Barrister Harry Potter asks whether we can believe the evidence of our own eyes. It's a vital question for the justice system today and Harry traces it back to the work of 18th century Philosopher David Hume. Hume, a key figure in the Scottish Enlightenment, wrote about miracles, arguing they were most likely the product of wishful thinking and faulty perception. His arguments are still important for barristers, judges and juries still reliant on eye witness testimony to decide guilt or innocence. To find out how our eyes deceive us, Harry meets professor Amina Menon, expert in eye witness evidence at Royal Holloway, University of London. And Harry visits professor of philosophy Peter Millican at Oxford University to ask whether Hume's methods can help us overcome our inbuilt biases. Producer: Melvin Rickarby.