evidence: In the public imagination politicians are professional liars par excellence, or as the writer George Orwell once put it: "Political language … is designed to make lies sound truthful and murder respectable." [...] In her essay Truth and Politics, published in The New Yorker in 1967, the philosopher Hannah Arendt was already lamenting the fact that politics and truth don’t mix. But even Arendt was aware that not all lies are the same. There are lies that are minimal forms of deception, a micro-tear in the fabric of reality, while some lies are so big that they require a complete rearrangement of the whole factual texture, a shift to another reality. In today’s terminology, Arendt was alerting us to the difference between a lie, and the 2016 Oxford Dictionaries Word of the Year – "post-truth". [...] We can cope with politicians lying, but we cannot afford the risk of allowing politicians to deligitimise truth.