Online research in philosophy

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.

Physical objects are the most familiar of all objects, and yet the concept of a physical object remains elusive. Any six-year-old can give you a dozen examples of physical objects, and most people with at least one undergraduate course in philosophy can also give examples of non-physical objects. But if asked to produce a definition of ‘physical object’ that adequately captures the distinction between the physical and the nonphysical, the average person can offer little more than hand-waving.

Since our visual perception of physical things essentially involves our identifying objects by their colours, any theory of visual perception must contain some account of the colours of things. The central problem with colour has to do with relating our normal, everyday colour perceptions to what science, i.e. physics, teaches us about physical objects and their qualities. Although we perceive colours as categorical surface properties of things, colour perceptions are explained by introducing physical properties like reflectance profiles or dispositions to cause certain experiences in normal human perceivers. Hence, it seems as if colours as they are experienced by us have no place in the physical world, because they are fundamentally different from the properties which we ascribe to physical objects in scientific accounts of colour perceptions. This special issue on perspectives on colour perception presents new suggestions to solve to this major problem.

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.

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 historically most central epistemological issue concerning perception, to which this article will be almost entirely devoted, is whether and how beliefs about physical objects and about the physical world generally can be justified or warranted on the basis of sensory or perceptual experience—where it is internalist justification, roughly having a reason to think that the belief in question is true, that is mainly in question (see the entry justification, epistemic: internalist vs. externalist conceptions of). This issue, commonly referred to as “the problem of the external world,” divides into two closely related sub-issues, which correspond to the first two main sections below. The first of these issues has to do with the nature of sensory experience and its relation to the physical world; it is typically (though as we shall see not altogether perspicuously) formulated as the question of what are the immediate objects of awareness in sensory experience or, in a variant but essentially equivalent terminology, of what is given in such experience. Perhaps the most historically standard, though not currently the most popular answer to this question has been that it is sense-data (private, non-physical entities that actually have the immediately experienced sensory qualities) that are the immediate objects of awareness or that are given. The second issue has to do with the way in which beliefs about the physical world are justified on the basis of such sensory experience. If it is concluded that physical objects are not themselves given, the two main answers to this question are representationalism or indirect realism (the view that the immediate objects of experience represent or depict physical objects in a way that allows one to infer justifiably from such experience to the existence of the corresponding “external” objects) and phenomenalism (the view..

John Foster addresses the question: what is it to perceive a physical object? He rejects the view that we perceive such objects directly, and argues for a new version of the traditional empiricist account, which locates the immediate objects of perception in the mind. But this account seems to imply that we do not perceive physical objects at all. Foster offers a surprising solution, which involves embracing an idealist view of the physical world.

Perception is sensory awareness. Cognition is reflective awareness. Consciousness is awareness-as-such. In Indian psychology, as represented by Samkhya-Yoga and Advaita Vedanta systems, consciousness and mind are fundamentally different. Reality is the composite of being (sat), knowing (cit) and feeling (ananda). Consciousness is the knowledge side of the universe. It is the ground condition of all awareness. Consciousness is not a part or aspect of the mind. Mind is physical and consciousness is not. Consciousness does not interact with the mind, the brain or any other physical objects or processes. Nor does it have any causative role in mental activity. Hence the existence of consciousness does not interfere or upset the apparently closed physical system. Mind in this view is the interfacing instrumentality that faces consciousness on one side and the brain and the rest of the physical world on the other. Mind is closely connected with the different systems of the brain. In normal perceptions, the mind takes the forms of objects via the channels of the sensory system and the processes in the brain. The forms themselves are non-conscious representations of the world of objects. The mental forms (vrittis) become conscious experiences in the light of the purusha. The vritti in sensory form is perception and with the reflection of the purusha it becomes cognition. All conscious perceptions are therefore cognitions.

An attempt is made to pinpoint the way in which perception is related to belief. Although, for familiar reasons, it is not true to say that we necessarily believe in the existence of the objects we perceive, nor that they actually have their ostensible characteristics, it is argued that the relation between perception and belief is more than merely contingent There are two main issues to address. The first is that `collateral' beliefs may impede perceptual belief. It is argued that this still assigns an essential role to belief in perception, though the belief may be of an attenuated form. The second is Fred Dretske's claim that even attenuated belief may be entirely absent from perception. It is argued that (a) `non-epistemic' perception can be understood only by employing the concept of `epistemic' perception; (b) that the former can occur only partially-i.e., within perceptions that are otherwise epistemic; and (c) that by switching attention from the perception of objects to the Phenomenological tradition's concern with the perception of world, we can see that perception must be entirely permeated with `doxastic' force.