 What should her answer be when she is awakened on Monday and asked how confident she is in the coin’s landing heads? Lewis (2001) employs the Principle of Conditionalization to argue that the answer is \(1/2\). His reasoning proceeds as follows: Sleeping Beauty, upon her awakening, acquires no new evidence or acquires only a piece of new evidence that she is already certain of, so by conditionalization her credence in the coin’s landing heads ought to remain the same as it was before the sleep: \(1/2\).