Artificial intelligence was still in its infancy when Skinner raised a question that remains remarkably relevant today. He was worried that as machines got better at producing output, people would quietly stop doing the harder work of thinking, and nobody would notice the swap until it was done. Fifty-odd years later, we've built the machines. Now we get to find out whether he was right.

When I give talks about AI, I bring a hammer on stage. Then I ask the audience a question: how many of you can use a hammer?  Every hand goes up. Of course it does. The hammer is a brilliant tool. It's fast and easy to learn. You can get proficient in an afternoon. And it's wildly versatile. You can build stuff, break stuff, pry stuff apart. You can use it to attack or to defend yourself.