Floaters

As one ages, black specks can appear in one’s visual field. These are called floaters. They are caused by bits of fiber detaching from the retina and are normally not a serious issue. A particularly large piece became noticeable to me not too long ago, like a little black spider hanging in the right periphery of my visual field. I went to a retinal specialist, who found no problem and said it might just stay there although after a while I wouldn’t even notice it anymore.

Well, it’s still there, and I do still notice it occasionally. But it is even more on my mind than in my visual field. For the philosopher in me finds this commonplace phenomenon to be quite intriguing.

The problem arises from how to speak about it. It seems perfectly natural for me to say that I see the floater. But wait a minute. Normally when we say we see something, we mean that we are looking at it with our eyes. More specifically, there are several conditions that need to be met, including:

1.      Our visual system is fully intact and functional.

2.      We are awake and conscious.

3.      Our eyes are open.

4.      There is ambient light.

5.      There is an object outside of the eye that is what we are seeing.

In the case of a floater, Condition 5 is not satisfied. The object I say I am seeing is inside my eye.

            Well, of course there are also visual phenomena that occur even when none of the conditions is satisfied. Visual dreams are an obvious example (although perhaps Condition 2 is partially satisfied because we are conscious in some sense during a dream, and Condition 1 is normally satisfied but need not be since someone with an impaired visual system may still be able to dream visually). Then there are visual phenomena that may satisfy only Condition 2 (or 1 and 2), such as images we can summon up in our mind at any time; for example, most of us can imagine a red apple with our eyes closed in a dark room and no apple present. We might even call this a waking dream, especially if it is part of a narrative (You have a reverie of eating an apple in an orchard).

            But a floater is different from a mere visual image not only because it is only Condition 5 that is not satisfied, but also because there is an object that we say we are seeing. But here is where things get tricky, and in more than one way. First of all, as noted, the object is not outside the eye; so even though the visual experience does involve the eye, we are not using the eye the way we normally do when we are looking at an object. Secondly, there is an ambiguity about what we say we are seeing.

Strictly speaking a floater is a visual phenomenon. In this respect it is like the “apple” I am imagining when awake or dreaming, or like an afterimage, etc. However, when I spoke of there being an object inside the eye, was I not referring to something other than a visual phenomenon? The floater is, as we say, “in the mind.” Meanwhile there is also a clump of gel floating in the fluid medium of my eyeball. The floater is caused by light entering my eye and casting the shadow of this clump onto my retina. When the ophthalmologist peered into my eye, he could, presumably, see that clump in the normal way of seeing: with his eyes. What intrigues me now is whether I too am seeing that clump.

At first it seems that the answer is no. What I am seeing (in some sense of that word) is the floater, a strictly visual phenomenon that is resident in my visual field, whereas the clump of gel is a strictly physical phenomenon resident in my eyeball. Presumably also the appearance of the floater is different from the appearance of the clump.

On the other hand, there is a case to be made that I am seeing the clump. Compare looking at railroad tracks receding into the distance: It is possible to experience these as converging; and yet we can also, and may quite spontaneously, see them as parallel. I think it is natural to say that we see the tracks, meaning the physical tracks that are parallel, and relegate the converging tracks to our visual field or our mind. Analogously, do I see the clump of gel that is in my eyeball even as I experience a floater in my mind?

But there is a difference. In the case of the railroad tracks it is one and the same person who sees (in one or more senses) both pairs of tracks. We can engage a kind of Gestalt shift from the one to the other. In the case of the floater and the clump, two people are required. I, experiencing the floater, cannot shift to seeing what the ophthalmologist sees (unless of course I am shown a picture of the clump).

After reflecting on all this, I want to say that the last case is a case of my seeing something in a straightforward sense … and that what I am seeing is the clump of gel. Thus I would need to modify Condition 5, thus: There is a physical object that is what we are seeing. The floater is simply how the clump appears to me, analogous to how a real red apple appears to me. Sometimes an appearance will become quite divorced from what one is seeing; for example, a coil of rope can look like a snake, and even be mistaken for a snake. Nevertheless what one is seeing is a coil of rope, despite being taken in by an appearance, which can often be readily dispelled.

 Note that a red apple can and surely does appear differently to different people. Obviously it will look different to a colorblind person and to myself who am not colorblind. (But it even looks different just to me with one eye or the other eye alone, or to me using both eyes but under varying lighting conditions.) Just so, the clump in my eyeball looks different to me and to the ophthalmologist. It’s that simple.

What especially intrigues me about all this is that it is suggestive for the notorious mind/body problem. On its face it seems absurd to say that, for example, the apple image “in your mind” is in fact something going on in your brain. After all, so one argument goes, if a team of physiologists peered into your brain when you were imagining the apple, they would not see an apple or even an apple image. But, analogous to the clump of gel in my eyeball, might that “argument” show only that the brain activity looks different to someone else and to oneself?

ADDENDUM. Perhaps what I am seeing is not the clump but its shadow. After all, that is what is cast on my retina. In that case, the doctor and I would not be seeing the same thing. On the third paw, might not my doctor have seen the shadow too when he shone his bright flashlight into my eyeball? In that case the analogy relevant to mind/body would still hold, but now of our both seeing the shadow, not both seeing the clump.

Thank you to Oli Alston and David Brubaker for stimulating this conversation.

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