PHIL 101 - Lecture 18
- 1. Dualism March 28 2007
- 2. Dualism We’ll end with Descartes’ argument for what may be his most famous conclusion According to Descartes we don’t think by having bodies arranged in a clever way (like a fancy computer) Rather minds are separate things
- 3. Dualism The view that minds and brains are two kinds of things is called dualism The view that there is only one kind of substance is called monism The most common kind of monist view is materialism , the view that there are only material entities A monist who only believed in mental entities is an idealist
- 4. Dualism The argument Descartes makes at the start of the Meditation is made slightly more explicit at on page 54 Descartes relies on the possibility of our existing without our bodies
- 5. Dualism It is possible that my mind and my body could be separated If it is possible that my mind and my body could be separated, then they are distinct entities So my mind and my body are not identical
- 6. Dualism and Possibility Premise 2 is very odd It looks like Descartes is arguing something of the form: p is possibly true, so it is actually true He is arguing from the possibility of minds and brains being not identical to their being actually not identical
- 7. Dualism and Possibility This looks like a bad idea Consider the following argument It is logically possible that Cornell will win the NCAA basketball championship next year So, Cornell will win the NCAA basketball championship next year Don’t take that argument to Vegas!
- 8. Dualism and Possibility But actually this premise is correct This is because of special properties of claims about identity If a and b are identical, they have all of the same properties Really, it’s improper to use ‘they’ there because they are one thing
- 9. Dualism and Possibility Here is a property a has: Necessarily being where a is Since b is a , that’s also a property of b So if a and b are identical, b has the property: Necessarily being where a is That is, a and b must be in the same place
- 10. Dualism and Possibility If my mind and my brain were identical, then they would by necessity be co-located If they aren’t necessarily co-located, i.e. if God can separate them, then they are not identical And that’s Descartes’s second premise
- 11. Dualism and Possibility Descartes also has an argument for the first premise If I can conceive of something without contradiction, then that thing is at least metaphysically possible. I can clearly conceive of a world in which I exist but my body does not. So it must be possible for me to exist without my body.
- 12. Dualism and Possibility Arnauld argues that when we don’t understand something we conceive its possibility even though it’s impossible See pages 107-112 of Cottingham So perhaps this argument is too strong We’ll come back to similar arguments when we look at David Chalmers’ argument for a version of dualism
- 13. Dualism and Possibility But Descartes could get by without this strong claim, for there are other differences between mind and body My body changes while my mind stays the same My mind changes while my mind stays the same 1 is possible, 2 is impossible
- 14. Dualism and Possibility We don’t need to imagine mind being split from body to see 1 is possible Just consider what happens when my body digests food while I’m asleep My body changes, my mind does not More fantastically, imagine replacing a neuron with a chip that plays the same role
- 15. Responses We’ll end with three responses that could be made to this Cartesian argument First, we will question the logical principle involved Second and third, we’ll look at two ways in which this may not lead to any form of dualism
- 16. Leibniz’s Law The logical principle that Descartes is using is often called Leibniz’s Law Many people think that Leibniz’s Law needs to be qualified in certain cases Lois Lane believes Superman can fly Lois Lane does not believe Clark Kent can fly But still Superman is Clark Kent!
- 17. Leibniz’s Law You might infer that the law doesn’t hold when we’re talking about beliefs And once you’ve allowed in a qualification to the law, you might wonder whether other qualifications come in But this is not much of a positive response to Descartes
- 18. Constitution Two more responses will look at ways in which Descartes’s argument might be sound , but not entail dualism The body might constitute the mind The mind might be a property of the body In neither case is the mind identical to be body, but nor is dualism true
- 19. Constitution Consider the relationship between an orchestra, say the New York Philharmonic (NYP), and its members The NYP is not identical to its members It is over 170 years old, and none of its members are that old
- 20. Constitution So is there some thing , the orchestra, over and above the members, and wholly distinct from them No; the members constitute the orchestra In previous times, different members constituted the orchestra
- 21. Constitution We might say the same thing about the body/mind relation as the players/orchestra relation The body constitutes the mind The mind might have been differently constituted It is not some extra thing in the world It is not distinct from the body
- 22. Constitution Note that we can conceive of the orchestra being non-physical I think that’s probably possible Maybe we’d call it the NY Angelic A physical thing could have been constituted by non-physical stuff Minds might have been non-physical, but actually are physical
- 23. Properties Here is a variant of Descartes’ argument for dualism My body changes without my weight changing My weight changes without my weight changing Since 1 is possible and 2 is impossible, my body is not identical to my weight
- 24. Properties Should we conclude there is some extra thing in the world, my weight, that is wholly distinct from my body? That would be absurd My weight isn’t any kind of thing at all, so it isn’t a distinct thing Rather, it is a property of my body
- 25. Properties Descartes’ argument for dualism leaves open the possibility that my mind is a property of my body Gilbert Ryle, who’ll we start on next time, thinks that is the right response to make