Just because you’re smart doesn’t mean you get things right the first time. That’s the premise behind What Have You Changed Your Mind About? (Harper Perennial), a new anthology. In it, 150 “big thinkers” describe what they now think they were wrong about earlier in their lives. Much of this has to do with technology and education. Among the highlights:

Ray Kurzweil no longer thinks that intelligent aliens exist. The oft-cited futurist and inventor, a pioneer in artificial intelligence and in making reading machines for the blind, says that conventional thinking holds there should be billions of such civilizations and a number of them should be ahead of us, “capable of vast, galaxy-wide technologies. So how can it be that we haven’t noticed” all of the signals they should be creating? “My own conclusion is that they don’t exist.”

Roger C. Schank used to say “we would have machines as smart as we are within my lifetime.” Now Mr. Schank, a former Yale University professor and director of Yale’s artificial-intelligence project, says: “I no longer believe that will happen… I still believe we can create very intelligent machines. But I no longer believe that those machines will be like us.” Chess-playing computers that beat people are not good examples, he says. Playing chess is not representative of typical human intelligence. “Chess players are methodical planners. Human beings are not.” We tend, Mr. Schank says, “to not know what we know.”

Randolph M. Nesse “used to believe that truth had a special home at universities.” Mr. Nesse, professor of psychiatry at the University of Michigan and an expert on evolution and medicine, now thinks “universities may be the best show in town for truth pursuers, but most of them stifle innovation and constructive engagement of real controversies — not just sometimes but most of the time, systematically.” Faculty committees, he complains, make sure that most positions “go to people just about like themselves.” Deans ask how much external financing new hires will bring in. “No one with new ideas … can hope to get through this fine sieve.” —Josh Fischman