It's surprising how often, in highly complex domains where we are trying to figure out what to do, an obvious or simple default can perform extremely well. This is sometimes even true when the defaults are clearly not optimal. Here are simple defaults in four complex domains that can be surprisingly hard to outperform: 1. Charity: give money to the poorest non-drug addicted people you can find, and let them do whatever they want with the money. GiveWell, which has spent yea...