Logic puzzles feel like magic until you learn that good solvers all use the same handful of moves. Here they are.
- Write everything down. Working memory is small. A sketch, grid or list stores the facts so your mind can reason.
- Restate the question. Many errors come from solving a slightly different puzzle than the one asked.
- Start with the most restrictive clue. A clue that pins something down exactly (the only one who...) beats vague ones.
- Use elimination. Cross off what cannot be true. When only one option is left, you have a fact.
- Test an assumption. Say "suppose this is true" and follow it. If it leads to a contradiction, the opposite must hold. This is the engine behind knights-and-knaves puzzles.
- Look for the forcing move. Ask "what is the one thing that cannot be anything else?" and start there.
- Check your answer against every clue. Do this at the end, always.
A tiny example
Ana, Ben and Cy own a cat, a dog and a fish. Ana does not own the cat. Ben owns neither the dog nor the cat. Who owns what?
Ben cannot have the dog or the cat, so Ben has the fish. That leaves the cat and dog for Ana and Cy, and Ana does not own the cat, so Ana has the dog and Cy has the cat. One forcing clue, then elimination.
When you are stuck
Walk away for a few minutes. Solutions often appear when you stop forcing them. Also try drawing the problem differently: a table, a map, a timeline.
Practise on real brain-itchers in the Puzzle Vault, or crack Today's Enigma.