Yves Smith of Naked Capitalist is at the center of a growing argument among analysts like me and mainstream economists as to whether economics as practiced is really useful. The mainstream people keep writing papers on the subject "How could we have known?" making excuses as to why they missed it and why their theories, especially Keynesian stimulus, are not working. This is a 6-page thought piece and a rebuttal to a Brad Delong paper. May not help you decide where the technical sell point on the S&P is, but will help inoculate you when you read economics BS.