To be overly verbose compared to the other replier's pithy joke:
Capital punishment works as a two-way deterrent. The "fear of execution" element isn't for those who would do the crime anyways, it's to encourage greater care and caution amongst the "lesser" criminals, in example a mugger would avoid hitting someone in the head if they knew the difference between brain damage and no-brain-damage mugging was a week in a slammer or death.
As for the ones who would do the crime anyways, it still lowers crime rate in the area, because almost all criminals are multiple-offenders. Most murderers are also batterers, assaulters, thieves, money launderers, or extortionists. And the greatest indicator for if someone will murder, is if they have in the past: If you are willing to kill one, you're usually willing to kill two. Permanently stopping a violent maniac can reduce the overall crime count in a neighborhood by dozens, if not hundreds, over the course of their otherwise-lifespan.
There's an anecdote that's frequently mentioned on the Lotus Eaters, gangs of thieves would check each other before committing burglaries for weapons to make sure no-one was carrying.
To be overly verbose compared to the other replier's pithy joke:
Capital punishment works as a two-way deterrent. The "fear of execution" element isn't for those who would do the crime anyways, it's to encourage greater care and caution amongst the "lesser" criminals, in example a mugger would avoid hitting someone in the head if they knew the difference between brain damage and no-brain-damage mugging was a week in a slammer or death.
As for the ones who would do the crime anyways, it still lowers crime rate in the area, because almost all criminals are multiple-offenders. Most murderers are also batterers, assaulters, thieves, money launderers, or extortionists. And the greatest indicator for if someone will murder, is if they have in the past: If you are willing to kill one, you're usually willing to kill two. Permanently stopping a violent maniac can reduce the overall crime count in a neighborhood by dozens, if not hundreds, over the course of their otherwise-lifespan.
There's an anecdote that's frequently mentioned on the Lotus Eaters, gangs of thieves would check each other before committing burglaries for weapons to make sure no-one was carrying.