The concept-swapping fallacy could be dismissed out of hand as a mere playing on words that does not deceive anyone were it not for the fact that under certain circumstances it can, and does, have serious practical consequences. This is eminently the case of the alleged proof that a supranational organisation such as the League of Nations is a logical impossibility, for it would destroy the nation-states that would try to set it up. This "proof", constructed of all pieces by German legal scholars, was instrumental in preventing the establishment of such an organisation and in preparing the ground for future war.