Six years ago, I changed my mind about the benefit of being able to change my mind.
In 2002, Jane Ebert and I discovered that people are generally happier with decisions when they can't undo them. When subjects in our experiments were able to undo their decisions they tended to consider both the positive and negative features of the decisions they had made, but when they couldn't undo their decisions they tended to concentrate on the good features and ignore the bad. As such, they were more satisfied when they made irrevocable than revocable decisions. Ironically, subjects did not realize this would happen and strongly preferred to have the opportunity to change their minds.
Now up until this point I had always believed that love causes marriage. But these experiments suggested to me that marriage could also cause love. If you take data seriously you act on it, so when these results came in I went home and proposed to the woman I was living with. She said yes, and it turned out that the data were right: I love my wife more than I loved my girlfriend.
The willingness to change one's mind is a sign of intelligence, but the freedom to do so comes at a cost.