LSAT Logic Games: Some Common(ly Overlooked) Deductions


Manhattan Prep LSAT Blog - LSAT Logic Games: Some Common(ly Overlooked) Deductions by Chris Gentry

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Almost all test-takers seem to share two concerns about LSAT Logic Games: speed and speed. Oh, and people also seem to worry about speed for some reason.

Sound familiar? If so, you may want to read Daniel Fogel’s excellent post from a few months ago before you continue.

All done? Good!

There are two places for speed on LSAT Logic Games: speed in the questions and speed in the deductions.

Speed in the deductions can be learned! In my opinion, this comes from practicing two things: first, making the deductions. Occasionally, try creating a game setup with no time constraints. Can you come up with at least 4 deductions?

Second, and possibly more important where speed is concerned, is classifying the type of deductions. Some of the most common deductions are what I call “spacing” or “ordering” deductions. These are all over the linear games. Six saxophone solos will occur, one at a time, in order from first through sixth. Solo L must occur after solo J. Et cetera, et cetera, et cetera.

In my experience, most LSAT test-takers are pretty comfortable with the deductions that arise from these types of rules. It’s the next category that is really off-putting to many test-takers: numerical deductions. (“Off-putting” may be a wild understatement here—many people actively despise the kinds of games that tend to have these deductions!)

Consider the second game from the June 2007 LSAT. (This is the LSAT that’s free to download from LSAC’s website.)

There are a few challenges in this game.

  1. Most people address what films can/will be shown on which day. It’s much, much more rare to indicate the flip side of that coin: what films will not be shown on what day? (In fact, this is a common failing when a rule contains the words “but not both”.)
  2. People rarely (in my experience, almost never) take the time to address the numerical options up front. What’s the maximum number of films? The minimum?

When you encounter LSAT Logic Games with numerical restrictions, this is always a fruitful deduction path to consider. Sometimes these kinds of deductions show up directly in the questions, as in question 8 for this game.

Sometimes these deductions can lead to frames! If you have 10 New Actual, Official LSAT Preptests (PrepTests 52-61), consider PT 56, game 2.

Each park is planted with exactly 3 of 4 varieties. Interesting…how many “outs” will there be for each park?

At least one park will be planted with both maples and sycamores. Interesting… could both parks be planted with both maples and sycamores? Exactly one park planted with both? If a park doesn’t have both M and S, could it have neither M nor S?

If you follow these numerical thoughts, you realize that three diagrams completely encompass this game!

Good luck, and work on those grouping games! Follow the numbers! ?

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Chris Gentry is a Manhattan Prep LSAT, GMAT, and GRE instructor who lives in Atlanta, Georgia. Chris received his Bachelor of Science in chemical engineering from Clemson and JD from Emory University School of Law before realizing that he genuinely enjoys the challenge of standardized tests, and his true passion is teaching. Chris’ dual-pronged approach to understanding each test question has helped countless of his students to achieve their goal scores. What are you waiting for? Check out Chris’ upcoming LSAT courses here.

  1. knappi September 25, 2017 at 5:26 pm

    Hi, Jasmine! Here’s Chris’s answer:


    When that happens, it usually means one of two things:
    a) the test writer has written a game with some very well-hidden deductions
    b) the test writer has written a game with no deductions.

    If it’s option A, you need to sit back after the game, think, and reflect on those deductions. Use the correct answers to the global “Which of the following must be true?” or “Which of the following is a person who CANNOT take place 4?” questions as guides. The correct answers to these are deductions that you could have spotted from the beginning. Then, make yourself a note on what rule or rules led to that deduction, because you may see that type of rule again.

    If it’s option B, you’ll need lots and lots of hypothetical diagrams. If you don’t think the rules combine in ways that will craft deductions, go ahead and build 3 potential diagrams that work within the rules before you try any of the questions. Get some comfort with the way the rules inform the possible options in the diagram. Then dive in!”

  2. Jasmine September 24, 2017 at 9:26 pm

    Chris, any advice for test takers who encounter a game that just totally trips them up? I’ll do really well with timing and the questions, except for about one in every 15 games, when it’ll take me 15 minutes to get half the questions right. Why does that happen?