Reusing Information in Local “If” Questions

[Mastering_LSAT]

Hello,

I am confused about the LGB (2019 ed.) statements on pages 128 and 156 regarding the effect of local rules on some of the logic games overall.

The “if” clause in a question stem should be considered and applied “for that question only” (p.128 LGB). However, sometimes question stems of local questions have important impact on the entire logic game and could be “useful elsewhere in the game” (p.156 LGB).

How is it possible if we consider a new rule (introduced by a question stem of a local question) for that question only?

Most importantly, should such “new rule” introduced by a local question (e.g., “If A is placed first, then which one of the following must be true?”) and a correct answer to that question (e.g., “B is placed third” then) be completely disregarded when we are answering the remaining questions? In other words, when we are answering the remaining questions of our logic game, we should never use the knowledge of the local question stem (e.g., “A is first”) and the correct answer to that question (e.g., “B is third”), unless the initial setup, rules, and inferences allow us to reach such conclusions (i.e., “A is first”, “B is third”) independently.

Thank you for your time and help.

[Dave Killoran]

Hi Mastering,

Let's see if we can make this clearer, although you may discover that since this concept keeps coming up, as you get deeper into the book it gets clearer naturally.

The “if” clause in a question stem should be considered and applied “for that question only” (p.128 LGB).

This is correct. However, the condition itself does not persist after the question, which is what is being addressed here specifically. So, if they told you L is sixth in a Local question, that condition is dropped when you move to the next condition.

However, sometimes question stems of local questions have important impact on the entire logic game and could be “useful elsewhere in the game” (p.156 LGB).

How is it possible if we consider a new rule (introduced by a question stem of a local question) for that question only?

Take a look again at the example there, and consider for a moment what the stem is telling you The question stem itself, while Local, told you a global truth about the game: L could be sixth. That information might potentially be useful elsewhere in, for example, a List question asking where L could go (and yes, such a thing has occurred multiple times before). The fact that it's Local does not mean that the information in the stem itself is not globally valid; in fact, the LSAT never introduces contradictory information in Local stems unless they explicitly suspend a rule. So, when the stem says L is sixth, it's automatically possible globally (prior to any other considerations like additional local rules).

The point is that the stem itself can at times reveal certain things about a game. In other words, in asking questions, sometimes the test makers give additional information that is usable.

Most importantly, should such “new rule” introduced by a local question (e.g., “If A is placed first, then which one of the following must be true?”) and a correct answer to that question (e.g., “B is placed third” then) be completely disregarded when we are answering the remaining questions? In other words, when we are answering the remaining questions of our logic game, we should never use the knowledge of the local question stem (e.g., “A is first”) and the correct answer to that question (e.g., “B is third”), unless the initial setup, rules, and inferences allow us to reach such conclusions (i.e., “A is first”, “B is third”) independently.

Thank you for your time and help.

This is first addressed in the book earlier, on around Page 25, in the section titled Reusing Work. To quote from the Reusing Work section:

• "For example, suppose the first question in a game produces a scenario
  where A is in the first position. Then, the second question asks for a
  complete and accurate listing of the positions A can occupy. Based on the
  first question, A can clearly be in the first position, and therefore you can
  eliminate any answer in the second question which does not contain the
  first position as a possibility. Thus, the work you do in some questions can
  be used to help answer other questions. This is true as long as the work
  you are referencing conforms to the conditions in the question you are
  currently answering."

But, the same concept will come up repeatedly when we do actual games as you see us reuse work from one question to help answer others. And, specifically, look at the Re-Using Information section on page 167 (sorry, I only have the 2020 edition in front of me for page references). It should answer your question satisfactorily! If not, please let me know.

Thanks!

[Mastering_LSAT]

Hello Dave. Many thanks for the very responsive and comprehensive answer!