In 1950, the great physicist Enrico Fermi posed a question that people have been puzzling over ever since: Where is everybody? The universe has been around for billions of years, so why haven't we seen any signs of alien civilizations? This episode features physicist Stephen Webb, who describes some of the potential solutions to the puzzle. Stephen and Julia also discuss questions such as: What evidence have we gotten so far that helps us answer the Fermi problem? How do we estimate how rare/difficult it is for human-level intelligence to evolve? And why does it matter what the answer to Fermi's question is?

In this episode, economist Bryan Caplan argues that the main reason getting a college degree is valuable is because of signaling (i.e., it proves that you have traits that employers value, like conscientiousness and conformity), and not because college teaches you useful knowledge or skills. Julia proposes several potential challenges to Bryan's argument, and they discuss why it matters how much of education's value is signaling.

The security dilemma is a classic problem in geopolitics: Often when one nation takes measures to protect itself from attack (like adding to their stockpile of missiles), other nations see that and worry it means the first nation is preparing to attack them, which leads to a dangerous feedback loop of escalation. In this episode, Ben Buchanan (postdoctoral fellow at Harvard studying cybersecurity and statecraft) explores how this dilemma plays out in the realm of cybersecurity: Why is the dilemma harder to resolve than it used to be with traditional warfare? And is there anything that might help?

This episode features tech and policy journalist Timothy Lee, discussing a question that's increasingly in the spotlight: How much should tech companies be actively moderating their users' speech? For example, should Facebook be trying to fight fake news? Should Twitter ban bullying? Should Reddit ban subreddits that they consider hate speech? Timothy and Julia look at the question not just from the legal perspective, but also from the moral and strategic perspectives as well.

This episode features Jessica Flanigan, professor of normative and applied ethics, making the case that patients should have the right to take pharmaceutical drugs without needing to get a prescription from a doctor. Jessica and Julia discuss a series of related questions, such as: Should there be exceptions made for drugs that have negative repercussions on society as a whole? And what is the morally relevant difference between a doctor imposing treatment on someone without consent, and the government withholding treatment from someone without consent?

In this episode, economist Timur Kuran explains the ubiquitous phenomenon of "preference falsification" -- in which people claim to support something publicly even though they don't support it privately -- and describes its harmful effects on society. He and Julia explore questions like: Is preference falsification all bad? Are there ways to reduce it? And how much has the Internet changed the dynamics around preference falsification?

In this episode Julia talks with Doug Hubbard, author of How to Measure Anything, about why people so often believe things are impossible to quantify like "innovation" or "quality of life." For example, because people often have a deep misunderstanding of the meaning of probability. Or because they're reluctant to violate "sacred taboos" by putting a number on something like the value of human life. Or because it feels vulgar to "reduce" important things to a number. Doug explains how he responds to these objections and others.

Philosopher Eric Schwitzgebel returns to the show to explore several related questions: His taxonomy of the three different styles of thinker -- "Truth," "Dare," and "Wonder" -- and whether one of them is better than the others. His case for why it's bad to interpret people "charitably." And his seemingly paradoxical claim that we are frequently wrong about our own conscious experience.

This episode features Zach Weinersmith, creator of the philosophical webcomic Saturday Morning Breakfast Cereal, and the co-author (with his wife Kelly Weinersmith) of the new book Soonish: 10 Emerging Technologies That'll Improve and/or Ruin Everything. Julia and Zach talk about which new technology is the most likely to happen, which would be most transformative, and which would pose the most risk to the world. Also, has our society become too risk-averse? And what are the main bottlenecks to technological development?

This episode features bestselling author Robert Wright making the case for why Buddhism was right about human nature: its diagnosis that our suffering is mainly due to a failure to see reality clearly, and its prescription that meditation can help us see more clearly. Robert and Julia discuss whether it's suspicious that a religion turned out to be "right" about human nature, what it means for emotions to be true or false, and whether there are downsides to enlightenment.