Online research in philosophy

We can perceive shapes visually and tactilely, and the information we gain about shapes through both sensory modalities is integrated smoothly into and functions in the same way in our behavior independently of whether we gain it by sight or touch. There seems to be no reason in principle we couldn't perceive shapes through other sensory modalities as well, although as a matter of fact we do not. While we can identify shapes through other sensory modalities—e.g., I may know by smell (the scent of mango) that the object causing my sensory experience is round—this is not perceiving an object as shaped, but rather inferring from the character of one's sensory experience and collateral information that an object of a certain shape caused it. That it is possible to perceive shape by other modalities, however, is suggested by the case of bats and aquatic mammals like dolphins which navigate through their environment by a form of sonar. It is plausible that they have some form of auditory representation of space, and so of shape. These facts about shape perception raise important questions about the relation between those features of perceptual experience which are intrinsic to different sensory modalities and the nature of our perceptual representation of shapes, and, more generally, of the space within which we perceive shaped objects to be located. John Campbell's paper, "Molyneux's Problem" (see above), raises a number of interesting and important questions about the nature of our perception of shape properties, particularly the cross-modal nature of shape perception, and ties them to more general questions about the nature both of perceptual..

Drawing on work in psychophysics, psychometrics, and sensory neurophysiology, Clark analyzes the character and defends the integrity of psychophysical explanations of qualitative facts, arguing that the structure of such explanations is sound and potentially successful.

The primary objects of hearing are sounds: everything we hear we hear by hearing a sound. (This claim differs from Berkeley’s that we hear only sounds and from Aristotle’s that we only hear sounds.) Colored regions are primary objects of sight, and pressure resistant regions are primary objects of perception by touch. By definition, the primary objects of perception are physical. The properties of the primary objects of perception are exactly the properties sense-datum theories attribute to sense-data. Indirect Realism holds that awareness of sense-data (or something similar) mediates our perception of primary objects. Direct Realism denies this. The question when the perception of a primary object, such as parts of the surfaces of a hat and coat, is thereby the perception of a non-primary object, such as a person, is independent of the disagreement between Direct and Indirect Realism.

The purpose of this paper is to clarify Prajñākaragupta’s view of mental perception ( mānasapratyakṣa ), with special emphasis on the relationship between mental perception and self-awareness. Dignāga, in his PS 1.6ab, says: “mental [perception] ( mānasa ) is [of two kinds:] a cognition of an [external] object and awareness of one’s own mental states such as passion.” According to his commentator Jinendrabuddhi, a cognition of an external object and awareness of an internal object such as passion are here equally called ‘mental perception’ in that neither depends on any of the five external sense organs. Dharmakīrti, on the other hand, considers mental perception to be a cognition which arises after sensory perception, and does not call self-awareness ‘mental perception’. According to Prajñākaragupta, mental perception is the cognition which determines an object as ‘this’ ( idam iti jñānam ). Unlike Dharmakīrti, he holds that the mental perception follows not only after the sensory perception of an external object, but also after the awareness of an internal object. The self-awareness which Dignāga calls ‘mental perception’ is for Prajñākaragupta the cognition which determines as ‘this’ an internal object, or an object which consists in a cognition; it is to be differentiated from the cognition which cognizes cognition itself, that is, self-awareness in its original sense.

In his book A Theory of Sentience, Austen Clark argues that the content of sensory representations can be expressed as sentences constructed from a language of sentience. Such sentences specify that a determinate feature obtains in a particular space-time region, but the language's limited vocabulary prohibits the sentences from referring or attributing features to objects. In this paper, I show that this view is flawed in at least two ways. First, if sensation has the capacities that Clark and others attribute to it, then the vocabulary of sense extends further than he supposes, and a limited language of sentience cannot justify a prohibition of object representation within sentience. Second, even if the language of sentience is as impoverished as he claims, and thus even if the representational capacity of sentience is correspondingly limited, object individuation can plausibly occur at the level of sensation. In the course of defusing Clark's major argument for an “object-less” theory of sentience, I offer reasons to believe both that sensory representations can be impressively sophisticated in what they say about the world, and that object representations can be surprisingly basic.

A theory of perception must be capable of explaining the full range of conscious perception, including amodal perception. In amodal perception we perceive the world to contain physical features that are not directly detectable by the sensory receptors. According to the active-externalist theory of perception, amodal perception depends on active engagement with perceptual objects. This paper focuses on amodal visual perception and presents a counter-example to the idea that active-externalism can account for amodal perception. The counterexample involves the experience of so-called ‘impossible objects’, objects experienced in perceptual character as having geometrical properties that no physically real object can have.

Vision has been the primary focus of naturalistic philosophical research concerning perception and perceptual experience. Guided by visual experience and vision science, many philosophers have focused upon theoretical issues dealing with the perception of objects. Recently, however, hearing researchers have discussed auditory objects. I present the case for object perception in vision, and argue that an analog of object perception occurs in auditory perception. I propose a notion of an auditory object that is stronger than just that of an intentional object of audition, but that does not identify auditory objects with the ordinary material objects we see.

Austen Clark offers a general account of the forms of mental representation that we call "sensory." Drawing on the findings of current neuroscience, Clark defends the hypothesis that the various modalities of sensation share a generic form that he calls "feature-placing." Sensing proceeds by picking out place-times in or around the body of the sentient organism, and characterizing qualities (features) that appear at those place-times. The hypothesis casts light on many other troublesome phenomena, including the varieties of illusion, the problem of projection, the notion of a visual field, and the existence of sense-data.

This work argues for a Direct Realist view of the perception of public objects. It argues against the need for special intermediary sensory objects, or sense impressions, requiring only stages in a physical process beginning with events at the surface of a physical object, the resultant stimulation of one's sense organs, and finally the excitation of the sensory portions of one's brain.

The paper argues that material objects are the primary referents of visual states -- not places, as Austen Clark would have it in his A Theory of Sentience.