The following argument is valid:
- (Premise) Necessarily, it is unjust to condemn a person for something that she is in no way responsible for.
- (Premise) Necessarily, it is not unjust to condemn a person for having a gravely wicked character when she in fact has a gravely wicked character.
- (Premise) If physicalism is true, it is possible for a person to have a gravely wicked character that she is in no way responsible for.
- It is impossible for a person to have a gravely wicked character that she is in no way responsible for. (By 1 and 2)
- So, physicalism is not true. (By 3 and 4)
Still, I am not really all that confident of (2). Part of my lack of confidence has to do with Christian intuitions about not condemning others. But those intuitions may not be relevant, since (2) concerns justice, while the Christian duties of forgiveness and non-condemnation are grounded in charity, and a desire to oneself be forgiven by God, rather than in justice to the wicked. Still, I am not sure of (2).
The quantum tunneling argument I gave for (3) in fact established a stronger claim than (3): it established the claim that if physicalism is true, it is causally possible for a human person to be gravely wicked without any responsibility for that. This means that we can weaken (1) and (2) by replacing "person" with "human person" and "Necessarily" with "Causally necessarily". I don't know if this does much to make (2) more plausible.
Whatever the merits of the argument, I think it is an independently really interesting question whether (4) is true.