Let's say you're an American journalist whose editor has just tossed you a controversial medical story. Whom to ring? The first name in your rolodex will almost certainly be that of Arthur Caplan, chairman of the department of medical ethics at the University of Pennsylvania's School of Medicine. Because Caplan is quoted almost daily in the American press, he may be shaping the framework of ethical debates in the media more than anyone else.

So an interview with Caplan in the latest Technology Review, a magazine published at the Massachusetts Institute of Technology, helps to understand the forces shaping bioethical debates. "I'm a consequentialist," Caplan tells interviewer David Ewing Duncan. "I'm looking at outcomes. I'm trying to decide if a particular policy -- such as allowing surgeons to do face transplants -- would do more harm than good."

Fellow consequentialists include Princeton philosopher Peter Singer, but Caplan regards him as too rigorous in his logic. "He says that if animals are smarter than retarded children, then experiment on retarded children. I'm not willing to trust any theory that far. In general, I'm not looking for fundamental truths when I discuss ethics. What matters is what is most practical at a given time. I ask, 'What are the benefits and costs?' And I understand that the answer will change over time."

Caplan's bon mots are often insightful. When asked, for instance, why scientists look down on bioethicists, he responds: "In the culture of science, the only thing that counts is the science. If you're not doing that, it means you're not smart or good enough." These shrewd one-liners can seem facile, but this doesn't worry him: "It's a skill I have, and I'm a quick study, and I can track a lot of stuff."