Punishment assumes responsibility, this thought or conviction arises from the illusion that we have free will. The proponents of punishment argue that we have been created by a god who has endowed us with free will and when we act contrary to what society commands, then we have chosen to act that way.
Current research in neuroscience, though still at earlier stages of development, shows that decisions are made in the subconscious mind before seconds before we perform an action. Neuro-scientist Sam Harris has a book by the title Free will which yours truly is yet to read but where he shows that Free will is an illusion so convincing that people simply refuse to believe that we don’t have it. Any person who thinks we have free will argues that a person could have acted otherwise.
Our desire to revenge informs the desire for punishment and only till the society changes its understanding of human nature will we be able to move away from this desire. In this regard, we can’t take credit for doing what we call ‘good’ nor can we blame anyone for doing ‘bad’. We knowers need to understand the genesis of the words good and bad to be able then to guide our fellow men to a higher living.
And Nietzsche had this to say on capital punishment
How is it that every execution offends us more than a murder? It is the coldness of the judges, the painful preparations, the understanding that a man is here being used as a means to deter others. For guilt is not being punished, even if there were guilt; guilt lies in the educators, the parents, the environment, in us, not in the murderer- that is the motivating circumstances.