Conditional Reasoning Redux: The Only Cheat Sheet You Need on the LSAT

    LSAT Prep

    LSAT conditional reasoningFirst, a disclamer: you cannot bring a cheat sheet to the test center. Don't even think about it. And, if you follow the advice below, you wouldn't need to.

    The cheat sheet below is for those of you who are frequently baffled by the myriad ways in which conditional realtionships can be conveyed on the LSAT. As someone who only learned English in high school, I feel your pain - it sucks having 20 different ways of saying the same thing. Then again, that's what makes natural language different from coding. Before we get into the specifics of the cheat sheet, a word of caution: if you tend to see conditional reasoning everywhere, you've probably gone too far. Check out this blog post, and please resist the urge to diagram every other argument on the test. Diagram only when you believe it will help you understand what the author is saying. Personally, I only diagram stimuli containing more than two conditional relationships that either need to be connected in a chain (usually for the purposes of answering a Must Be True or a Parallel Reasoning question), or else cannot be connected because of a missing link (which needs to be deductively determined in order to answer an Assumption or Justify question).

    Feel free to print this and pin it above your desk. Or, if you care about trees etc., just bookmark it.

    You're welcome!

    Conditional Reasoning Cheat Sheet

    A → B

    (NOT B → NOT A)

    A → NOT B

    (B → NOT A)

    NOT A  B

    (NOT B → A)

    A ↔ NOT B

    (B   NOT A)

    ↔ B

    (NOT B    NOT A)

    If A, then B

    If not B, then not A

    All As are Bs

    A only if B

    Not A, unless B

    Not A, until B

    Only B can be A

    The only way to do A is to do B

    A depends on B

    Cannot have A without B

    None but B are A

    None except B are A

    Not until I do B can I do A

    If A, then not B

    If B, then not A

    No A are B

    No B are A

    Cannot have both A and B

    A depends on not B

    B depends on not A

    A only if not B

    B only if not A

    At most one of A or B is selected

    At least one of A or B is not be selected

    If not A, then B

    If not B, then A

    Without A, we must have B

    Without B, we must have A

    At least one of A or B is selected

    At most one of A or B is not selected

    Either A or B is selected

     

    Either A or B, but not both, is selected

    All except A are B

    All except B are A

    All but A are B

    All but B are A

    All except B are A

    All but A are B

    All but B are A

    A if and only if not B

    B if and only if not A

    Either A is selected without B, or else B is selected without A

    Either A is selected and B is not selected, or else B is selected and A is not selected

    If A then B, and if B then A

    A and B are interdependent

    All A are Bs and all B are A

    if and only ifB

    B if and only ifA

    Cannot have A without B, and cannot have B without A

    Either A and B are both selected, or else neither A nor B is selected

     

     

     Image courtesy of apenny.