I have felt privileged to know the remarkable scholar Peter Singer as a friend and colleague for over a decade. We first met, I believe, in the context of atheism, but our discussions have ranged far more broadly, and his impact on my own thinking has been substantial. He and I engaged in a public dialogue in Arizona eight or nine years ago, and preparing for that discussion changed my views about world in many ways. Peter actually had an impact on my life even earlier than that, as when my daughter was very young. The late Katharine Thalberg, who ran the famous Explore Bookstore in Aspen where I often did book signings, and who, along with her spouse Bill Stirling, rang an unsuccessful campaign to ban furs in Aspen, saw how much my then seven year old loved her dogs, and she gave Lilli a copy of Singer’s 1975 book Animal Liberation, to read when she got older. I don’t know if Lilli ever did read it, but she became a vegetarian well before I did. Peter, perhaps more than anyone else alive, has effectively promoted the cause of animal welfare, coining the term “species-ism” to describe the fact that a proper ethics should include an equal consideration of welfare for not just all people, but all creatures. He has backed up his position with a comprehensive discussion of the disgusting manner in which animals are made to suffer in the context of industrial scale food preparation for humans. That includes not just cattle, pigs, and chickens, but also fish. Whether or not one continues to choose to eat meat, we should all at least be aware of what we are signing on for by doing so. This year Peter updated Animal Liberation so that it is called Animal Liberation Now, to record the developments that have taken place in the almost 50 years since the book first appeared. His arguments remain as dramatic and clear as they were then, and what I particularly enjoy about Peter is how he combines the philosopher’s tools of analytical logic, with a scientist’s tools of gathering of evidence. The end result is a compelling treatise, and I was thrilled that Peter agreed to sit down again for a comprehensive discussion of the ideas in his book. We took advantage of this opportunity to talk about Peter’s interest in Effective Altruism, about which he has also written extensively. This is the effort to do the most good in the world by empirically examining both what sorts of charities do the most good for the most people, and also exploring how much of one’s own resources one can readily part with in the process without substantially changing one’s lifestyle. Once again, his discussions may change the way you think, and act. I hope you enjoy our comprehensive dialogue, for which he generously contributed significant time, as much as I did. And I hope it provokes the same kind of personal reflections for you as it did for me. As always, an ad-free video version of this podcast is also available to paid Critical Mass subscribers. Your subscriptions support the non-profit Origins Project Foundation, which produces the podcast. The audio version is available free on the Critical Mass site and on all podcast sites, and the video version will also be available on the Origins Project Youtube channel as well. And a reminder that The Origins Project Foundation is programming two live events in Southern California museums. Oct 15th, at the Bowers Museum, I will be giving a presentation on my new book, and Oct 17th Brian Keating and I will be recording a joint podcast at the San Diego Air and Space Museum. Go to originsproject.org for more info and the opportunity to purchase tickets. Get full access to Critical Mass at lawrencekrauss.substack.com/subscribe