A mathematical metaphor applied to the history and philosophy of science, “incommensurability” describes a symptom of change during a scientific revolution. Even if they are practitioners of the same discipline, proponents of incommensurable theories or paradigms view the same discipline in fundamentally different ways, to the point that they are no longer trying to solve the same problems, they use the same words with different meanings, and according to Thomas Kuhn, actually operate in “different worlds” (Kuhn 1962, 150). Kuhn’s Structure of Scientific Revolutions rejected the modern idea that science progresses towards truth - instead, science changes over time with no reference to any objective truth. Person: Thomas Kuhn
Elsewhere: Stanford Encyclopedia of Philosophy 
Year: 1962