I remember the first time I met Peter Singer. It was in 1974. He was a polite, affable Australian with curly brown hair, glasses and a plastic belt. Little did I know that behind his refusal to wear leather was one of the most influential moral philosophies of our time.
His seminal book, Animal Liberation, appeared a year later. It laid out a careful argument for giving moral standing to animals on the basis of their capacity to suffer. It galvanized movements around the world to restrict animal research and abolish factory farming. It also set off passionate debates that are reflected today in arguments about the morality of third-trimester abortions, stem-cell research and the removal of feeding tubes from people in permanent vegetative states.
It is easy to demonize Singer, 58, since his theory points toward conclusions that some find morally repugnant for example, that euthanasia might be the appropriate response to the intractable suffering of an infant born with a terrible genetic malady. Those who scorn his views can rarely produce an argument about why he is wrong they simply don't like his conclusions. But ethics is all about arguments, not moral pronouncements. I don't always agree with Peter. But he is a man whose reasoning merits consideration by everyone. There are few philosophers, living or dead, about whom that can be said.
Caplan is director of the Center for Bioethics at the University of Pennsylvania