Puzzles, Charts & DilemmasUntie the question first.https://puzzleschartsanddilemmas.com/2026-10-31T00:00:00ZAnscombe's Quartet: One Fitted Line, Four Different Shapeshttps://puzzleschartsanddilemmas.com/charts/anscombes-quartet/2026-10-31T00:00:00ZAnscombe's quartet as distributed with R: four sets of 11 points share means, variances, correlation and fitted line to two significant figures, yet differ.Puzzles, Charts & DilemmasExperience Machine: A No to Plugging In Does Not Say Whyhttps://puzzleschartsanddilemmas.com/dilemmas/experience-machine/2026-10-31T00:00:00ZRefusing Nozick's experience machine while trusting it shows something besides how life feels matters to you, but not what. One-change swaps sort the reasons.Puzzles, Charts & DilemmasGalileo's Falling Bodies: The Argument That Needed No Towerhttps://puzzleschartsanddilemmas.com/thought-experiments/galileo-falling-bodies/2026-10-31T00:00:00ZGalileo's tied stones show that Aristotle's falling rule clashes with a premise its defender grants. In air, his dialogue says, the big ball lands just ahead.Puzzles, Charts & DilemmasGravity Train: Uniform Earth, Straight Tunnel, About 42 Minhttps://puzzleschartsanddilemmas.com/thought-experiments/gravity-train/2026-10-31T00:00:00ZIn a uniform, frictionless Earth, any straight gravity train tunnel takes about 42 minutes one way; a 2013 preprint finds about 38 through the real center.Puzzles, Charts & DilemmasKnights and Knaves: 108 of 256 Puzzles Have a Single Answerhttps://puzzleschartsanddilemmas.com/puzzles/knights-and-knaves/2026-10-31T00:00:00ZUnder this page's rules, 108 of the 256 two-speaker knights and knaves puzzles have exactly one answer. Try the featured puzzle; its checked answer is folded.Puzzles, Charts & DilemmasMinard's Map: By His Figures, Most Losses Came Before Winterhttps://puzzleschartsanddilemmas.com/charts/minard-map/2026-10-31T00:00:00ZBy the figures on Minard's 1869 map, his bands shrink by a net 412,000 men, and 267,000 are gone before the retreat and its cold. All 26 figures, redrawn.Puzzles, Charts & DilemmasNewcomb's Problem: Rules Split if the Predictor Tops 50.05%https://puzzleschartsanddilemmas.com/puzzles/newcombs-problem/2026-10-31T00:00:00ZIn Newcomb's problem, expected value figured on your choice favors one box once the predictor beats 50.05%; dominance favors both. Philosophers still disagree.Puzzles, Charts & DilemmasNightingale Rose Diagram: Its Monthly Rates Are Yearly Rateshttps://puzzleschartsanddilemmas.com/charts/nightingale-rose-diagram/2026-10-31T00:00:00ZEach wedge of Nightingale's 1858 rose is one month's deaths scaled to a yearly rate per 1,000 men. Her own table, all 24 months, recomputed and redrawn.Puzzles, Charts & DilemmasPrisoner's Dilemma: In One Round, Betrayal Pays Each Playerhttps://puzzleschartsanddilemmas.com/dilemmas/prisoners-dilemma/2026-10-31T00:00:00ZIn one round of the prisoner's dilemma, betraying pays each player more whatever the other does, yet two betrayals leave both worse off than two silences.Puzzles, Charts & DilemmasRiver Crossing Puzzle: Under Its Rules, Two Shortest Routeshttps://puzzleschartsanddilemmas.com/puzzles/river-crossing-puzzle/2026-10-31T00:00:00ZRiver crossing puzzle with a wolf, goat and cabbage, written as four rules: under them, 10 of 16 bank layouts are safe and two orders tie for fewest crossings.Puzzles, Charts & DilemmasShip of Theseus: Plutarch's Version Had Only One Shiphttps://puzzleschartsanddilemmas.com/thought-experiments/ship-of-theseus/2026-10-31T00:00:00ZPlutarch's Ship of Theseus has one ship. The rebuilt rival appears in Hobbes's De Corpore (1655), and Hobbes gave a rule that answers it for the repaired ship.Puzzles, Charts & DilemmasSimpson's Paradox: One Berkeley Table, Two Honest Summarieshttps://puzzleschartsanddilemmas.com/charts/simpsons-paradox/2026-10-31T00:00:00ZBerkeley 1973, six largest departments: 44.5% of men and 30.4% of women were admitted, yet women had the higher rate in 4 of the 6. The counts, redrawn.Puzzles, Charts & DilemmasTower of Hanoi: 8 Disks Need 255 Moves on Three Pegshttps://puzzleschartsanddilemmas.com/puzzles/tower-of-hanoi/2026-10-31T00:00:00ZThree-peg Tower of Hanoi: 8 disks take 255 moves, and the 64-disk tower in Lucas's legend takes about 585 billion years at one move a second.Puzzles, Charts & DilemmasUnexpected Hanging Paradox: The Proof Fails, but Where?https://puzzleschartsanddilemmas.com/puzzles/unexpected-hanging-paradox/2026-10-31T00:00:00ZThe unexpected hanging paradox, or surprise test paradox: a proof that a surprise test is impossible, then a surprise test. Six diagnoses, with their sources.Puzzles, Charts & DilemmasVeil of Ignorance: At Most 1 of 81 Groups Chose Rawls's Rulehttps://puzzleschartsanddilemmas.com/dilemmas/veil-of-ignorance/2026-10-31T00:00:00ZRawls argued choosers behind a veil of ignorance would protect the worst-off. In one lab study, 1 of 81 student groups chose to maximize the lowest income.Puzzles, Charts & Dilemmas