Are we really living in a post-truth world? It has been an extraordinary year for the concept of veracity. Brexit. Trump. Experts have taken a beating, facts have apparently taken second place to emotion and feeling. And what about truth? It seems like fewer and fewer people, whether voters or politicians, care what’s true anymore. Step forward the Oxford English Dictionary’s word of 2016: "post-truth". Is this just shorthand to help liberals make sense of a world they don't like? Or does it mark something more meaningful? Are we really no longer interested in truth or is our toxic political climate clouding our ability to agree on what the facts are? In a series of special programmes as 2017 begins, Radio 4 examines inflection points in the world around us. In the first programme, Jo Fidgen explores how our brains process facts when they become polluted by politics. Producer: Gemma Newby