Among the issues in American politics that inspire the most ideological fervor these days, stem cells and missile defense are at the top of the list. Missile defense has a long history: To conservative Republicans, it is a fixture of the Reagan legacy, of American strength, independence, and nuclear realism in the post-Cold War world. To liberal Democrats, missile defense is destabilizing, hegemonic, unworkable, and unwise. It will provoke a new arms race and a new age of nuclear brinkmanship. Besides which, terrorists can always attack us with nuclear car bombs anyway.

The issue of stem cells is new-a continuation of the moral and political divide over abortion, but with perhaps even greater complexity and significance. Pro-lifers see research on embryonic stem cells as involving the utilitarian destruction of the unborn. And they see it as the gateway to the darker, more ambitious modern genetic project of designing our descendants and challenging our mortality. Among the supporters of this research, the pro-capitalists and many "soft" pro-lifers foresee staggering benefits that far outweigh any associated evil. The pro-choicers see no evil at all, only a great humanitarian opportunity to extend individual health and autonomy.

What is interesting, though, are the parallel claims and counterclaims made by those who advocate or reject these emerging technologies. The advocates proclaim: If we lift the respective bans-the ABM treaty and the NIH regulations barring federal funding of embryonic stem cell research-technological miracles will follow. The skeptics proclaim: These technologies are untested, immoral, and irresponsible. On each issue, the pro-technology faction asserts not only the virtue of deploying either missile defense or stem cells, but the necessity of doing so-lest terrorists attack us or diseases kill us

And usually-here is perhaps the most interesting point of all-the advocates of one technology reject the other. That is, missile-defense hawks, who tend to be conservatives, are usually stem cell doves; stem cell hawks, who tend to be liberals, are usually missile-defense doves. There are exceptions, but the discontinuity is common enough to be worth considering.

Perhaps not surprisingly, the two subjects are seldom discussed in the same political breath. But the relationship between the politics of nuclear weapons and the politics of the new biology is fundamental: Both stem cell research and missile defense force concrete judgments about whether modern technology enhances life or threatens it, whether it expands freedom or destroys it. Both inspire grand fears about where modern technology is leading us. Both raise questions about whether we can control what we create and what we are, and about whether such control is desirable, undesirable, or tragically necessary.

For conservatives in particular, these issues present a riddle-especially for those who seek both to augment American greatness and power, on the one hand, and to demand of the nation a technological reticence, a reverence for the unmanageable mystery of creation, and a spirit of restraint and acceptance in the face of suffering, on the other. These conservatives seem to want a "just hegemony" in international affairs, built on America's will to set the world right. But when it comes to the irrationalities and inevitability of suffering, disability, sickness, and death, they ask the nation to adopt, as bioethicist Gilbert Meilaender eloquently puts it, "the posture of one who waits, who knows his fundamental neediness and dependence."

In short, they seek both the posture of the heroic statesman and the posture of man as witness. American conservatism, at its best, cultivates both, in deference to a paradox inherent in the human condition. But politically, it is not enough simply to lift the ban on weapons-builders and maintain the ban on medical researchers, declaring oneself pro-defense and pro-life. Rather, this conservative disposition must be seen to make sense.

For the fact is, as Meilaender and others have suggested, the philosophical problems posed by our willingness to fight just wars and our desire to cure diseases are not very different. Both endeavors confront us with seemingly impossible questions: When may we take life to affirm life? Can embryos ever be justly sacrificed to help the sick and dying? Are discarded embryos acceptable "collateral damage" in the war against disease? When does courage require of us that we endure our fate, and when that we exert the will to set the world right? How and when should we use power to extend the "pursuit of happiness," be it American power overseas or medical power at home? In short: How much goodness and how much justice can men achieve here and now? And when does wisdom require a heroic acceptance of tragedy, forbearance rather than "progress" and "solutions"?

In my view, building a missile defense system and halting all embryonic stem cell research are the moral and realistic choices. But those who adopt this set of positions must recognize the grand wagers they rest on: namely, that a nuclear attack is possible but not inevitable; that missile defense is workable and will deter our enemies rather than embolden them; that the biological quest to overcome suffering-to set the world right by ending disease and perfecting imperfection-is somehow misguided; and that the further down this path we go, the less able we will be to accept, endure, and redeem our mortality and to love and honor the imperfect among us, which in the end means all of us. This treating of life as a problem to be solved has given us the modern capacity to cure disease, but also our increasing penchant for euthanasia, assisted suicide, mass Prozac, and selective abortions.

Certainly, these two conservative positions (pro-missile defense and American power, anti-embryonic stem cell research) are difficult to reconcile-the one a mobilization of modern technology, the other a call to rein it in. To acknowledge the force of the opposing views-the futility of fighting nuclear weapons with more weapons, the rightness of extending the lives of the sick and the dying even at the cost of destroying "mere cells"-is a necessity.

Perhaps the answer, if there is one, lies in America's exceptional conservatism, which in the past has inspired both the will to fight tyranny and the wisdom to acknowledge man's limits, and hence his longing for transcendent redemption or justice. To ask comfortable citizens to give their lives defending freedom around the world; to ask the sick and dying to love the mystery of life more than their own lives-both require a courageous commitment to something larger than self-interest. For a purely political conservatism oriented toward giving the voters what they want, such demands are a losing strategy. For a philosophically grounded conservatism willing to risk demanding from people the sacrifices of which they are capable, these issues are an exceptional opportunity