There have been many studies that show that the death penalty deters crime. People will be less likely to risk committing a crime and being caught if they know they can be executed as a result. At the very least, people will not be able to offend again if they have been executed.
The death sentence does deter crime. Some of the crime is not committed because they know that they could be sentenced to death. I think this is a good thing to leave alone because it does help knowing that such a strict sentence could be executed if they did the crime.
Yes the death penalty can help deter some crimes. There is a big difference between the chance of spending your life in prison and the chance of being put to death. There are some criminals who are going to commit crime regardless but it will also help prevent some of the crimes.
In countries like Singapore where they employ caning and capital punishment, the crime level is extremely low. People are afraid to cross the line. Drug trafficking is a capital offense and Singapore does not have a drug problem. The U.S. version of the death penalty is more like a life sentence. People spend 30-50 years behind bars before they are actually executed. This does not strike fear in anyone.
The death sentence is not used consistently, therefore I do not feel like it deters crime. It is rare for a death sentence ruling to be handed down by a judge in the United States and the case must involve fairly specific crimes before it can be considered. If it were used more universally, it may reduce crime, but it would obviously require following through on numerous death penalties in a succession, before it would make an impact.
A death sentence doesn't really deter crime any more than the regular threat of jail would deter crime. Most people don't murder because they first take the time to picture themselves being executed for it. People who murder other people tend to not worry too much about the consequences and many have mental health issues that might keep them from completely rationalizing the situation.
There isn't any evidence to suggest that crime is lowered because the death penalty. In the US we have the death penalty, and we have a bad crime rate. Scandinavian countries banned the death penalty and have very low rates of crime. Furthermore, do we really need to give the government the ability to kill its own citizens? What century is this again?
Take Norway, it has a hugely low crime rate, and in Norway, prisons are like vacation houses, in fact, many of you Americans would love to stay in one, I know I would. Capital punishment isn't a deterrent, people don't really care what the punishment is, just what they get from breaking the law!
People tend to sit in lockup for years before they are put to death. I would argue that even though I am sentenced to death, I would be able to prolong my life through appeals and stretching out the sentencing. Also, I might look at getting put to death as a welcome opportunity if I am stuck in a cell all day every day.