if united states support capital punishment would be willing t abandon it if convicted murderers could be sentenced to life imprisonment with absolutely no chance of parole? similarly if united states oppose the death penalty would they change their opinion if evidence emerged that proved that it really was an effective deterrent?

The answer to your first question is possibly. We won't know until the situation changes. Many states have already abandoned capital punishment.

http://www.deathpenaltyinfo.org/states-and-without-death-penalty

Statistics around the world have shown that the death penalty is not a deterrent. Did you know that in England in the 1800s, pickpockets were hung? Yet in the crowds that gathered to watch these hangings, pickpockets still plied their trade.

To answer your question, we need to consider the perspectives and dynamics involved in both scenarios.

1. If the United States supports capital punishment:
If convicted murderers could be sentenced to life imprisonment with absolutely no chance of parole, it could potentially lead to a reconsideration of the support for capital punishment. Some factors influencing this decision might include:

a. Cost: Life imprisonment without parole is generally more cost-effective than the death penalty, which involves lengthy legal processes and extensive appeals.
b. Moral concerns: Some proponents of capital punishment may have moral objections but support it as a deterrent. If life imprisonment without parole is considered an equally effective deterrent to murders, it could sway their opinion.
c. Rehabilitation: Those in favor of rehabilitation over punishment might also see a life sentence with no parole as a chance for potential reform or redemption.

Ultimately, the decision to abandon capital punishment would be based on the collective judgment of lawmakers, policymakers, and society as a whole, considering factors like public opinion, political considerations, and the impact on the criminal justice system.

2. If the United States opposes capital punishment:
If evidence emerged proving that the death penalty was an effective deterrent, it could potentially lead to a reconsideration of opposition. However, changing a deeply ingrained position is complex and requires thorough examination. Some factors to consider include:

a. Moral objections: Opponents of the death penalty often argue that it violates the right to life and has ethical implications. The emergence of evidence on deterrence may not alleviate concerns related to morality.
b. Legal considerations: In the United States, capital punishment is subject to extensive legal procedures, including appeals. The potential for wrongful convictions and issues with the fairness of the legal system are additional factors that may not be easily overcome by deterrence evidence alone.
c. Alternative approaches: Even if the evidence suggested that the death penalty was a deterrent, opponents might still argue for alternative methods of addressing crime, such as rehabilitation, restorative justice, or focusing on social and economic factors impacting crime rates.

Ultimately, the decision to change the stance on capital punishment would require a comprehensive analysis of the evidence, ethical considerations, public opinion, and potential alternatives to determine the best course of action.