this classic work. This edition revises the earlier guidebook entitled _Descartes and the Meditations_ (2003). It has been thoroughly revised, and contains expanded treatment of the method of doubt, theory of ideas, and new discussion of Descartes' theory of vision.