Thursday 3 September 2015

Descartes' Menagerie of Demons (2015)

From The Philosopher, Volume CIII No. 2

By Danko Antolovic

Recent films like The Matrix trilogy and Science fiction in general have made many people familiar with the Cartesian demon: a powerful entity able to intercept all the mind's inputs and outputs and manipulate them in order to create an impenetrable illusion - the matrix - in which I think, I perceive and in which I think, I act - yet which is, in reality,  entirely generated by the demon.

René Descartes introduces such a demon in his Meditations on the First Philosophy, in which he seeks to ascertain what, if anything, is absolutely true. He argues as follows: the evidence of my senses is not reliable because it is logically possible that all of my sensory impressions are fabricated by the demon: I may not have a body, nor sense organs, the world may not exist at all, there may be no such things as matter and space. All that I am sure of is that I think and I know that I think, therefore I cannot be nothing. I must be something, a thinking thing, and no demon can deceive me into believing that I am if I am not. (I use the first person singular here to denote analytic introspection, just as Descartes did originally.)

Descartes further asks:
I have established something that I am certain of - I exist - but why is it that I am certain of it? 
It is, he argues, because I can see it very clearly, with complete immediacy. He then asserts an important principle: what I can see very clearly in my mind must be true. What else do I see very clearly? I see that I have certain ideas, and they must be something and not nothing because it is I, the thinking thing that exists, who has them. All my thoughts truly exist, my perceptions also exist insofar that they are a form of my thoughts, even if their content is fabricated by the demon. Further, I see very clearly certain relationships between my ideas. For example, I have the idea of the triangle as a geometric figure, and from that idea it follows that the sum of its angles always equals two right angles: to see that, I can follow a simple geometric proof, each step of which I can clearly grasp. Similarly, any other mathematical truth is equally evident.

In this principle of 'seeing things very clearly' Descartes encounters a second demon, the demon of sensory habit. This demon does not have the mind-enslaving, matrix-spawning power of the first demon (in fact, philosopher David Hume secured quite a firm grip on its pointed tail a century later), but it is a sly and seductive imp: it makes me extrapolate commonplace sensory experiences into universal truths. For instance, the idea of a triangle and the theorem about the sum of its angles follow from Euclid's axioms of ordinary geometry, and these axioms are self-evident because they describe, in a somewhat idealised fashion, my common sensory experiences. The 'ordinary' geometry describes a so-called flat space, the only space that most of us will ever perceive, but our actual physical space is in fact very slightly curved, because of the proximity of a large mass, our Earth. This is not of purely academic concern either: the Global Positioning System (or GPS), which keenly impacts our modern life, takes into account this non-flatness of space in order to provide accurate locations. If we could draw a large triangle in space near the Earth, by shining laser beams from one satellite to another, we would find that the sum of its angles is slightly but measurably less than 180 degrees.

I see clearly that the sum of angles of a triangle adds to two right angles, but this clarity is an illusion created by the two demons: the first one created a sensory world of the flat space for me, and the second made me believe that my habitual sensory impressions constitute a universal truth. Had the matrix-demon fashioned my sensory world to appear like the vicinity of an enormously dense stellar object, such as a black hole or a neutron star, my intuition of triangles would be noticeably different.

I must therefore suspect my intuitions. I cannot deny my self-awareness, nor the reality of my thoughts, but most of my intuitions are derived from the sensory world, and are therefore subject to demons' influence. I find within me the speculative ability to set my own rules (axioms), independent of the senses, and investigate where they lead by drawing various interesting and self-consistent conclusions from them. But even here I see the hand of the habit-demon: I follow the rules of logic and insist on self-consistency as an abstract requirement, but I really do it because these things work in the real world and make intelligent discourse possible. But if the reality is demon's illusion and there isn't anybody to conduct intelligent discourse with, then I may well let the devil take all logic and consistency: what still remains is my self-awareness and the clear intuition of my existence as the Cartesian 'thinking thing.'

Having established the reality of himself as a thinking thing, Descartes asks : where did I come from? If I had created myself, I would have the remarkable ability to create something from nothing, and surely I would be aware of that. On the contrary, I find no such ability in me, and I see that I am a very limited being. Something greater than me must have created me, and that thing itself does not need a creator, and is God. Moreover, I have a very clear idea of God, and since a finite thing cannot give rise to an infinite one, this idea was placed in me by this greater being, and therefore God exists.

Appealing repeatedly to the principle that what is seen clearly must be true, Descartes continues: the idea of God includes every perfection, and therefore it must include existence, because that which exists is more perfect than that which does not. It is contradictory to think of God as non-existent, and therefore again, God must exist. Finally, all deception, however cunning, is an imperfection, a sign of weakness, and therefore the perfect God cannot be a deceiver. Because of God's perfection I know that I am not at the mercy of a demon, and - and this is an astounding feat of circular reasoning - because of that same perfection and honesty of God, I can be certain that what I see clearly must be true.

Objections to Descartes' reasoning about God were raised early on by his contemporaries. We could say that Descartes fell prey here to a third demon, the demon of the childhood's 'Why?' which must have an answer to every question. It is not malevolent, this sprite of infantile curiosity, but with its childlike insistence on answers it can seduce me into preferring a flawed explanation over no explanation at all. How flawed? For one thing, it does not follow that the idea of an infinite being could not arise within me, by my own power: I can envision finite beings that are less limited than me, and the idea of an infinite being is an abstraction from that, a postulated absence of any limitation. I grasp such a concept the same way I grasp the Euclidean concept of an infinite line: not as a concrete thing, perceived in all its parts, but as an absence of any upper bound on its length. It is true that I do not know my origin as a thinking thing, but it does not follow that my speculative concept of an infinite being corresponds to anything transcending my thought or existing outside it.

In his second argument for God's existence, Descartes more or less repeats the well-known proof proposed by Anselm of Canterbury: imagine the most perfect of all things; if it does not exist, it is less perfect than it would be if it did, and so is not the most perfect; therefore the most perfect thing must exist, and is God. Much has been said and written about Anselm; let us just pursue the point that this most perfect being must be omnipotent, since not being able to do something is an imperfection. So, can the omnipotent God create a stone that is too heavy for him to lift? If he is omnipotent, he must be able to do everything, including depriving himself of omnipotence or being both at once. The notion of omnipotence includes its own opposite and leads to contradictions, and the God of Anselm and Descartes is either self-contradictory or else transcending logic and contradiction, and is incomprehensible in either case.

Why is any of this important? During the last few centuries, empirical/scientific way of thinking has effectively superseded the older reliance on beliefs that cannot be justified with the evidence of the senses. To be sure, many unfounded propositions are regularly bandied about in public and private discourse; however, when it comes to practical decisions that entail allocation of scarce resources and hard effort, be these decisions public or private, we exercise sober factuality and do not act on the basis of augury, prayers, sacrificial offerings or hallowed traditions. We are expected to be scientific about it, and we approach all hypotheses as potentially false, trusting them only when they are backed by incontrovertible evidence.

Descartes' 'Meditations' are a remarkable early attempt of a scientific mind to come to terms with the implications of the method of skeptical inquiry. Descartes takes skeptical empiricism at its word, and asks: 'All right, what can I know for certain if I follow this method?' The stark answer is: nothing, except my own thoughts. Now, scientific judgment deals in probabilities rather than in absolute certainty, and it is easy to respond that the straightforward alternative - the world exists and looks something like the image presented by our senses - is a likelier one than Descartes' fantastically contrived matrix-demon. That is not an entirely honest answer, however: we deem the demon unlikely because our practical knowledge tells us that such a feat would be enormously difficult to pull off within our sensory world. What is likely or unlikely outside the sensory world, and that is where Descartes' hypothetical demon resides, we have no means of judging. It is more honest to admit that we cannot distinguish a 'real' sensory world from seamless illusion, and that the entire empirical enterprise proceeds on the assumption that the demon does not exist, since we could do nothing about it if it did.

More significant than the demon itself, for modern empirical thought, is the chasm that Descartes' reasoning opened between the knower and the known. I know myself as a thinking thing with absolute clarity, and I know nothing certain about the physical things that I perceive with my senses. That distinguishes, in Descartes' view, the mind and the (hypothetical) body as two entirely different substances right from the start. Later in the 'Meditations,' after he had re-established the existence of the physical world by means of divine goodness, Descartes again observes that the mind is perceived as one, clear and indivisible, while all bodies are divisible and subject to erroneous and imperfect knowledge. It can be said that scientific empiricism operates within this framework of Cartesian duality to this day.

Modern empiricism tacitly accepts the existence of a lucid mind, a knower behind all the factual knowing. There is a self that is not mistaken about its existence, somebody who (discounting the verifiable effects of sleep, inebriation, illness or random distractions) sees things clearly and whose thoughts exist reliably. The knower is susceptible to the habit-demon, but that demon can be exorcised relatively easily: on one hand, there are provisional, inductive generalisations that we draw from sensory experience, and we call them scientific theories. But we can also draw abstract generalisations, axiomatic systems of pure mathematics, which are constructs of the mind independent of the evidence of the senses, and as long as we are conscious of the difference, the habit-demon has no dominion over us. And then there is the sensory world which, in agreement with Descartes, we acknowledge as something that is independent of our will and thought. We accept the simplifying assumption that something distinct from the knower, an objective knowable world, lies behind the sensory evidence, and that it is not a fabrication. The great open question of scientific empiricism is whether this duality of knower and known is resolvable or not.

Subsuming the sensory world under my 'self' by a pure act of mind seems to be possible only as a fantasy... 

Descartes himself bypasses this duality by invoking the agency of God, the omnipotent, never-deceiving being in whom all intellectual difficulties are resolved. But this is only a subterfuge that stops further inquiry. The omnipotent being is self-contradictory, the ultimate idol-demon that stands outside any logical discourse available to the human mind and admits only of solitary, all-abandoning faith: a credo quia absurdum (I believe, because it is absurd).

Without invoking supernatural help of such calibre, we may attempt to resolve Cartesian duality by absorbing the sensory world into the mind itself: what we perceive as sensory input is the product of the mind, the world is maya, an illusion which the spirit is trapped in. This is not an illogical position, but it is difficult to see where to go with it. I perceive my conscious mind as an indivisible entity, known as well as it can be, and I 'see clearly' that it is not generating my sensory world. If the world is the mind's product, it must be coming from some part of my mind that I have no access to, and which is then already in the realm of the matrix-demon. Is it possible for me to gain that access, to awaken into an enlightened state from which I can see the unity of the knower and the known? Not by any immediately obvious act of my conscious mind. Meditative traditions prescribe practices by which such states can be supposedly attained, but they generally work on the physiology that surrounds the mind, and thereby tacitly acknowledge the phenomenal world as independent and capable of influencing the mind. That is hardly anything new, and there is little reason to believe that meditative traditions have somehow spiritually accounted for the sensory world. Subsuming the sensory world under my 'self' by a pure act of mind seems to be possible only as a fantasy.

We can also take the opposite approach and assume that the objective world truly exists, and that knowledge of it is a reflection, a trace of the world within some physical entity capable of retaining such a trace; in other words, we will subsume the knower under the known. We will then follow the images of the world through sensory organs and into the nervous system; inside, we will discover memories, which are accumulated records of earlier traces of the world; we will find neural structures that classify, process and summarise past and present traces of the world, and other structures that initiate actions on the basis of this processing, all the way out again to the motor signals that move the body and make it act upon the outside world. And the matrix-demon will say: 'I hope you enjoyed my little show. It is a pity you weren't available to take part in it.'

And of course, according to all that is known about the phenomenal world, I could not be present within that show. Nothing in the known physics translates the computations and signal processing within the nervous system (or anywhere else) into a subjective experience; I, the thinking thing, which cannot be mistaken about its own existence, do not arise from material phenomena which do not know that they exist. Not only is the world a construct of the demon: all the physiology surrounding my perceiving, knowing, feeling, willing, all the actions of the mind are part of the matrix. All except the element ergo sum in Descartes' famous cogito, that one part of the thinking thing which is aware of itself and cannot be fooled about it. This is roughly the argument which the philosopher and mathematician Gottfried Wilhelm Leibniz raised against materialist interpretation of the mind, half a century after Descartes, and that argument still stands.

Unless there is a way out. Perhaps there is something still unknown in the structure of the world, some subtle organisation of matter that lets mindless signal processing loop back onto itself, look into a mirror somehow, and give rise to self-awareness. That is a wildly speculative proposition, one which, as scientists, we are willing to entertain only because nothing can be a priori - self-evidently - excluded from the world of phenomena. If I could derive my existent self-awareness from the phenomenal world, I would know that both I and the world existed, the knower and the known would be reconciled, and Descartes' demon would be exorcised once and for all.

And so, following Descartes into modern scientific empiricism, we are left with a curious choice, a dilemma whose factual resolution, if a resolution is possible at all, must profoundly shake the cherished self-image of mankind. Either the 'thinking thing' is a solitary thought of unknowable origin and destiny, fundamentally different from the world which it perceives and of whose existence it can never be sure; or it is an ephemeral spray of self-awareness on the waves of the unthinking ocean below, a wisp of thought, a form bound to an unknown fate among all the other ever-changing forms of the material world.

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Dr. Danko Antolovic is a scientist and technologist at Indiana University, in Bloomington, Indiana, United States.


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