I've posted this elsewhere, and it was originally a response to something that someone else said, but I'll repost it again here because I enjoy discussing it. -------------------------------------------------------------------------------------------------- The utilitarian justification is one of interests, highly regarded within preference utilitarianism. Most liberal arguments fall short when it comes to addressing conservative opposition to abortion. But the justification based on interests is remarkably successful in this regard. The typical opposition to abortion is that it destroys innocent human life. Liberals usually object that the fetus is not "human life." I think this is the wrong issue to be addressing. We can establish that the fetus is human life, just as multitudes of cells throughout the human body are "human life." We cannot, however, establish that the fetus is human life of significant moral value as easily. The embryo lacks moral value entirely because it does not have a single trait of personhood. It is not self-aware, (meaning that it does not have the capacity to view itself as a distinct entity existing over time), it does not have the capability to form rational moral preferences about its future, and it lacks the capacity to feel pain. It does not possess the capacity to feel pain until it is a late fetus. Hence, the reason that the killing of an embryo or fetus is not morally equivalent to the murder of an older human is because the embryo or fetus (Ill say fetus for convenience) is not a self-aware being, and does not possess certain necessary traits of personhood, such as the aforementioned self-consciousness, rationality, and for a long time, the capacity to feel pleasure and pain. A fetus does not have the same claim to life as a being that possesses those characteristics, and a fetus lacks personhood. Many nonhuman animals possess greater traits of personhood than a fetus does, and it is considered morally acceptable to kill those animals because they taste good. As for the common claim that a fetus is a potential person, a potential person does not possess the same moral rights as an actual person. It does not hold that a potential X is equivalent to a current X. While a being is a fetus, it does not possess self-consciousness, that is, the capacity to view itself as a distinct entity over time. It may someday possess self-consciousness and other traits of personhood, such as rationality and the capacity to feel pleasure and pain, but at the moment, it does not. Hence, killing a fetus that lacks the capacity to make rational preferences, (such as the desire to live) is not morally equivalent to killing a being which does possess the capacity to make rational preferences, because killing the latter would deny and prevent the satisfaction of such preferences, which is antithetical to Enlightenment values of liberty and self-determination. It is more wrong to drop a chicken into a pot of boiling water than it would be an egg. It is more wrong to chop down a venerable oak tree than to pull out an acorn. Recall that just about every cell on your body is a potential person. Recall that the existence of potential persons is thwarted by celibacy and contraception, and you do not consider those things to be morally wrong. (Presumably.) The argument regarding the potential personhood of a fetus certainly does not get you very far. The feminist author Judith Jarvis Thomson has used the following analogy to justify abortion. A famous violinist is stricken with a disease, and requires an extremely rare blood type to survive. You have the blood type, and so a society of music lovers kidnaps you, and attaches your circulatory system to that of the violinist. You could get up and leave if you want to, but if you do, the violinist will die. However, if you remain connected to the violinist for nine months, he will fully recover. Is it morally acceptable for you to disconnect yourself from the violinist? Thomson holds that it is. To me, this is the wrong example to be using becase the fetus lacks personhood. A better example would be if your circulatory system were attached to that of a rat, and the rat would die if you got up and disconnected yourself. Would disconnecting yourself be acceptable in this instance? I suspect that most conservatives would agree, and the only morally relevant difference between the fetus and the rat is that the rat possesses more traits of personhood than the fetus does. Most conservatives consider it acceptable to place rat traps in a rat infested area to prevent the rodents from gnawing through food and other supplies. A single rat can probably incur damage of a few dollars, whereas an inconveniently timed pregnancy can incur damages of thousands of dollars. Conservatives may argue that the two situations are not comparable, and to some extent this is true, as a rat is a more advanced being than an early embryo or even a late fetus. It possesses a rudimentary level of self-consciousness and is capable of feeling pain. Ultimately, we must consider the interests of a woman in not going through nine months of disability and a painful childbirth, as well as whatever economic difficulties an inconveniently timed childbirth may bring outweigh whatever rudimentary interests a fetus that is not a self-aware or rational being has.