how much of their criminal behavior is due to mental illness/disorder and how much is due to free will
The two possibilities are not mutually exclusive. Also, depending on what definition for “free will” you plug in, you can get pretty much any result you want in moral and philosophical issues.
The two possibilities are not mutually exclusive. Also, depending on what definition for “free will” you plug in, you can get pretty much any result you want in moral and philosophical issues.