The only way that bookstores can profitably sell books at below-market prices is to get the books at a discount from ...
AnthonyHJune 19, 2020
Why Not A? Not CM -> PSB
Hi,
I was not able to rule out answer A. The stimulus guides us to invoke the sufficient condition - "not catering to masses" (Not CM). When doing so, I could not arrive at the conclusion that the bookstore was able to profitably sell books below market prices (PSB).
In the video explanation, the instructor states that it "could be true" by invoking PSB as the sufficient condition instead of the necessary condition.
My contra positive diagram looked like this:
No CM & No Exclusive Access --> No HSV -> No D-> No PSB
My positive argument looked like this:
PSB --> D--> HSV--> CM or EA, or both
Why is PSB assumed to be more sufficient than Not CM?
If we start with Not CM in the contrapositive, we see that concluding PSB is not a possible option in the logic chain above. The missing premise is that EA exists; without this, we cannot make a valid conclusion that satisfies the necessary condition - Profitably selling books below market price (PSB).
Hence, I couldn't eliminate A from the list.
Is there a concept or rule that I'm not applying somewhere?
Anthony
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Your chains look correct. The issue seems to stem from the first link in the contrapositive chain- "No CM & No EA." To move down the chain, we need to have both no CM and no EA. Since we are not told whether EA exists, we don't have enough information to continue down the chain. In other words, there could be exclusive access or there could not be exclusive access, we don't know. We cannot make our way down the chain with what we presently know, but this only means that we cannot conclude anything about profitable sales. It does not mean that there can or cannot be profitable sales. Therefore, we don't know enough to say that (A) must be false.
Does that make sense? Hope it helps! Please let us know if you have any other questions!
AnthonyHJune 20, 2020
Hi Skylar, thank you for clarifying this for me. So in essence, answer A is Not Necessarily False. The question stem would have had to say that No EA is also true for (A) to be deemed Must Be False. Without the information about EA, no conclusion can be drawn with certainty.
