Online research in philosophy

Experiences of all kinds have a distinctive character, which marks them out as intrinsically different from states of consciousness such as thinking. A plausible view is that the difference should be accounted for by the fact that, in having an experience, the subject is somehow immediately aware of a range of phenomenal qualities. For example, in seeing, grasping and tasting an apple, the subject may be aware of a red and green spherical shape, a certain feeling of smoothness to touch, and a sweet sensation. Such phenomenal qualities are also immediately present in hallucinations. According to the sense-data theory, phenomenal qualities belong to items called “sense-data.” In having a perceptual experience the subject is directly aware of, or acquainted with, a sense-datum, even if the experience is illusory or hallucinatory. The sense-datum is an object immediately present in experience. It has the qualities it appears to have.

Some of Austin's general statements about the doctrines of sense-datum philosophy are reviewed. It is concluded that Austin thought that in these doctrines "directly see" is given a new but inadequately explained and defined use. Were this so, the philosophical use of "directly see" would lack a definite sense and this would correspondingly affect the doctrines. They would lack definite truth-value. Against this, it is argued that the philosopher's use of "directly see" does not support Austin's general thesis that the sense-datum doctrines lack truth-value.

Examples of sensory illusion show the failure of the attempt of traditional sense-datum theory to account for something's phenomenally appearing to be F by postulating the existence of a sense-datum that is actually F. the Muller-Lyer Illusion cannot be explained by postulating two sensibly presented lines that actually have the lengths the physical lines appear to have. Illusions due to color contrast cannot be explained by postulating sense-data that actually have the colors the physical samples appear to have.

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.

Sense data are the alleged mind-dependent objects that we are directly aware of in perception, and that have exactly the properties they appear to have. For instance, sense data theorists say that, upon viewing a tomato in normal conditions, one forms an image of the tomato in one's mind. This image is red and round. The mental image is an example of a “sense datum.” Many philosophers have rejected the notion of sense data, either because they believe that perception gives us direct awareness of physical phenomena, rather than mere mental images, or because they believe that the mental phenomena involved in perception do not have the properties that appear to us (for instance, I might have a visual experience representing a red, round tomato, but my experience is not itself red or round). Defenders of sense data have argued, among other things, that sense data are required to explain such phenomena as perspectival variation, illusion, and hallucination. Critics of sense data have objected to the theory's commitment to mind-body dualism, the problems it raises for our knowledge of the external world, its difficulty in locating sense data in physical space, and its apparent commitment to the existence of objects with indeterminate properties.

Of all the problems attending the sense-datum theory, arguably the deepest is that it draws a veil of appearances over the external world. Today, the sense-datum theory is widely regarded as an overreaction to the problem of hallucination. Instead of accounting for hallucination in terms of intentional relations to sense data, it is often thought that we should account for it in terms of intentional relations to properties. In this paper, however, I argue that in the versions that might address the problem of hallucination, this newer account is guilty of a vice similar to sense-datum theory’s: it draws a veil of abtracta over the concrete world.

When I perceive a physical object I am directly aware of something. This something may be called a sense?datum, leaving the question open whether it is indeed the physical object itself. Still, this question must be asked. It seems impossible that the sense?datum can be identical with the physical object for we do not always say we have different physical objects when we say we have different sense?data. On the other hand, the plain man does not think of the physical object as something other than the sense?datum. It is suggested that the plain man regards the sense?datum as in a sense identical with the physical object he is perceiving. But it is a peculiar sense of ?identity? which is in question, one which does not conform to the rules logicians lay down for this word.