Yes, the threat of capital punishment deters crime, because some people will think twice before committing a crime, knowing that they could be executed for it. For murders that are premeditated, it is likely that potential offenders will think about deadly consequences before they will make the decision to commit the crime anyways.
The death penalty can definitely deter crime - even if nobody committing a crime stops before a crime and says 'should I not commit this because of the death penalty?' the psychological factor over the entire population dos have some effect. This isn't to say whether or not the penalty should be instituted, but rather that there is, regardless, an effect on crime.
Capital punishment is certainly something that would cross the mind of somebody who were contemplating about committing a crime that could result in that punishment. However, this thought probably wouldn't have an effect on certain people. If the criminal is intent on committing such a heinous crime, their own death probably wouldn't carry too much weight. It does, however, affect other individuals and ultimately deters crime.
Sex is one of the most addictive pleasure. Death penalty and even hell can't deter rapists if women are prostitute like. Arab countries are one of the least rape cases in women, not because of death penalty, but modesty. While in USA and India has high rape cases because of immodesty even there's death penalty in India and some parts of the USA. Love is the greatest pleasure from God while lust is the greatest pleasure from Satan. It's easy to love a godly being, but it's hard to love a satanic being (sexually attractive women), instead it's easy to treat them badly. The greater the pleasure, the greater we will suffer when we lose or resist it.
When the law banned not wearing helmet when riding a motorcycle and seat belt in car to reduce accidental deaths. Why the law can't implement dress codes to reduce rape cases, like Arab countries doing?
No, capital punishment does not deter crime. The death penalty is used so rarely that it has almost no effect on the amount of violent crime committed. In addition to this, there are many groups that speak against the death penalty, further causing capital punishment to not work as a deterent.
I don't think that the death penalty deters people anymore than the threat of prison deters some people. The people who are scared of the death penalty are probably not the people who are murdering people to begin with. I don't think that most murderers think very rationally about their possible fate when they are carrying out a crime.
When a criminal is in the heat of impulse or anger or is trying to figure out how to survive until tomorrow, then the fact that capital punishment exists is not going to deter him. He does not believe it is really going to happen and often it does not.
The death penalty does not lower crime, and does not deter crime; however, it does remove evil from this world, and provide justice for victims loved ones. A person that commits a death penalty crime does not care about life enough to care about the consequences. Some may be narcissistic, but they do not honor life.