This continues a series of posts ( 1 , 2 , 3 ) I've been writing that tries to improve on Indian PM Narendra Modi's clumsy demonetization, or what I prefer to call a policy of surprise note swaps. The main goal of Modi's demonetization (i.e. note swapping) is to attack holdings of so-called "black money," or unaccounted cash. The problem here is that to have a genuine long-run effect on the behavior of illicit cash users, a policy of demonetization needs to be more than a one-off game. It needs to be a repeatable one. A credible threat of a repeat swap a few months down the road ensures that stocks of licit money don't get rebuilt after the most recent swap. If that threat isn't credible, then people will simply go back to old patterns of cash usage. It's worth pointing out that the idea of behind demonetization precedes Modi by many decades. In a 1976 article entitled Calling in the Big Bills and a 1980 a follow-up How to Make the Mob Miserable , Jam...