All scientists, social and otherwise, have heard of paradigms and Thomas Kuhn. No one, it seems, has read Kuhn's book The Structure of Scientific Revolutions but everyone has a sense of what a paradigm is. Kuhn's book is no help on this point, as dozens of authors at the “Philosophy of Science” symposia have pointed out. We need a metaphor to understand it.
Almost all commentators agree that Kuhn's use of the paradigm concept is extremely loose and variable. Some have claimed to find 23 different meanings of “paradigm” in Kuhn's book. In the second edition of Structure of Scientific Revolutions, he adds a 36-page “postscript” in which he attempts to clarify his thoughts. Kuhn asserts that the scientific community engages in “normal” or “dogmatic” research for long periods between short bouts of “extraordinary” research. During the dogmatic stasis, there is consensus, and controversy ceases; the community concentrates on “puzzle-solving” to force nature to fit the paradigm. Only during “extraordinary periods” do unsolved puzzles, anomalies, and paradoxes turn into arguments against the paradigm rather than against the data or the observer.