Someone watching the Democratic candidates debate could be forgiven for wondering if they're viewing a year-old videotape.

But the reality is Sens. Hillary Rodham Clinton and Barack Obama are so hidebound by ideology and beholden to left-wing interest groups that actual events are not allowed to intrude on their scripts.

There has been, for instance, no appreciable change in the position of the candidates — or Democrat Party leaders — on Iraq since the grimmest days of sectarian violence, even though the military surge has brought tremendous success. Former opponents have joined our side, and many signs of national unity are springing up at the micro — and, yes, the macro — level.

"Surrender! All is lost!" remains the battle cry of the Democrat Party. That might be "change," but it hardly qualifies as "hope."

Similarly, despite recent breakthroughs in adult and umbilical stem cell research that many scientists say make the ethically troubling notion of killing human embryos unnecessary for research, Democrats are still busy damning George W. Bush for the fact that Christopher Reeves didn't rise up and walk.

Clinton and Obama almost daily repeat the canard that George W. Bush has halted stem cell research. In reality, Bush only denied federal funding for such research; then again, in their worldview, the denial of taxpayers' money to pay for embryonic stem cell lab work is the same as banning it. But even more troublling is Clinton and Obama's callousness in refusing to even consider any ethical quandary in taking one life for the benefit of another.

But what do you expect from people who are willing to lose a war in order to score political points and for whom even banning the grotesqueries of partial birth abortion is not worth offending the smallest part of their political base?

Pro-life conservatives generally have two straw men to battle when arguing their case, one from each end of the life cycle — the case for embryonic life and some variation on the Terry Schiavo case. In each instance, the charge of religious extremism is likely to be hurled.

Because the charge that the argument in favor of embryonic right to life is purely a religious one, prominent bioethicists Robert P. George and Christopher Tollefsen set out on what might seem a peculiar task. In Embryo: A Defense of Human Life, they decide to make the case for the rights of human embryos absent any religious argument whatsoever.

Whatever you think of this daunting — and occasionally rhetorically awkward -- task, most readers will be persuaded by the authors' main thesis by the book's opening brilliant illustration. In fact, the first dozen pages or so, with minor editing, would make a superb pamphlet for pro-life groups to distribute.

The authors open Embryo with a subchapter called Noah and the Flood. No, this Noah's not the 600 year-old patriarch pf Old Testament fame with his floating zoo; he's the youngest person to be rescued from Hurricane Katrina's floodwaters.

Noah Benton Markham had been one of 1,400 frozen embryos rescued from a New Orleans hospital threatened by the rising waters. As the authors point out, had it not been for rescue workers:

Noah would have perished. For it was Noah who was frozen in one of those canisters, Noah who was brought from New Orleans by boat, Noah who was subsequently planted in his mother's womb, and Noah who was born on January 16, 2007.

The frozen embryo brought out that day, the authors point out, could not have become anything other than Noah. His parents might have been able to have another baby, but it would not have been Noah. Noah could not have been recreated at another time. Noah was genetically complete when the police officers brought him to safety, it was his life that was saved.

Therefore, the authors conclude, and this is "confirmed by all the best science":

(H)uman embryos are from the beginning, human beings sharing an indentity with, though younger than, the older human beings they will grow up to become.

To one extent or another, the rest of Embryo is a scientific defense of this proposition, and an answer to nearly every argument commonly made against it.

The authors are convinced that the argument can only be won by removing religion from the argument and focusing solely on "science" and "universally accepted philosophical methods of inquiry."

Of course, arguing such matters in a non-religious vacuum creates its own problems — and begs its own questions.

George and Tollifsen argue persuasively that there is no time at which a human embryo is "not a person." Thus, it has the rights all persons enjoy --  most basically, the "right not to be killed."

While the right of a person not to be killed is universally accepted in the West, it is also the result of a particular religious ethos — one rejected by Mao, Stalin, Hitler, Saddam and bin Laden to name a few.

It is the rejection of the Judeo-Christian ethos that leads scientists who would never dream of rejecting the right to life to a breathing human to deny it to embryonic humans. One can hardly argue that those scientists are ignorant of the genetic makeup or human completeness of the embryo.

However, since the same scientists — along with leftist politicians and hard-core feminists -- confuse the issue by arguing that resistance to killing or experimenting on embryonic human life is made on purely mystical grounds and not scientific ones, George and Tollefsen have performed a vital service with this book.

Embryo is a brief but not an easy read. While the authors have a clear and concise writing style reminiscent of James Q. Wilson's thoughtful books on ethics and the law, the issues here are of necessity sometimes discussed in highly technical terms.

However, whether you read it straight through, digest it in chunks or keep it as a handy reference guide for sticky arguments —  such as why it is not hypocritical for a pro-lifer to say a fireman, if forced to choose, should rescue a 5-year-old girl rather than a tray of embryos — Embryo is a valuable addition to the library of anyone who engages in the war of ideas.