When Does Human Life Begin?

Arthur Caplan

When does human life begin? For those in the “personhood” movement in the United States, there is no doubt about when that happens—it is at conception, when the sperm meets the egg. The personhood movement has gained a foothold among antiabortion activists who are looking to pass laws that define embryos as people with full rights. Personhood advocates aim to outlaw all abortions, along with in vitro fertilization, embryonic stem-cell research, and emergency contraception. Granting embryos personhood would also mean that someone who killed a pregnant woman at any stage in her pregnancy would be at risk of prosecution for a double homicide. And in those states that restrict a woman’s right to utilize a living will if she is pregnant, no living will could apply from the moment of conception.

A personhood law has been enacted in North Dakota. Wisconsin, Florida, and Colorado are seeing the most recent attempts by personhood proponents to write their stance into state law.

Personhood measures have made the Colorado ballot twice before, in 2008 and 2010, led by the efforts of a Denver-based nonprofit group called Personhood USA. Those measures did not pass. Last year, nine states had personhood bills either introduced in their state legislatures or put forward as ballot initiatives, as occurred in Colorado. So far, none has passed.

Put aside the fact that those who advocate for personhood never say when personhood precisely begins—when a sperm reaches an egg, when it penetrates the egg, when genetic recombination begins, or when a new genome is formed. There is plenty about personifying an embryo that makes no empirical sense.

Those who argue that personhood begins at conception base their claim on the assertion that every human life begins with conception. That is true. But what they fail to acknowledge is that conception does not always create an embryo life, much less a baby. In fact, it usually does not.

Why is this fact not well publicized? Because scientists and doctors have, sadly, held themselves aloof from the whole contentious argument. Many endorse the view of the U.S. National Academy of Sciences (NAS), which stated in 1981 that the existence of human life at conception is “a question to which science can provide no answer.” Since that time, scientists and physicians have remained more or less mum—or self-censored—on this issue.

While it is true that the law or theology can stipulate when life and personhood begin, it is also true that science and medicine have found facts that bear on the possible answers to that question. While the facts, as the NAS noted in 1981, do not tell us what we ought to say about when personhood begins, they do certainly, contrary to the NAS view, lay out boundaries for what can be said about the starting point. So what are the facts? Sometimes, conception creates more than one life—twins or triplets, but then one of those lives is absorbed into the body of another—fetal resorption. It really is not clear how many lives can be started at the moment of conception, and to say that a person always begins at conception is patently false.

The biggest empirical problem with the view that personhood begins at conception is the scientific fact that a large percentage of embryos lack the capacity, under any circumstances, to become human beings. During the period of embryonic development that begins with fertilization and ends a few days later with successful implantation of the blastocyst into the uterine wall—the period known as “preimplantation development”—up to 50 percent of human conceptions fail to survive, most likely due to genetic errors in the embryo.

Miscarriage is the most common type of pregnancy loss, according to the American College of Obstetricians and Gynecologists. Studies show that anywhere from 10 to 25 percent of all clinically recognized pregnancies (meaning that an embryo has implanted) end in miscarriage, depending in part on the age of the woman.

The biological facts don’t tell us where to draw the line as to when personhood begins. But they do show that many embryos that result from conception—indeed, the majority of them—lack the capacity to become living human beings. They do not produce disabled humans. They cannot produce any sort of human life. Science and medicine know this. They are simply too intimidated to say so.

In its moral zeal, the personhood movement makes a huge mistake when it tries to legislate a starting point for human life that is inconsistent with biology. And scientists are making an inexcusable blunder not to point out factual errors by those engaged in the argument about when life begins. Human life is very difficult to start. More often than not, it fails postconception. To argue that personhood begins at conception is to reach for a moral stance that the facts simply do not support.

So, what then? When might we reasonably say that personhood begins?

A starting point that is far more consistent with the facts of biology is not conception but the emergence of the human brain. We declare persons dead when their brains have lost the capacity to govern the core functions necessary for life—breathing, excretion, and the like. When a fetus has developed a brain that can support its basic biological functions, probably at around six months of life, it can be reasonably argued that personhood has begun.

Those in the personhood movement in the United States have let their animus toward abortion blind them to the facts that have emerged about human embryology over the past fifty years. And scientists, sadly, have been unwilling to correct them. Conception is the start of something, but it is more the start of the possible rather than the actual. It is not until a being emerges that has the traits necessary for individual existence that we can and should say that a person has begun. How law and public policy want to handle that fact is still debatable. But to ask the law to treat embryos as persons from the moment of conception is to head down a path where the facts ought not permit anyone to go.

Arthur L. Caplan is the Drs. William F. and Virginia Connolly Mitty Professor of Bioethics at New York University and director of the Division of Medical Ethics at New York University Langone Medical Center.

Caplan Receives National Science Board Award

The National Science Board (NSB) has named Arthur L. Caplan the 2014 recipient of its Public Service Award for an individual, which recognizes exemplary service in fostering public understanding of science and engineering.

“Years before the cloned sheep Dolly appeared on the global stage, Arthur Caplan was working to raise public awareness and discussion about ethical implications of science,” said Ruth David, chair of the NSB’s Committee on Honorary Awards. “Arthur engaged with reporters, wrote and talked about ethical and policy questions related to science, medicine and bioengineering, and encouraged his peers and students to do likewise.”

Caplan is the founding head of the Division of Bioethics at New York University Langone Medical Center in New York. He is the author or editor of thirty-two books and over six hundred papers in peer-reviewed journals. He has chaired a number of national and international committees and writes several regular columns, including one for Free Inquiry since 2006. He is also a fellow of several professional organizations, including the Hastings Center, the American College of Legal Medicine, and the American Association for the Advancement of Science.

Caplan has previously received the McGovern Medal of the American Medical Writers Association and the Patricia Price Browne Prize in Biomedical Ethics, and he was named a Person of the Year for 2001 by USA

—Andrea Szalanski, Free Inquiry managing editor

Arthur Caplan

Arthur Caplan is director of the University of Pennsylvania’s Center for Bioethics and a nationally prominent voice in the debates over cloning and other bioethical concerns.