The only way that bookstores can profitably sell books at below-market prices is to get the books at a discount from ...
djw1117February 5, 2014
D Diagrammed
I've successfully walked my way through A, B, C, and E and accounted for why they are not necessarily false. But I don't fully understand the logic behind D, particularly the contrapositive of a compound either/or.
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Thanks for your message. The video explanation for this question is now live inside of LSATMax.
Hope this helps! Please let us know if you have any other questions or concerns.
tselimovicAugust 2, 2014
I was unaware that "must" introduces a necessary condition as it did not come up in the lesson. Are there statements similar to "must" statements which we should look out for seeing as it is important to memorize the different statements?
NazAugust 4, 2014
There are various indicator words that introduce necessary conditions. The most common are "then," "only," and "if only." This isn't a complete list, however. What you want to remember is to always understand what the sentence is saying. The necessary condition is the part of the sentence that is required. It is the independent condition in the statement--whereas, the sufficient condition is always dependent on the necessary condition.
An easy way to think about it is to ask yourself whether the condition you are looking at is required for the other condition's existence. If it is required, then it is the necessary condition.
The statement at question is: "To generate such volume, bookstores must either cater to mass tastes or have exclusive access to a large specialized market."
If A must be B, that means A has to be B or A REQUIRES B. Thus, we can rewrite the sentence to say: "To generate such volume, it is required that bookstores either cater to mass tastes or have exclusive access to a large specialized market."
The bookstore either catering to mass tastes or having exclusive access to a large specialized market is required for the existence of generating "such volumes."
It's easier to grasp the meaning of each sentence rather than to only look for indicator words. If you face a sentence that you feel does not have indicator words you have memorized, ask yourself which part of the sentence requires the other part. This is the sure fire way to identify the sufficient and necessary conditions correctly.
Hope that clears things up! Please let us know if you have any more questions.
