Knowing what it's like to see green

You know what it’s like to see green. Close your eyes. Do you still know what it’s like to see green?

I think so.

Maybe you got lucky and saw some green patches while closing your eyes. But I am not assuming that happened. Even if you saw no green patches, you knew what it is like to see green.

Philosophers who are really taken with qualia sometimes say that:

1. Our knowledge of what it is like to see green could only be conferred on me by having an experience of green.

But if I have the knowledge of what it is like to see green when I am not experiencing green, then that can’t be right. For whatever state I am in when not experiencing green but knowing what it’s like to see green is a state that God could gift me with without ever giving me an experience of green. (One might worry that then it wouldn’t be knowledge, but something like true belief. But God could testify to the accuracy of my state, and that would make it knowledge.)

Perhaps, however, we can say this. When your eyes are closed and you see no green patches, you know what it’s like to see green in virtue of having the ability to visualize green, an ability that generates experiences of green. If so, we might weaken (1) to:

2. Our knowledge of what it is like to see green could only be conferred on me by having an experience of green or an ability to generate such an experience at will by visual imagination.

We still have a conceptual connection between knowledge of the qualia and experience of the qualia then.

But I think (2) is still questionable. First, it seems to equivocate on “knowledge”. Knowledge grounded in abilities seems to be knowledge-how, and that’s not what the advocates of qualia are talking about.

Second, suppose you’ve grown up never seeing green. And then God gives you an ability to generate an experience of green at will by visual imagination: if you “squint your imagination” thus-and-so, you will see a green patch. But you’ve never so squinted yet. It seems odd to say you know what it’s like to see green.

Third, our powers of visual imagination vary significantly. Surely I know what it’s like to see paradigm instances of green, say the green of a lawn in an area what water is plentiful. If I try to imagine a green patch, if I get lucky, my mind’s eye presents to me a patch of something dim, muddy and greenish, or maybe a lime green flash. I can’t imagine a paradigm instance of green. And yet surely, I know what it’s like to see paradigm instances of green. It seems implausible to think that when my eyes are closed my knowledge of what it’s like to see green (and even paradigm green) is grounded in my ability to visualize these dim non-paradigm instances.

It seems to me that what the qualia fanatic should say is that:

3. We only know what it’s like to see green when we are experiencing green.

But I think that weakens arguments from qualia against materialism because (3) is more than a little counterintuitive.

Imagination and dreams

When I visualize a car in my imagination, the experience is obviously different from seeing a car. It's not even close. Similarly, if I imagine a sound, the experience is obviously different from hearing it. In part this is due to shortcomings of my imagination. But I suspect it's not just that. Rather, imagined experiences are qualitatively different from actual experiences. This isn't the difference disjunctivists get at between hallucinations and veridical experiences. I am willing to concede that a hallucination and a veridical experience could be phenomenally the same, but then both would be different from imagined experiences. There are, of course, structural analogies. Imagining a red triangle is related to imagining a blue square much as seeing a red triangle is related to imagining a blue square. And there may be some resemblance between imagining a red triangle and seeing a red triangle.

Here's a hypothesis about dreams: The "visual" experiences in dreams are phenomenally more like the ones in visual imagination than like seeing, but one's ability to tell the difference is suppressed.

Voyeurism and lustful fantasies

Consider the following three activities, all done for a sexual end and without the consent of the other parties:

1. Wearing special "x-ray" goggles that show one what other people look like under their clothes
2. Wearing special computerized goggles that quite accurately extrapolate from the visible features of other people and from visual data about how their clothes lie on them, using a large database of body types, and show what other people very likely look like under their clothes
3. Walking around and using the visible features of other people and visual data about how their clothes lie on them to imagine what other people look like under their clothes.

Now, (1) is a clear case of voyeurism, a violation of sexual privacy, and hence wrong. But is (2) really significantly morally different from (1)? We can imagine a continuum of more and more accurate portrayals. But (3) is basically (2), as done with an inferior instrument. Hence, it is wrong as well.

The argument doesn't apply to every case of lustful fantasy—I think there are other arguments, like this one—but I think it captures some of why many cases of sexual fantasies are wrong and creepy, indeed are a kind of non-consensual sexual relation.

Images of the soul

I bet a lot of people when they think about the soul imagine something nebulous—a kind of glow, or gas, or force-field, or the like—permeating the body. Certainly, this is how I imagine it. It's funny that nobody imagines the soul to be like a rock. Yet, aren't both images just as much off? The nebulous something—that fails convey the stability and unity of the soul. And the rock—that fails to convey immateriality.

(I am not about to urge that one not imagine anything when thinking about the soul. When I think about mathematical entities, I do imagine physical objects—for instance, graphs—that represent them. But that only rarely leads me astray—much more often, it helps.)

Empty rooms and modal imagination

Humeans think they can imagine a brick coming into existence without any cause. This requires that not only they imagine a brick without imagining a cause, but that they imagine the brick and the absence of a cause. But the task of imagining absences as such is a difficult one. If I tell an ordinary person to imagine a completely empty room, the subject is likely to imagine an ordinary room, with walls but no furniture. But has the subject really imagined an empty room? Likely not. Most likely the imagined room is conceptualized in a way that implies that it has air in it. For instance, we could ask our subject what it would be like to sit in that empty room for eight hours, and our subject is unlikely to respond: "You'd be dead, since the room has nothing in it, and hence no oxygen either."

Could one with more directed effort imagine a room without any air in it? I am not at all sure of that. While we have the concept of vacuum as the absence of anything, it is not at all clear that we can imagine vacuum. Our language may itself be a giveaway of what we imagine when we imagine, as we say, a room filled with vacuum—indeed we are not really imagining an empty room. Moreover, most likely we are imagining the room as embedded in a universe like ours. But a room in a universe like ours will be pervaded with quantum vacuum as well as with electromagnetic and other fields, and perhaps even with spatial or spatiotemporal points. Whether these items count as things or not is controversial, of course, but at least it is far from clear that we've really imagined a truly empty room.

It is true that philosophers sometimes claim that they can imagine a world that consists only of, say, three billiard balls. But a claim to imagine that is surely open to question. First of all, the typical sighted person's imagination is visual. The balls are, almost surely, imagined visible. But if so, then it is an implicit part of what one is imagining that there are photons bouncing off the billiard balls. Furthermore, unless one takes care to specify—and I do not know how one exactly one specifies this in the imagination—that the balls obey laws very different from those of our world, there will constantly be occasional atoms coming off the edges of the billiard balls, and hence there will be a highly diffuse gas around the balls. Suppose all of this physics is taken care of by our careful imaginer. Still, have we really imagined a world containing only three billiard balls? What about the proper parts of the billiard balls—doesn't the world contain those? What about properties such as roundness, or at least tropes such as this ball's roundness? And aren't there, perhaps, relations between the balls? We see that unless one is a most determined nominalist, the content of the imagined world is going to be rather richer than we initially said. There are details implicit in the imagined situation which we have omitted.