I’ll close my eyes and imagine some shape. Maybe I’ll go through a geometrical proof. I notice that there is a very great difference between what imagining is actually like, and how I talk about imagining.
When I close my eyes and actually imagine things, there are no pictures: I close my eyes and see all black, then I imagine a shape and I still see all black. Again, taking a picture of a snowflake makes something whiten, but imagining doesn’t. There is, for example, no field of consciousness that whitens. It’s not that something whitens in a “less vivid” way, as Hume would have it – nothing whitens at all. And where is this shape I’m imagining anyway? As soon I try to see where it is, it vanishes.
This whole argument appeals to experience: if you come back and tell me that you actually see red when imagining stop signs, I can’t say anything to it; but I doubt that this is the case. When I look out my window at the snow and imagine stop signs, the one image isn’t placed over the other (If it were, I’d see pink). Say I look out at the sidewalk and try to imagine someone there that I really want to see. How do I “see” “them” “there”? None of the colors I look at change, nor do I sense anything differently, and yet the very process of “seeing” in this way can increase the pulse rate.