Democratic presidential nominee Barack Obama raised some eyebrows in last month's Saddleback Civil Forum on the Presidency when in reply to the question "At what point is a baby entitled to human rights?" he said:

 Well, I think that whether you're looking at it from a theological perspective or a scientific perspective, answering that question with specificity, you know, is above my pay grade.

In the explanations that Obama and others have since offered to expand upon this answer, it quickly became clear that Obama was not answering the question as it was asked. His answer, instead, was directed to the question of when life begins, and in addressing that question Obama did not mean to suggest that he was not capable of grasping the scientific facts that would underlie an answer, but that the question is essentially about theology, and that he's no theologian.

Obama and his running mate both made that particularly clear this past weekend, when in separate interviews both were asked to clarify their views on the beginning of human life. Obama said:

 As a Christian I have a lot of humility about understanding when does the soul enter into, in, it's a pretty tough question. And so all I meant to communicate is that I don't presume to be able to answer these kinds of theological questions. 

Biden, as usual far more expansive in his answer, put it this way:

 I'd say, "Look, I know when it begins for me." It's a personal and private issue. For me, as a Roman Catholic, I'm prepared to accept the teachings of my church. But let me tell you. There are an awful lot of people of great confessional faiths--Protestants, Jews, Muslims and others--who have a different view. They believe in God as strongly as I do. They're intensely as religious as I am religious. They believe in their faith and they believe in human life, and they have differing views as to when life--I'm prepared as a matter of faith to accept that life begins at the moment of conception. But that is my judgment. For me to impose that judgment on everyone else who is equally and maybe even more devout than I am seems to me is inappropriate in a pluralistic society. 

Both insist that the question of when a human life begins is a theological question, and so one without a generally applicable answer. But in fact, the question of when a new human life begins is not fundamentally a theological question but a biological question. After conception is concluded, a new biological organism exists that did not exist before -- a member of our species in every way, alive and human. That is when the life of that human being starts. That life will proceed in one continuous path until death, whether that comes days later in a lab dish, months later in a clinic, or decades later in a nursing home surrounded by children and grandchildren. Human life has a straightforward scientific definition, and its beginning in biological terms is complicated only by questions about the process of conception itself. When conception is completed and a developing embryo exists, a life has begun.

That fact does not by itself necessarily settle the abortion or embryo research debates. After all this new human being is at first very small, for a little while does not resemble anyone we encounter in our daily life, and at first does not even feel pain or exhibit any but the simplest autonomic responses. The embryo and the fetus are different in some important physical respects from most of us. So the question is not when life begins, but whether every human life is equal.

For some people, this question of equality does have a theological component, for others it does not. But either way the question obviously has a political and legal component, and indeed America's political tradition offers one answer to the question, written in the Declaration of Independence. We can disagree with the answer, but to do so we must take up the appropriate question: not when does life begin, but whether we are all created equal. Do all human beings share in some minimal equal humanity that entitles us to some minimal equal protections, like the protection from intentional killing, regardless of our age, our size, our capacities, abilities, and circumstances?

That's not a question that answers itself. But it is the question at the heart of the abortion and embryo research debates, and Senators Obama and Biden are avoiding the question by insisting they lack an answer to the prior question -- the question of the beginning of life -- which they wrongly assert to be a matter of theology.

Now tell me again which party seeks refuge in theology when it doesn't like the facts that science helps us know.

-- Yuval Levin is a fellow at the Ethics and Public Policy Center and senior editor of The New Atlantis. His new book Imagining the Future: Science and American Democracy, will be published later this month.