What is it to Have a Mind?

1. What is it to Have a Mind?

2. What is it to Have a Mind? Two Central Questions: • What are minds? • How do minds relate to/interact with bodies?

3. What is it to Have a Mind? Recall our list of mental states: • Thoughts • Beliefs • Desires • Current experiences and sensations • Emotions

4. What is it to Have a Mind? A mind is something that can be in such states as these. But what is a mind and how does it relate to physical things like our bodies?

5. Substance Dualism It is common to think that we are not just physical things, but that we have a non-physical nature.

6. Substance Dualism Substance Dualism: There are substances of two fundamentally and irreducibly distinct kinds in the word: mental stuff, and material stuff.

7. Substance Dualism According to substance dualism minds are immaterial things that are not made up of physical matter. This lines up closely with the idea of that we have a soul or a spirit.

8. Substance Dualism It is probably true that the vast majority of people are substance dualists: • Most major religions endorse something of this kind • Many people believe they can survive the death of their bodies • You see this assumed in fiction all the time (books and movies about ghosts).

9. Leibniz’s Law In order to make sense of Descartes’ arguments it is useful to have the following principle: Leibniz’s Law: If A and B are numerically identical then A and B share all of the same properties.

10. Kinds of Identity Qualitative Identity: A and B are qualitatively identical if and only if A and B have all the same properties. Numerical Identity: A and B are numerically identical if and only if they are one and the same thing.

11. Kinds of Identity So Leibniz’s law says that if A and B are numerically identical then they must also be qualitatively identical. (Not the reverse)

12. Leibniz’s Law In other words, if A and B have different properties then they cannot be the same thing.

13. Leibniz’s Law An example of how you might use the principle: • Superman is flying across the sky. • Jimmy Olsen is not flying across the sky. • Therefore, Superman is not Jimmy Olsen.

14. Argument from Doubt Argument from Doubt • I can doubt the existence of my brain and body. • I cannot doubt the existence of my mind. • Therefore, my mind is not the same thing as my brain or body.

15. Argument from Doubt I can doubt the existence of my brain and body. This premise is supported by thinking about the evil demon scenario. In such a case I don’t have a body or brain, so I can consistently doubt that I have a body or brain.

16. Argument from Doubt I cannot doubt the existence of my mind. This follows from Descartes’ cogito. I cannot consistently doubt that I have a mind, because doubting is a mental state!

17. Argument from Doubt Therefore, my mind is not the same thing as my brain or body. Follows from the premises by Leibniz’s law. My body has a property that my mind lacks (being able to be doubted by me to exist) so they can’t be the same thing!

18. Argument from Doubt If this argument works, then it establishes that substance dualism is true: • My mind is not identical to my body • Therefore they must be two, different things.

19. A Fallacious Inference There is problem with how Leibniz’s Law is applied in the argument from doubt.

20. A Fallacious Inference Consider the following argument: • Lois Lane doubts that Clark Kent can fly. • Lois Lane does not doubt that Superman can fly. • Therefore Superman is not identical to Clark Kent.

23. A Fallacious Inference What if Manti Te’o reasoned as follows: • I believe that LennayKekua is dead. • I don’t believe that RonaiahTuiasosopo is dead. • Therefore, LennayKekua is not identical to RonaiahTuiasosopo.

24. A Fallacious Inference What is going wrong? You can’t use what we believe, doubt, or can doubt about things in order to prove that they are not identical using Leibniz’s Law.

25. A Fallacious Inference So we need an argument that does not make use of Leibniz’s law in this fallacious manner. Fortunately Descartes gives us one!

26. The Conceivability Argument “First, I know that everything which I can clearly and distinctly understand is capable of being created by God so as to correspond exactly with my understanding of it. Hence, the fact that I can clearly and distinctly understand one thing apart from another is enough to make me certain that the two things are distinct, since they are capable of being separated, at least by God……On the one hand I have a clear and distinct idea of myself, in so far as I am simply a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far as this is simply an extended, non-thinking thing. And accordingly, it is certain that I am really distinct from my body, and can exist without it.” (Sixth Meditation)

27. The Conceivability Argument The Conceivability Argument • If I can conceive of some state of affairs without contradiction, then that state of affairs is possible. • I can conceive of myself as existing without my body. • Therefore, it is possible for me to exist without my body. • It is not possible for my body to exist without my body existing. • Therefore, I am distinct from my body. (by LL)

28. The Conceivability Argument The entire force of the argument depends on premise 1: the claim that conceivability entails possibility.

29. Conceivability and Possibility Despite the claim’s intuitive force, most philosophers think that it is false. That is, it is possible for someone to conceive of something, without that thing being possible.

30. Arnauld’s Triangle Steve knows about right triangles, but does not know the Pythagorean theorem (a2+b2=c2) Suppose we ask him if it is possible to build a room in the shape of a right triangle with the following dimensions: 4x7x10. He may very well say yes!

31. Arnauld’s Triangle Furthermore, he may try to imagine the room, plan where he would put furniture in it, etc. But such a room is impossible! Hence, the fact that Steve can conceive of such a room does not entail that the room is possible.

32. Amnesia Case Suppose I have amnesia and don’t remember my name. I hear about this terrible instructor: Tim Butzer. I imagine a world in which Tim Butzer is dead and I am attending a party to celebrate his timely demise.

33. Amnesia Case But since I am Tim Butzer, it is impossible for Tim Butzer to be dead, and for me to be attending a party! Hence, conceivability does not entail possibility.

34. Hesperus and Phosphorus Hesperus is the first visible star in the evening and Phosphorus is the last visible star in the morning. Someone could imagine a case in which Hesperus is in the sky while Phosphorus is not. Indeed they may think this happens every evening!

35. Hesperus and Phosphorus But Hesperus and Phosphorous are actually both Venus! So every time Hesperus is in the sky Phosphorous is too (they are the same thing).

36. Conceivability and Possibility All three cases share a common feature: the subject in each is ignorant of some key facts about the case.

37. Conceivability and Possibility But it seems as if Descartes (or we) could be in precisely the same situation with regards to the relationship between minds and bodies.

38. Conceivability and Possibility Since conceivability does not entail possibility Descartes’ argument is not sound. Therefore, we have no good argument for substance dualism.

39. Next Time All we have done is show that some arguments for dualism are not sound. Next time we will look at arguments which attempt to show that dualism is false.

40. Problems for Dualism Papers Due on Thursday

41. Getting Clear on Dualism According to the dualist: • Minds and bodies are two fundamentally different kinds of things. • Minds are immaterial.

42. Getting Clear on Dualism But what does it mean for something to be immaterial?

43. Getting Clear on Dualism Material things have certain kinds of properties: • Spatial location • Extension • Mass • Motion • Solidity

44. Getting Clear on Dualism Immaterial Object: Lacks spatial location, extension, solidity, motion, mass, or any physical properties Dualists claim that minds are things of this kind.

45. Interactionism But minds interact with physical things. • Mental events can cause physical events. • Physical events cause mental events.

46. Interactionism Interactionism: Minds interact causally with physical things.

47. Interactionism Interactionism is an enormously plausible thesis. It seems to be one of the most basic and obvious facts about minds that they are able to interact with bodies.

48. Interactionism The main problem for dualism is that it seems to be inconsistent with interactionism.

49. First Problem:Causal Overdetermination According to every systematic theory of physics since Newton, every physical event in the universe has a physical cause. This is in tension with the dualist’s claims that some physical events have mental causes.

50. First Problem:Causal Overdetermination Say that I raise my hand. According to our best physics, there is a physical cause sufficient to produce this action. According to the dualist there is also a mental cause for this action.