John T. Noonan, Jr. argues against the moral permissibility of abortion on the grounds that from the time of conception, the being in question is a human and thus has the same serious right to life that all humans have. He thinks that if a being is conceived by human parents, then that being is also biologically human. He seeks to “buttress” this claim with an argument about the probability that a fetus will develop into a full-grown human. Herein, I will consider both of his arguments and find them both to be unsuccessful. First, I will argue that the fact that a being is a member of the species Homo sapiens does not guarantee that it has a serious right to life. Second, I will argue that Noonan fails to notice a crucial fact about how contraception works, which shows that his view on abortion entails the impermissibility of contraception.
§1: The Biological Argument
Noonan thinks that the serious right to life that humans have is based on the fact that they are human, i.e. their species membership. He writes, “it is wrong to kill humans, however poor, weak, defenseless, and lacking in opportunity to develop their potential they may be . . . similarly it is morally wrong to kill embryos.” However, he thinks that even a conceptus is human and that conception is the “decisive moment of humanization.” He supports that assertion with the claim that conception is when “the new being” gets its (human) genetic code. Furthermore, he writes, “It is this genetic information which determines his [the new being’s] characteristics, which is the biological carrier of the possibility of human wisdom, which makes him a self-evolving being.” If Noonan is only trying to establish that a conceptus or a fetus is a member of the species Homo sapiens, then I think he is correct. With this claim in mind, one might construct an anti-abortion argument as follows:
- Any innocent being that belongs to the species Homo sapiens, has a serious right to life.
- It is prima facie morally impermissible to kill any being that has a serious right to life.
- Therefore, it is prima facie morally impermissible to kill any innocent being that belongs to the species Homo sapiens. [from 1 and 2]
- Any human fetus is an innocent being that belongs to the species Homo sapiens.
- Therefore, it is prima face morally impermissible to kill a human fetus. [from 3 and 4]
- But abortion is by definition an act that involves killing a human fetus.
- Therefore, abortion is prima face morally impermissible. [from 5 and 6]
Here I think Noonan is conflating two distinct categories: one biological and one moral. To say that a fetus is a member of the species Homo sapiens is to say nothing about its moral status. The moral category with which Noonan conflates species membership is that of personhood. Exactly what properties a being must possess in order to be considered a person is controversial. Philosophers often consider properties like sentience, consciousness, autonomy, etc. as being constitutive of personhood—in most cases, fetuses lack many of these essential properties. However, what is not controversial is whether or not premise 1 is true or false. It seems to me that it is false. Why? Because there is a whole range of counterexamples, which—at least intuitively—show that sometimes an innocent being that belongs to the species Homo sapiens does not have a serious right to life.
A somewhat controversial example of when an innocent member of the species Homo sapiens does not seem to have a serious right to life are cases of innocent threats. These are cases in which an innocent person poses a threat to you—regardless of whether he or she realizes it. Imagine a case in which a villain shots a circus performer out of a canon that is aimed at you. You know that if the performer hits you, you will die, but he will survive. However, you also know that if you shot the circus performer, the impact of the bullet with his body will slow him down enough so that he will not kill you, but the shot will kill him. Is it morally permissible to shoot the circus performer to save your own life? I think so and I think many would agree. Even though he is innocent, he poses a threat to your life and, unless you have some special obligation to him, he does not have the right to ask you to sacrifice your life for his. Thus, in this case, an innocent member of the species Homo sapiens (i.e. the circus performer) does not have a serious right to life.
In addition, imagine the case of an anencephalic baby. Here the baby is certainly biologically human, but is born without an upper brain (the part responsible for consciousness). What it does have is a lower brain and thus is capable of respiration, circulation, digestion and other basic functions. However, without an upper brain—or the possibility of an upper brain transplant—it will never have consciousness, memory, personality, desires, hopes or any other mental experiences. Perhaps one will object that anencephalic babies only live a short amount of time, e.g. a few minutes, hours, or perhaps weeks. But we do not think that a being’s right to life depends upon how long they have left to live. For example, would it be morally permissible to kill a healthy and conscious human who was going to die in the next few minutes or hours or weeks? I think not. Thus, the remaining length of a being’s life is not relevant to that being’s right to life. In addition, we might amend the example to one in which the anencephalic child is able to breath and have a working heart for years due to artificial assistance. In that case, the remaining length of its life is no longer short.
Another example of when an innocent member of the species Homo sapiens does not seem to have a serious right to life is the following case. A woman passes out in a parking lot near where some construction work is being done. A person driving a steamroller does not notice her passed out on the pavement and runs over her head destroying her upper brain. Like in the case of the anencephalic baby, this woman has no chance of ever being capable of higher mental functions. We could even take the example a step further to distinguish it from the anencephalic baby. Let’s say that the steamroller also destroyed her lower brain as well and thus her body cannot even respirate or pump its own blood. “Fortunately,” there is a doctor nearby with a machine that can breath and pump blood for the woman for the rest of her life. Does this woman have a serious right to life? I think not. Consider yourself in such a situation. Would you be seriously opposed to having the plug pulled if your brain was completely destroyed—or even if just your upper brain was destroyed? Again, it seems to me that most people would not be seriously opposed to this. Thus, I conclude that premise 1, i.e. Noonan’s implicit assumption that any innocent member of the species Homo sapiens has a serious right to life, is false.
Perhaps it will be objected that in the second two counterexamples the humans in question are already dead and that is why they do not have a serious right to life. This objection is correct in one sense and incorrect in another. There are two ways that a typical human can die: (1) biologically and/or (2) psychologically. Biological death is the death of a human organism and psychological death is the death a human person. A human organism, such as a human without an upper brain, is alive in the sense that a lower animal or plant is alive. Both human organisms and these other living things have biological processes like the functioning of organs, digestion of food, growth, reparations of parts, etc. For example, processes like the growth of hair, fingernails, and toenails will continue as will general aging and typical biological processes like menopause. A human without an upper brain can reproduce skin cells to heal a wound in the same way a tree can regrow its bark. What such a human cannot do is reflect upon this situation, understand it, discuss it with others, etc. That kind of behavior is unique to persons and requires an upper brain.
Furthermore, some brain dead women have even given birth. One women was able to gestate a fetus for more than three months after she was declared brain dead. It is true that these women received artificial assistance from machinery such as respirators, but the fact they relied on such machinery does seem to me to indicate that they were not alive in the biological sense. Consider the case of a person who is perfectly healthy apart from the fact that she relies on a respirator to breath for her. Would we not consider her to be alive in the biological sense? I think so. All that was needed to show that these innocent members of the species Homo sapiens are alive is proof that they are biologically alive. Thus, the objection that the anencephalic baby and brain dead woman were already dead in the biological sense is unsuccessful.
§2: The Probability Argument
The second argument that Noonan offers is meant to help support his first argument and not meant to stand on its own as an argument against the moral permissibility of abortion. This argument is based on the probability that the conceptus (the union of the spermatozoon and the ovum) or fetus will develop into a full-grown human being. He claims that the fetus has a 4 out of 5 chance of developing into a being with the traits common to full-grown human beings, e.g. the capacity for wisdom. In order to show the importance of such a high probability, he asks us to consider a case in which a hunter shoots at a shaking bush. If the probability that there is a human being in the bush is known to be 4 out of 5, then Noonan thinks that most people would judge the hunter to be acting impermissibly if he shoots into the bush.
However, one may ask why contraception is not wrong according this probability argument. Is it not true that spermatozoa and ova also have the potential to develop into a human? Noonan anticipates this objection by claiming that there is an enormous gap in probabilities between the probability that a fetus will develop into a full-grown human and the probability that a spermatozoon will. In fact, he notes that the probability that a spermatozoon will develop into a full-grown human is 1 in 200,000,000. He claims that the probability argument “is not aimed at establishing humanity,” but rather “an objective discontinuity [between the two probabilities] which may be taken into account in moral discourse.” Noonan then reconsiders his hunter example, but changes the probability that the movement in the bushes is caused by a human from 4 out of 5 to 1 out of 200,000,000. He then claims that few people would consider a hunter careless if he shoots into a shaking bush with such a minute chance that the movement is caused by a human. Thus, if one destroys a conceptus or a fetus, then one destroys a being that had a 4 out of 5 chance of developing into a full-grown human, whereas if one destroys a spermatozoon, one destroys a being that only had a 1 in 200,000,000 chance of developing into a human.
First, it is quite puzzling why this argument is necessary. If Noonan thinks that the conceptus is already a member of the species Homo sapiens and thus a possessor of the rights that all other members have, what does it matter if it develops into a full-grown human? According to Noonan, it seems to already have the same right to life that a full-grown human has. Thus, this argument from probability seems superfluous.
Second, Noonan misunderstands what his probability argument actually shows. His claim about the difference in probabilities between a fetus and a single spermatozoon developing into a full-grown human can be articulated as the following probability claim:
(PC): The difference between the probability that a spermatozoon will develop into a full-grown human and the probability that a fetus will develop into a full-grown human is enormous.
However, this claim can be interpreted in at least two ways. In the first way, it is a claim about what would be true of any randomly selected spermatozoon and fetus. That is, if you were to randomly select a spermatozoon and a fetus, then the probability that latter would develop into a full-grown human is much greater than the probability that the former would. And, this seems to be what Noonan is arguing for. However, this probability claim fails to establish what I think Noonan wishes it to establish—or at least to support—namely, that for all spermatozoa and all fetuses, the probability that the latter will develop into a full-grown human is much greater than the probability that the former would. If this were true, then all fetuses would have a much greater probability of acquiring all the rights that full-grown humans have then all spermatozoa. Yet, his argument clearly does not establish this claim. Consider the following example and think about which being has a greater chance of developing into a full-grown human: (1) A spermatozoon that is about to fertilize an ovum in a healthy women or (2) A fetus inside of a woman with uterine cancer. Clearly the spermatozoon in (1) has a far greater chance of developing into a full-grown human than the fetus in (2). Thus, Noonan has failed to establish his intended conclusion about all spermatozoa and all fetuses.
Third, even if we forget about the previous objection, the probability argument faces another problem. Noonan seems to miss a crucial fact about how contraception works, namely that it stops or kills all spermatozoa, not just a single one. Thus it makes little sense to compare the probability that a single spermatozoon will develop into a full-grown human with the probability that a fetus will develop into one. What needs to be compared to the probability that a fetus will develop into a full-grown human is what the probability is that a given ejaculation will result in a spermatozoon fertilizing an ovum. And, given enough occasions of sexual intercourse, the probability that a spermatozoon would have fertilized an ovum had it not been for the contraception is extremely high—unless the male is infertile or has had a vasectomy.
Fourth, Noonan only considers the probabilities involved in male contraception and thus says nothing about the probability that a given ovum will develop into a full-grown human. As David Boonin notes, Noonan’s original contraception example paints a rather deceptive picture of the probability that contraception kills a being that will develop into a full-grown human with the probability that a fetus will. There is not an enormous difference between the probability that a given egg will develop into a full-grown human and the probability that a given fetus will.
Once it is seen that the probability that a given spermatozoon or ovum will develop into a full-grown human—given enough instances of intercourse—is much closer to the probability that a given fetus will develop into a full-grown human, then Noonan is left with the following dilemma: either (1) contraception is as morally impermissible as abortion (or nearly as morally impermissible) or (2) the probability that a given being will develop into a full-grown human is irrelevant to the moral permissibility of abortion. I suggest that neither is a pleasant option for Noonan.
Herein, I have considered Noonan’s argument(s) against the moral permissibility of abortion and found that they all fail to show—or even support—the conclusion that abortion is morally impermissible. Thus, if abortion is in fact morally impermissible, it is not for the reasons discussed above.
 John T. Noonan, Jr., “An Almost Absolute Value in History,” in Intervention and Reflection: Basic Issues in Medical Ethics 8th ed., edited by Ronald Munson (Belmont, CA: Thomson Higher Education, 2008), 574.
 Throughout this paper I will consider abortions to be acts that kill fetuses. However, all my statements regarding the fetus will apply to cases of aborting the conceptus, embryo, or zygote. In addition, I will use the expression “full-grown human” to refer to a human that can reason and feel pain—a being that most people think has a uncontroversial right to life. Noonan speaks of a fetus developing into a baby outside the womb, but moral status of newborn infants has been by multiple defenders of abortion (for example, see: Michael Tooley, “Abortion and Infanticide,” Philosophy and Public Affairs 2, no. 1 (Autumn, 1972): 37-65; Michael Tooley, Abortion and Infanticide (Oxford: Claredon Press, 1983), 309-416; and Peter Singer, Practical Ethics 3rd ed. (Cambridge: University of Cambridge Press, 2011), 151-154 and 159-167). Thus, I have chosen to use a less controversial notion of a being that has a serious right to life.
 John T. Noonan, Jr., “Deciding Who Is Human,” Natural Law Forum 13 ( 1968): 134.
 Noonan 2008, 575.
 For example, Mary Anne Warren lists the following five traits as crucial to the concept of a person: consciousness (especially sentience), reasoning, self-motivated activity, the ability to communicate, the existence of self-concepts and self-awareness (see: Mary Anne Warren, “On the Moral and Legal Status of Abortion,” The Monist 57, no.1 (January, 1973): 55).
 Dick Teresi, “The Beating Heart Donors,” Discovery Magazine (May 2012). Accessed on July 6, 2012: http://discovermagazine.com/2012/may/10-the-beating-heart-donors/article_view?b_start:int=3&-C
 Mark Strasser fails to note this fact and treats the probability argument as if it were supposed to be a standalone argument against the moral permissibility of abortion (see: Mark Strasser, “Noonan on Contraception and Abortion,” Bioethics 1, no. 2 (1987): 199).
 Noonan 2008, 575.