A CENTRAL THEME of Mindstorms is that people seldom get anything exactly right on the first try. Intellectual activity does not progress, as logicians and the designers of school curricula might want us to believe, by going step-by-step from one clearly stated and well-confirmed truth to the next. On the contrary, the constant need for course corrections, which I call "debugging" in this book, is the essence of intellectual activity.
Having stated this view so emphatically, I would be embarrassed if I did not use the opportunity of a new edition to comment on "bugs" in the original. I begin by noting some that have more to do with the presentation of ideas than with the ideas themselves. Most of these problems had their origin in a mistaken model of the book's public. In my 1993 book, The Children's Machine: Rethinking School in the Age of the Computer, I comment on how much I learned because so many teachers, especially elementary school teachers, not only read Mindstorms but also exercised real ingenuity in adapting the realities of life in contemporary schools to ideas that I imagined as having their application only in a more futuristic setting. My failure to anticipate the extent to which the book would be picked up by teachers shows itself most clearly in the gratuitous use of such examples as New