Descartes Discussion Points 1. Foundations (p.95) Descartes believes that real knowledge is only possible if it is built on fixed foundations, which he compares to a fulcrum needed for a huge lever. Nowadays the search for foundations is challenged by those who believe justification is either external (e.g. reliabilism) or is internal coherence. Neurath's Boat, which has no anchor but stays afloat because its planks fit together nicely, is the alternative model. Most foundationalists rely on basic sense experience, so Descartes is unusual in looking for a rational foundation. Maybe any search for rational foundations is doomed to end in solipsism. 2. Sceptical method (95) As a way of discovering totally certain foundations, Descartes invents a technique of ruthless doubt. If there is any doubt, a belief must be rejected. Maybe he doesn't distinguish enough between scepticism as a method and as a doctrine. It is a good method, which goes back to Socrates, and is the basis of modern science as well as philosophy. As a doctrine it is probably too demanding, and he should have relaxed a bit once he found that none of his beliefs could be fully justified. The doctrine demands total certainty, and this may be beyond human beings (or even a logical impossibility for God!). 3. Senses deceiving us (96) His first sceptical argument is that if senses have once deceived you, that proves they are not reliable, so they must be rejected. (This deception could be either uncertain information from the world, or false information generated by the senses, or a misinterpretation of what is experienced.) It may be correct that we should be cautious about sense experience (as illusions repeatedly prove), but it is not clear what the argument proves. Surely we should be cautious about senses before they even deceive us once? And if they deceive you once, what should you conclude? Don't trust your ears because your eyes deceived you? Don't trust your senses when looking at distant objects? Don't trust your senses if mine have deceived me ? A sceptic won't even be sure that his senses have deceived him. 4. Dreams (96) He suggests that rejecting sense experience is madness, but then realises that we believe mad experiences every day, when we dream. Near the end (p.168) he decides that we are not dreaming, because we cannot connect the parts of dreams together coherently. His rejection of dreams near the end seems optimistic, based on the demon being severely limited by the existence of a non- deceiving god. He needs some concept like a 'super-dream' to explain why our waking lives are so vivid and consistent. The truth is we can never escape the dream argument; if we 'woke up' now, it might just be into another level of dreaming. 5. Ultimate reality (97) Descartes’ investigations are aiming at establishing some ultimate reality (perhaps the physical world) which is beyond doubt. His whole aim, in the first meditation, may be misconceived. Even by the end of the book he isn't totally certain about any features of reality, because he admits that we make some errors. He thinks that if we agree that physical objects are there then most of our problems are solved, but there remain questions about secondary qualities, quantum physics etc. 6. Uncertainty of maths (98-9) At first he thinks that maths may be something which is totally certain, but then realises that some powerful force could delude him about maths, and make him foolishly over-confident. If pure luck has created him, then maths is even less reliable. It is arguable that simple arithmetic is more self-evident to us than any arguments about powerful forces or the luck of nature. If we can't get the right answer to 2+3, should we waste our time trying to reason about reality? The theory of evolution offers an account of nature which might produce reliable maths (as a way of thinking that results in survival). If God could deceive us about maths, presumably the demon could deceive us about the Ontological Argument. 7. Mental Interference (98, 100) The possibility of a powerful force interfering with his mind is one of his major sceptical arguments. At first he thinks God might do this, but then thinks an Evil Demon would have a better motivation. We might suggest an evil scientist, or ‘The Matrix’. This is argument is also hard to deny. Every thought that appears in my mind could be a projection by aliens or a hypnotist. Descartes eventually says that something is self-evident even if my mind is a receiving station (because it is clear and distinct), but we could take that further and say that arithmetic is also self-evident, and even that consistent sense experience must self- evidently be accepted. 8. Memory (102) He realises that his memory might be unreliable, so even if he did find the truth, he might not be able to hang on to it. He is probably not sceptical enough about memory, and he underestimates its importance. Bertrand Russell said the universe might have been created five minutes ago, in which case most of our memories are fiction. If he can't trust his memory he can't accept the Ontological Argument, because he must hold all the steps of the argument simultaneously in his mind. 9. Solipsism (103) The realisation that he himself might be creating a delusion that the world exists (instead of an outside force causing it) implies the possibility that nothing exists at all except his own mind – a view which is now known as ‘solipsism’. The horrible logic of solipsism is hard to escape. Descartes uses the Ontological Argument to prove that something exists outside his own mind. The best known modern attempt is Wittgenstein's Private Language argument, which claims that a solitary language is a logical impossibility, because a rule-following language has to be a community activity. Empiricists have less trouble with solipsism, though Berkeley thought existence was nothing but perception, which seems to create a mental prison of sense experiences. Solipsism may be a logical possibility, but it hardly looks like the best explanation of our experiences. 10. The Cogito (103) He realises that the proposition “I exist” has to be true whenever he is thinking. Even if all his thoughts are wrong, he must exist to be wrong. This is true only when he is actually thinking, and it is then a necessary truth (which couldn’t be false). The argument does not seem to be an abduction from evidence, or a deduction following logical steps, but a claim that a truth is self-evident. Since the alternative seems to be that nothing exists, Descartes obviously has a point. If thoughts could exist without a thinker (and Plato's theory of Forms encourages this possibility) then the argument would fail, but it would then be hard to see what connects sequences of thought. We could suggest that he has pointed out an obvious presupposition of all our thinking and language, and that it is just a dull tautology, but he could fairly reply that the idea that we must exist is hardly an arbitrary idea; it is a totally inescapable idea, and therefore very significant. We could say that he is over-optimistic about the stability of the "I" he has proved (the Cartesian Ego), and on p.127 he himself recognises that his self could be fragmentary, especially if his thoughts are fragmentary. Hume's 'bundle' theory of the self is of a fluctuating thing which couldn't form the basis for Descartes' philosophy. Indeed, it is hard to see how the addition of "I" to his observation that there are thoughts actually explains anything, so Ockham's Razor might suggest that we leave it out. However, if his Cogito does no more than show the limits of possible scepticism, that would make it an important idea. 11. A Thinking Thing (105) Once he is sure he exists (when thinking), he wonders what he is. He rejects Aristotle’s ‘rational animal’, and decides he is only the minimum required for thinking, which he calls a ‘thinking thing’ (res cogitans). His idea of his self is extremely narrow and lacking in individuality, and there seems to be no evidence for this 'thing' apart from the thinking. However, it is a good commitment for a rationalist to make, because it means he can trust the existence and stability of his understanding, which is the basis of all his other ideas. His belief in dualism seems an inevitable next step. 12. Imagination (106) Once he is certain of himself as a thinking thing, he wants to expand his understanding to the external world. He considers whether imagination might provide the necessary bridge, but realises that is no more reliable than dreams. Later (150) he uses the chiliagon example to prove that imagination is far less important than his understanding. He seriously underestimates the importance of imagination. It may not link him to reality, and he may be right that we can understand things we can't imagine (God? infinity?), but imagination is surely an essential and integral part of our ability to reason and understand. Doesn't he use his imagination when he is deciding that the molten wax is still wax? 13. Phenomenalism (107) As he realises the difficulty of finding a bridge from his mind to the external world, he begins to wonder whether he can only ever be certain of his experiences, and can never say for sure what the experiences are of. This view (which he rejects, because he "cannot help believing" in objects) is nowadays known as Phenomenalism. He dismisses this view too quickly. Realism isn't true just because we want it to be, and sceptical and cautious philosophers often find they can get no nearer to reality than phenomenalism. Without God, this might be where Descartes came to a halt. 14. Wax example (108) He checks what he has found so far about his mind by considering normal experience of objects. A lump of beeswax can completely change its sense experiences, but he still judges it to be wax, so he is indeed a thinking, judging thing, for whom experience is secondary. This is also true when he judges rather than sees that there are people in the streets. Descartes never says why he judges the puddle to be still wax, and the suspicion is that it is because of comparison with other experiences, particularly watching the process of melting, and remembering that when it cools down it re-solidifies. However, he could still defend his view that it is judgement which finally decides what the puddle is, and which makes the comparisons. The wax is an unusual example, and might be compared with water/ice, wood/ash, and Socrates turned into a pig by a magician. 15. Rationalism (109) It is now clear that Descartes is highly sceptical about his senses, but cautiously confident about his reason. He is clearly what we now call a Rationalist, who believes that human knowledge is assembled by reason, and does not arise directly from sense experience. Once we realise this, it becomes clear that many of Descartes' arguments can be attacked by putting forward the empiricist view of things. Perhaps experience is as obvious as my own existence; maybe experience gave me the idea of a supremely perfect being; maybe our knowledge of wax grows directly from experience (by making connections in the brain); maybe a priori knowledge cannot be synthetic. Maybe reason is a cultural or biological construct, not a pure Platonic ideal. 16. Truth (113) He observes a crucial element in the operation of his understanding, which is that he accepts propositions as true whenever he ‘clearly and distinctly conceives’ them. He offers this as a definition of truth. His idea of truth is very subjective and open to relativism, but then he doesn't have much choice. He depends on occasional detection of errors to verify which ideas were really clear and distinct, but how does he detect errors? His theory seems to lead to the coherence theory of truth (in which ideas are clear and true if they interlock like jigsaw pieces, with no contradictions), and this is a respectable modern view. Empiricist will tend to disagree, preferring the correspondence theory, which is impossible for Descartes as he doesn't trust the external facts which are supposed to correspond to the internal propositions. 17. Categories of Ideas (115) He notes that his understanding contains three types of thought – ‘ideas’, ‘attitudes to ideas’ and ‘judgements’. The ideas are of three types – innate ideas (known a priori), adventitious ideas (experiences which just happen to us) and invented ideas (which we imagine). His analysis of ideas is very interesting and seems right, but there are criticisms. His idea of pure judgements doesn't do justice to the complicated mental process involved in rational thought (which includes imagination, and even emotion). Innate ideas are controversial. The real picture seems more complicated, but Descartes made an important start to the topic. 18. Innate Ideas (143) Descartes is committed to a classic belief of rationalists (like Plato, who illustrated the point with the slave boy in “Meno”), that ideas are built into a rational mind, and can be understood and learned from by the ‘natural light’ of reason. His examples are triangles, a chiliagon, the concept of a supremely perfect being, and the fact that what has been done cannot be undone. This concept is much attacked by empiricists like John Locke (1690), who asked how we could tell the difference between innate ideas and learned ones. Hume (1739) said all our ideas, without exception, are built up from 'impressions', which are mostly sense experiences. It may be that geometry is built up from man-made definitions, and so we have created triangles. 19. Trademark Argument (128-30) Among the ideas which are obvious to his ‘natural light’ are the ideas of perfection, of infinity, and of the idea of these qualities being united in one being. Such thoughts are too great to have been invented by him, so this being must have placed them there. God must exist, because he can see the mark of God in his own mind, like a trademark on a human artefact. The obvious reply is that perfection and infinity are built up from experience ('what could the ultimate footballer do?', 'if I continue this line without stopping, where will it end?'). We might also wonder whether unicorns and the Loch Ness monster must exist, just because we find the ideas of them in our minds. 20. No Deceiver (131, 158) Given that there is God, and that he must be perfect, he concludes that he is "no deceiver", which will mean that all his experiences contain "some truth", and that radical or global scepticism can't be true, and the demon can't control reality. It seems a rather human point of view that God (like nice people) won't deceive us. Maybe we can't cope with the truth, or it would hurt us too much, or we don't deserve it. Descartes seems a bit unimaginative at this point. 21. Ontological Argument (144-7) Returning to God, he notes that he has a concept of a triangle, and can discover truths about it (its internal angles make two right angles) by analyzing the idea. He realises he can do the same with his concept of a ‘supremely perfect being’. It must contain all appropriate perfections, and among these must be real existence; without this it would fail to be the concept he is considering. It is therefore a necessary truth that God has to exist, as a consequence of the very concept itself. (see separate handout ) We can attack the preliminaries of the argument, which are innate ideas, synthetic a priori knowledge, and the concept of a 'supremely perfect being', but the heart of the discussion is over whether existence is one of the characteristics of a supremely perfect being. Kant says that the sentence "the supremely perfect being must exist" is either analytic or synthetic; if it is analytic, then existence is taken for granted in the concept of the supremely perfect being, and the whole thing is a "miserable tautology"; if it is synthetic then it could be false, and evidence will decide its truth. In any case "existence is not a predicate", which means that existence is not a characteristic of things, like being omnipotent or green. If existence is a predicate then arguments about the existence of things like coins would be impossible, because one side is talking about existent coins and the other side about non-existent coins, which makes a nonsense of the argument. If you insist that there is a red monster in the lake, and I insist that there is no green monster in the lake, our disagreement becomes pointless. If you defend an existent God, and I attack a non-existent God, what are we talking about? 22. Cartesian Circle (149 top) Unfortunately Descartes goes on to assert that his acceptance of ‘clear and distinct conception’ as true must be a reliable method, because God would never allow him to be totally deceived about such thing. However, he forgets that he has already used this concept of truth to prove God’s existence in the first place, because he clearly and distinctly conceived the concept of a supremely perfect being. This is a straightforward error, but does it matter? It certainly reveals a lack of confidence in clear and distinct conceptions that he needs God to prop them up. If, however, he just accepts clear and distinct conceptions without divine support, his sequence of argument might still work. But his faith in his clear and distinct conceptions has to be even stronger than the Cogito. 23. Mind and Body (156, 164) Descartes has implied ever since the Cogito that his mind is of a different order from his body, but he now tries to prove it. His mind necessarily exists when he is thinking, but his body doesn’t; mind does think, but physical things don’t; brains occupy space, but ideas don’t; the brain is divisible, but the mind is a unity. He therefore says mind and body are separate substances (‘dualism’). The major attack on Cartesian dualism is the 'interaction' problem. If mind and body are totally separate substances, how can they affect one another, as they seem to; stubbing my toe hurts , and I decide to move my arm. Nowadays we know that mind and brain are so closely interwoven that it is hard to imagine them being separate. Is an out-of-body experience really possible? How would the mind see things, if it has no physical retina to react to photons? How could we survive death? Descartes' own arguments for dualism tend to beg the question. Perhaps the brain does think; maybe the mind is divisible, with a scalpel. 24. God and error (161-6) ‘God is no deceiver’, he says, so the external world must exist, and all experience must contain some truth. Why, though, do we commit errors? He decides that external errors (like misjudging the size of stars) are due to the fact that our senses are suited to local knowledge needed to run our individual lives. Errors that put us in danger (like not detecting poisons) are unavoidable, because poison-detection would mess up our normal perception. Self-generated errors (like dropsy sufferers wanting excessive drink) only arise when we are ill, which is still a perfectly natural process. In fact our senses are wonderful, as the nervous system demonstrates. Descartes seems to be evading the problem of why God would allow me to make such dangerous mistakes. No parent would want their child to be so vulnerable to poisons and illness. The point that we are only reliable in areas where our own lives are at stake is fair enough, and matches the modern evolutionary view. The efficiency of the nerves is nicely chosen, and a good example of divine design, if evolution is ignored.

Peter Gibson