An atomic bomb ended world war 2. (well, 2 atomic bombs).
When violence escalates to all out war, it eventually ends when one side or the other runs out of a desire or the ability to fight. This in no way justifies the escalation of violence that I can see. By the way, the atomic bomb didn't end the escalation, it only ended the Pacific war. It BEGAN the escalation of the cold war when other nations realized that they were going to have to have these huge bombs, too, to protect themselves from us.
A killer wouldn't kill if he didn't think he'd get away with it. (Unless it was truly a crime of passion, in which case you might see a person turn himself in).
Most murders are not thought out ahead of time, so that the murderers considered the consequences. Most murders are committed as a visceral response to some imagined threat, or offense, on the part of the intended victim, or as part of a drug/alcohol/emotional/delusional mental state in which murder appears reasonable at that moment. This is why it has been shown that capital punishment is not a significant deterrent to capital crimes. Moreover, we have created a culture in which murder has long been presented as an acceptable way for human beings to resolve their problems, and in which hand guns are readily available to unstable and irresponsible members of society. So it's no surprise, then, that many of these members use them with deadly effect on us and each other.
The authority of the state to put people to death isn't taken seriously because everyone figures they'll get off, plead for a lighter sentence, make parole, whatever it is.
Most murderers are not considering the consequences of their actions at all. AFTERWARDS, they will do so, and then try to hide or get off, but the killing itself is usually not calculated. So this argument doesn't stand. I know it seems logical to you, but you are not the kind of person who is likely to murder someone (unless you use drugs or alcohol regularly).
Killers kill because of various reasons... someone cheated on them... someone stole from them... someone disrespected them, etc...
The reasons are irrelevant. What is relevant is that they believe killing is a reasonable response to these real or imagined problems with other people, in the moment that they kill. And they feel this way because they've seen killing used by the 'good guys' to solve such problems in hundreds and thousands of movies and TV shows, and because they are given this message even by state sanctioned capital punishment.
How many millions of people are stolen from, cheated from, and disrespected that DON'T commit first degree murder with at least 1 of several aggravating factors?
They aren't part of this issue, because they aren't part of the problem.
Teach the lesson that they can't get away with it... they'll be less likely to do it.
This is a proven fallacy.