What an interesting chapter! I was not very familiar with this material before. I wonder how much of it is explicit in the sources and how much is DeWitt extrapolating though.
Particularly impressive points as I understood them:
- The need for soul atoms (ie the nervous system, sort of) to interact with the body to give rise to sensation. This makes sense to me even though it is apparently a controversial issue in current philosophy. But it does seem to follow from the physics.
- The automatic vs intentional thinking, this is very perceptive psychology and also makes a lot of sense. It brings to mind the later dual process theory.
- The courtroom analogy. Is this entirely DeWitt? Again very clarifying and brings context to "all sensations are true".
I did not entirely grasp why it should be worse to think that Acheron might exist than to be sure that it does.
I also wonder what evidence could have led Epicurus to claim that the rational soul is situated in the chest. The Stoics apparently also thought this so perhaps it was a cultural idea? Or because you die if you get stabbed there?