John Brockman [5] has run out of questions. Brockman, a literary agent, runs the science and philosophy site Edge.org [6]. Every year for 20 years, he has asked leading thinkers [7] to answer a particular question, such as: “What questions have disappeared?” or: “What do you believe is true even though you cannot prove it?” This year, though, Brockman announced that he has no more questions left. So he asked his final question: “What is the last question?”

“Judge a man by his questions rather than by his answers,” Voltaire insisted. Questions help us define what we don’t know and force us or others to justify what we think we do know.

Asking questions is relatively easy. Asking good questions is surprisingly difficult. A bad question searches for an answer that confirms what we already know. A good question helps to reset our intellectual horizons. It has an answer that we can reach, yet unsettles what we already know. ...