Dr Peter Boghossian is a freelance philosopher and former academic. He was jointly responsible for the 'Sokal squared' hoax, as a result of which he was investigated by his then-employer, Portland State University, for research misconduct. He later left the university and now travels the world engaging bystanders in 'street epistemology' - open, reasonable conversations on a range of topics. We talked to him about whether there are moral facts, what people think about in prison, whethe...