Responses to both Derrick and Jonathan follow.

Derrick,

You say, "If your optic nerves were severed, or the visual areas of your brain were removed, then you would not have any visual experience at all."

I agree.  You wouldn't have any visual experience.  Whether or not something occurring in the eye could be classified as "a visual experience" is another matter.  It depends on what we count as "a visual experience" and what would happen in an eye that was disconnected from the rest of the brain.


Jonathan,

You say, "When I talk of reportable experience I simply mean experience that is of the sort that can be reported, discussed or referred to, in the sense that your 'experience simpliciter', is patently discussable."

I agree that experience simpliciter is discussable, in theory.  But I think there are aspects, levels, or elements of experience which are, practically speaking, unreportable.  We may learn to access these elements in the future, and we may learn how to discuss them in neuroscientific terms--so the unreportability here is not necessary, but only contingent.

I will give you an example to illustrate what I mean.  This is something that I just came across, and I find it very interesting. If you go to this link, you can see an optical illusion published by Scientific American.  It shows a checkered board with squares alternating between light and dark shades of gray.  The illusion is that two of the squares (marked A and B) look like they are quite different shades, when in fact they are identical.  They are the same color and brightness.  The note attached to the picture says, "Our brain does not perceive the true brightness and color of each square . . ."  Yet, if you are good at manipulating your eyes, you can focus only on squares A and B, so that the rest of the picture fades into the background.  When only squares A and B are in focus, it is clear that they are the same shade and brightness.  (I am not sure why, but some people find it impossible to manipulate their focus in this way.  I guess I'm lucky.  I happened upon this "solution" to the illusion without much effort at all.)

Contrary to what Scientific American says, the brain does perceive the true brightness and color of each square.  Yet, that aspect of our experience is not reportable . . . or, at least, it takes some effort to adjust our vision to make it reportable -- and for some people, this adjustment may not even be possible.  Our reportable experience is what we are capable of saying truthfully about what we experience. But we can still have experiences (or aspects, levels, or elements of experiences) which we cannot report, or which we have a very strong tendency to report incorrectly.  It also seems plausible that there could be aspects of our experiences which we do not even know how to recognize as such--aspects which are not known in the way that color and brightness are known to us--and which we could therefore not even begin to think about reporting.

As for blurred vision, I will concede that point for now.  It is not crucial for any of my arguments.

You say, "The problem is not that Derrick is wrong. He is merely stating the first premise of a usable theory of experience."

Then perhaps you can answer the question I addressed to Derrick:  If experience is information (as would be the case if, as Derrick says, experience is output), then how do we distinguish between information which is experience and information which is not experience?  Perhaps you (and Derrick) want to argue for the existence of phenomenal information, though that notion carries some baggage associated with epiphenomenalism.

By the way, I don't see any reason to worry about terms like "image" when discussing the functionality of the eyes--I am under the impression that it is standard to talk about retinal images in all sorts of scientific contexts; nor do I find any problem with the terms "system" or "function" here.  (I do recall a PhilPapers discussion in which functionalism was criticized, and I recall observing that the variety of functionalism which is perhaps most alive today did not seem to be implicated.)

Regards,
Jason
May 15, 2010