One of the five simple notions to solve problems is the concept of inversion. To solve problems we need to look at them both forward and backward.
But how does this look in practice? Let me give you an example that Charlie Munger gave during a speech.
Munger liked to give his family little puzzles. And one of the puzzles he gave his family was:
There’s an activity in America, with one-on-one contests, and a national championship. The same person won the championship on two occasions about 65 years apart.
“Now,” I said, “name the activity.”
Any ideas? How would you answer this?
“In my family,” Munger said, “not a lot of light bulbs were flashing.” Except for one.
But I have a physicist son who has been trained more in the type of thinking I like. And he immediately got the right answer, and here’s the way he reasoned:
It can’t be anything requiring a lot of hand-eye coordination. Nobody 85 years of age is going to win a national billiards tournament, much less a national tennis tournament. It just can’t be. Then he figured it couldn’t be chess, which this physicist plays very well, because it’s too hard. The complexity of the system, the stamina required are too great. But that led into checkers. And he thought, “Ah ha! There’s a game where vast experience might guide you to be the best even though you’re 85 years of age.”
And sure enough that was the right answer.
Flipping one's thinking both forward and backward is a powerful sort of mental trickery that will help improve your thinking.