US shipping · Rate shown at checkout · Each item made to order
The Logical Thought

The Logical Thought

The Notebook

Puzzles with worked answers, fallacies in their natural habitat, and numbers that behave strangely. No math degree needed.

Two Doors, Two Guards, One Question Puzzles Two Doors, Two Guards, One Question One guard always lies and the other always tells the truth. You get a single question. Here is the question, and why it works. Four Cards, One Rule Puzzles Four Cards, One Rule A famous test of everyday logic that most people fail on the first try. Which two cards do you actually need to turn over? The Three Switches Puzzle Puzzles The Three Switches Puzzle Three switches, one closed room, one bulb, and only one trip through the door. The trick is noticing a clue that your eyes cannot see.