One of the historical election landmarks last year had nothing to do with race or the presidency. Rather, it had to do with pigs and chickens — and with overarching ideas about the limits of human dominion over other species.

 

Fred R. Conrad/The New York Times

Nicholas D. Kristof

I’m referring to the stunning passage in California, by nearly a 2-to-1 majority, of an animal rights ballot initiative that will ban factory farms from keeping calves, pregnant hogs or egg-laying hens in tiny pens or cages in which they can’t stretch out or turn around. It was an element of a broad push in Europe and America alike to grant increasing legal protections to animals.

Spain is moving to grant basic legal rights to apes. In the United States, law schools are offering courses on animal rights, fast-food restaurants including Burger King are working with animal rights groups to ease the plight of hogs and chickens in factory farms and the Humane Society of the United States is preparing to push new legislation to extend the California protections to other states.

At one level, this movement on behalf of oppressed farm animals is emotional, driven by sympathy at photos of forlorn pigs or veal calves kept in tiny pens. Yet the movement is also the product of a deep intellectual ferment pioneered by the Princeton scholar Peter Singer.

Professor Singer wrote a landmark article in 1973 for The New York Review of Books and later expanded it into a 1975 book, “Animal Liberation.” That book helped yank academic philosophy back from a dreary foray into linguistics and pushed it to confront such fascinating questions of applied ethics as: What are our moral obligations to pigs?

John Maynard Keynes wrote that ideas, “both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed the world is ruled by little else.” This idea popularized by Professor Singer — that we have ethical obligations that transcend our species — is one whose time appears to have come.

“There’s some growth in numbers of vegetarians, but the bigger thing is a broad acceptance of the idea that animals count,” Mr. Singer reflected the other day.

What we’re seeing now is an interesting moral moment: a grass-roots effort by members of one species to promote the welfare of others. Legislation is playing a role, with Europe scheduled to phase out bare wire cages for egg production by 2012, but consumer consciences are paramount. It’s because of consumers that companies like Burger King and Hardee’s are beginning to buy pork and eggs from producers that give space to their animals.

For most of history, all of this would have been unimaginable even to people of the most refined ethical sensibility (granted, for many centuries those refined ethicists were also untroubled by slavery). A distinguished philosopher, Thomas Taylor, reacted to Mary Wollstonecraft’s 1792 call for “the rights of woman” by writing a mocking call for “the rights of brutes.” To him, it seemed as absurd that women should have rights as that animals should have rights.

One of the few exceptions was Jeremy Bentham, the philosopher who 200 years ago also advocated for women’s rights, gay rights and prison reform. He responded to Kant’s lack of interest in animals by saying: “The question is not, Can they reason? nor, Can they talk? but, Can they suffer?”

In recent years, the issue has entered the mainstream, but even for those who accept that we should try to reduce the suffering of animals, the question remains where to draw lines. I eagerly pushed Mr. Singer to find his boundaries. “Do you have any compunctions about swatting a cockroach?” I asked him.

“Not much,” he replied, citing reasons to doubt that insects are capable of much suffering. Mr. Singer is somewhat unsure about shellfish, although he mostly gives them the benefit of the doubt and tends to avoid eating them.

Free-range eggs don’t seem offensive to him, but there is the awkwardness that even wholesome egg-laying operations depend on the slaughtering of males, since a male chick is executed for every female allowed to survive and lay eggs.

I asked Mr. Singer how he would weigh human lives against animal lives, and he said that he wouldn’t favor executing a human to save any number of animals. But he added that he would be troubled by the idea of keeping one human alive by torturing 10,000 hogs to death.

These are vexing questions, and different people will answer them differently. For my part, I eat meat, but I would prefer that this practice not inflict gratuitous suffering.

Yet however we may answer these questions, there is one profound difference from past centuries: animal rights are now firmly on the mainstream ethical agenda.