When I was younger, someone gave me some excellent advice. “If you don’t know the answer to something,” he said, “it’s perfectly OK to say so. Those three words — I, don’t, and know — would have saved the world an awful lot of trouble.”

It’s undeniably good advice, and I have tried to live by it. When it comes to the big questions — “Is there life elsewhere in the universe?” “Who won the Republican presidential debate?” “What exactly is almond milk?” — I find it easy to claim total ignorance. But even for smaller questions, “I don’t know” is a nearly perfect response. It’s the most flexible answer you can give.