What good are bumper stickers? So far in my life I have never seen anyone pull the car over and say to the passenger, “You know what? You CAN’T hug the world with nuclear arms, can you?” or, “I just visualized world peace and it was awesome.” They are not really arguments, let alone compelling ones. Bumper stickers don’t really change people’s lives. Nevertheless it is nearly impossible to go anywhere for a short drive in just about any town and not see the simple black “W,” a Shepherd Fairey, “Hope” illustration of Obama, a name followed by a “2012,” or a pithy statement about how just such-and-such a…