I have very strong beliefs about the death penalty. I believe it is the only just punishment for murder; that ALL murderers should be executed; that anything less than execution is a grave miscarriage of justice for a crime that is so horrible the mind cannot even wrap around it. I also think that pain should be part of the death penalty... that a murderer doesn’t deserve a quick and painless death but rather a healt…
What if they did the murder because of a brain tumor messing up their impulse control ability? Humans are just complicated machines that go wrong sometimes. I do however share your emotional position and it would make me feel better to see (actual) murderers get the death penalty.
But as another comment pointed out, we do account for this.