 The puzzle was introduced to the philosophical community by Adam Elga (2000), who argued that when Beauty woke up, her credence in Heads should be 1⁄3. Lewis argued that the correct answer was 1⁄2. The core of his argument was that before Beauty went to sleep, her credence in Heads should be 1⁄2. That was agreed on all sides. Moreover, nothing happened that surprised Beauty. Indeed, everything happened exactly as she expected it would. Lewis argued that “Only new relevant evidence, centred or uncentred, produces a change in credence” (2001c: 174), and that Beauty got no new evidence. This idea has featured heavily in subsequent work defending the 1⁄2 answer to the Sleeping Beauty puzzle.