You could make the case that Peter Singer has done more good than anyone else alive. A professor of ethics at Princeton University, Singer is the author of Animal Liberation (1975), which instigated the modern animal rights movement. Singer didn’t give us cruelty-free cosmetic production or vegetarian restaurants, but he has done more than anyone else to popularize such ideas. What’s more, by writing persuasive articles about people’s moral obligation to give away money, Singer has caused tens, maybe hundreds of thousands of dollars to be donated to famine relief organizations. Yet Singer also believes that it is OK to kill babies.