Though they may use different terms, all scientific researchers are familiar with the concept of a SWAG (Scientific Wild-Ass Guess). It is what their gut instincts tells them the right answer will be long before they have sufficient data to derive that answer. Good researchers know not to trust SWAGs; they are wrong too many times. But sometimes a SWAG not only gets publicized, it gets enshrined in the scientific literature. The estimate of climate sensitivity is one of those cases.