First off, I am a dualist, but I am not a dualist of the Cartesian stripe. I think that Cartesian dualism/substance dualism (different term for same thing) has been seriously challenged by the findings of modern neuroscience. However, both property dualism and hylemorphic dualism still remain unchallenged. I am a proponent of hylemorphic dualism, but I will try to stay (fairly) objective.Thought Experiment (p. 221)

Minds are immaterial, and bodies are not. The mind is able to grasp immaterial objects, such as numbers and Platonic Forms. The body, itself is not. The mind has subjective experiences, such as qualia. The body does not have subjective experiences. These are enough to establish the body and mind as separate, yet interacting entities. Consciousness is immaterial, the body is not. Descartes and I disagree on some items of this list (I think it is possible to imagine yourself not having a mind- see Churchland and Dennett). I also think that the argument from consciousness can be construed as a Soul of the Gaps argument, because its an inductive argument. I would much rather show the metaphysical necessity of a separate mind than attempt to create an inference to the best explanation or cumulative case.Stop and Think p. 224 I do not think that being of two minds really counts against substance dualism or the indivisibility argument. The interaction problem is far more problematic for Cartesian Dualism.Stop and Think p. 225Well, there are several ways to deal with it. Many materialists (physicalists- is there really much of a difference?) would argue that we simply arent conscious, and that consciousness is illusory. This is the position of eliminative materialism, which has severe problems that I wont go into here. A physicalist could also claim that consciousness is ontologically reducible to a complex series of neurotransmitters. Finally, a physicalist could claim that consciousness is an emergent property of the brain, and while it is not ontologically reducible, it is certainly inseparable from the brain.I will respond to the negative evaluation first from a Cartesian view, then from a Thomistic/hylemorphic view.Responding to the negative evaluation:1. This is indeed a severe problem for the Cartesian dualist. However, one could argue that God is the reason for the connection (occasionalism). On a Thomistic view (or a property dualist view) this isnt really a problem. On both views, the mind is linked to the brain, though they are separate entities and not ontologically reducible.2. Again, a problem for the Cartesian dualist. This is resolved by epiphenomenalism, which holds that events in the body and brain can create events in the mind. Again, however, this does not have any effect on the Thomistic viewpoint. If we accept the brain and minds linkage, then its only logical that brain damage would have an effect.3. Another issue for Cartesian dualism, but not for property or Thomistic dualism. This does seem like an issue for substance dualism, and its one that I actually dont have an answer for. However, Im coming from the position that I think Cartesian dualism wrong, as its beholden to a metaphysically mechanistic picture. I subscribe to the Aristotelian-Thomistic picture, which does have some support from modern science.