06/14/2010 05:12 am ET | Updated May 25, 2011

I Feel Your Pain Even When You Can't: Another Assault on a Woman's Right to Choose

Nebraska lawmakers passed a bill banning abortions after 20 weeks based on the theory that a fetus at that stage feels pain. In doing so, their attempt to restrict abortion paradoxically undermines every argument anti-abortionists put forth in making their case.

If abortion opponents use pain as the threshold for deciding when abortion is acceptable, then they must agree that all abortions prior to the threshold of pain are no longer in dispute. If not, why use pain in the discussion at all? If abortion prior to pain is unacceptable, what use is pain then as a measure of when abortion is acceptable (if never)?

Setting abortion at the threshold of pain perception also has another important implication. With pain now in the mix, the idea of "personhood" for a fetus must also be abandoned. Think about it: you cannot argue that a fertilized egg deserves all the rights of a fully-formed adult when you agree an egg can be aborted because an egg cannot perceive pain. Can't have it both ways.

So I say we call the bluff. With Nebraska's precipitous action we reduce the abortion argument down to one single question: at what developmental stage can a fetus experience the sensation of pain? Unintentionally the Nebraska lawmakers created the formulation that before pain perception, abortion is always OK; after, only under tightly prescribed circumstances. Let us all agree then, using this logic from the Nebraska law, that abortion prior to the day that a fetus can feel pain is never again to be questioned. No more legal challenges or legislative roadblocks to any abortion prior to pain perception.

Since pain is now so critically central to the abortion debate, let us clearly understand what the term means. As with much of biology, because we ourselves experience pain we falsely believe we understand it. The greatest fallacy is that a reaction to any noxious stimulus implies the reacting animal feels pain. Not true at all.

Pain is not a simple reaction to stimulus. Pain is not just a stimulated nocioceptor sending electrical signals to the brain. Let me emphasize here a crucial point: reacting negatively to a noxious stimulus does not imply pain perception. A bacterium will react quickly against a harmful chemical and swim quickly in the opposite direction. Nobody would claim the bacterium is feeling pain. A jelly fish will do the same. So will an earthworm. Animals routinely react to avoid a noxious environmental signal. Unless you want to start a global "save the worms" campaign, you probably do not want to argue that an earthworm feels pain, even when reacting to an unpleasant stimulus. Reaction is not perception. While making for good copy, a fetus reacting to a pinch does not mean the stimulus is perceived as painful.

In contrast to reaction, pain is an awareness of input from peripheral receptors as a consequence of high-level processing of signals reaching the brain. Unlike reactions, which respond consistently to a given input, perceived pain differs in response to an identical stimulus depending on many factors, including emotional state. Think of the pain of stubbing your toe. Then imagine your reaction if you stubbed your toe in the excited aftermath of learning that you won $1 million in the Lotto. Emotional state matters. Feeling pain requires a functioning brain, with reasonably complex processing capabilities.

Now let us apply these ideas to the growing fetus. Does an egg feel pain? Does sperm feel pain? Does a single cell feel pain? A group of eight cells? A blastula? A two-week embryo? Of course not; because these entities have no brain. We know that in the absence of a central nervous system, the early embryo is incapable of any sensation; signals from the periphery would have nowhere to go to be processed! We can safely and unambiguously conclude that the early embryo with no developed brain tissue cannot feel anything at all, let alone feel pain, anymore than a cluster of cells can. Or a jelly fish.

What about early brain development? Until a brain is formed with a functioning cortex, the embryo has no ability to form any conscious thought. Such thought is by definition necessary for perception, which depends on emotional state. Without perception there is no pain, just reaction. So, now all questions of abortion come down to the more specific question of when during development a fetus acquires a functioning cortex.

Neural development begins early in a human fetus, but the process is slow relative to other organ systems. The three main lobes that will become the brain form by the 29th day. About six to eight weeks after fertilization, the first detectable brain waves can be recorded, but the brain is not nearly fully formed, and the cortex is little distinguished from other brain regions. Before eight weeks, in the absence of any brain function, the growing embryo is a little different in its human potential from a fertilized egg. Therefore before eight weeks all abortions are fully acceptable -- if pain perception is used as a determining threshold because pain perception prior to eight weeks is impossible.

But let us stop the charade. Pain is not a viable measure to determine when an abortion is acceptable. I am confident that the Nebraska law will be challenged and defeated. Pain cannot be reduced to some mathematical formula or applied equally across different individuals. This appeal to pain perception is a scarcely-disguised attempt by the anti-choice movement to make a legal procedure so onerous as to be outlawed in practice. Nevertheless, we have made great progress with the passage of this bill. Here is why.

The fact that "pro-life" proponents suggested pain as a threshold, however flawed the idea, means the life-begins-at-conception argument is forever dead. If they believe that life starts at the moment of fertilization, then how possibly could they accept abortion after conception but prior to pain perception? No more arguments about life's sanctity, or personhood for a fertilized egg, or life beginning at conception. Otherwise they would by their own logic be condoning murder up to the point where the victim could feel pain. Murder without pain is perfectly okay by this reasoning; no other conclusion is possible once the anti-choice movement introduced pain perception into the debate.

Pain perception fails as a threshold test. But in introducing the idea, the anti-abortion movement unwittingly destroyed their misguided arguments about life's beginning and personhood for a fertilized egg.

So where do we go from here?

If a fertilized egg is potentially a human being so too are eggs and sperm, even if to an unequal degree. All require certain conditions to realize the potential to become human. Ovulation and male masturbation would be acts of murder by the same logic that confers the status of humanness on a fertilized egg or early-stage embryo. But somewhere between a just-fertilized egg and a baby about to exit the birth canal lies a distinction between potentially human and human. Because that line is difficult to draw does not mean that the line does not exist. Clearly, the division between potentially human and human is increasingly difficult to distinguish with time from conception, but even later stages of the embryo pass milestones that offer important guidelines.

Later stages of embryonic growth do not offer a sign as clear as brain development, but the fetus provides another point of determination. Before a fetus is capable of living outside the womb at week 23, even with invasive medical intervention, the line from potential to actual human has not been crossed. Before week 23, a premature baby cannot survive. Viability between weeks 23 and 26 is uncertain. After week 26, survival is possible, although lungs do not reach maturity until week 34, and a suite of life-time medical problems can be expected. Medical advances can only push this point of viability so far back toward conception, because functioning lungs, even if not mature, must be present for a fetus to survive outside the womb. No amount of medical intervention before that point of development will change this fundamental fact of biology, which establishes a second threshold for abortion at 23 weeks. A science-fiction scenario of an artificial womb in the far future would not change this calculation of natural embryogenesis.

Some women argue that society never has any proper role in determining what a woman can do with her own body. I agree only up to a point. Nobody would argue that a fully formed baby just half-way through the birth canal but not yet breached would be eligible for abortion. At some point during development, a fetus becomes a baby with all the rights of an adult human. That is just common sense since a baby eventually comes out. Once born we know the baby enjoys all the rights of an adult; what about 10 minutes before birth? Two days?

At the point in development where a baby is fully viable outside the womb with no medical intervention, whenever during development that point may be reached, society has a role in determining the rights of the baby. At the point where viability is possible with extraordinary medical intervention, society's role is more ambiguous. But one thing is clear: as a matter of biological fact no fetus is viable prior to 23 weeks; and therefore society has nothing to say about what a woman does with her own body up to that stage of development. Real ambiguity exists between 23 and 34 weeks. After 34 weeks the evidence starts weighing heavily on the other side.

While the abortion debate is complicated, one thing is now clear since the anti-choice movement adopted pain as a threshold. We now all agree that all abortions prior to 23 weeks are perfectly acceptable.

Nobody likes abortion. That is not the question being debated. Prevention, not abortion, is the vastly preferred method of family planning. Abortion is an invasive surgical technique, physically and psychologically traumatic, expensive, and potentially dangerous. Whereas sex should be as frequent as desired, unwanted pregnancy should be exceptional rather than routine. Part of the adult responsibility commensurate with having an active sex life is prudent and careful use of contraception. Abortion should not be viewed as a contraceptive. However, if an unwanted pregnancy occurs, a women's right to choose her own reproductive destiny must be protected.