October 2010 LSAT Section 1 Question 9

In the first paragraph, the author refers to a highly reputed critic's persistence in believing van Meegeren's forger...

samarrastia001 on November 5, 2018

Example 1, eliminating answer choice B

I want to understand if I should stick to the approach i used for eliminating answer choice B: For example 1, in the passage setting up diagram i determined: P: A --> B OR C P: C--> B ---------------------- C: A--> B when looking at answer choice B, before taking the time to set up the diagram and determine that it was a "flawed" argument (takes a while for me & can be time constraining) I automatically crossed out the answer choice because I determined the set up in answer choice B used terminology AND instead of OR, should I have crossed it out because of this determination or should I have continued to set up the diagram where then I easily saw that they used a Necessary condition to conclude the sufficient as follows: P: A--> B AND C P: B AND C -------------- C: A ? Please advise if I should make this a habit or break this habit. Thank you in advance!

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Ravi on December 26, 2018

@samarrastia001,

This is a great question. Answer B is wrong for both using AND instead of OR and for using a necessary condition as a sufficient condition. It's far different from the valid argument structure that appears in the stimulus and answer choice C.

You mentioned that these questions sometimes take a lot of time for you. Your ability to eliminate answer B after reading that it was using AND instead of OR is fine, as we know from reading the stimulus that we have to see an OR in the answer choice. Your strategy is fine.

If you'd like extra assurance, take note of questions like this where you're finding that you're eliminating wrong answers very quickly, and track your accuracy on these questions. You'll likely find that your accuracy is quite high (you sound like you have a strong grasp of conditional logic), and this will further boost your confidence.

Does this answer your question? Let us know if you have any other questions!