For years, the abortion debate has focused on one question: when does life begin? If you believe that life begins at conception, you should oppose abortion. If you believe life begins when a fetus can live outside the womb, then you should be pro-choice.

In his address to the nation Thursday night, President Bush also said this question was central. "Are these frozen embryos human life?" he asked.

But the stem cell debate--and Bush's own decision--has actually moved us to focus on a very different question: when is life sufficiently precious to preserve?

That may sound like a soulless question. Surely, while we may not agree on when life begins we can at least agree that once it does begin it should be protected. But to a degree not fully acknowledged by activists, Americans already approach the question in that more nuanced way -- and President Bush has now implicitly joined their ranks.

The classic pro-life view says, in effect, that "a life is a life is a life." But most Americans make far more distinctions about "life."

Almost everyone considers plant life less sacred than animal life. Even vegetarians kill asparagus plants, though they had an active life system that took in nutrients, secreted waste and emitted energy. Most of us also distinguish between forms of animal life. Few think it murder to step on a bug; most view it as horrendous to eat a stallion.

Kosher Jews and Muslims who follow laws of halal are implicitly creating yet another class of animal--those that are precious enough to require a compassionate death (unlike, say, a mosquito), and yet not so noble as to be off-limits (like humans).

Most important, we make distinctions about human life. Though there are some who believe that if one opposes abortion, one must also oppose the death penalty, most Americans separate the issues and deem executing a murderer to be, in the abstract, permissible. The reason, of course, is that that particular life is not "innocent."

Even when we decide to execute someone, we have rules about what the best way of killing is--our version of kosher laws. Just as a cow must be killed swiftly and with a minimum of pain, a human must be executed by lethal injection.

Helping someone to die (through euthanasia) is also looked upon with favor by many Americans, but it's obviously not proper to "help" them against their will. Sending soldiers to die is acceptable if the war is appropriate.

In short, we hold different standards for different types of human life in different situations. In all these cases--the death penalty, euthanasia, and war--we are saying it is okay to take a life if it's for a just cause.

And then there is life within the womb. Activists on both sides of the abortion debate avoid viewing life on a continuum. Pro-life activists do not believe there is a difference between the life in a fertilized egg and the life that exists seconds before birth.

More on the
Stem Cell Debate

More on the
Stem Cell Debate