Sam Harris speaks with Peter Singer about the concept of universal moral truths, the ethics of violence, free speech, euthanasia, animal welfare, and other topics. Peter Singer is the Professor of Bioethics at the University Center for Human Values at Princeton University.  He is the author of Animal Liberation, The Most Good You Can Do, Ethics in the Real World, and most recently Why Vegan? He is also the co-founder of The Life You Can Save, a nonprofit devoted to spreading his ideas about why we should be doing much more to improve the lives of people living in extreme poverty. Website: www.petersinger.info Twitter: @PeterSinger   Episodes that have been re-released as part of the Best of Making Sense series may have been edited for relevance since their original airing.