The evolution of models involves change within lineages and their speciation on the basis of differences in ideational construals, in interpersonal values, and/or in textual foci, creating different communities of users. A so-called revolution — Kuhn’s paradigm shift — occurs when one of the evolving variants used by a small marginalised community comes to be used (selected) by a significant number of practitioners — or in the short term, the significant practitioners — of a field. That is, revolution is lineage replacement: the (relatively rapid) supplanting of one lineage by another through a significant change in the proportion of potential users adopting the model.