Physicalism about minds: Human minds, wills and their states are entirely constituted by the physical.

Dualism: Human minds and wills are at least partly constituted by something beyond the physical, or at least their states are.

A handful of arguments for dualism

Identity

  1. (Premise) If physicalism is true, then either the error, conventional, body, brain, memory or purely physical animal theories of personal identity are true.
  2. (Premise) None of the latter are true.
  3. Hence, physicalism is false.

 

Free will

  1. (Premise) If physicalism is true, then either we have no free will or compatibilism is true or freedom is grounded in quantum fluctuations is true.
  2. (Premise) We have free will.
  3. (Premise) Compatibilism is false.
  4. (Premise) Freedom is not grounded in quantum fluctuations.
  5. Therefore, physicalism is false.

 

Descartes

Let P(e) be short for “The existence of e is not open to doubt, no matter what demon may deceive me.”

  1. (Premise) P(me).
  2. (Premise) There is no body x such that P(x).
  3. (Premise) If x=y, and F(x), then F(y).
  4. (Supposition for a reductio) I am identical with a body x.
  5. P(x). (By 1, 3 and 4)
  6. not P(x). (By 2 and 4)
  7. Hence, I am not identical with a  body.

 

Survival

  1. (Premise) If physicalism holds, then it is logically impossible to survive the complete destruction of the body.
  2. (Premise) It is logically possible to survive the complete destruction of the body.
  3. Therefore, physicalism does not hold.

From categoriality

  1. (Premise) If physicalism holds, then my thoughts have physical properties such as charge, energy, shape or mass.
  2. (Premise) My thought that there exist triangles does not have any physical properties such as charge, energy, shape or mass.
  3. Therefore, physicalism is false.

 

A handful of arguments for physicalism

Simplicity

  1. (Premise) If a simpler theory can explain the same data as a more complex one, the simpler is more likely true.
  2. (Premise) Physicalism can explain the same data as dualism can.
  3. (Premise) Physicalism is simpler than dualism.
  4. Therefore, probably, physicalism is true.

 

Closure

  1. (Premise) If an entirely physical event has an immediate cause, then the cause is entirely physical.
  2. (Premise) If dualism holds, then some entirely physical event is caused by something not entirely physical.
  3. Therefore, if dualism is not true.

 

Successes of neuroscience

  1. (Premise) The presuppositions of a highly successful science are likely to be true.
  2. (Premise) Physicalism is a presupposition of neuroscience.
  3. (Premise) Neuroscience is a highly successful science.
  4. Therefore, physicalism is likely to be true.

 

Robots

  1. (Premise) If it is logically possible for a mind and its contents to be entirely constituted by the physical, human minds are constituted by the physical.
  2. (Premise) It is logically possible for a robot to be conscious.
  3. (Premise) If a robot had a mind, that mind and its contents would be entirely constituted by the physical.
  4. Therefore, it is logically possible for a mind and its contents to be entirely constituted by the physical. (By 2 and 3)
  5. Therefore, physicalism is true. (By 1, 4 and the definition of physicalism)