P1. Bumper stickers for political campaigns that have ended are evidence for the public choice idea that political participation is expressive rather than instrumental. What could be more about you and less about concrete objectives than a call to action for an event that’s already happened?
P2. Bernie Sanders bumper stickers survive all out of proportion to how much support he had.
C1. Supporting Sanders is expressive at an above-average level.
C2. Sanders supporters are lazy and haven’t gotten around to taking off the stickers. (heh)