Philosophers indeed console themselves by saying that we have a “clear enough” sense of the phenomenon of consciousness, even if we can’t quite capture it in words. As Chalmers suggests, we seem to know what consciousness is from personal experience. And we may be tempted to say the same of seeing – we know what seeing is from personal experience, even if we can’t quite put it in words.Consciousness can be startlingly intense. It is the most vivid of phenomena; nothing is more real to us. But it can be frustratingly diaphanous: in talking about conscious experience, it is notoriously difficult to pin down the subject matter ... What is central to consciousness, at least in the most interesting sense, is experience. But this is not definition. At best, it is clarification.Trying to define conscious experience in terms of more primitive notions is fruitless ... The best we can do is to give illustrations and characterizations that lie at the same level. These characterizations cannot qualify as true definitions, due to their implicitly circular nature, but they can help to pin down what is being talked about. I presume that every reader has conscious experiences of his or her own. If all goes well, these characterizations will help establish that it is just those that we are talking about. (The Conscious Mind, pp. 3–4.)
To see a tree is for the tree to “appear” to me. The tree becomes manifest. It “shows itself.” It becomes there for me!These explications are not particularly helpful. They seem simply to be different ways of emphasizing that I see the tree. In Chalmers’s terms, they are characterizations that “lie at the same level.” So they throw no light on what it is that we know from personal experience.
Likewise, if I look at a tree, and try to focus on the fact that I see the tree, it is difficult to pin down the “seeing” because I seem to have nothing to focus on except the tree. The “seeing” seems to vanish into emptiness, as Moore puts it.The moment we try to fix our attention upon consciousness and to see what, distinctly, it is, it seems to vanish: it seems as if we had before us a mere emptiness. When we try to introspect the sensation of blue, all we can see is the blue: the other element is as if it were diaphanous. (‘The Refutation of Idealism,’ p. 450.)