"After Singer's talk, I began thinking through the consequences of his morality. A question occurred to me: "Should we also stop animals from eating each other?" I was sure others had made such arguments as reductio ad absurdums of vegetarianism, but I thought I might be the first to be genuinely interested in it from a moral perspective. "Of course not," said my friend. "It's not our fault if the animals kill each other." "You mean," I said, "that you think it's perfectly moral to let that guy" — I pointed at a random guy nearby — "go around killing people?" "Well, OK," he said. "But it's different with animals, because they don't know any better." "You mean it would be OK to let him go around killing people if he was mentally ill and didn't realize he was doing it?" "You should go ask Singer," he said. So I did — he was signing books outside the lecture hall and as the line ended I asked him my question. His answer was even better than I imagined: "We would if we knew how to do so without making things worse and disturbing the ecosystems and so on." "Thanks!" I said, impressed."