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)

Dretske’s Dreadful Theory Of What We See

In a presentation from 2008, the late (as of 2013) Stanford philosophy professor Fred Dretske argues that seeing includes the perception of objects (including relations between objects), properties (shape, size and colour etc.) and facts. For Dretske, the facts we perceive are “things we come to know by seeing”. He claims that there is a danger that we take a failure to notice or detect objects and properties as a failure to actually see them. He presents the following two images in order to explain this claim.

Image A

Image B

Image B contains an additional shape. In his presentation, Dretske presents the images one after the other and inserts a transition between the two that makes it difficult to see the difference between them. In Dretske’s view: “One should not conclude from the fact that you didn’t see that there was a difference to the conclusion that you didn’t see the object that made the difference.” He remarks:

Even if you don’t detect it, even if you don’t notice it, even if you don’t know that you are seeing different things. Even if you don’t see the fact that there is a difference, you still might see the objects and properties that make the difference. You just don’t realise you do.

It should be obvious that if you do not detect, realise or notice that the traffic lights are red, then you cannot be said to see them (at least in respect of their being red). Nonetheless Dretske holds that seeing is independent of conscious awareness. In his view, we can genuinely see objects and properties without detecting, noticing or knowing that we do so. Dretske uses this questionable conclusion to promote his theory of conscious experience. He claims that: “Your experience of an object is conscious if it gives you knowledge of that object.”

For Dretske, all knowledge is knowledge of facts, and in order for an experience to be conscious, it must provide such knowledge. But this is absurd. If we look at a familiar object, we do not lose consciousness of it because it ceases to give us knowledge. If consciousness depends on the acquisition of knowledge, then all lapses in attention must be accompanied by lapses in consciousness. This is quite evidently not the case.

We perceive the phonemes, morphemes and sentences in which facts are typically stated but it is debatable whether we actually perceive facts at all. Earlier today I asked my partner “When did you last see a fact.” She looked at me quizzically and remarked: “You don’t see facts.” Some people might contend that texts, graphs and diagrams etc. can be seen and thus are visible facts, but it is important to note that representations of facts are not the facts they are used to represent. Many facts can be demonstrated, but it does not follow that a demonstration of a fact can be reduced to the fact it is intended to demonstrate.

Earlier in his presentation, Dretske states: “The facts we see—the things we come to know by seeing—we come to know them by seeing objects and their properties.” Clearly then, Dretske realises that perception of things is not the same as the “perception” (his use, not mine) of facts. Facts must be derived in some way from perception, but quite how they are derived Dretske neglects to mention.

The absurdity of Dretske’s position becomes more pronounced towards the end of his presentation. He argues that when we look at a wall of 350 bricks for a few seconds, we acquire 350 “distinct pieces of knowledge—one for each brick in the wall.”  Not only this, but during the Q&A session it becomes clear that he thinks we acquire “infinite” knowledge “for free” when we look at things. The reason he believes this is because he is committed to the idea that the perception of facts involves the acquisition of what he calls “tacit knowledge”.

You don’t have to actively think something to know it. There are a great many things you know tacitly, not because when you acquired the knowledge you are actually thinking about it or believing it but because you have the kind of experience of it which, if you do later think about it, will tell you what you need to know.

There is no such thing as a memory “telling” us anything, so Dretske can only mean that we have to interpret an experience ("later think about it") to derive factual knowledge from it. If we do not think about it—if we do not interpret the memory by means of our conceptually enabled inferential skills—then we cannot be said to have yet formed any factual knowledge on the basis of the memory. An analogy will help. If we have a workshop full of materials, we may be capable of using these to create some tools, but unless we actually manufacture these tools, we cannot claim to possess them. Tacit knowledge, and knowledge in general in fact, is not something that we possess like a scar or a souvenir, it is something we are capable of doing, something we are capable of bringing about by the application of skill.

When we fail to see a difference between two different things, at least two factors need to be taken into consideration. Firstly, our sensory organs may be limited by evolutionary constraints that give rise to regularly occurring fallibilities in certain circumstances. Secondly, the circumstances of encounter (the illumination, position, angle of view, delay between images etc.) may limit discrimination more than might otherwise be the case. Certainly any actual differences within our visual field may have a causal influence upon our sensory system, but this does not mean that these influences are dealt with at some non-conscious, unconscious or “sub-personal” (Dennett 1987) level of seeing that we "just don't realise". It just means that there are various complex processes involved in perception that are not conscious and that some of these have insufficient influence to rise to the level of purposeful action: consciousness.

At the 25:00 minute mark of the presentation, Dretske discusses an image of a square divided into nine coloured portions. He claims that if each of the nine squares was coloured the same shade of blue and placed so close together that we couldn't see the edges between them, we would still see nine squares. This is like arguing that we see the screen when we watch a movie. If pressed, we would probably agree that the screen is visible while we watch Star Wars or Gone With The Wind etc. But what we would be very unlikely to concede, and what follows from Dretske's thesis, is that we see each pixel on the screen and thus gain millions of distinct pieces of knowledge—one for each pixel. It should also be noted that pixels are themselves divisible into individual photons. Do we have distinct pieces of knowledge of photons too? 

At some point we have to acknowledge that all sensory systems are limited in various ways and it therefore follows that these limitations make it impossible to discriminate between things (that may in fact be quite different) in certain circumstances and in certain respects. It is by virtue of differences that all creatures discriminate between things. Without sensory discrimination there would be no life. Nonetheless, sensory discrimination is not free of limitations. Without these limitations, there would be no question of our mistaking any one thing for another different thing, and there would also be no question of our accepting a flat thing as a viable stand-in of a three-dimensional thing. The fact that things of one sort (images say) can be mistaken for things of another sort (three dimensional objects for example) makes images supremely apt as representational tools; as things that can stand-in for the objects they represent.

I suggest that any explanation of perception that fails to account for the role of discrimination failure within our practices of nonverbal representation is probably doomed.

On The Indivisibility Of Brain And Body

The other day my four-year-old son mentioned his brain. I asked him if he had any idea where it was and he said he didn’t know. I was on the verge of explaining that the brain is where we do our thinking when I hesitated.  Saying that the brain is where thinking goes on is like saying that the heart is where circulation goes on or an oven is where food preparation occurs. The astrophysicist Carl Sagan once famously said: “If you wish to make an apple pie from scratch, you must first invent the universe.” The same could be said of thought.

This doesn’t mean to say that we cannot understand thought, or that the brain is a black box forever closed to neuroscience. It simply means that thought is not something that can intelligibly be attributed to brains or neurons. Thought is something that skilled organisms do in virtue of tools and techniques that they acquire to a very substantial degree from culture – just like the tools and techniques etc. that enable food preparation.

Either thinking is an action or else it is not. If it is an action then it is mistaken to suppose that brains think, because brains are not agents and cannot act. Only embrained bodies – persons – are agents and only agents are capable of doing things.

If we want to insist that thinking is not an action, then we face multiple difficulties and objections. For example, it would no longer be coherent to respond to the question “What are you doing?” by saying “I’m just thinking,” and we would face the formidable challenge of distinguishing between ongoing brain processes that are clearly not actions and the thoughts that we have decided do not qualify as actions either.

Similar absurdities arise when we entertain sci-fi fantasies about brains in vats. A brain in a vat wouldn’t have experiences, not even memory experiences. Strictly speaking, memory recall is not an experience. Whilst we have ways of recounting the past and these capacities – consciously entertained – often elicit emotional responses, these responses are not in the brain, they are embodied (including the brain of course). Not only are brains incapable of actions but they have no feelings either. They have no sense receptors. Nor do brains memorise feelings – they don’t have to. When we recall a memory the associated emotional responses are generated anew in the body including the brain. So a brain stripped of a body wouldn’t have feelings of any kind – either emotional or sensory. It would be a thing with a notional capacity to initiate actions but no opportunity to do so, nor to feel the embodied frisson of recall. And if the trauma of surgery did not kill it outright, the trauma of desperate isolation would almost certainly lead to a very rapid demise. Even people with locked-in syndrome are not “cut off” from sensation, and the accounts of those who have survived paint a unimaginable picture of desolation and despair.

Your brain is your body and your body is you.

Overrated Consciousness

The following video is by a YouTube and BlipTV "broadcaster" I subscribe to who goes by the name of Conferencereport. It's a succinct, clear and beautifully argued meditation on the oft referred to idea of the universe becoming conscious of itself. I'm not convinced I'd subscribe to his concluding remarks (about preferring wings to consciousness) but the earlier analogy about monkeys is hilarious.