This morning I took my car to be repaired. The mechanic shook his head: “This is a new model,” he said. “I’ve no idea how it works.” Later, I visited the hospital to discuss a planned operation. I asked the surgeon if she would use a new technique I’d read about online. “Oh, that sounds interesting,” she said. “I’d never heard of that before.”

Okay, okay: none of this actually happened. But imagine how shocked you would be if it did. We simply assume that professionals keep up to date with the changing state of knowledge that’s necessary to do their job.