Paradigm Shifts

by Ed Yourdon

In the days since September 11, many of us feel that our world has been turned upside down -- almost as if the law of gravity had been repealed. Natural laws like this -- whether in the field of astrophysics, chemistry, biology, or electrical engineering -- were what Thomas Kuhn had in mind when he discussed the concept of a "paradigm shift" in his famous book The Structure of Scientific Revolutions (http://www.amazon.com/exec/obidos/ASIN/0226458075/cutterinformatco). My Microsoft Word dictionary says that one of the definitions of "paradigm" is "a generally accepted model of how ideas relate to one another, forming a conceptual framework within which scientific research is carried out." And a paradigm shift occurs when the existing framework requires so many exceptions and special cases, and when it fails to address so many important problems, that it collapses under its own weight and is replaced by a new, simpler, more persuasive paradigm.