Few philosophers have as wide of an impact on the general public as ethicist Peter Singer, this week's guest on Rationally Speaking podcast. Singer's utilitarian arguments about how we should treat animals, why we have a moral obligation to give to charity, whether infants should count as "people," and more have won him widespread fame -- and notoriety -- over the last few decades, and launched multiple movements. Tune in to hear his discussion with Massimo and Julia about why he's a utilitarian, and how his views of utilitarianism have recently changed (and find out how he influenced Massimo's life years ago).