By “soul”, I mean something beyond the body, which nevertheless is an essential part of “me”.
I will use the method Reductio ad absurdum (“reduction to the absurd”): I will assume the opposite of what I am trying to prove. If this leads to an absurd outcome, I will be able to conclude that the original assumption was false.
1. Assumption: I am merely an organised collection of material “stuff” (atoms, molecules, cells, etc).
2. Therefore, what I call “my thoughts” are merely sequences of electrochemical changes in my brain.
3. All beliefs are thoughts.
4. Therefore, a belief is a sequence of electrochemical changes in the brain.
5. These electrochemical changes are caused by external events in the past (plus a certain amount of quantum randomness).
6. Therefore, my beliefs (including my original assumption) are not connected to the actual truth about the universe.
7. This is absurd. [As CS Lewis wrote: “You cannot have a proof that no proofs matter.”]
8. Therefore, there is something more to “me” than my physical body, which one may identify as “the soul”.