The Sentience Criterion

13 Pages Posted: 16 Oct 2020

See all articles by Sherry F. Colb

Sherry F. Colb

Cornell University - Law School

Michael C. Dorf

Cornell Law School

Date Written: 2017


Readers of this symposium issue who have not read Beating Hearts may find themselves in something like the position of a classics scholar trying to reconstruct the views of a pre-Socratic philosopher whose works are known only through fragments discussed by others.1 At best, one can hope for an incomplete understanding. Accordingly, we begin with a brief summary of the main ideas of our book.

Beating Hearts addresses a puzzle: Why is there so little overlap between the pro-life and animal rights movements, given that both aim to protect innocent life from human violence? Our answer is that at their respective cores, the movements give very different moral weight to membership in the human species. Although of course all movements are big tents, most people who identify as pro-life regard membership in the human species as a sufficient condition for a right to live, while most people who endorse animal rights deny that being human is a necessary condition for a right to live and a right against being made to suffer to serve others’ preferences. The difference that humanity makes or does not make resolves the puzzle.

As a normative matter, Beating Hearts sides with the animal rights position, even as we acknowledge that the best defense of this position has some overlap with the pro-life movement’s concern for the interests of at least some human fetuses. In place of humanity, we argue that sentience—the ability to have subjective experiences, including pain and pleasure—grounds the most basic rights. Most reasonably complex animals, including nearly all of the animals used by people for food and fiber, are sentient, as are fetuses after some point in their development. (The exact point, like so much about abortion, is subject to political as well as scientific contestation.) Thus, we contend that the killing and use of animals and the abortion of sentient fetuses raise serious moral questions, whereas the vast majority of abortions, which take place before fetal sentience, do not cause harm to any being capable of being harmed and therefore do not trigger the same kind of moral concerns.

Beating Hearts is partly a book about moral duties. We argue that, except in extreme circumstances, humans have a duty to refrain from consuming animal products—that is, a duty to be vegan. We also argue that, absent a good reason (such as a substantial health risk), women ought not to abort sentient fetuses. But Beating Hearts is also a book about the law. Not all moral duties are, ipso facto, legal duties, and so, following familiar feminist arguments justifying an abortion right even assuming a fetus is a moral person,2 we conclude that women ought not ever be compelled by the state to remain pregnant. For most of pregnancy, that judgment entails a right to abortion, but sufficiently late in pregnancy we allow that a woman who wishes to vindicate her interest in bodily integrity might be required to do so by inducing labor and delivery of a healthy baby.

We also express skepticism about many efforts to regulate the treatment of animals raised for human use. We are not “pro-choice” with respect to the consumption of animal products in the way that we are pro-choice with respect to abortion, because we do not think that there are reasons of principle why animal consumption should be left to individual conscience. Rather, our skepticism about using the law to better the lot of animals is rooted in our sense of what is possible as a practical matter. We acknowledge that ameliorative reforms of the sort that sometimes win support in referenda—such as those setting minimum cage sizes for laying hens and gestating sows—could do some good for the animals to whom they apply and could even play a role in catalyzing more meaningful reforms. However, because nearly all animal welfare measures accept the basic premise of the animal exploitation industries—that human exploitation of animals is morally acceptable if not gratuitously cruel—we express doubt about the likelihood that the sorts of measures that can garner support in our current era would lead to meaningful and lasting change.

That admittedly tentative assessment has implications for how animal rights activists ought to spend their time and energy. We explore those implications and other common questions that face the animal rights and pro-life movements in Part II of Beating Hearts. In addition to considering the prospects of gradualism in each movement, we address two particularly fraught questions: First, when, if ever, should activists use gory images to shock people into recognizing the horrors of the challenged practices? And second, given the magnitude of the evils as seen by activists, why should violent means of attacking those evils be categorically rejected?

Although Beating Hearts stakes out positions, it also acknowledges that people of good faith will reach other conclusions and that some puzzles—such as how to care for purpose-bred animals who cannot simply be set loose in nature—have no perfect solution. This brief summary necessarily omits a great deal of the ways in which our views recognize the strength of competing claims. In responding to particular points made by the participants in this symposium, we hope to give some further indication of the book’s nuances.

Keywords: Animal Rights, Animal Rights Movement, Pro-Life, sentience, activists, abortion

Suggested Citation

Colb, Sherry F. and Dorf, Michael C., The Sentience Criterion (2017). Boston University Law Review, Vol. 97, No. 17, 2017, Cornell Legal Studies Research Paper, Available at SSRN:

Sherry F. Colb

Cornell University - Law School ( email )

Myron Taylor Hall
Ithaca, NY 14853
United States

Michael C. Dorf (Contact Author)

Cornell Law School ( email )

Myron Taylor Hall
Cornell University
Ithaca, NY 14853-4901
United States


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