One day when I was a paralegal, I was thinking about how a background in psychology would really help a judge or lawyer. After all, wouldn't you better be able to tell when people are telling you the truth? Then I realized that law is, at its essence, applied psychology. So here is some interesting psychology about the death penalty*:
In their comprehensive study of homicides, the leading evolutionary psychologists Martin Daly and Margo Wilson note that most homicides between men originate from what is known as “trivial altercations.” A typical homicide in real life . . . begins as a fight about trivial matters of honor, status, and reputation between men (such as when one man insults another or makes moves on another’s girlfriend). Fights escalate because neither is willing to back down, until they become violent and one of the men ends up dead. . . . .
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Incidentally, this is why the death penalty may not deter murder. The logic of the death penalty assumes that most murders are premeditated. A potential murderer carefully and rationally weighs the costs and benefits of the act, and decides not to murder if the costs outweigh the benefits. This might describe a fictional murderer on Columbo, but not real-life murderers, who do not stop to think before escalating their trivial altercations into fatal fights.
The logic of the death penalty also assumes that execution is the worst fate possible. From an evolutionary psychological perspective, there is something worse than death, and it is the total reproductive failure that awaits any man who does not compete for mates in a polygynous society. If they compete and fight with other men, they may die, by being either killed by the other man or executed by the state. If they don’t compete, however, they will definitely die, reproductively, by leaving no copies of their genes. So they might as well compete even at the risk of death; the alternative is much worse.
So you see, capital punishment may not deter because death is always a risk when choosing to enter any activity. Interestingly, this may explain why sterilization seems so cruel and inhumane.