This bonus episode for PPF+ to accompany our bad ideas series is about what’s gone wrong with the idea of sovereignty. David talks to historian of ideas Lucia Rubinelli about how a seventeenth-century vision of politics still exerts its grip in the twenty-first century. Why does political authority have to have a single source? What are the alternatives? And did Brexit really give the UK its sovereignty back?

David talks to Helen Thompson about Francis Ford Coppola’s manic masterpiece of the Vietnam War Apocalypse Now (1979), a film that almost destroyed its director and some of its cast. What is its relationship to Conrad’s Heart of Darkness? What is it trying to say about American culture and American power? And is its subject in the end the madness of movie-making itself?

Why do so many American presidents say that Westerns are their favourite movies in general and Fred Zinnemann’s High Noon (1952) is their favourite in particular? David looks at how the story of Marshal Will Kane, played by Gary Cooper, chimes with many politicians’ experiences of high office. Let down by his deputy, his predecessor, the mayor, the judge and the people, he has to go it alone to get the job done. Is this how presidents see themselves? Are they right or are they kidding themselves?

In this extra episode to accompany our thinking machines series, David and Shannon talk about where we are with AI today and try to sort the reality from the hype, the science from the fiction. Are these machines anywhere near thinking like us? How can their failures of reasoning be exposed? Was Biden right to warn that managing AI will be the ultimate test of political leadership? And why does AI reflect what we were rather than what we might become?

To accompany our new series on the history of thinking about thinking machines, in this bonus episode David explores the meaning and legacy of Mary Shelley’s Frankenstein (1818). What does a horror story have to say about the romance of science? Are we meant to sympathise with creator or creature? And does this extraordinary novel have a moral for the age of AI?

David and Chris Clark continue their conversation to explore how the great powers stumbled into war in the summer of 1914. Could the Austrians have backed away from war? Could Russia, Germany or France have de-escalated the crisis? Why in the end did Britain feel obliged to join in? How might the disaster have been avoided?