A paradigm is a fundamental image of the subject matter within a science. It serves to define what should be studied, what questions should be asked, how they should be asked, and what rules should be followed in interpreting the answers obtained. The paradigm is the broadest unit of consensus within a science and serves to differentiate one scientific community (or subcommunity) from another. It subsumes, defines, and interrelates the exemplars, theories, and methods and instruments that exist within it.

The most famous use of the paradigm concept is that of Thomas Kuhn. As influential as the concept, and the theory of scientific revolutions in which it is embedded, were, there is great ambiguity in the way Kuhn used the concept. One critic found 21 different ...