Incommensurability

Thomas Kuhn introduced incommensurability in The Structure of Scientific Revolutions (1962) as his most precise and most contested observation about paradigm shifts. He did not mean that practitioners in different paradigms cannot communicate. He meant something narrower and more disturbing: that certain key terms—the terms that carry the paradigm's core assumptions—change their meaning across paradigm boundaries in ways that prevent complete translation. “Mass” in Newtonian mechanics and “mass” in Einsteinian mechanics are not synonyms operating in different theoretical contexts. They are different concepts sharing a name. The difference is invisible in casual conversation and surfaces as genuine misunderstanding when the conversation turns to foundations. The AI transition has produced exactly this kind of terminological drift: the word “programming” now indexes fundamentally different conceptual structures depending on which paradigm the speaker inhabits, and the resulting miscommunication looks like disagreement between stubborn people when it is, in Kuhn's precise sense, an encounter between incommensurable frameworks.