Direct and Indirect Realism - History

History

Aristotle was the first to provide a description of indirect realism. In On the Soul he describes how the eye must be affected by changes in an intervening medium rather than by objects themselves and speculates on how sense impressions can form our experience of seeing, reasoning that an endless regress would occur unless the sense itself were self-aware. He concludes by proposing that the mind is the things it thinks. He calls the images in the mind "ideas".

Indirect realism has been popular in the history of philosophy and has been developed by many philosophers including Bertrand Russell, Baruch Spinoza, René Descartes, and John Locke, the 17th century philosopher who most prominently advocated this theory. The term he used was not "sense-datum" but "idea". Locke thought objects had two classes of qualities:

• Primary qualities are qualities which are 'explanatorily basic' - which is to say, they can be referred to as the explanation for other qualities or phenomena without requiring explanation themselves - and they are distinct in that our sensory experience of them resembles them in reality. (For example, one perceives an object as spherical precisely because of the way the atoms of the sphere are arranged.) Primary qualities cannot be removed by either thought or physical action, and include mass, movement, and, controversially, solidity (although later proponents of the distinction between primary and secondary qualities usually discount solidity).

• Secondary qualities are qualities which one's experience does not directly resemble; for example, when one sees an object as red, the sensation of seeing redness is not produced by some quality of redness in the object, but by the arrangement of atoms on the surface of the object which reflects and absorbs light in a particular way. Secondary qualities include colour, smell, and taste.

In contemporary philosophy, epistemological dualism has come under sustained attack by philosophers like Wittgenstein (the private language argument) and Wilfrid Sellars in his seminal essay "Empiricism and the Philosophy of Mind." Indirect realism is argued to be problematical because of Ryle's regress and the homunculus argument. However, recently reliance on the private language argument and the Homunculus Objection has itself come under attack. It can be argued that those who argue for 'inner presence', to use Antti Revonsuo's term, are not proposing a private 'referent', with the application of language to it being 'private' and thus unshareable, but a private use of public language. There is no doubt that each of us has a private understanding of public language, a fact that has been experimentally proven; George Steiner refers to our personal use of language as an 'idiolect', one particular to ourselves in its detail. The question has to be put how a collective use of language can go on when, not only do we have differing understandings of the words we use, but our sensory registrations differ.

The reason for continued confusion is that "both direct and indirect realism are frankly incredible, although each is incredible for different reasons". The direct realist view (Gibson, 1972) is incredible because it suggests that we can have experience of objects out in the world directly, beyond the sensory surface, as if bypassing the chain of sensory processing. The pattern of electrochemical activity that corresponds to our conscious experience can take a form that reflects the properties of external objects, but our consciousness is necessarily confined to the experience of those internal effigies of external objects, rather than of external objects themselves. Unless the principle of direct perception can be demonstrated in a simple artificial sensory system, this explanation remains as mysterious as the property of consciousness it is supposed to explain. But the indirect realist view is also incredible, for it suggests that the world that we perceive is merely a pattern of energy in the physical brain inside our head. This could only mean that the head we have come to know as our own is not our true physical head, but merely a miniature copy of it inside a copy of the world contained within our true physical skull. The external world and its phenomenal replica cannot be spatially superimposed, for one is inside your physical head, and the other is outside. The existential vertigo occasioned by this concept of perception is so disorienting that only a handful of researchers have seriously entertained this notion or pursued its implications to its logical conclusion. (Kant 1781/1991, Koffka 1935, Köhler 1971 p. 125, Russell 1927 pp 137–143, Smythies 1989, 1994, current, Harrison 1989, Hoffman 1998, Lehar current, Hameroff current)"