Horrified by the tragic loss of innocent human life in the then-ongoing Vietnam War, a young philosopher by the name of Tom Regan went to the university library and buried himself in books on war, violence, and human rights, determined to prove that the American involvement in the war was morally wrong. One day, he picked up Mohandas K. Gandhi’s autobiography, The Story of My Experiments with Truth. Reading it with great care and interest, he must have come across the following lines:

“To my mind the life of a lamb is no less precious than that of a human being. I should be unwilling to take the life of a lamb for the sake of the human body. I hold that, the more helpless a creature, the more entitled it is to protection by man from the cruelty of man.”

Little did he know that this literary encounter with Gandhi would change his life forever and have a lasting and profound impact on the history of moral philosophy. He asked himself, “How can I oppose the unjustified killing of human beings in Vietnam and at the same time fill my freezer with the dead body parts of innocent animals?” Shortly thereafter, in 1975, he wrote his first article on the moral status of animals. As its title, he chose The Moral Basis of Vegetarianism, the same title as that of a 1959 essay by Gandhi. He argued that vegetarianism and, more generally, the idea of animal rights are not the products of excessive sentimentality they are often perceived to be, but rather “have a rational foundation.” In the decades that followed, he further developed and defended that argument in more than twenty books, hundreds of articles, and countless public lectures across the globe, and became one of the philosophical leaders of the animal rights movement. In a telling reminder that the power of ideas knows no national or cultural boundaries, he wrote later in his life:

“I think it is fair to say that I would never have become an animal rights advocate if I had not read […] [Gandhi’s] autobiography.”

On Friday, February 17, Tom Regan passed away. He died of pneumonia at his home in Raleigh, North Carolina, at the age of 78.

Regan’s most notable book, The Case for Animal Rights, was first published in 1983, and has since been translated into several languages. It contains the most comprehensive account of his theory of animal rights and played a crucial role in establishing the intellectual respectability of the animal rights movement. With more than 400 pages of dense philosophical reasoning, it is not an easy book to read, but the basic argument is not difficult to understand: If all human beings have equal rights, as virtually everybody agrees they do, these rights must be based on a relevant similarity between them. That similarity cannot be the fact that all human beings are members of the same species, as it would be no less arbitrary to base rights on species membership than on being of a certain gender or race. Rationality, the ability to use language, and moral agency, features we like to think make us special among the animals, are not plausible candidates either. After all, there are some of us, such as young children and people with certain severe cognitive impairments, who are incapable of rational thought, language-use, and moral agency. The relevant similarity, Regan argues, is that each one of us is an experiencing subject of a life, a one-of-a-kind individual with a unique life story. But so are many non-human animals, which he explained with his characteristic eloquence at the Royal Institution of Great Britain in 1989, with an estimated audience of one million people watching the BBC live broadcast:

“The other animals humans eat, use in science, hunt, trap, and exploit in a variety of other ways have a life of their own that is of importance to them, apart from their utility to us. They are not only in the world, they are aware of it and also of what happens to them. And what happens to them matters to them. Each has a life that fares experientially better or worse for the one whose life it is. Like us, they bring a unified psychological presence to the world. Like us, they are somebodies, not somethings. In these fundamental ways, the non-human animals in labs and on farms, for example, are the same as human beings.”

We must hence accept, on pain of inconsistency, that these animals, too, have moral rights, including the right not to be killed or made to suffer. The practical implications of this view are nothing short of radical and include, most importantly, the total abolition of the use of animals as experimental subjects and as sources of food, clothing, and entertainment.

Combining scholarly rigor and dispassionate attention to philosophical detail with the infectious passion of moral conviction, Regan was as close to the ideal of a moral philosopher as only very few others. He was also a wonderful person and one of the kindest people I ever knew. While he will be missed by many, I take comfort in knowing that his words will endure, calling on us to treat animals with the respect they are due, and continue to inspire generations to come.