Taxes typically serve two purposes: to raise revenue, the most straightforward and the only one intended by the Constitution, and the more sinister purpose of shaping the behavior of others. This second use has been increasingly favored by progressives who are now using the term “nudge” to describe pushing people to do what they want by making the alternatives more expensive. Ex-Mayor Michael Bloomberg has been the champion of this technique, aggressively pushing New Yorkers to stop smoking, stop eating trans fats and stop drinking sodas of 16 ounces or more.