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## Sufficiency/Necessity framing

General questions relating to LSAT Logical Reasoning.
Logan0320
• Posts: 2
• Joined: Jan 19, 2022
#94850
Love the LRB so far, but wouldn’t it reduce a lot of confusion to frame Chapters 10 ‘Justify’ and 11 ‘Assumption’ as 10. ‘Sufficiency’ and 11. ‘Necessity’ instead?

The substantive basis for the distinction between the two categories is whether the correct choice provides [1] a sufficient condition versus [2] a necessary condition for the conclusion. When organized into ‘Justify’ for sufficient condition questions versus ‘Assumption’ for necessary conditions questions, however, confusion easily follows from the sufficient condition questions that ask for an ‘assumption’ that justifies the conclusion.

Why not just call them Necessity questions versus Sufficiency questions?
Dave Killoran
• PowerScore Staff
• Posts: 5810
• Joined: Mar 25, 2011
#94884
Hi Logan,

Thanks for the question! Here are a few thoughts that address your question as to why we don't use those terms:

1. Actually, we already do! In the LRB, for instance, the opening section is titled: Justify the Conclusion Questions (Sufficient Assumptions). And then in the next chapter: Assumption Questions (Necessary Assumptions). So, any confusion is immediately addressed right up front. And, the issue is really only on the Justify side since since the Assumption/Necessary Assumption naming is nearly identical. But why keep the Justify term then?

2. And because our term--Justify the Conclusion--more accurately describes the process you are asked to complete. The term "Sufficient Assumption" actually tells you little to nothing about the process unless you understand that ultimately you are justifying the conclusion by providing a piece that, when added, makes the argument makes sense. This then forms the reasoning behind our original technique of the Justify Formula, which can make these questions incredibly easy at times.

Interestingly, the names we chose predate the use of sufficient/necessary assumptions by LSAC. At the time we identified sufficient assumptions as a unique question type, no one had done so yet--we were the first. Later, LSAC admitted to the use of these sufficient side questions, and used the sufficient/necessary terminology that you reference. So, by that time, our use was long-ingrained, and after looking at the naming options, I saw no reason to change the terms to something less accurately descriptive. But, just to make sure no one was confused, I added the references in #1 above.

I hope that helps explain it. Thanks!
Logan0320
• Posts: 2
• Joined: Jan 19, 2022
#96491
Hi Dave,

I agree with your analysis to the extent that a primarily Justify/Assumption dichotomy may outcompete a primarily Sufficient/Necessary structure for many practical cases. I disagree, however, that the "term—Justify the Conclusion—more accurately describes the process [we] are asked to complete."

For example, PT 12, LR 1 #22, the stem asks "Which of the following is an assumption that would allow the company's president's conclusion to be properly drawn?" The current LRB clearly categorizes this stem as a Justify question (LRB 2022, p. 346 top half), thereby leading a test taker to search for an answer choice that sufficiently proves the stimulus. The correct answer choice, C, however, is not a sufficient condition, but rather a necessary one, as Kelsey points out on the forum (viewtopic.php?t=6106).

I understand that the Justify/Assumption dichotomy works for most testtakers in most situations, but in situations like this, the Sufficient/Necessary would not have led to the misinterpretation of the stem.

Also, I'm uncertain of your point that "'Sufficient Assumption' actually tells you little to nothing about the process unless you understand that ultimately you are justifying the conclusion." First, my perspective is to label the question type Sufficient Condition/Necessary Condition questions and entirely drop the word assumption, which I see as at least occasionally unnecessarily misleading, since both Justify and Assumption questions under your paradigm conceptually can be categorized as assumptions, i.e. not only can necessary conditions be categorized as assumptions, sufficient conditions can also be categorized as assumptions. This is further supported by the LSAT's usage of the word "assume" in what you label as justify questions. In my head, the term 'Assumption' in the Justify/Assumption dichotomy is therefore not mutually exclusive and collectively exhaustive, since they are not mutually exclusive in all cases. Conversely, the relevant population of questions either seek for a necessary condition or a sufficient condition.

Curious to read your thoughts. I started at a 149 two months ago and I'm already PTing in the high 160s—once again, thank you.

Logan
atierney
• PowerScore Staff
• Posts: 215
• Joined: Jul 06, 2021
#96671
The distinction between justify the conclusion/necessary assumption questions is probably as ambiguous as the terms necessary/sufficient can be in a general context. Let us remember that necessary and sufficient, as general terms, have different meanings than those covered in the PowerScore context. Indeed, when I first came to PowerScore, I was struck by this difference.

If a condition is sufficient for an event to occur, it guarantees the occurrence of this event occurring. Indeed, this is my personal understanding of what the term sufficient means. If a condition is necessary however, it is required for the event to occur, but not necessarily (intended) sufficient, i.e. it does not guarantee the occurrence of the event. Now, notice that these two terms are not mutually exclusive, under this context, i.e. something can be both necessary and sufficient; thus the distinction draws upon the nature of the effect of the said condition.

The idea behind Justify questions (based upon LSAC's question stem language, and not any book's categorization of questions) is to look for those conditions/qualifications not stated in the stimulus that have the effect of allowing the conclusion to logically follow. I believe this is a way to justify the conclusion, where the word justify, being a sufficiently broad term, gives leeway in terms of allowing students to identify either sufficient or necessary conditions, i.e. whatever helps logically fill any gaps in the conclusion as a whole. Indeed, this very wording clears up any confusion students might have with respect to the nature of the condition in the question you highlighted.

In my estimation, the nature of questions, in terms of their labeling, is only significant in so far as it enables the student to identify the question's nature. I do not believe splitting hairs over labels, when the label does not set a colloquial or familiar context for most students (yourself notwithstanding), is helpful in instructing on strategies on answering said questions. I appreciate these posts, because I do think they raise interesting questions with respect to the processes of reasoning at play, but I think a failure to focus on said reasoning, mechanistically or otherwise, is a mistake on both the part of test-taker and instructors as well.

I don't know if you and I are completely different in terms of how we process these questions, and indeed, the answer to that question, I believe, is significant in its own right, but I know, for me, labeling of questions has a negligible effect to overall performance. And that I think, justifies an almost arbitrary labeling indeed.

Let me know if you have further questions

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