PHIL 101 - Lecture 18


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PHIL 101 - Lecture 18

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