Gilbert Harman famously wrote:
When Eloise sees a tree before her, the colors she experiences are all experienced as features of the tree and its surroundings. None of them are experienced as intrinsic features of her experience. Nor does she experience any features of anything as intrinsic features of her experiences. And that is true of you too. There is nothing special about Eloise’s visual experience. When you see a tree, you do not experience any features as intrinsic features of your experience. Look at a tree and try to turn your attention to intrinsic features of your visual experience. I predict you will find that the only features there to turn your attention to will be features of the presented tree (1990, p. 667).Perceptual experience is, Harman says, "transparent": If you try to examine it or attend to it directly, your attention will pass right through it to the features of the outside world presented by that experience. You can attend to the green of the tree, but not to the visual experience of greenness that the light from the tree produces in you, to the cylindricality of its trunk, but not to your visual experience of that cylindricality. Michael Tye, Fred Dretske, Sydney Shoemaker, and others have recently said similar things, and the claim traces back to G.E. Moore (who did not, himself, entirely endorse it). Others, like Charles Siewert and Amy Kind, have challenged such strong claims of transparency.
I've been thinking about the transparency of warped windows. (I feel that I am lifting this analogy from someone, but I don't know who. Siewert? Kind? You? Reminders welcome.) When I look at a tree through a warped window, I might be interested in learning about the tree or I might instead be interested in learning about the window. Now perhaps I can't in a strict sense even see the window. It's not dusty, for example. If so, I can't attend to it visually in quite the same way I can visually attend to the tree; and yet I can in another sense attend to it, in part by attending to the tree. I can notice how warped the tree looks and in what parts, and how that warping changes as I move my head around. Since I know certain things about what trees are like, and especially that they don't noodle around systematically as a move my head, I can discern certain features of the window by looking at the tree. I can know, for example, where it's warped and how badly. Perceptual attention to the tree combines with general knowledge about trees, general knowledge about windows, and proprioceptive knowledge of my own movements and intentions to produce knowledge about the window. Was I, then, attending to the window? It seems to me quite natural to say that there's an important sense in which I was -- even perhaps a perceptual sense.
(Does the fact that general knowledge played into my judgments about the window make it merely "intellectual" attention or inference and not perceptual attention? That seems too strict a requirement on perceptual attention: General knowledge informs my perceptual judgment that the batter is making a run, and even that she's a batter; yet I can attend perceptually to the batter and to the fact that she is now making a run.)
Of course, the window doesn't need to be warped in any way for me to do all this: I might conclude that the window is a perfect, undistorting transmitter.
This perceptual knowledge of the window is in some ways mediated by my perceptual knowledge of the tree. But in other way, it's not mediated. Causally, in the transmission of light, the window is closer to me. I am reacting directly to input conditioned by the window and learning things perceptually about the window on the basis of that input. If the window were different and the tree the same, I would notice that difference; changes in my knowledge of it are not mediated by changes in the outward tree. Are they mediated by changes in my perceptual representation of the tree? Well, what exactly is that representation and where in the visual system? In some sense, I am representing, perceptually, the tree as constant and unchanging. Is there some representation, perhaps "earlier" in the visual system, of the tree as noodling around? Well, maybe -- but if we go early enough we might not have the category "tree" to apply, and there may be no sense in privileging the interpretation of the changing representations as representations of changes in the tree rather than changes in the medium through which light is being transmitted from the tree.
Introspective judgments about perceptual experience often, I think, work similarly and raise a similar tangle of issues. I see something green. I'm not so much interested in learning about the thing in the world as about my experience of it (since I'm a philosopher, or maybe a perceptual psychologist). General knowledge about the world (that there's a green thing there, that lighting conditions are normal) combines with knowledge about my perceptual system (I'm good at seeing green things), combined with proprioceptive knowledge and knowledge of my intentions (my eyes are open, I'm undistracted), to produce the judgment, at least partly perceptual, that I'm having a visual experience of greenness. I look out at night and notice the starburst of light from the lamps; I notice how the lamps' starbursts change when I squint and tilt my head, and can tell in that way that it's a perceptual distortion due to something in me. But that's not all there is to it: There's a responsiveness to my experience that does not depend on what's going on with the lamps. The experience itself, like the window (but even "closer in", as it were) has a direct effect on my judgments about it. It's not purely a matter of perceiving something out there (perhaps erroneously) and then making some abstract inferences.
Or so it seems to me today.