Let us lay our cards on the table. I believe in the application of the death penalty where it is warranted. What would warrant this drastic action? The premeditated taking of life in a situation other than self-defense. It should not be used to punish rape, as heinous as that crime is, nor attempted murder, unless the victim is left in a permanent vegetative state, nor manslaughter. But it should be used.
One argument you'll often hear against the death penalty is that it doesn't reduce crime. Whether or not it does is immaterial. This take on the death penalty is used to confuse the issue, to bring in a specious argument that drops the context of each individual case. It is not the purpose of the death penalty to reduce murder in general; its purpose is to mete out the harshest of punishments for the highest of all crimes. The death penalty's purpose is to apply justice to that particular individual in that particular case. If it serves as a cautionary tale to others, so be it.
I could go on about this, but you get the idea of where I stand on this issue, especially on the issue of the death penalty as a non-deterrent.