It long has been understood that the advance of technology, know-how more broadly, has been the wellspring of economic progress. It has been less well recognized that the advance of human know-how has been extremely uneven, very rapid and cumulatively great in some fields, like communications and computation, and quite limited in other fields, like house building and education. This paper begins to explore the reasons for this unevenness. At one level an important reason is that the sciences behind various technologies have advanced unevenly, but this only pushes the question back a stage; why the unevenness of scientific advance? The paper makes use of a comparison between medicine and education to make many of its points. (C) 2002 Elsevier Science B.V. All rights reserved.
