Imagination has always been something that interests philosophers—John and Ken open this episode by discussing the views on imagination held by Hume and Descartes. After elaborating on the philosophical aspect of imagination they get some input from a scientist: Professor Alison Gopnik, a returning guest of the show, joins John and Ken to help puzzle out the role of the imagination in childhood, in adulthood, and in philosophical discussion. What exactly is imagination? Gopnik offers her perspective, which differs from that of John’s favorite philosopher, David Hume. Ken pushes Gopnik to explain why everything around us is imagined, and what makes for productive imagination. Gopnik explains why Harry Potter exemplifies the way we construct imagined worlds, and Ken tries to sort out whether traveling at warp speed fits the model.

John, Ken, and Gopnik go on to talk about counterfactuals, or what would have happened were something to have been different than it actually was. They debate the significance of “almosts,” and why having almost achieved something can hurt more than having not achieved it by a large margin. Listeners add to the discussion, questioning how imagination is related to blindness, depression, inspiration, generalization, and education. Gopnik condemns a Dickensian villain for his opposition to imagination, and our hosts remind us that Einstein wasn’t great at math; he was great at imagining.

The show concludes with a discussion of how the role of imagination changes over the course of one’s life. As children, we live in a free space where all we have to do is think. Gopnik suggests and evolutionary division of labor between old and young, and explains why time spent daydreaming is far from wasted. Ken poses one final question for Gopnik, wondering whether we can imagine the impossible.

• Roving Philosophical Report (seek to 4:20):  Polly Stryker speaks to experts in imagination—Jane Perry at UC Berkeley’s Child Studies Center, and, naturally, children. Both Perry and the children explain the value of games, and Stryker finds out that her favorite childhood pastime is still cool. Perry lets Stryker know what she’d say to anyone who discourages children from letting their imaginations roam free.

• Philosophy Talk Goes to the Movies (seek to 48:15): John and Ken have a suggestion for you if you’re feeling the need to kick back and watch a film: Woody Allen’s Matchpoint. Though not explicitly focused on imagination, this film has lots of philosophical material to ponder, particularly regarding luck. Beyond the basic issue of basic luck, this movie brings up the issue of moral luck—for instance, is the man that kills his lover worse than the man who might have done so but was never put into that situation?  And finally the question of whether there is any justice in the universe—find out what John and Ken have to say about it.  Then watch the film and ponder for yourself.