A man on the subway platform is carrying an umbrella. Someone asks him, “Is it supposed to rain?” The man with the umbrella responds with a discussion of cumulus and cumulo-nimbus cloud formation. He describes the earth’s energy budget and the differences between warm and cold fronts. He diagrams the local weather map on the floor of the subway platform and explains what weather forecasters mean when they say there’s a twenty percent chance of rain. “So, you’re saying it’s going to rain,” a woman exclaims, but the man with the umbrella responds that there are no certainties in weather, that it’s all a matter of probabilities, that it might rain, or it might not, and that even the nature of rain, that is, what rain is, as opposed to other forms of precipitation, is only a matter of critical judgment. When a guy in a suit says, “You’re not telling us anything,” the man strolls to the middle of the subway platform and puts up his umbrella. It starts to rain.