Naturalism or Preternaturalism?

"Dream Vision" by Albrecht Dürer, 1525.*

Naturalism in philosophy is (roughly) the view that the structure and behaviour of the universe is governed by natural—not supernatural—laws. Many naturalist philosophers also hold the view that science is the best means for investigating the nature of reality, including the reality of consciousness. Others would point out that many contemporary perplexities are not due to a lack of scientific evidence or insight but are instead the result of various conceptual errors over which science has no authority. After all, we don’t look to science to adjudicate on questions of logic. Sense is not science.

I’m a member of a Facebook discussion group on the subject of naturalism. The group is managed by Tom Clark, who also runs a website by the same name (naturalism.org). In an article about lucid dreaming, Clark writes: “As people learn about lucid dreaming, an interesting fact about the brain will become known: it is a virtual reality generator. But an even more remarkable fact is waiting in the wings: waking experience is virtual reality too.”

Like Clark, I sometimes have lucid dreams, but unlike him, I don’t regard these as evidence that “the brain constructs a conscious phenomenal world”. Clark’s view is very similar to what is known as “mind-body dualism”, since it seeks to explain the relation between mind and matter by way of supernatural, or in Clark’s case preternatural, powers. I hope it is clear that even a preternatural explanation conflicts significantly with the aims and commitments of naturalism. This post is a very brief attempt to bring this conflict into relief.

Across the natural world, many organisms have developed deceptive strategies that aid their survival. Camouflage is just one example of this evolutionary achievement. Dissimulation is another. It might not be obvious, but all forms of deception exploit various weaknesses, whether these be perceptual weaknesses or weaknesses of knowledge or understanding. This raises a very serious problem for Clark, because in order to generate any form of virtual reality, the brain would have to exploit some form of weakness, constraint or limitation on the part of the consumer/victim/user. In the competitive context of organismic life, there is something to be gained from deceiving potential predators or prey. But in the case of the internal organs like the brain, the advantages are obscure. Organs obviously don’t prey on other parts of an organism and nor can they exploit anything or be exploited in any way that isn’t to the advantage or detriment of the organism as a whole. So from this evolutionary perspective, Clark’s dualistic claims simply do not stack up.

Clark repeatedly uses terms like “generates”, “constructs”, “builds”, “models” and “represents” to characterise the alleged creative abilities of the brain. When we speak of a gust of wind creating a mess or a tsunami creating destruction we do not suppose that the wind or sea are creators. Clark’s use of these terms, on the other hand, invokes a very different sense of “creation”; a sense that is little different from the supernatural explanations that naturalism ordinarily seeks to avoid.

What is true of terms like generation, construction, creation etc. is also true of action in general: 

When we describe a wheel as rotating, a ball as rolling downhill, water as flowing, a pendulum as swinging back and forth, a ship as steaming ahead, we are not describing them either as acting or as acting on anything. We are merely describing what they are doing. (Hacker 2010, p.144. Original emphasis)

Brains certainly do things in the same way that other inanimate objects do things, but any actions brains are involved in are actions of the organism as a whole. No organ, not even a brain, can take action on its own behalf. This is why we rightly regard brains as integral to the organisms of which they are parts. It makes no sense to treat brains as autonomous agents with their own generative powers.

Naturalism usually takes the view that explanations should seek to make as few assumptions as possible. But the virtual reality hypothesis requires an order of complexity, coherence, organization and generative action far beyond anything found in the natural world. In fact it is far beyond anything found in the cultural world either. The assumption that brains are devious creators is almost as extravagant and implausible as it is possible to conceive. Only an omniscient deity would be a more unlikely puppet-master.

*Dürer's text reads: "In 1525, during the night between Wednesday and Thursday after Whitsuntide, I had this vision in my sleep, and saw how many great waters fell from heaven. The first struck the ground about four miles away from me with such a terrible force, enormous noise and splashing that it drowned the entire countryside. I was so greatly shocked at this that I awoke before the cloudburst. And the ensuing downpour was huge. Some of the waters fell some distance away and some close by. And they came from such a height that they seemed to fall at an equally slow pace. But the very first water that hit the ground so suddenly had fallen at such velocity, and was accompanied by wind and roaring so frightening, that when I awoke my whole body trembled and I could not recover for a long time. When I arose in the morning, I painted the above as I had seen it. May the Lord turn all things to the best."

Long before making this image, Dürer wrote: "How often do I see great art in my sleep, but on waking cannot recall it; as soon as I awake, my memory forgets it."

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.

Difficulties for the Philosophy of Illusion

Illusion:

1.     a deceptive or misleading appearance

2.     a false or misleading impression, idea, belief or understanding

3.     a false perception of an object or experience due to the mind misinterpreting the evidence relayed to it by the senses.

The concept of illusion is an ancient one, yet its venerable pedigree and widespread popularity are no guarantee of its value as a tool for uncovering the nature of perception. It is a handy concept for sure, but perhaps we should be wary of convenience, especially as a route to insight.

Examples of illusion are not difficult to come by - many are the stock-in-trade of conjurers and ‘illusionists’, but where some illusions might be distinguished, especially from the tricks and entertaining feats of stage-artists, is in the degree to which they might be regarded as having something to reveal about the workings of perception. When a conjurer uses slight of hand to “deceive the eye”, we do not suppose that this has anything useful to tell us about our sensory capacities. The idea that, with sufficient skill and dexterity, the hand can move more expertly than is easily perceived is unsurprising. Optical illusions, on the other hand, produce puzzling responses or anomalous visual artefacts that call for more sophisticated explanations.

Philosophers – knowing that their theories often stand or fall on the evidence of scientific enquiry – frequently refer to optical illusions in order to substantiate their claims. However, during the 1960’s, an important body of evidence emerged that cast significant doubt on many of these claims, yet has gone largely unacknowledged in philosophical circles.

Müller-Lyer Illusion

In a 1966 study undertaken by Segal et al into cross cultural variations in susceptibility to optical illusions the researchers found significant variance between differing communities and age groups across the globe. Some groups, for instance, reported little or no difference between the apparent lengths of the lines of the famous Müller-Lyer diagram. An earlier study by Hudson (1960), of culturally isolated South African children, encountered very similar findings. Both studies attributed their results to a lack of habitual exposure to pictures amongst the communities studied. Hudson dubbed this lack of familiarity: ‘pictorial illiteracy’. In fact, even children well schooled in language and arithmetic skills (but lacking pictorial literacy) were not susceptible to what is commonly described as the ‘pictorial illusion of depth’ and were therefore unsusceptible to the depth cues that many optical illusions exploit.

In 2006 Robert N. McCauley and Joseph Henrich write:

For those who experience it, the illusion may persist, but susceptibility to the Müller-Lyer illusion is neither uniform nor universal. Moreover, a plausible argument can be made that through most of our species’ history most human beings were probably not susceptible to the illusion.

If this is correct, and corroborating evidence can be provided from the art historical record to support it - then there is good cause to doubt the relevance of illusion in the explanation of perception. Moreover, if the following evidence is anything to go by, these doubts are in greater need to explanation than ever.

In numerous well documented studies, it has been shown that when people reach to grab three-dimensional versions of optical illusions, their grip aperture (the distance between finger and thumb) is unaffected by the illusion. So, whilst we may be inclined to say that one part of an optical illusion appears to be larger than the other, our ability to physically interact with these illusions is unaffected.

From an evolutionary point of view, it is of the utmost importance that we do not confuse a distant object for a small object, especially if the distant object has significance for our potential to survive. It is extraordinarily fortunate in fact, that the capacity to recognise and use perspectival images (in which distant objects are depicted at disproportionate scales than nearby objects) has not been entirely overridden by the evolution of our perceptual skills. If the research of Hudson, Segal et al is correct, then it would seem that this capacity to derive depth cues from perspectival images is a learnt skill and is not an immediately available part of our genetically acquired perceptual repertoire. And McCauley and Henrich are surely right when they speculate that our susceptibility to illusions must be a relatively recent consequence of the increasingly widespread use of pictorial imagery. What better explanation do we have for the widespread indifference amongst animals to our attempts to interest them with images?

"The Innocent Eye Test", Mark Tansey, 1981

I hope the evidence presented here makes it clear that the standard view of illusion - as deceptive, misleading or false - is thoroughly inadequate as a tool for the investigation of the nature of perception.  If our theories don’t fit the evidence then it is time to change our theories. I suggest that we start with the theory of illusion.