One of the main arguments used by people who are in favor of the capital punishment is that it has a deterrent effect on the people. Obviously, it is perfectly easy to imagine that the mere thought of being executed should deter any potential murderer, who will then think twice before committing his crime or even abandon his idea of killing someone.
However, when we look at the figures of murder rates where death punishment is applied, the rates are not lower than where it has been abolished. In fact, murder rates are the same, or at least almost the same, in the countries- or states in United States- where death penalty is applied in comparison with those where it is not.
Why do we kill people who kill people to show killing is wrong?