It's a difficult argument to make in our culture. In a society in which abortion on demand from conception until natural birth has been legal for over 30 years, many have already succumbed to indifference when it comes to protecting the developing human organism. Abortion has even become a tool in reproductive medicine. Ironically, infertile couples who want their own biological children not only take the blessing of a child too much in their own hands by seeking in-vitro fertilization in the first place, but often turn their morals over to scientists, who create and destroy embryos and perform selective reduction abortions in order to give couples the child they crave.

Now that research scientists have promised us there is another use for these tiny beings, already ignored in many ways, why should we stand in the way? Especially when some supporters of human embryonic stem cell research promise it will be salvation for any and all disorders of the human body from aging to Alzheimer's? All we need do is turn over our money and any scruples we have about needlessly protecting human embryos. Even while researchers who wished to gain access to the cache of frozen embryos from in-vitro fertilization clinics were assuring Congress that they would never deliberately create human embryos for research, such research was taking place. (Repeatedly using the terms frozen, extra or unwanted is also an interesting rhetorical tactic. No embryo is useful to scientists unviable and frozen. They must be viable, thawed and healthy to be of any value to researchers at all.) Now, of course, deliberately cloning new human embryos hallmarked specifically for destruction as therapeutic cloning material is advocated, in fact, more ethically acceptable, they argue, since informed consent is obtained from the donors at the outset.

Genetic research has affirmed scientifically what the modern Church has taught theologically: There is an unbroken genetic and developmental continuum from conception to adulthood. The DNA from our parents is present right from the start and provides the embryo with a unique, individual distinctiveness, which though not yet genetically expressed, is present nonetheless. While not all the embryos survive the developmental milestones from embryo to newborn, if we deny the embryo protection before any point we select on this developmental continuum, we do so arbitrarily.

Neither scientists, nor ethicists, neither theologians nor legislators can agree at which point we become persons. While the most expedient course might be to ignore the rights of any developing human life until we issue a birth certificate, such action ignores the scientific and philosophical truth that our past, present and futures are lived in continuity. A toddler may not yet have the right to vote. Does this diminish his or her personhood? Women and African Americans were not accorded equal protection under our constitution until relatively recently in the life of our country. Was personhood somehow conferred on them by constitutional amendments, or were we sadly centuries late in recognizing they already possessed it?

The lack of consensus about the spiritual and moral status of the human embryo only makes it more important to guard against doing harm and embrace, instead, the belief that all developing human life should be treated with the same respect due a person from life's beginning to its natural end.

This precludes creating or destroying human life in the laboratory or bioengineering a category of sub-human embryos destined to become stem cell products. The happy scientific truth that an effective and ethically acceptable alternative to human embryonic stem cell research exists is beside the point. Even if there were not, we still could not destroy some human lives for the potential benefit of others.

Nor should we overstate the promise of manufacturing and destroying human embryos, enlisting a cadre of disease sufferers to preach about the potential benefits of destroying human embryos for their health or our own. Not every method of solving a medical problem can or should be tried – Tuskegee and Nuremberg are not that long ago.

Happily, a newly discovered alternative to human embryonic stem cell research exists. Stem cells do exist in the adult human body (including the umbilical cord, placenta and amniotic fluid) and not only show great therapeutic potential, but have already yielded clinical success.

We must slide no further down the slippery slope of disregard for the developing human person.