Can we hold our opinions lightly?

Remember when you comfortably sorted people out into the rough categories: optimist/pessimist or introvert/extrovert? And then, one day, you discovered that those categories arise from the work of the early 20th century psychiatrist, Carl Jung. You understood then and there that this cannot be law. You weren't relying on something written in the sky, or carved into a stone. No, someone came up with it a number of years before you were born. Now you still say, "You are such an introvert," and flash your knowing smile, but I can tell you're thinking all the time, "Is that right?"