With the possible exception of equal rights, perhaps the most controversial issue across the United States today is the death penalty, Many argue that it is an effective deterrent (威慑) to murder, while others maintain there is no convincing evidence that the death penalty reduces the number of murders.
The principal argument advanced by those opposed to the death penalty, basically, is that it is cruel and inhuman punishment, that it is the mask of a brutal society, and finally that it is of questionable effectiveness as a deterrent to crime anyway．In our opinion, the death penalty is a necessary evil．Throughout recorded history there have always been those extreme individuals in every society who were capable of terribly violent crimes such as murder．But some are more extreme than others.
For example, it is one thing to take the life of another in a fit of blind rage, but quite another to coldly plot and carry out the murder of one or more people in the style．of a butcher．Thus, murder, like all other crimes, is a matter of relative degree．While it could be argued with some conviction that the criminal in the first instance should be merely isolated from society, such should not be the fate of the latter type murderer.
The value of the death penalty as a deterrent to crime may be open to debate．But the overwhelming majority of citizens believe that the death penalty protects them．Their belief is reinforced by evidence which shows that the death penalty deters murder．For example, from 1954 to 1963, when the death penalty was consistently imposed in California, the murder rate remained between three and four murders for each 100,000 population．Since 19 the death penalty has been imposed only once, and the murder rate has risen to 10.4 murders for each 100．000 population．The sharp climb in the state's murder rate, which began when executions stopped, is no coincidence．It is convincing evidence that death penalty does deter many murderers．If the bill reestablishing the death penalty is vetoed (否决), innocent people will be murdered some whose lives may have been safe if the death penalty were in effect．This is literally a life or death matter．The lives of thousands of innocent people must be protected.
The principal purpose of this passage is to ______.