There are countless crimes that have been committed that were done by people who had been arrested for similar offenses in the past, but were able to get off on plea bargains, community service, rehab programs, etc. These crimes could have been prevented if that person was either still in jail, or too afraid to risk the consequences of committing the crime. I would argue that the number one deterrent of people committing homicide is not actually committing the act, but the fear of getting caught and spending the rest of their life in jail. Our current justice system basically has a 3 strike rule where you are essentially allowed to commit 2 felonies before you get in real trouble. I have actually been a victim of 1st degree burglary twice this year (a felony) and both times someone was found and convicted of the burglary, which is a rarity. In both cases the perpetrators had been convicted of 1st degree burglary before and only received probation. The second time they were convicted (since their past probation period was up) they were both only given a probation period of a longer period and community service since they plead guilty. Both people where able to commit 2 felonies and not serve a single day in prison. What's to deter them from continuing to do this if they are just going to get a slap on the wrists?
Statistically, i've heard that Countries that invoke hash punishments dont actually have a lower crime rate. But I suspect thats still because they arent "harsh enough". I've always wanted far more harsh punishment for crime, for two reasons. It may or may not act as a better deterrent in the first place. If anything it likely would (but there is also the argument that it could make the hardcore criminals that much more violent as they know they're getting severely punished anyways). And Second, it would keep them off the streets longer, which in the end is more important in terms of public safety. But in addition, we definately have to investigate the factors that contribute to the reasons why people commit crimes in the first place and work on correcting those areas as well.
More harsh punishments will wire people's brain to say "Wow! I didn't like that! I better not do it again..." which will reduce repeated offenders. People will see the harsh punishments and will be less likely to attempt to do it. It's just about our common sense. Haha
I am writing no, if the opinion presented about harsher punishment is being proposed as a viable way to prevent first time offenses from occurring. This is an extreme example, but as far as I know, there isn't any evidence to conclude without any reservation that the death penalty is a deterrent against murder. Many murders occur in the midst of an emotional/spur of the moment experience which means rational thought is not as possible.
Higher punishment would expect a person to rationally weight the crime outcome against the punishment and assume they will get caught, then choose not to do the crime. Several problems present themselves with this line of thought: Rational thinking and the assumption of the worst on the part of the would be criminal. Hmm?
Countries with some of the lightest sentences such as Finnland or Sweden actually have some of the lowest crime rates.
Focus on rehabilitation. People who are harshly punished only learn to resent the system and be more willing to commit crimes when they believe they can get away with it. Particularly in the US where the presence of gangs in prisons is rampant, so a criminal mindset is easily communicated.