The Harry Potter series puts the reader in a child-like position. We are exposed to an exotic and unfamiliar world, and we must make sense of the strange goings-on in the world of magic. This parallels every child’s problem in coming to understand the strange goings-on in what adults appreciate as the real Muggle world. These problems are ultimately unsolvable. Nobody has a complete understanding of the world around us, but most people come to some basic, commonsense understanding. To be an adult member of twenty-first century Western culture involves, in part, knowing about such things as germs, tigers, and presidents. In the world of Harry Potter, common sense includes such things as jinxes, hippogriffs, and Ministers of Magic. Part of the fun of the series is following Harry’s encounters with the unfamiliar world of magic. Harry did not grow up in the magic world (he lacks magical common sense), and the readers learn along with him.

It is all too evident that there are many kinds of knowledge and skills that we would like to have as part of our common sense that are not. One of the central questions in cognitive development is why some things seem to be effortlessly learned by almost everyone, while other things take a lot of hard work and are learned by a select few. The classic example is speaking versus reading; almost everyone learns to speak, but we require special institutions and schools to get people to read, and even then not  …