FALSUM guide
Riddle, deduction puzzle and logic puzzle: what separates them
A riddle is solved by wit or wordplay and its answer cannot be demonstrated, only recognised. A deduction puzzle is solved by reasoning over given evidence and has one justifiable answer. A logic puzzle adds formal constraints that combine until every possibility but one is eliminated.
Riddle: wit and recognition
"What has hands but cannot clap?" A riddle works by association or double meaning, and its answer is validated because it fits, not because it was deduced. It is an excellent format for warming up a group and a poor one for working together, because you cannot reason your way toward the answer.
Deduction puzzle: evidence and contradiction
Here there is a path. The case describes a situation, someone gives an account, and something in that account will not hold. The reader locates the incompatibility and explains it. The answer is defended with the text in hand, which makes it arguable aloud: two people can disagree and settle it by rereading.
This is the territory of The Impossible Version, with 50 independent cases of logic and contradiction for adults.
Logic puzzle: constraints that combine
A formal logic puzzle gives a set of restrictions — who can be where, what order is possible — and asks you to cross them until only one valid configuration remains. It resembles a sudoku with names more than it resembles a story. It invites pencil, grid and crossings-out, and has the advantage that checking is mechanical: either it satisfies every constraint or it does not.
RASTROS works in this band, with 100 single-solution cases across five levels.
The same premise in all three formats
One scene — a man comes home soaked and says he was fishing — shows what each format does with it.
As a riddle: "What comes home wet from a man who never touched the water?" The point is the phrasing, and the answer is either recognised or not.
As a deduction puzzle: you are given his statement, the photograph he offers and the time the rain started, and asked to name what does not fit. There is a path, and there is room to argue.
As a logic puzzle: you get five neighbours, five arrival times and a set of constraints about who got back before whom, and you reconstruct the full order. The story becomes scenery; the grid does the work.
Why the distinction matters when buying
All three are sold under interchangeable labels — "puzzles", "riddles", "brain teasers" — and that accounts for a good share of the disappointments. Someone who wants to argue in a group and buys formal logic puzzles ends up with a grid solved in silence. Someone who wants to think alone with a pencil and buys riddles has nothing to do after the first minute.
The useful question before buying is not the difficulty level but the kind of activity you are after: recognising, arguing or combining.
Which to choose
- To break the ice in a group: riddle.
- To argue aloud with a way to settle it: deduction puzzle.
- To solve alone, with a pencil and no hurry: logic puzzle.