capital punishment

I dont know if we, human beings, have a right to send another human being to the gallows. But what I know is that we should do something only if its useful. So the question arises what purpose does capital punishment serve? Is it there only for retribution or is it a sufficient deterrence for future criminals?

Capital punishment just for retribution... I dont know.
And is it a sufficient deterrence... I dont think so. One can say that there are two kinds of criminals who get or ought to get capital punishment. Firstly, there are terrorists, gangsters, professional killers, drug lords etc, i.e. their lives are at risk anyway. Secondly, there are rapists, killers, communalists, politicians like Saddam etc, i.e. the risk to their lives is not so much.

For the first category, if losing one's life was a deterrence, one would change professions.
For the second category, the question arises whether a 30-40 yr prison term or say a life term is a bigger deterrence than capital punishment or not? Now this is debatable, as Gaurav would say a prison term gives one a chance to live, but on the otherhand a 30-40 yr prison term destroys one's life.... again I dont know.

Looking from a different perspective, if people who actually perform the executions feel no guilt, there should be no problems with concept of capital punishment. However, if they have feelings of guilt, then capital punishment must be abolished. I mean what's the harm in doing something if no one feels bad, and what's the point in doing something if one feels guilty about it.