We like to think of doctors as experts, whose recommendations are backed up by solid evidence. So why does it keep happening that a widely used medical intervention -- like estrogen replacement therapy, or heart stents -- turns out to be useless, or even harmful? This episode features Dr. Vinay Prasad, author of "Ending Medical Reversal: Improving Outcomes, Saving Lives," who talks with Julia about why medical research is so often fatally flawed, and what we can do about it.

Julia invites philosopher and blogger Dan Fincke onto the show, inspired by a productive disagreement they had on Facebook. Their topic in this episode: civility in public discourse. Do atheists and skeptics have a responsibility to be civil when expressing disagreement, and does that responsibility vary depending on who their target is? Is there a legitimate role for offensive satire? And might there be downsides to civility? Dan and Julia also revisit the subject of their original disagreement: the recent NECSS decision to rescind Richard Dawkins' speaking invitation, on account of a video he tweeted which compared feminists to Islamists. Dan and Julia attempt to put the Dawkins case study in the broader context of the civility debate, asking questions like: What makes something offensive, and can someone be *unjustifiably* offended?

You've probably heard about victims of con artists -- like the people who hand over their life savings to sketchy gurus or psychics, or the people who wire thousands of dollars to a "Nigerian prince" who just needs some help getting his far bigger fortune to you. And you've probably thought to yourself, "What a sucker. I'd never fall for something like that." But are you sure? In this episode of Rationally Speaking, Julia interviews Maria Konnikova, science journalist and author of "The Confidence Game: Why we fall for it... Every time," who explains why con artists are so effective that even the best of us are vulnerable. Along the way, they explore questions like: Why do people refuse to believe they've been conned? Are con artists getting more sophisticated over time? And how do con artists view themselves -- do they rationalize their actions, or are they impassive sociopaths?

Do you remember when you were a kid, and you had that great day at Disneyland where you got to meet Bugs Bunny? No? Think harder. It was a sunny day... In this episode of Rationally Speaking, Julia interviews psychologist Elizabeth Loftus, whose pioneering work on human memory revealed that our memories can be contaminated by the questions people ask us, or by misinformation we encounter after the fact -- even to the point of making us remember entire events that never could have happened. (Like meeting Bugs Bunny, a Warner Bros character, at Disneyland.)

In this episode, psychologist Susan Gelman describes her work on the psychological trait of essentialism: the innate human urge to categorize reality and to assume that those categories reflect meaningful, invisible differences. Julia and Susan discuss why the discovery of essentialism in children was such a surprise to scientists, how the language we use affects the way we view reality, and whether essentialism is to blame for bad philosophy.

We're all familiar with Santa Claus -- but how much do you *really* know about that jolly old elf? In this episode, Julia interviews philosophy professor David Kyle Johnson, the author of "The Myths that Stole Christmas." Kyle explains the little-known, and somewhat sinister, origin story of Santa Claus -- and then Kyle and Julia debate whether it's ethical to lie to your children about the reality of Santa Claus (and possible alternatives to explore).

There are two contradictory stories about politics and class: On the one hand, that the Republicans are the party of the fat cat businessmen and the Democrats are the party of the people. And on the other hand, that the Republicans are the party of the salt-of-the-earth Joe Sixpacks, while the Democrats are latte-sipping elites. In this episode, professor of statistics and political science Andrew Gelman shines some clarifying light on the intersection between politics and class in America, explaining what the numbers really show. He and Julia also cover the question, "Is it rational to vote?"

This episode of Rationally Speaking features Jesse Richardson, a creative director who has been using his advertising background "for good and not for evil," as he puts it -- by building skeptic sites that go viral. Jesse's most famous creation is "Your Logical Fallacy Is," an illustrated poster featuring the names and descriptions of various common fallacies. Julia asks: Aren't many so-called logical fallacies not actually fallacious? Is encouraging people to call out fallacies helping rational discourse overall, or harming it? And is there a trade-off between accuracy and virality?

Most people are terrible at predicting the future. But a small subset of people are significantly less terrible: the Superforecasters. On this episode of Rationally Speaking, Julia talks with professor Phil Tetlock, whose team of volunteer forecasters has racked up landslide wins in forecasting tournaments sponsored by the US government. He and Julia explore what his teams were doing right and what we can learn from them, the problem of meta-uncertainty, and how much we should expect prediction skill in one domain (like politics or economics) to carry over to other domains in real life.

Parents in the United States are spending more time and energy than ever to ensure that their children turn out happy, healthy, and successful. But what does the evidence suggest about the impact of their efforts? Economist Bryan Caplan (and the author of "Selfish Reasons to Have More Kids") argues that, despite our intuition that parenting choices affect children's life outcomes, there's strong evidence to the contrary. Bryan and Julia discuss his case, and explore what that means for how people should parent and how many kids they should have.