If concept-swapping is a fallacy consisting in arguing in favour of a synthetic statement disguised as an analytic one, then there is nothing more important for philosophical methodology than to have a firm and clear grasp of the analytic-synthetic distinction. A useful byproduct of this would be that we will be in a position to understand why serious scholars spend so much time arguing about definitions, thereby treating terminological questions as though they were substantive. Although this strange phenomenon can be observed in all areas of philosophy nowhere is there more at stake as when concept-swapping is taken to decide questions of law.