What do you know about <topic>? How do you know that? How confident are you that you're right? I don't find these questions easy to answer. In fact, they cause me a considerable amount of hemming, hawing, head-scratching, and "um" -ing. Paradoxically, I used to find these questions easy to answer, but now that I'm older I consider prior-Jeffrey to be ridiculously naive and arrogant. I used to have all the (wrong) answers; now that I'm a bit wiser I struggle to come up with any answer!