Every election is an exercise in perfecting our union. We seek leaders with talent, experience and wisdom who will guide the nation through demanding times while upholding its values. As we sift through presidential candidates and platforms in the 2008 campaign, we will examine the basic American principles and challenge ourselves -- and the candidates -- to articulate how as president they would work to perfect the nation in the service of its inhabitants' unalienable rights. We begin those examinations with this editorial, to be followed in coming days and weeks by elaborations on the issues that define this campaign in the context of the values that shape this nation.

To begin: We respect candidates who speak plainly about their faith, and we acknowledge the bonds some voters feel toward leaders who profess the same religious beliefs as theirs, but we are wary of candidates who seek favor and power by promising to magnify the presence of religion in American law and life and to engraft religious precepts onto the Constitution. We reject the assertion, made earlier in the campaign by Sen. John McCain (R-Ariz.), that the Constitution established a Christian nation, and hold instead that it established a nation of laws that protect freedom to adhere to and practice religious faith according to individual conscience. In conflicts between individual liberties and social or religious values -- such as the ability of any two adults to marry even if their union is not sanctioned by religious establishments or self-appointed experts -- we side with the individual.

We seek candidates who can distinguish between eternal values and mere tradition. A 21st century American president should not lead as though it were still the 1800s, and as though the nation had endless lands to exploit and oceans and skies too vast to be harmed by industry. The nation can ill-afford a wistful and self-indulgent descent into frontier-era thinking, and should instead recognize the perfect consistency between careful stewardship of resources and a continued exploration of the frontiers of human ingenuity. The United States must have a president open to science and aware of the planet's limits.

On the issue of new arrivals to this country -- those who enter legally and those who enter or stay without permission -- we acknowledge the clash between our support for new Americans seeking opportunity and our respect for the rule of law. We look for a president with the intelligence and leadership to square law with economic and social reality, giving us laws that protect both our borders and the ability of newcomers to continue the American story. We dismiss anxiety over the fate of our language and culture, knowing that they are not only strong but further strengthened by new blood and new thinking.

We expect a president to be unafraid to explore ways to erase injustice and promote each American's opportunity to learn and to achieve, and to be equally unafraid to end experiments that prove unproductive or that infringe on the liberty of others. We expect a president to be committed to the ongoing project of perfecting the union.

Next: "Life" explores abortion, stem cell research and the death penalty. The complete "American Values" series and an explanation of it can be found at latimes.com/values08 and at the Opinion L.A. blog. Each editorial will be posted upon publication.

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