The Republicans present a far wider range of thought, from the coyly phrased pro-choice position of Rudolph W. Giuliani, to Mike Huckabee's support for a national ban on abortion, to Ron Paul's support for a reversion to state authority on the matter. While that last idea is tempting for its potential to remove this intractable issue from national politics, the threats to women's free exercise of the right to abortion remain too numerous for us to trust in a federalist solution.

Simply put, if abortion opponents succeeded in overturning Roe vs. Wade, it is unlikely they would then settle for a landscape where abortion remained legal in 45 or 48 states. Huckabee's position, which we oppose absolutely, nevertheless has the value of consistency: If you believe abortion is murder, you have no choice but to fight it at all levels. It's a more coherent stance than, for example, those of Mitt Romney and John McCain, who oppose abortion but make exceptions for cases of rape and incest. So we'll respectfully disagree and call for a candidate whose views, and likely Supreme Court choices, support upholding Roe vs. Wade.

The death penalty is frequently citedas abortion's twin, an issue that reveals the hypocrisy of liberal or conservative positions that oppose killing in one instance but not the other. But the question of capital punishment is properly understood as one of the state's use of force: How much violence must the government inflict in order to secure the well-being of its citizens? It is clear to us, from both the ease with which a life sentence can be made to stick and the lack of evidence of capital punishment's deterrent effect, that killing an incarcerated person does not fall within the scope of reasonable state use of force.

No politician has ever wanted to look soft on crime, so it's no surprise that among the Democratic and Republican candidates, all but the outliers (Paul and Democrats Mike Gravel and Dennis J. Kucinich) compete mainly in how vociferously they can support the death penalty. Fortunately, this is an area in which the president matters substantially less than in the case of abortion. There have been only three federal executions in the last 40 years. Although the choice of president in 2008 may make some difference at the level of court appointments, capital punishment remains an issue for state governments. Here the news is encouraging, as 13 states have repealed it outright, others are edging toward repeal, and the number of annual executions continues its precipitous drop from a grim modern peak of 93 in 1999. We hope the next president will not interfere with capital punishment's death by natural causes.

For all of the habitual attention to abortion and the death penalty, it's the weird cousin of the life issue that is the most intriguing from a societal standpoint. Last month's news that scientists in Japan and Wisconsin had modified adult skin cells to behave as embryonic stem cells seemed at first to have resolved this issue, but that's only true if you believe that the debate over stem cells, cloning and genetic modification is a subset of the debate over abortion. It is not. It is, or could become, the central life debate of our time, and depending on your perspective, the questions it raises are either exhilarating or horrifying. If you could ensure that your children would never get melanoma, should you do that? How about nearsightedness? Should we be modifying humans in hopes of making them more fit for survival in a warming climate? How about for handling complicated technology, or space exploration?

If these ideas seem excessively science-fictional, consider that when Leon Kass, the conservative University of Chicago professor who would later serve as head of President Bush's Council on Bioethics, wrote a 1972 screed against the then-novel science of in vitro fertilization, he warned that it could someday make mothers of "single women, widows or lesbians." Yesterday's absurdity is today the mainstay of many lives.

Given the expected level of discourse in a presidential campaign, we may be lucky that the candidates are not keen to explore the frontiers of life. Still, it's a missed opportunity. With respect to John Lilburne, the right to human life, and in fact the definition of human life, is increasingly unsettled, and the country deserves a president who can address this change calmly and intelligently.

Next: "Liberty" and "Justice" explore the costs to personal freedoms of the war on terror, and the president's part in preserving equal justice under the law. The complete "American Values" series can be found at latimes.com/values08.

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