I love this question.
I asked it a couple of times last week and enjoyed watching the typical confusion followed by revelation. It’s a fast and elegant way to become aware of counter-examples and open your mind.
I’m running a self-application experiment this week and I urge you to join me: Every time I catch myself being narrow-minded and over-simplifying things (indicated by my being very ‘certain’) I’m going to ask:
What do I have be ignoring to think that?
If you join me in this game, I would love to know what happens…