Hello World: Being Human in the Age of Algorithms

by Hannah Fry

Thomas Bayes, the British Presbyterian minister and talented mathematician after whom the theorem is named. Back in the mid-1700s, he wrote an essay which included details of a game he’d devised to explain the problem. It went something a little like this:32 Imagine you’re sitting with your back to a square table. Without you seeing, I throw a red ball on to the table. Your job is to guess where it landed. It’s not going to be easy: with no information to go on, there’s no real way of knowing where on the table it could be. So, to help your guess, I throw a second ball of a different colour on to the same table. Your job is still to determine the location of the first ball, the red one, but this time I’ll tell you where the second ball ends up on the table relative to the first: whether it’s in front, behind, to the left or right of the red ball. And you get to update your guess. Then we repeat. I throw a third, a fourth, a fifth ball on to the table, and every time I’ll tell you where each one lands relative to the very first red one – the one whose position you’re trying to guess. The more balls I throw and the more information I give you, the clearer the picture of the red ball’s position should become in your mind. You’ll never be absolutely sure of exactly where it sits, but you can keep updating your belief about its position until you end up with an answer you’re confident in.