I breezed through a book shop the other day and glanced at a book called, ‘This book does not exist’ which described itself as taking you on adventures in the paradoxical. It entertained my nerdy department briefly and had I had more than a bike pump, a bottle of water and a daft look with me I might have bought it. Anyway the paradoxes I remember enough to regurgitate are as follows. ( Is it really a) Paradox? 1 A hang man says to his ‘client’ I am going to give you a surprise hanging some time during the next working week. I will hang you on Monday, Tuesday, Wednesday, Thursday or Friday but I won’t tell you the day because it needs to be a surprise. The hangee replied, 'well if you have not done it by Thursday midnight, I will know it’s going to be on the Friday so that won’t be a surprise. So you can’t do it on Friday. By the same reckoning, if you haven’t done it by Wednesday Midnight then I will know it is going to be on Thursday so that would not be a surprise,' and so o...