Mayor: The law prohibiting pedestrians from crossing against red lights serves no useful purpose. After all, in order to serve a useful purpose, a law must deter the kind of behavior it prohibits. But pedestrians who invariably violate this law are clearly not dissuaded by it; and those who comply with the law do not need it, since they would never cross against red lights even if there were no law prohibiting pedestrians from crossing against red lights. The mayor's argument is flawed because it ['fails to consider whether the law ever dissuades people who sometimes but not always cross against red lights', 'takes for granted that most automobile drivers will obey the law that prohibits them from driving through red lights', 'uses the word "law" in one sense in the premises and in another sense in the conclusion', 'provides no evidence that crossing against red lights is more dangerous than crossing on green lights']