Avery Pennarun, a Google employee, on the not-so-simple job of working with the smartest programmers on the planet:

Logic is a pretty powerful tool, but it only works if you give it good input. As the famous computer science maxim says, „garbage in, garbage out.“ If you know all the constraints and weights - with perfect precision - then you can use logic to find the perfect answer. But when you don’t, which is always, there’s a pretty good chance your logic will lead you very, very far astray.