Remember the time when political discourse was founded on those quaint concepts - facts, evidence and expertise? Now it seems partisanship infects every corner of the realm of ideas, according to Paul Krugman. Stephen Sackur interviews the Nobel Prize-winning economist and New York Times columnist, whose latest book suggests America's political and economic future is threatened by zombie ideas peddled largely by America's conservative movement. Has he become addicted to the partisan warfare he professes to despise? Show less