I'm not sure what you're getting at. Yes, there are multiple levels of abstraction. Yes, from the fact that someone hasn't said X, you cannot infer with 100% certainty that they do not believe X. I doubt anyone could disagree with these banal statements, but they don't have anything to do with this discussion.<p>&#62;Have you read Douglas Hofstadter's classic Godel, Escher, Bach?<p>Yes, I've read it. Thanks for the recommendation.