One of the most notorious public pronouncements on the subject of risk was enunciated by the former Secretary of Defense under the Bush administration, Donald Rumsfeld (2002), when he stated in the context of dangers in Iraq: “Reports that say that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns-the ones we don’t know we don’t know.” While the public and press were perplexed by this apparently bizarre statement, in fact, Rumsfeld had enunciated a fundamental principle of risk analysis.