Karl Popper reminded us the strengh of science is its ability to test falsification, not truth.
It's almost too late for the valuable lessons because no one can be taught anything they don't care to learn. The only way to make the personal advantage of critical thinking accessible to them is through their own experience -- this way: Think of an instance in your past when you thought you were right and got hurt because you were mistaken. That shows that sometimes you think you are right, not because you are right, but only because you are convinced.
If you can be mistaken and not know it, how are you going to discover where? Doubt is important because you bet your future on the quality of your mental map of reality. People who doubt their own certainty willingly interact with others to improve how they understand their world.
This carries over to society. Cultural behaviors may be relative, but the minimum behavior at the edge where two cultures meet is not. We call that edge "society." Just as an individual values doubt, doubt is important for society. The strength of democracy isn't that it gets things right. It doesn't. But democracy codifies the humility we just might be wrong and commits to a process to learn where and try to do better.
