1. DUALISM

2. Dualism Monism Traditional Religion Experience Our bodies may be damaged whilst our minds are active Our mental experience is private Science Neurological biology Empiricism Logical positivism (behaviourism)

4. Dualists believe that there are material substances (bodies) and mental substances (minds) that are distinct from each other Plato and Aristotle were Dualists

5. Plato In the Phaedo Plato gave two arguments for thinking that the souls are not dependant on bodies and can exist separately: All unseen things are unchanging and ‘simple’ (not divided into parts) If they don’t have parts they can’t be ‘broken up’ or destroyed The soul is unchanging and simple, so it can’t be destroyed

6. Everything comes about from its opposite When you change something, you change it from what it is, to what it (currently) is not Life is changed into death which is separation of soul and body So the joining of the soul and a body must cause life and the soul must be pre-existent

7. Plato used the term nous to describe the part of the individual that survives the death of the body (the soul or mind) In both arguments Plato presumes that the soul exists

8. Cartesian or Substance Dualism In the Sixth Meditation, Descartes argued that his mind and body are distinct things Not only are they distinct things, they are distinct kinds of things (they have different primary attributes) His mind is a thinking substance, and his body is physically extended and has mass

9. In The Description of the Human Body Descartes says that the body has material properties and works like a machine The mind (or soul) is non- material and does not follow the laws of nature

10. However Descartes thinks that the mind and body are closely connected: “Nature teaches that I am present to my body not merely in the way a sailor is present in a ship, but that I am most tightly joined and, so to speak, commingled with it, so much so that I and the body constitute one single thing”

11. Descartes speculates about the nature of this “commingling” of the mind and body He says that he is aware of his body and its surroundings by means of sensation Pain, hunger, and thirst are “confused sensations” which enable his mind to detect the needs of his body

12. His experiences of colours, sounds, and odours lead his mind to judge that: “various other bodies exist around my body, some of which are to be pursued, while others are to be avoided”

13. The brain is part of the body and certain brain events cause sensations to occur in his mind “my mind is not immediately affected by all the parts of the body, but only by the brain, or perhaps even by just one small part of the brain”

14. He also thinks that his mind is capable of causing events to occur in his body Experiencing pain “as if it is occurring in the foot … provokes the mind to do its utmost to move away from the cause of the pain”

15. So the mind controls the body However the body can also influence the otherwise rational mind (as when people act out of passion) Most of the previous accounts of the relationship between mind and body had been uni-directional

17. The Passions of the Soul Descartes argued the mind and body causally interact at the pineal gland which is "the seat of the soul" He believed this because the soul is unitary, and unlike other areas of the brain the pineal gland appeared to be unitary

19. Descartes appears to endorse dualistic interactionism: Dualism: Mind and body are fundamentally distinct kinds of things Interactionism: Mind and body directly causally interact with each other

20. Rene Descartes Elizabeth of Bohemia

21. Elizabeth’s challenge a body can only be directly caused to move by physical contact with another body a non-extended thing can’t make physical contact with anything So unless X is extended, it can’t directly cause a body to move

22. The Interaction Problem (1) If X directly causes a body to move, then X is extended (2) If X is a thinking substance, it is not extended (3) So, if X is a thinking substance, X cannot directly cause a body to move

23. Descartes endorses premise (2) Elisabeth offers considerations in favour of (1) Her line of thinking is intuitive and is in line with Descartes’s own mechanistic physics

24. Descartes first responds by saying that we cannot understand or explain mind-body causation by thinking about body-body causation The two kinds of causation are fundamentally distinct

25. Descartes uses our idea of weight as an example of this confusion Scholastic physics regarded weight as an intrinsic property of a body that impelled it to move towards the centre of the earth If bodies have weight, they can be caused to move without having any physical contact with another body According to Descartes's physics, bodies do not have this property (gravitational effects are explained by the movements of invisible particles surrounding the earth that push objects toward its surface) When we attribute weight to bodies, we are incorrectly attributing to them the causal power of minds

26. In her response, Elisabeth says: I admit it would be easier for me to concede matter and extension to the soul, than the capacity of moving a body and of being moved, to an immaterial being This is because she cannot conceive of an immaterial thing as anything but the negation of matter

27. She then offers a possible solution: that the soul moves the body by communicating information to it, however, the information can only be interpreted and understood by the body if the body possesses intelligence and Descartes denies that matter can be intelligent

28. Descartes replies that if it is easier for her "to attribute matter and extension to the soul” she should do so By doing this she will be able to conceive of the union of soul and body, but at the same time come to realise that they are two distinct things!

29. Elizabeth this unsatisfactory because (a) if the soul is not extended (as Descartes maintains) how will conceiving it as such explain away the interaction problem? Also, (b) if we are to conceive of the union of body and soul, this would involve conceiving of some sort of causal connection, but that's precisely the thing that she is not able to do!

30. Up until now, Elisabeth was primarily focused on asking how the immaterial mind could causally influence the actions of the material body Now, she asks for clarification on the other side of the interaction problem: How is it that the "passions" (i.e., bodily feelings like hunger or physical pleasure) can interact with the non-material mind to influence our thoughts?

31. In The Meditations Descartes says that that the question “what am I?” can be answered by considering what is essential for me to have to exist He says that he can doubt whether he has a body because his perceptual experiences could be mistaken or he could be being deceived into believing he had a body by an evil demon The Knowledge Argument

32. However he cannot doubt that he is thinking Because he is thinking he must exist (Cogito ergo sum) He concluded that he exists as a being “the essence of which is to think” It would be possible for him to exist without a body, but not without a mind

33. We can object that he hasn’t shown that the mind exists as a separate substance, he could be no more than a succession of thoughts

34. Just because Descartes can think of his mind existing without his body, this doesn’t mean that it really can exist without his body If the mind is the body, his conception is wrong

35. We need an independent reason to think that the mind is distinct from the body We should be cautious in using what we can conceive of as a test for probability This can be illustrated using the ‘masked man fallacy’:

36. Once Descartes has established that he exists and that God exists, he thinks it is reasonable to assume that we do have bodies, even if it is possible that we do not However as minds can exist without bodies, the two must be separate

37. Argument from God’s omnipotence I have separate ‘clear and distinct’ ideas of mind and body God has the power to produce things which I clearly and distinctly perceive ‘precisely as I conceive them’ Therefore, God has the power to make my mind exist separately from my body Therefore, my mind is distinct and separate from my body

38. The Indivisibility Argument If we can say that the mind has properties which the body does not (or vice versa), then we can use Leibniz law of indiscernibility to conclude that the mind is not the same as the body

39. The body is divisible into parts The mind is not divisible into parts Therefore, the mind and the body are different substances

40. Leibniz’s law of the indiscernibility of identicals states that if two things have different properties they are not identical If and only if ( ∀ ) for all properties (F), x and y have the same properties then x is identical to y ∀ F(Fx ↔ Fy) → x=y

41. I know I am thinking (I have a mind) I do not know that I have a body Therefore my mind and my body are not the same thing

42. Masked man fallacy (illicit substitution of identicals) The substitution of identical designators in a true statement can lead to a false one

43. Lois Lane doesn’t know who Superman is… Lois Lane knows who Clark Kent is… THEREFORE CLARK KENT IS NOT SUPERMAN

44. Suppose I believe (rightly) that a masked man robbed a bank, I also believe that my father has not robbed the bank. I conclude that my father is not the masked man

45. If I only believe that my father is not the masked man, I could be wrong Similarly I could be mistaken about the properties things have

46. Summary The knowledge argument proves I am essentially a thinking being (a mind) I have separate ‘clear and distinct’ ideas of mind and body, each with separate properties God has the power to produce things ‘precisely as I conceive them’ The body is divisible but the mind is not Therefore they are different substances

47. Is the mind a substance, if not what is it? Is the mental divisible? Is everything thought of as physical divisible? Do thoughts require a thinker? Are thinkers substances?

48. Do thoughts need a thinker? In an appendix to the Meditations called ‘Objections and Replies’, Descartes claims that thoughts logically require a thinker Substances possess properties. e.g. the chair (substance) is solid (property) Properties can’t exist without substances Similarly thoughts can’t exist without a thinker

49. Substances can persist through changes in properties e.g. a thinker can think a series of thoughts Descartes implies that he is the same ‘thinking thing’ that persists from one thought to another However he also admitted that: ‘I exist – that is certain. But for how long? For as long as I am thinking. But perhaps no longer than that; for it might be that if I stopped thinking I would stop existing’

50. So even if we agree that there can’t be a thought unless something thinks it, that doesn’t entail that it’s the same subject Each thinker might exist for just one thought

51. In dreamless sleep, we cease to think consciously If Descartes wishes to establish that he is the same person from one day to the next, he will need the idea of the mind as a substance that persists even when there is no thought

52. Descartes might reply that he remembers things and that many of his mental states (beliefs, hopes, plans) are the same Therefore he must be the same substance before and after the cessations in thought

53. Even if we accept that thoughts require a persistent thinker this does not imply that the mind is a mental substance We could be a physical substance with thoughts

54. If we conceive of mind as something that thinks and of body as something that is extended it does not follow that we conceive of mind as something that thinks and isn’t extended or of body as something that is extended and does not think

55. There is nothing in the initial conceptions of mind and body that oppose each other Likewise, there is no contradiction or (obvious) contradiction in conceiving of body as something that is extended, but which may, in some instances, also think

56. If this is right, then we can conceive of mind and body as distinct substances or we can think of thought and extension as properties of the same substance