If people don't have free will, then can we be held morally responsible for our actions? And what would happen to society if we were to collectively shed our belief in free will? In this episode Julia talks with philosopher Gregg Caruso, who advocates a position of "optimistic skepticism" on the topic. Skepticism because people don't have free will as a sense of moral responsibility, but optimistic because society would be better off if we accept that we do.

Naturalism is the stance that everything that exists in the universe arises from "natural" causes, of the sort observable by science -- not supernatural ones. It's practically a foundational tenet of skepticism. But does it imply that there can be no meaning, or purpose, or morality in the universe? This episode features physicist Sean Carroll, author of the recent bestseller The Big Picture: on the Origins of Life, Meaning and the Universe Itself. Sean and Julia talk about the new "ism" he introduces in the book, "poetic naturalism," and how it attempts to resolve the apparent conflict between science on the one hand, and things like morality, free will, consciousness, and meaning on the other.

Julia chats with the authors of Algorithms to Live By, about how to apply key algorithms from computer science to our real life problems. For example, deciding which apartment to rent, planning your career, and prioritizing your projects. In the process, they discuss the assumptions that underlie those algorithms (and what to do about the fact that those assumptions are inevitably violated by the messy real world), and why procrastination might actually be the right algorithm for the wrong problem.

It's the annual live Rationally Speaking episode, taped at the Northeast Conference on Science and Skepticism in NYC! This year features returning guest Jacob Appel, a bioethicist (and lawyer, and psychiatrist). Jacob and Julia discuss various bioethical dilemmas, such as: How do you handle parents who want to withhold medical treatment from their child for religious reasons? Is it unethical for American doctors to test new medications in the third-world? And what kinds of principles does a bioethicist use to justify their decisions, beyond "that's just my personal opinion"?

In this episode Julia talks with philosopher of cognitive science Colin Allen about whether fish can feel pain. In the process they explore a cluster of related questions: Are fish conscious, and how could we tell? What's the difference between pain and suffering? And are there evolutionarily adaptive reasons why animals would have the subjective experience of pain, as opposed to just instinctive reflexes to avoid potentially harmful stimuli?

Ever make a plan to diet, or exercise, or study, and then -- when the scheduled hour rolls around -- decide, "Nah, I'll just put it off another day"? If you said "no," I don't believe you! This episode features behavioral psychiatrist (and economist) George Ainslie, who demonstrated the existence of this ubiquitous phenomenon in human willpower, called hyperbolic discounting, in which our preferences change depending on how immediate or distant the choice is. George and Julia discuss why hyperbolic discounting exists, and how it can be modeled as a negotiation between your current self and your future selves. In the process they explore some of the benefits and risks of this "intertemporal bargaining" approach to willpower, and how it relates to philosophical thought experiments such as the Prisoner's Dilemma and Kavka's Toxin.

For centuries, scientists have wondered what makes humans so much smarter than other species. Some proposed it was the size of our brain (though that didn't explain why whales weren't smarter than us); others thought it was the size of our brain relative to our body size (but there were problems with that explanation as well). In this episode, neuroscientist Suzana Herculano-Houzel lays out the mystery of the "Human advantage," and explains how a new technique she invented several years ago has shed light on some of these longstanding mysteries.

You're probably already aware that it's hard to change someone's mind with logical arguments and evidence, especially about emotionally charged topics. But are there exceptions? David McRaney, bestselling author of "You Are Not So Smart" (and host of the blog and podcast by the same name) describes his experiences with people who have done an about-face on some important topic, like 9/11 conspiracy theories. He and Julia discuss a technique for changing someone's mind with evidence, how individual mind-change mirrors scientific progress, and what happens when you confront Trump fans with facts that contradict their narrative.

He's been called a "Data vigilante." In this episode, Prof. Uri Simonsohn describes how he detects fraudulent work in psychology and economics -- what clues tip him off? How big of a problem is fraud relative to other issues like P-hacking? And what solutions are there?

You've probably heard about cognitive biases -- the systematic errors human brains make when we try to reason or make decisions. But what if our biases are actually a sign of rationality? This episode features Tom Griffiths, professor of cognitive science at University of California, Berkeley and the director of the Computational Cognitive Science lab. Tom makes the case for why our built-in reasoning strategies might be optimal after all.