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- Sat Jul 25, 2015 11:26 am
#19174
This post is in response to:
Ok, let's break this down. The problem here occurred because you misinterpreted the last rule by making a Mistaken Reversal, and that is leading you to incorrectly consider answer choice (A). Let’s take a moment to analyze the last rule:
"R is not scheduled for Thursday unless L is scheduled for Monday."
The critical part of the sentence is the word "unless," and when "unless" appears it introduces the necessary condition, and then the rest is negated and becomes the sufficient condition (this process is what we call the Unless Equation, which is covered below). Hence, the proper diagram for the rule is:
R Th 
L M
Let’s review that again. To diagram a statement involving “unless” (or its analogues “except,“ “until,” or “without”), take the following two steps:
1. The clause modified by “unless” becomes the necessary condition.
2. The remainder is negated—which normally involves removing or adding a “not”—and becomes the sufficient condition.
Thus, in the rule under consideration, “unless” modifies “L is scheduled for Monday” and that becomes the necessary condition; the remainder, “R is not scheduled for Thursday,” is negated to “R is scheduled for Thursday” and becomes the sufficient condition. Hence the diagram: R Th L M
So, with this diagram in mind for question 12.1, when L is scheduled for Monday, the necessary condition is met. This does NOT mean, however, that R must be scheduled for Thursday (it is possible but not certain). To infer R is on Thursday would be a reversal of the statement and erroneous. Since (A) tries to say that it must be true that R is on Thursday, answer choice (A) is therefore wrong.
Please let me know if that helps. Thanks!
Ok, let's break this down. The problem here occurred because you misinterpreted the last rule by making a Mistaken Reversal, and that is leading you to incorrectly consider answer choice (A). Let’s take a moment to analyze the last rule:
"R is not scheduled for Thursday unless L is scheduled for Monday."The critical part of the sentence is the word "unless," and when "unless" appears it introduces the necessary condition, and then the rest is negated and becomes the sufficient condition (this process is what we call the Unless Equation, which is covered below). Hence, the proper diagram for the rule is:
R Th L MLet’s review that again. To diagram a statement involving “unless” (or its analogues “except,“ “until,” or “without”), take the following two steps:
1. The clause modified by “unless” becomes the necessary condition.
2. The remainder is negated—which normally involves removing or adding a “not”—and becomes the sufficient condition.
Thus, in the rule under consideration, “unless” modifies “L is scheduled for Monday” and that becomes the necessary condition; the remainder, “R is not scheduled for Thursday,” is negated to “R is scheduled for Thursday” and becomes the sufficient condition. Hence the diagram: R Th
L MSo, with this diagram in mind for question 12.1, when L is scheduled for Monday, the necessary condition is met. This does NOT mean, however, that R must be scheduled for Thursday (it is possible but not certain). To infer R is on Thursday would be a reversal of the statement and erroneous. Since (A) tries to say that it must be true that R is on Thursday, answer choice (A) is therefore wrong.
Please let me know if that helps. Thanks!
Dave Killoran
PowerScore Test Preparation
Follow me on X/Twitter at http://twitter.com/DaveKilloran
My LSAT Articles: http://blog.powerscore.com/lsat/author/dave-killoran
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PowerScore Test Preparation
Follow me on X/Twitter at http://twitter.com/DaveKilloran
My LSAT Articles: http://blog.powerscore.com/lsat/author/dave-killoran
PowerScore Podcast: http://www.powerscore.com/lsat/podcast/
