Understanding 75 The sister test in robotics is equally hard. The goal is to simulate the physical human form, its movements and mannerisms. It’s easy to get close, but close is not good enough. The term “Uncanny Valley’ has been coined to describe the discomfort humans have with something that tries to simulate a human being but does not quite get there. I think it is part of the reason Madam Tussaud’s waxworks are so fascinating. Humans have a love-hate relationship with facsimiles of themselves. They love the flattery but feel a sense of revulsion at anything that comes too close. Searle and Turing In the Turing Test, we limited our senses to the purely symbolic: using only typed words on a screen. I could break the lock on the door and go into the room to see what was there. “Aha!” I would say. “T can see you're a computer, I, therefore, know you'll be good at sums and bad at creativity” But Turing wants us to see if the difference is given away purely through intellect. He argues there is no way to tell. But if you follow my argument from chapter 1, there is one way: ask the computer to find a non-computable solution to a mathematical puzzle. This is, in practice, a difficult test to pose because it might take a very long time. Twenty- five billion people have lived on planet Earth during the last 350 years, and about 5 million of them were mathematicians. None of them was able to solve the problem posed by Pierre de Fermat until Andrew Wiles turned up but this is a clear difference between humans and computers. However long you give a computer it would never be able to solve the problem. This creativity test would take centuries to run if non-computable thought was rare, but I think we see it often — on display even when we tell jokes. In which case computers and humans should be easy to tell apart: humans are the funny ones. I am not saying you can't build a brain; our brains are physical devices, after all. I just believe a computer or a mechanistic mac