Are new concepts revolutionary or evolutionary?

Thomas Kuhn's account of conceptual change in his seminal work The Structure of Scientific Revolutions. Kuhn believed that conceptual change is a revolutionary process, during which mutually exclusive paradigms compete to replace one another

Others believe that conceptual change is an evolutionary process.

Toulmin criticized the relativist elements in Kuhn's thesis, arguing that mutually exclusive paradigms provide no ground for comparison, and that Kuhn' made the relativists' error of overemphasizing the "field variant" while ignoring the "field invariant" or commonality shared by all argumentation or scientific paradigms.

In contrast to Kuhn's revolutionary model, Toulmin proposed an evolutionary model of conceptual change comparable to Darwin's model of biological evolution. Toulmin states that conceptual change involves the process of innovation and selection. Innovation accounts for the appearance of conceptual variations, while selection accounts for the survival and perpetuation of the soundest conceptions. Innovation occurs when the professionals of a particular discipline come to view things differently from their predecessors; selection subjects the innovative concepts to a process of debate and inquiry in what Toulmin considers as a "forum of competitions." The soundest concepts will survive the forum of competition as replacements or revisions of the traditional conceptions.

From the absolutists' point of view, concepts are either valid or invalid regardless of contexts. From the relativists' perspective, one concept is neither better nor worse than a rival concept from a different cultural context. From Toulmin's perspective, the evaluation depends on a process of comparison, which determines whether or not one concept will improve explanatory power more than its rival concepts.