Sense-data.html



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In the most general terms, sense data are the signals gathered through any of the many external and internal sense organs. Although the term may be used in a straightforward physiological sense it also has specific connotations in the philosophy of perception.

From the philosophical point of view, sense data relate to the concept of indirect or representational realism. Historically, a number of philosophers have presaged the modern natural science view that the 'most immediate objects' in our perception of the world are mental objects in the form of sense data received by (some part of) the mind/brain. Within the mind mental object, which may represent things outside the mind, interact with something that makes up awareness, in the process of a perceptual act (see Husserl) or the phenomenon of inner sense (see Immanuel Kant or René Descartes).

For example, according to this view, when I see the President on TV a representation of the President is formed in my mind/brain through the reception and interpretation of sense data. It is important to note, however, that 'representation' in this sense has a different meaning from that in which the television picture represents the President. Where a television picture is a re-presentation of something that might be presented directly (the President in person) there is no more direct route available to the mind than a representation in the form of sense data (at least in a natural science account), so 'presentation' might be a more accurate term.

The idea that our percepts are based on sense data is supported by a number of arguments. The first is popularly known as the Argument From Illusion. ¹ From a subjective experience of perceiving something, it is theoretically impossible to distinguish perceiving something which exists independently of oneself from an hallucination or mirage. Thus, we do not have any direct access to the outside world that allows us to distinguish it from an illusion based on identical sense data.

A more powerful argument comes from the logical extension of the effects of genetic variation in sense receptors. Mice can be bred with different combinations of taste or smell receptors so that, potentially, 'taste p' belongs to chemicals x and y and 'taste q' belongs to chemicals r and s for some mice but 'taste p' belongs to x and r and 'taste q' belongs to y and s for other mice. (Since the central connections of the receptors are the same it is reasonable to assume that taste p is the same for the two types of mice, at least to the extent that this is meaningful.) Genetic variations in humans in any sense organ should have the same sort of effect. The key point is that a taste is not a property of something in the world, but a property of an interaction between something in the world and a particular sensory structure. Nothing is red in the worlds of birds or bulls, which have more and fewer colour receptors than we do respectively. The argument extends to every aspect of our sense of the world, even our sense of movement, which can be manufactured from sense data that cannot indicate the distance moved, as discussed by William James in the nineteenth century.

Sense data theories have been criticised by philosophers such as J.L. Austin and Wilfrid Sellars and more recently by Kevin O'Regan and Alva Noë. Much of the early criticism may arise from a claim about sense data that was held by philosophers such as AJ Ayer. This was that sense data really do have the properties they appear to have. Thus, in this account of sense data, the sense data that are responsible for the experience of a red tomato really "are red". In one sense this is ridiculous, since there is nothing red in a brain to act as a sense datum. However, in another sense it is perfectly consistent - in the sense that the data "are red" if experienced directly, even if they are not if they are experienced in a contrived and inappropriately indirect way by looking at someone's brain. Certainly, the tomato itself is not red except in the eyes of a red-seeing being. Thus when we say something 'is red' there is a false assumption that things can have appearances without reference to that to which they appear - as implicit in the sense data theory. Thus the criticism that sense data cannot really be red is made from a position of presupposition inconsistent with a theory of sense data - so it is bound to seem to make the theory seem wrong. More recent opposition to the existence of sense data appear to be simply regression to naïve realism.

References

External links

• Sense Data - an article by Michael Huemer in the Stanford Encyclopedia of Philosophy.

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