Sufficient & Necessary Questions - - Question 8

The only way that bookstores can profitably sell books at below-market prices is to get the books at a discount from ...

egracer May 21, 2017

Diagramming either/or

In the video, instead of diagramming either/or as was done in the sufficient / necessary lecture (by picking one of the two either/or variables as the sufficient condition and negating it), you diagrammed the either/or statement as a necessary condition of the high sales volume sufficient condition. How do you know when to diagram it as part of another condition, or when to diagram it on its own?

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Mehran May 27, 2017

@egracer notice here it is not a simple either/or statement.

Rather our "either/or" is actually part of the necessary condition that is being introduced with "must."

"To generate such volume, bookstores MUST either cater to mass tastes or have exclusive access to large specialized market, such as medical textbooks, or both."

So this principle would be diagrammed as follows:

HSV ==> CM or EA or both
not CM & not EA ==> not HSV

Hope that helps! Please let us know if you have any other questions.

julia July 30, 2018

Question 8 for Sufficient and Necessary Questions, I still do not get why you are saying d-hsv when we do not get discounts for higher sales profit. I get that you are negating it but can you explain it in another way? Because I am not getting your explanation. Thank you

Christopher July 30, 2018

@julia, the statement is not saying that you cannot get discounts even if you have higher sales volume but rather that you cannot get a discount unless you have a high sales volume. Does that answer your question?