LSAT Logic Games Diagrams: How to Set Up and Notate Rules

Logic Games diagrams are not decorations. They are the working memory of the game. Every rule you translate into a symbol is a rule you never have to re-read mid-question. Every slot you fill in based on a deduction is work you do once, not five times.

Students who try to hold all the rules in their head fall apart by Question 3. Students who draw clean, complete diagrams can solve a five-question game by glancing at the page. The goal is to make the diagram do the thinking.

Draw the base structure before you write a single rule. For a sequencing game with six slots, draw six boxes in a row and label them 1 through 6. For a two-group assignment game, draw two labeled columns. For an in/out game, draw two columns labeled 'In' and 'Out.'

Keep the base compact — roughly six centimeters wide. You will draw a new copy of this base for each question that requires a fresh diagram, so making it small saves time.

Write a roster of entities above the diagram. If the game has six people — A, B, C, D, E, F — write all six on one line. Cross off each entity as you place it so you always know who is unaccounted for.

Ordering rules: 'A comes before B' → A — B (with a gap) or A < B. 'A comes immediately before B' → AB (no gap, written as a block). 'A does not come immediately before B' → draw AB with a slash through it.

Placement rules: 'A is in slot 3' → write A directly in the slot. 'A is not in slot 1 or 6' → write a small 'not A' under slots 1 and 6 on your base diagram. These are called 'not laws.'

Grouping/assignment rules: 'A and B are on the same team' → AB (block). 'A and B are on different teams' → A/B (slash between them). 'If A is on Team 1, then B is on Team 2' → conditional arrow: A₁ → B₂.

Conditional rules: 'If A is selected, then B is not' → A → ¬B. Always write the contrapositive immediately below: B → ¬A. This prevents the most common conditional error — forgetting the contrapositive under time pressure.

Any time you write a conditional rule, immediately write its contrapositive on the next line. Do not skip this step, even when you think you will remember it. Forgetting a contrapositive under timed conditions costs you a question.

Example: Rule says 'If the red tile is used, the blue tile is not used.' Write: R → ¬B. Below it: B → ¬R. Done. You never have to derive the contrapositive again during the game.

This two-line habit takes three seconds and pays off on at least one question in every game with conditional rules.

'Unless' translates to 'if not': 'A is not selected unless B is selected' → ¬B → ¬A. Contrapositive: A → B.

'Only if': 'A is on the team only if B is on the team' → A → B. Contrapositive: ¬B → ¬A.

'Except' often signals a near-complete constraint: 'Every entity except F must be in Group 1 or Group 2' means F can be in Group 3. Handle it by noting the exception directly on the entity in your roster.

The words change but the translation rule is always the same: identify the sufficient condition (the trigger), identify the necessary condition (the result), and draw the arrow. Then write the contrapositive.

Many questions add a new condition just for that question ('For this question only, suppose A is in slot 2'). When you see this, draw a fresh copy of your base diagram and work in that new condition before answering.

Never modify your master diagram with question-specific conditions. Mark the master with permanent inferences only. A sloppy student who writes 'Q3 condition' into the master diagram will get Q4 wrong because the condition is no longer active.

The only way to make diagramming fast is to do it repeatedly until the notation requires no thought. Ten to fifteen games with full setup — not just reading, but actually drawing every diagram — is usually enough to make the process feel natural.

Verbloom's Logic Games drills give you immediate feedback on rule interpretation, so you can identify whether a diagramming error or a reasoning error caused a wrong answer. Start at verbloom.dev.