The American philosopher Eric Switzgebel has made a name for himself in recent years by challenging a lot of what people think they know, and, in particular, by challenging what people think they alone know—things about their own conscious mental experience. For example, he has challenged the notion that mental images are picture-like, which a lot of people believe. People confidently state that they “had an image in their heads” of this or that and discuss the contents of it (oh, I was looking at an image in my head of Grandma’s house as it appeared back when I was a kid in ’85), but when you press them on this, their image report turns out to be extremely unreliable in a way that pictures–real pictures–aren’t. If I ask someone to visualize a candle, he or she will report having done this. He or she might say something like, “I…