Isn’t the matter of whether animals ought to be accorded the basic right not to be treated as our resources a matter of opinion? What right does anyone have to say that another should not eat meat or other animal products or how they should otherwise use or treat animals?

Animal rights are no more a matter of opinion than is any other moral matter. This question is logically and morally indistinguishable from asking whether the morality of human slavery is a matter of opinion. We have decided that slavery is morally reprehensible not as a matter of mere opinion, but because slavery treats humans exclusively as the resources of others and degrades humans to the status of things, thus depriving them of moral significance.

The notion that animal rights are a matter of opinion is directly related to the status of animals as human property; this question, like most others examined here, assumes the legitimacy of regarding animals as things that exist solely as means to human ends. Because we regard animals as our property, we believe that we have the right to value animals in the ways that we think appropriate. If, however, we are not morally justified in treating animals as our property, then whether we ought to eat meat or use animals in experiments or impose pain and suffering on them for sport or entertainment is no more a matter of opinion than is the moral status of human slavery.

Moreover, as long as animals are treated as property, then we will continue to think that what constitutes “humane” treatment for your animal property really is a matter of opinion because you get to decide how much your property is worth. Just as we have opinions about the value of other things that we own, we can have opinions about the value of our animal property. Although our valuation of our property may be too high or too low relative to its market value, this is not generally considered a moral question. So when Jane criticizes Simon because he beats his dog regularly in order to make sure that his dog is a vicious and effective guard dog, Simon is perfectly justified in responding to Jane that her valuation of his property is not a moral matter up for grabs, but a matter of his property rights.

On another level, this question relates to a subject discussed in the Introduction, the position that all morality is relative, a matter of convention or convenience or tradition, with no valid claim to objective truth. If this were the case, then the morality of genocide or human slavery or child molestation would be no more than matters of opinion. Although it is certainly true that moral propositions cannot be proved in the way that mathematical propositions can, this does not mean that “anything goes.” Some moral views are supported by better reasons than others, and some moral views have a better “fit” with other views that we hold. The view that we can treat animals as things simply because we are human and they are not is speciesism pure and simple. The view that we ought not to treat animals as things is consistent with our general notion that animals have morally significant interests. We do not treat any humans exclusively as the resources of others; we have abolished the institution of human property. We have seen that there is no morally sound reason to treat animals differently for purposes of the one right not to be treated as a thing, and that the animal rights position does not mean that we cannot prefer the human over the animal in situations of true emergency or conflict where we have not manufactured that conflict in the first place by violating the principle of equal consideration.

If animals have rights, doesn’t that mean we have to intervene to stop animals from killing other animals, or that we must otherwise act affirmatively to prevent harm from coming to animals from any source?

No. the basic right not to be treated as a thing means that we cannot treat animals exclusively as means to human ends–just as we cannot treat other humans exclusively as means to the ends of other humans. Even though we have laws that prevent people from owning other humans, or using them as unconsenting biomedical subjects, we generally do not require that humans prevent harm to other humans in all situations. No law requires that Jane prevent Simon from inflicting harm on John, as long as Jane and Simon are not conspirators in a crime against John or otherwise acting in concert, and as long as Jane has no relationship with John that would give rise to such an obligation.

Moreover, in the United States at least, the law generally imposes on humans no “duty to aid” even when other humans are involved. If I am walking down the street and see a person lying passed out, face down in a small puddle of water and drowning, the law imposes no obligation on me to assist that person even if all I need to do is roll her over, something I can do without risk or serious inconvenience to myself.

The point is that the basic right of humans not to be treated as things does not guarantee that humans will aid other humans, or that we are obligated to intervene to prevent harm from coming to humans from animals or from other humans. Similarly, the basic right of animals not to be treated as things means that we cannot treat animals as our resources. It does not necessarily mean that we have moral or legal obligations to render them aid or to intervene to prevent harm from coming to them.

If animals have rights, does that not mean that we would have to punish the killing of animals in the same way we do the killing of humans?

No, of course not. It is certainly true that if we as a society ever really accorded moral significance to animal interests and recognized our obligation to abolish and not merely regulate animal exploitation, we would very probably incorporate such a view in criminal laws that formally prohibit and punish the treatment of animals as resources. But that would not mean that we must punish the killing of an animal by a human in exactly the same way that we punish the killing of a human by another human. For example, our recognizing that animals have moral value does not require that we prosecute for manslaughter someone who, while driving recklessly, hits a raccoon. The prosecution of humans who kill other humans serves many purposes that are not relevant to animals. For example, criminal prosecutions allow the families of crime victims to experience some form of closure, and although there is ethological evidence that many nonhuman animals experience grief at the loss of family or pack members, a criminal trial would not be meaningful to them.

If we want to treat similar interests similarly, does our recognition that animals have a basic right not to be property mean that abortion should also be prohibited?

Abortion raises a number of difficult issues, particularly because of the religious dimension of the controversy. Many who oppose abortion believe that ensoulment occurs at the moment of conception. This belief leads some abortion opponents to oppose any measure that will interfere with the subsequent development of the fetus, including the use of intrauterine devices or drugs that prevent the implantation of the fertilized ovum on the uterus wall. As far as these abortion opponents are concerned, the fact that a fetus or fertilized ovum is not sentient is irrelevant; the fetus has spiritual “interests” and is considered a full and complete moral being in the eyes of God as soon as it possesses a soul.

Another complicating factor in the abortion debate is that as a cultural matter the status of a pregnant woman as a “mother” and of a fetus as a “baby” tends to kick in immediately after the woman learns that she is pregnant, particularly in cases in which the woman wants to have a child. That is, from the moment of conception, or learning of conception, we tend to think of the fetus as the human person–the baby–that it will become. But that characterization does not alter the biological fact that a fertilized ovum does not have interests in the way that the baby does.

If we approach the abortion question outside the framework of religion and souls, and outside social conventions that characterize a pregnant woman as a “mother” and a fetus as a “baby” from the moment of conception, it becomes much more difficult to understand how fetuses–particularly early-term fetuses–may be said to have interests. Although it is not certain that any fetuses are sentient, it is clear that early-term fetuses are not, and therefore they do not have interests in not suffering–they cannot suffer. Moreover, it is not clear how nonsentient fetuses can have an interest in continued existence. Although a normal fetus will continue to term and result in the birth of a human person, the nonsentient fetus cannot itself have an interest in continued existence.

Sentient beings are those who are conscious of pain and pleasure; those with some sort of mind and some sense of self. The harm of death to a sentient being is that she or he will no longer be able to have conscious experiences. If you kill me painlessly while I am asleep, you have harmed me because you have deprived me of having further experiences as a sentient being that I, by virtue of the fact that I have not chosen to commit suicide, wish to have. And our experience of sentient beings other than humans reasonably supports the position that allsentient beings share in common an interest in continuing to live–sentience is merely a means to the continued existence of organisms who are able to have mental experiences of pleasure and pain. We cannot analogize a fetus and a sleeping person; the fetus has never been sentient and therefore has never possessed the interests that are characteristic of all sentient beings.

If we claim that a nonsentient fertilized ovum has an interest in continued existence simply because there is a high degree of probability that in nine months it will become a child with interests, then we are committed to the view that a fertilized ovum has an interest in continued existence immediately upon conception. And if we can say that a fertilized ovum has an interest in continued existence immediately upon conception, it becomes difficult to understand why we would not also say that a sperm and an egg have interests in conception before their union occurs. The primary difference between the fertilized ovum, and the sperm and egg, concerns probability (it is more probable that a fertilized ovum will eventually become a human baby than it is that any particular sperm will fertilize an egg), and nothing more.

To the extent that we might say, for instance, that it is in the “interest” of the fetus that the pregnant woman not smoke cigarettes during pregnancy, such an assertion is no different from saying that it is in the “interest” of an engine to be properly lubricated or of a plant to be watered. Although it may be prudent for the pregnant woman not to smoke if she has an interest in having a healthy baby (just as it is prudent for us to put oil in our cars or to water our plants), the nonsentient fetus does not yet have an experiential welfare and does not prefer or want or desire anything. In the absence of a religious belief about the ensoulment of fetuses, it is difficult to understand why the abortion of an early-term fetus is morally objectionable or how abortion can be considered a harm to a nonsentient fetus. If the abortion of a nonsentient fetus is morally objectionable, then so would be the use of intrauterine devices or drugs, such as RU 486, that prevent the attachment to the uterine wall of a fertilized ovum. And we may be committed to the view that a sperm and an egg have an interest in being united so that the use of contraception violates the interests of the sperm and the egg. Again, in the absence of a religious framework, such views appear quite untenable.

What if we determine that some fetuses are sentient? Certainly, late-term fetuses react to certain stimuli. It may be the case that such fetuses are sentient and have an experiential welfare. In this case, it would make sense to say that such fetuses have interests. But even if we assume that sentient fetuses have a basic right that prevents their wholly instrumental treatment, abortion presents a most unusual conflict of rights. One right holder exists within the body of another right holder and is dependent upon her for the very existence that serves as the predicate for the fetus having interests in the first place. Such a conflict is unique, and protection of fetal interests risks state intrusion on the woman’s body and privacy interests in a way that no other protection of the basic right of another requires. If a parent is abusing her three-year-old, the state may remove the child in order to protect the child’s interests. The state cannot protect fetal interests without intruding on the bodily autonomy of the woman and forcing her to continue an unwanted pregnancy. But it may be the case that the sentience of fetuses militates in favor of abortion methods that are equally safe for the woman but that preserve the life of the fetus.