… from Paul Krugman:

[T]he surest way to get branded as not Serious is to figure things out too soon. To be considered credible on politics you have to have considered Bush a great leader, and not realized until Katrina that he was a disaster; to be considered credible on national security you have to have supported the Iraq War, and not realized until 2005 that it was a terrible mistake; to be credible on economics you have to have regarded Greenspan as a great mind, and not become disillusioned until 2007 or maybe 2008.