The reason this isn't the accepted ideal method for building an AI is that it -doesn't build an AI-.<p>A decision tree attached to your incoming email doesn't constitute an AI; its only automation. It isn't making decisions, and a structure of these decision trees, even complicated enough to perfectly mimic a person, is not an intelligence, its a philosophical zombie.<p>Yeah, it is theoretically possible to build a model of me that mimics me entirely by clearly defining the decision trees, but that's not the problem of AI: Its easy enough to teach it to do something, but hard to build something that actually learns.