To be honest, I was never that excited about Asimov’s famous Laws of Robotics. They struck me as one of those things that people repeat but have never really thought through – a bit like that dictum of Sherlock Holmes that you come across everywhere: “When you’ve eliminated the impossible, then what’s left must be the truth.” Well, it just doesn’t follow. When you’ve eliminated the impossible, then what’s left is the possible. Reality is seldom so obliging that when you’ve ruled out fairies, magic, and Martians, one neat and tidy answer is left as the solution to the problem. Almost invariably you end up with several equally plausible alternatives to choose from. What’s left includes the truth. Real police work, and real science, begin where Homes leaves off.