dualism

Argument from Semantic Determinacy of Thought

1. There is a fact of the matter about what concepts mean
2. There is no fact of the matter about what anything physical means
3. So, concepts are not physical

• O1: our thoughts aren't determinate
  • R1: self-defeating
• O2 (Peter Dillard): in computer science, there is a determinate difference between an and-gate, an or-gate
  • R1: physically determinate, not semantically determinate
• O3: neuroscience shows connection between thought and brain
  • R1: the physical is necessary, but not sufficient, for thought

• Plurality Thesis
  1. Any physical object, O, will have some particle, P, along its edge which has just as good of a claim to be part of O as to not be part of O
  2. So, O-with-P has just as much of a claim to be the object as O-without-P
  3. So, both are objects that overlap everywhere but at P
  4. There are billions of particles like P around O
  5. So, for every object O, there are billions of overlapping O’s
• Argument from the Plurality Thesis

1. PA: Physicalism is true
2. So, Plurality Thesis
3. I am in a certain psychological state, E
4. By (1), my brain, B, is in E
5. By (2) and (4), there are billions of brains in E
6. ~(5)
   • S1: I clearly don’t share my psychological states with any other brains, much less billions
7. So, ~(1)
8. So, dualism is true

• N1: this isn't quite true--disproving physicalism leaves it open that you could be an ontological idealist
• N2: proves substance dualism

1. If the mind and some part of the brain, B, are identical, then the mind and B must have all properties in common
2. The mind has a property, F, and B lacks F
   • S1: intentional aspect of thought
   • S2: sensations
   • S3: first-person experience
   • S4: unity of consciousness
     1. People have a united conscious experience
     2. Complex things cannot have a united consciousness
        • S1: consciousness is not additive
        • S2: a set is not a thing, so it doesn't have properties
     3. A simple physical thing does not have a united consciousness
        • O1: there could be a CPU in the brain that is the locus of all awareness
          • R1: there is no evidence that brains work this way and good evidence they don’t
          • R2: such a module would be complex, leading this argument to regress back to a simple physical particle with united consciousness, which would be strange
     4. So, mind has a property the body doesn’t
3. So, the mind and B are not identical
4. So, dualism is true