It wasn’t enough for Sherry F. Colb and Michael C. Dorf to tackle two of the most polarizing, ethically challenging issues of our time: abortion and animal rights. They had to find common ground among all sides, and they had to somehow synthesize the arguments into a unified theory on the value of life.

How? For Colb and Dorf, the book begins with two paradoxes: Why do so many people who condemn practices like hunting favor the right to deliberately take a human life, or at least a potential human life? Why do so many people who fight to preserve even the simplest one-cell human believe in eating farm animals that have been raised to be slaughtered?

There’s little or no overlap between the arguments, because each side asserts exactly what the other denies. In the pro-life movement, simply being human grants you moral rights that aren’t owed to non-humans. In the animal-rights movement, where the species line is blurred, there’s an analogy between the servitude of farm animals and the servitude of women denied their reproductive freedom. But for all the disagreements, Colb and Dorf have found a new way to frame the debate.

“Sherry and Mike are seeking to displace reasoning, rationality, or moral agency as the criteria for something being an object of moral concern,” said W. Bradley Wendel, Professor of Law, moderating the program. “They want to replace it with sentience – the capacity to experience pleasure and pain. By shifting the focus from rationality to sentience, Sherry and Mike open up a space for the interests of animals, but remain committed to the right of a pregnant woman to terminate a pregnancy.”

For Deborah Tuerkheimer, Professor of Law at Northwestern Pritzker School of Law, that emphasis on sentience is the missing piece of the puzzle, using the ethical and legal consideration of each argument to complete our understanding of the other. “I was struck throughout the book by the tremendous execution of its underlying premise: namely, that given the moral centrality of sentience, we can learn a great deal about animal rights by thinking about abortion, and vice versa,” said Tuerkheimer. “This is difficult, fraught terrain, a reality that Professors Colb and Dorf candidly acknowledge. Still, work like Beating Hearts can undoubtedly help to mend our damaged world. It is an extraordinary feat.”

Then, notes in hand, Colb and Dorf took their turn at the lectern, answering a few of the many questions raised by their work. Is it morally permissible for humans to kill animals? (Almost never.) Under what circumstances, if any, is abortion morally permissible? (There is no short answer.) Did they think they could write about abortion and animal rights without upsetting people?

“It’s good,” said Dorf, “to have tenure.”