Thursday, 22 December 2016

The Achievement of Illusion

Akiyoshi Kitaoka

There’s an interesting discussion on the New York Review of Books at the moment between writer Tim Parks and realist philosopher Riccardo Manzotti on the subject of consciousness. Manzotti rejects the idea, popular in much cognitive neuroscience, that our experience of the world is a mediated product of the mind or brain. Instead Manzotti takes an “externalist” stance that conceives of experience as somehow “spread” out across the things of the world. Even if we agree with Manzotti’s realism, this needn’t commit us to either internalism or externalism. Experiences simply happen wherever they happen. A walk in the highlands certainly doesn’t happen in your head, but it makes little sense to say that it is spread over the mountains either.

One of the standard objections to realist accounts of consciousness is what is known as “the argument from illusion”. The basic idea is this. If we are susceptible to optical illusions and other illusory phenomena, then we cannot rely on perception. Manzotti responds:

“Mirages and Hallucinations are not necessarily ‘pure appearances’, one sees something that is really there, only that one takes to be something else. Yet it is not misperception, rather it is misjudgement!”

Few people would claim that mirages, hallucinations and illusions are not caused. But if one mistakes a reflection in a mirror for an actual thing, then it isn’t true that “one sees something that is really there”. If the mirror (the thing that is really there) isn’t seen and its reflection “is taken for something else”, then quite clearly the mirror has been misperceived. Such a response cannot be a “misjudgement” because judgement is not a precursor to perception. If you look before you leap, you don’t judge before you look.

Manzotti seems to have fallen into a conceptual trap. In his eagerness to refute internalism, he has adopted an opposing view when it would have made more sense to stick to his otherwise justified critique of internalism and to point out that consciousness is something we ascribe to whole people, not to their brains or minds.

Parks and Manzotti discuss an interesting optical illusion by Akiyoshi Kitaoka. What appear to be blue and green portions are in fact the same colour. Internalists argue that this illusion shows that everything we perceive is an illusion generated by the mind/brain. If so, this would be a truly miraculous achievement on the part of the brain even if it were sometimes wrong. However, a far simpler and more parsimonious explanation is that these apparent colours are merely the result of the very opposite of an achievement. They are the product of a very ordinary perceptual failure brought about by the circumstances in which the illusion is presented. Change the circumstances in the right ways and it becomes obvious that there is only one colour involved. No neural mysteries need be imputed.



The effect conforms the same principle used to make colour prints with inkjet printers or to produce colours on the screen you are currently using. In fact, the same basic principle enables us to place tiny black and white squares together to produce a patch that looks grey.




If it weren’t for the fact that all normally sighted people are susceptible to illusions in the same sorts of ways and in the same sorts of circumstances, then all illusionistic media (images, movies, representational paintings and drawings etc.) would be unacceptable as representations. There would simply be no ways and no circumstances in which such representations would be like the things they might otherwise represent.

Sometimes things can look like other things because they are genuinely alike. Two leaves from the same tree will usually be alike in a whole variety of respects. Such isomorphism is the very basis of what we take to be observer-independence, of what is objectively real. On the other hand, things can look like other things because in some regularly occurring or contrivable circumstances it can be difficult for us to discriminate between them in one or more respects. Equally, and for the same reasons, two things that are actually the same in one or more respects can seem to be different. The mastery of illusion is not an achievement of the brain, it is an achievement of human culture.

I will leave the last word to the Scottish realist philosopher Thomas Reid:

“The sceptic asks me, Why do you believe the existence of the external object which you perceive? This belief, sir, is none of my manufacture; it came from the mint of Nature; it bears her image and superscription; and, if it is not right, the fault is not mine: I even took it upon trust, and without suspicion. Reason, says the sceptic, is the only judge of truth, and you ought to throw off every opinion and every belief that is not grounded on reason. Why, sir, should I believe the faculty of reason more than that of perception?—they came both out of the same shop, and were made by the same artist; and if he puts one piece of false ware into my hands, what should hinder him from putting another?” (Thomas Reid, IHM 6.20, 168–169)

8 comments:

Paul Herman said...

Have you seen Daniel Khaneman's reconstructions of precognitive vision? What is received by the retina before being decoded by the brain? I agree with Reid that perception & reason are equally reliable, & would, therefore, consider them both mere human constructs incapable of understanding the ding an sich. If, indeed, there is such a thing as the thing in itself. And you?

Jim Hamlyn said...

Thanks Paul,

I have Kahneman's "Thinking Fast and Slow" but i don't recall any vision reconstructions, sounds a little odd to me to try to reconstruct the unconstructed.

I'm afraid that I find a lot of perceptual science to be wildly confused. The experimental findings are interesting but the theory is dreadful. As Richard Feynman once said: “I believe that a scientist looking at nonscientific problems is just as dumb as the next guy.”

Like Reid, I don't take perception to be a construct at all. How could that even work without being viciously circular? I think Kant was wrong, but it takes a lot or argument to show how. Wittgenstein helps a lot.

Paul Herman said...

Really? I don't see anything odd in attempting to reconstruct images as they are received by the retina, before being translated to an inner understanding of an assumed external reality.

Neither do I see anything circular, vicious or otherwise, in believing all sensation & subsequent reasoning as part of a reality constructed by the perceiving body.

We might consider the different understandings of an alleged external reality offered by the eighty or so types of eyes that belong to different animals in the world. A dog, even if it were as intelligent as a human, couldn't imagine the existence of colour, because of its lack of retinal rods. A monotone world shows a different understanding of reality, albeit a small difference when compared to the possibilities implied by potentially larger differences in all sensorial perceptions. With a slight difference that allowed us to see into the infrared range of light's spectrum, we could see in what we now think of as 'dark'. Whereas if we could see the ultraviolet end, we would see nothing at all, since air itself would become opaque.

By the same token we might consider the possibility of senses existing which we can't imagine because of our very lack of them, which would show us a reality different to that which we are able to perceive with those we do have.

But without going as far as that, we might consider something as simple as size. We know that the matter that makes up an atom is infinitesimal in comparison to the space the atom occupies. We appear to each other to be solid bodies but we know that, at an atomic level, we are made up of so much more space than matter, that if we were very small creatures, we could hardly distinguish the massing of atoms that a human is, from the less dense air that surrounds him.

An ear could never imagine the existence of an eye, & if it could, it couldn't conceive of what sight is even if sight were explained to it. We are accustomed to thinking, in our simplistic way, that our understanding of reality — external or internal — depends on our five limited & fallible senses. But, in fact, the minds which understand reality are made up of a million separate processes that couldn't imagine each other but which only make up a comprehensive understanding through the mind's conflation of them all, to produce understood reality.

I can see no reason to believe the mind's truth is objective. That its truth coincides with a truth outside of itself. Ergo: It is a construct.

I look forward to your rebuttal! Thanks Jim

Jim Hamlyn said...

"I don't see anything odd in attempting to reconstruct images as they are received by the retina, before being translated to an inner understanding of an assumed external reality."

What magical intelligence is "attempting" this alleged "reconstruction" and "translation"? And how does this inner intelligence come to know that its reconstructions and translations are accurate? By what standards of correctness and what units of measure does it conduct its operations? What raw materials does it have at its disposal to pull off such feats of reconstruction and what yardsticks, samples and examples? How did it learn to translate images into whatever it is that you suppose it translates the "images" received by the retina into? And for whom is it constructing this translation? You? Itself?

If that doesn't begin to expose the profound oddity of the current state of Cartesianism then I'm at a loss.

Paul Herman said...

Chuckle! I don't feel we are taking part in dialogue Jim. We haven't reached a point of actual debate because we aren't yet familiar enough with each other's stance. But, as a general rule, I prefer losing a debate, because it means that through a Socratic exchange I have reached a more profound truth. Your questions are rhetorical within the context of defending your beliefs.

And yet, they are questions that do have answers.

The study which attempted to reproduce the raw data received by retinas before reaching the brain, was undertaken with people who were born blind but recovered sight as adults. If you look into its parameters I think you'll find it credible. And, within the ontological questions we are considering, you may find it interesting.

But, like the other comments I made, I don't think you have considered or addressed my proposal's main point, or ratiocination.

My personal philosophy is a product of long study & contemplation, as, I'm sure, yours must be. And yet, mine is still, after a lifetime, in constant flux. I am always eager for the rare new idea that upsets its conclusions. And so, I am not as sure as you are of knowing the truths I believe in. That is to say, I am not sure they are truths, but only the best I can do with the understanding I have at present. My philosophy is, was, & likely always will be, merely a working theory. The joy its study gives me is in its consideration, not its elusive convictions.

Considering philosophy in dialogue with someone who feels the same way can also be a pleasure.

Jim Hamlyn said...

Thanks Paul, that's gracious of you.

Perhaps I should explain that my previous response was to your comment "I don't see anything odd in attempting to reconstruct images as they are received by the retina, before being translated to an inner understanding of an assumed external reality." I was attempting to bring its oddity into relief for you. Firstly, it isn't a settled matter as to whether the retina receives images. Certainly light falls on the retina in a way that is consistent with the images we produce with cameras etc. and if we could get inside our own eyes we would see what we would describe as the "projected image", but it doesn't follow that what we assimilate into the concept of image (think of mirror images for another slippery example) are images in the ordinary sense.

Secondly, we have good reason to be wary of taking the reception model of perception too seriously. Better would be to regard perception on the model of responsiveness. So instead of characterising perception as involving the reception of images I am suggesting that it is more parsimonious to characterise it as involving responsiveness to patterns of stimulation.

We also need to beware of assuming that the organism has to "reconstruct" a received image. Once we set aside the reception theory, it becomes clearer that the idea of reconstruction follows from the reception theory. The same goes for any "translation" for the benefit of "inner understanding". All of these terms beg the very questions they are intended to answer. If we want to understand such things as understanding, translation, reconstruction, images and perception it makes no sense to attribute them to the very processes that bring them about.

Does that make a little more sense?

Paul Herman said...

I will cede the point, Jim. It might be argued, however, that it comes at the cost of your supporting the larger epistemological question I used the retinal detail to illustrate.

You claim Kant was wrong—& by extension, Berkeley, Descartes, Hume, Heidegger, & some might claim even Plato, among others—in favour of Johnson, & all theologians (excepting the enlightened view espoused in the books held sacred by India: the Vedas & Upanishads; the Mahabharata & Ramayana).

I claim that it is that very subjectivity—the lack of 'point' in 'point of view'—to which you allude regarding the understanding of the functions of a retina, which make it impossible to claim any objective reality. If we discount Berkeley's God, the all-seeing & omniscient witness, then there can be no evidence of the existence of an a priori reality. A ding an sich. We may well all be just a part of Shiva's dream (among other possibilities).

There may even be other ways of perceiving that make the question moot, but, our not possessing those sensibilities make it impossible for us to imagine what they might be.

However, for the purposes of avoiding the tedium of arguing at odds, in case, at root, we are arguing Theism against Atheism, let me stop & ask: Does your philosophy rely on a metaphysical faith? I think our conversation can only be interesting—can only have a chance of leading to new, & perhaps mutual, understanding—if we are on the same side of that question. I am atheist, are you?

By the way, we lie at antipodal ends of the philosophical sphere in other areas, too. As art professionals we may find it more compelling to discuss the branch of philosophy called aesthetics. If you are interested in reading some of my collection of musings on philosophy & art, my Blog bares some of their essence here: http://www.hermanstudios.com/pmw00.html

Jim Hamlyn said...

"There may even be other ways of perceiving that make the question moot, but, our not possessing those sensibilities make it impossible for us to imagine what they might be."

You made a similar point earlier when you wrote:

"By the same token we might consider the possibility of senses existing which we can't imagine because of our very lack of them, which would show us a reality different to that which we are able to perceive with those we do have."

I tend to agree with Wittgenstein that most, if not all, philosophical problems are born of language. It is by examining the different "language games" in play that we get clear about our concepts and dispel the fog of philosophical theorising.

When you say that there may be other ways of perceiving, I think you are sending the concept of "perception" on holiday (as Wittgenstein might have said). Consider chess. It makes no sense to say that there are other ways of playing chess and it's impossible for us to imagine what they might be. If there are other ways to move the pieces on a chessboard, then the game wouldn't be chess. It might not even be a game. Likewise, if something does not conform to what we regard as perception, then it wouldn't qualify as perception.

My not having echolocation doesn't make it impossible for me to imagine what it might be like to have echolocation. And having echolocation wouldn't show a different reality. After all, sight doesn't show a different reality from touch. There are things we can see that we cannot sense with touch, but this doesn't mean that colours are any less real than the shape or size of things.

And as for metaphysics, I agree with Wittgenstein again: 'What we do is to bring words back from their metaphysical to their everyday use' (PI §116).

Post a Comment