"How boring would the world be," asks Simon Garfield, "if we knew precisely where everything was?"Simon reflects on the many mistakes and deceptions in some of our best-loved maps. He begins with the map of the London Underground where lines on the map bears little resemblance to reality but is "informationally brilliant".He talks about California, the subject of a "sustained cartographic foul-up": for 200 years it appeared on maps as an island, and it continued to do so even after navigators had tried to sail all the way round it - and failed.And then there's "one of the great phantoms in the history of cartography" - the Mountains of Kong. They were apparently a wide central mountain belt that in the eighteenth-century appeared to stretch across thousands of miles of West Africa. Despite being repeated on map after map for almost a century, however, they were a pure figment of imagination. Simon celebrates these mistakes, describing them as the "accidental discovery...of searching souls". In these days of digital maps, he hopes that we can still find "strange and charming and wonderful things - mountains that don't exist and islands of the imagination".Producer: Adele Armstrong.

The geographer and polymath Jared Diamond argues that apparently slight differences in geography can have profound consequences for the culture and history of nations.

Jerry Brotton, Professor of Renaissance Studies at Queen Mary, University of London, argues that how we see the world depends on where we stand on it.He takes us back to the Hereford mappamundi - with its unicorns, griffins, cannibals and fabled cities - a world picture completely consistent, logical, and comprehensible to the England of 1300.Google Hereford today, Professor Brotton says, and you find "a very different set of digital preoccupations"; not Babel or Jerusalem but how far we are from Hereford's Cider Museum or the nearest bike shop.He concludes that "each period in history gets the map it deserves, whatever version of salvation it offers".Producer: Adele Armstrong.

Tim Harford returns with a new series of Pop Up Ideas. This time Tim and his guests tell intriguing stories inspired by maps.In the first talk, Tim argues that maps - for all their beauty - can be dangerous. In the hands of powerful people, the map begins to shape the world in its image.He tells the story of th Johann Gottlieb Beckmann, who mapped German forests. He developed the idea of the "normalbaum", a kind of platonic ideal of what a tree should be, which could be planted in neat rows to make mapping and harvesting them easier.It appeared to be a brilliant idea and produced unprecedented growth in the forestry business. But the forests came to resemble the map - with all its uniformity - and eventually the resulting lack of diversity led to the destruction of the forests themselves.Tim then looks at the taxpayer-funded Home Owners Loan Corporation (HOLC) which operated in Depression-era America and refused "to grant credit to people, not because of their credit history, not because of their ability to repay, not even because of their need. But just because of where they lived on the map." Producer: Adele Armstrong.

Tim Harford presents the last in the series, 'Pop-up Ideas'.Tim explores the concept of 'The Tragedy of the Commons' - a term coined by the American ecologist Garrett Hardin in a hugely influential 1968 essay.He compares Hardin's work to that of the American political economist Elinor Ostrom, to reflect on the impact of mankind on the world around us.Producer: Adele Armstrong.

One of the world's most influential counter-insurgency experts, David Kilcullen, whose ideas were described by the Washington Post as "revolutionizing military thinking throughout the West", talks about the time-bomb of rapidly-growing coastal mega-cities."It took all of human history until 1960 for the world to get 3 billion people," he says. "But the latest estimate is that we're going to add the same number of people in just the next thirty years - and they'll all be going into cities, on coastlines, in the developing world".Through the story of a Somali commander he met in Mogadishu, David tells how the urban overstretch that tore Mogadishu apart in the 1990s, with frightening consequences, is happening in cities all over Africa, Asia and Latin America.Producer: Adele Armstrong.

Tim Harford is joined by Gillian Tett for the second in this new series of talks inspired by ideas in anthropology and the social sciences.The financial journalist describes how her background in anthropology led her to predict the financial crisis in 2008."For my doctorate I spent a year in a remote mountainous area of Tajikistan where I lived as a Tajik girl, wearing the local Atlas robes, fetching water and firewood and chasing goats," says Tett. She studied their rituals and social networks and how they helped to maintain village life.Later, she became a journalist for the Financial Times and put her anthropology "into a deep, dark, mental drawer" and almost forgot about it. "Having a PhD in economics or astrophysics gave you credibility. Knowing about Tajik wedding rituals did not!"She describes how one day, years later, she suddenly stopped and wondered: "what would happen if I was to look at the world of finance and business like an anthropologist peering at my Tajik village?".Tett explains how this set her journalism on a new path, a path that was to help her predict the economic turmoil of 2008.Producer: Adele Armstrong.

Tim Harford (the Financial Times' 'Undercover Economist' and presenter of Radio 4's More or Less) is joined by Malcolm Gladwell, David Kilcullen and Gillian Tett for a new series, 'Pop-up Ideas'.Following on from his earlier Radio 4 series 'Pop-up Economics', Tim and the others use key ideas in anthropology and the social sciences to tell fascinating stories about how we - and the world - work.The talks are recorded in front of an audience at the Southbank Centre in London.Malcolm Gladwell, staff writer at the New Yorker and best-selling author of books such as The Tipping Point and Outliers, tells an extraordinarily powerful story about how listening more carefully might have shortened the Vietnam War.One of the world's most influential counter-insurgency experts, David Killcullen, whose ideas were described by the Washington Post as 'revolutionizing military thinking throughout the West', talks about how future instability will emanate from rapidly-growing coastal megacities.The financial journalist Gillian Tett describes how her background in anthropology led her to predict the financial crisis in 2008.Tim Harford explores the concept of 'The Tragedy of the Commons' - a term coined by the American ecologist Garrett Hardin in a hugely influential 1968 essay.Tim compares Hardin's work to that of the American political economist Elinor Ostrom, to reflect on the impact of mankind on the world around us.Producer: Adele Armstrong.

Tim tells the story of Chris Ferguson who applied game theory to poker and won - big time. But, as Ferguson would find out, there's always a bigger game.

Tim Harford tells the story of Bill Phillips - war hero, engineer, crocodile-hunter, and one of the fathers of macro-economics.