Abortion is more often debated than defined. But what exactly are people disagreeing about when they disagree about abortion? A definition would seem desirable so as to avoid merely verbal disputes. If one person says abortion is always wrong, and another denies this, they may merely mean different things by “abortion” and not really have a substantive moral disagreement. So a clear definition seems desirable.

Abortion cannot be defined as the intentional, premature termination of a pregnancy, because an early induced labor or Caesarean section issuing in a healthy, viable child is also the intentional, premature termination of a pregnancy. Is abortion the intentional, premature termination of a pregnancy with the (further) intention to kill the child (fetus, embryo)? Certainly some types of abortion involve the intention to kill the fetus. For example, a saline injection abortion requires a precisely calibrated saline solution strong enough to kill the fetus before labor is induced. A partial-birth (or “dilation and extraction”) abortion of a viable (third trimester) fetus requires the puncturing of the skull and evacuation of the brain before the head leaves the womb; delivery of a living, viable fetus would entail the legal obligation to render life-saving medical care to the newborn, for it would be considered a person under the law, so clearly there is an intention to kill before completing delivery. A live-birth abortion involves the intentional inducing of labor before viability, issuing in a live but non-viable baby which is then set on a table and allowed to die. Is this an act of intentional killing? It would seem to be so, at least in most cases, since the procedure is intentionally initiated before viability to avoid the legal duty to render life-saving medical care to the born baby. The whole point is to deliver a live baby that one can then legally abandon and so cause to die. But can we imagine a woman choosing a live-birth abortion merely to get the baby out, without actually intending to cause its death? Perhaps. Imagine the victim of a rape who merely wants to get the rapist’s baby out of her body. She may foresee the death of the baby without intending it.

So there may be a problem with defining an abortion as the intentional, premature termination of a pregnancy with the further intention of causing the death of the fetus (embryo, baby). The most common abortion methods focus on evacuating the contents of the womb with suction-aspiration machines and/or loop-shaped knives or forceps, ensuring the killing of the embryo or fetus in the process; chemical abortions with RU-486 do the same without surgical intervention. In such abortions the woman’s intention may be, not to kill the child, but merely to render herself unpregnant. Again, imagine the victim of a rape thinking “I want it OUT of me!” The death of the child may be the unintended though foreseen side-effect of the only technically practical means of getting the embryo out of her at that point of the pregnancy. Even if she is not intending the death of the embryo, she still is getting an abortion. Or consider abortifacient means of birth control, like IUDs, or (sometimes) the pill or the morning-after pill. Abortifacients allow conception but prevent the implantation of a very early embryo in the womb, thus ensuring the death of the embryo. Does the woman necessarily intend the death of the embryo? She surely intends not to be pregnant. But her intention may merely be that – to end her pregnancy, accepting the death of the embryo as a foreseeable yet unintended side-effect.

Perhaps we can define abortion as the intentional, premature termination of a pregnancy by a means that foreseeably causes the death of the unborn embryo or fetus. (If we can describe a woman as pregnant from the moment conception occurs in her Fallopian tube, then we can also describe at least some abortifacients, e.g. IUDs, as terminating very early pregnancies; the pill and the morning-after pill are admittedly problematic since their effects are harder to foresee, for they can prevent either ovulation or implantation.) If this definition is a good one, then it is neither too broad nor too narrow; is ethically neutral, embodying no moral evaluation of abortion; avoids circularity; etc. Ethical neutrality is especially important here, since opponents and defenders of abortion must be able to agree at least on what they are debating. Note that in implying that some abortions may involve unintentional killing the definition does not tacitly approve of such abortions. Unintentional killing can be morally permissible or not depending on a host of additional factors. The neutrality of the definition allows us to separate the moral evaluation of abortion from the definition of the term.