CR question from the guide..

[ashish-mohan]

"If it rains, I will go to the beach". This statement clearly does not mean that if it does not rain, I will not go to the beach.

Basically A-> B does 'not' mean ~A -> ~B

So far so good.

MGMAT SC guide has a question which states (and I am paraphrasing): "Lower currency is shown to cause increase in exports". However, the answer to this question suggests that "Higher currency is shown to cause decrease in exports".
Basically A-> B in this case does mean ~A -> ~B

How do we differentiate between the above two question types.

Thanks.

[post2anupam]

I also have a question on similar lines.

CR CHAPTER 8 - Question No. 7:
Law of Demand
The law of demand states that, if all other factors remain equal, th higher the price of a good, the less people will consume that good. In other words, the higher the price, the lower the quantity demanded. This principle is illustrated when _____________

Now, the correct answer given in the guide gives an example when the price is lowered and the quantity increases.

For getting to this answer, we have to apply knowledge OUTSIDE the given argument. How can the reverse logic be ASSUMED? Both the premises in the argument, talk about higher price leads to decreased quantity.

[esledge]

The key in the Strategy Guides examples is the use of comparative language. They are really "the more/less this, the more/less that" statements about correlation. Rather than statements about whether something happens, they are about the degree to which something happens or is true. Notice the comparative words I've bolded below:

The law of demand states that, if all other factors remain equal, the higher the price of a good, the less people will consume that good. In other words, the higher the price, the lower the quantity demanded. This principle is illustrated when _____________

Now, the correct answer given in the guide gives an example when the price is lowered and the quantity increases.

The comparatives imply some other state: When the price is higher than what? A lower price. Then the quantity demanded is lower than what? A higher quantity demanded.

To conclude that lower price goes along with higher quantity demanded is to simply put these two rephrased premises together.

MGMAT SC guide has a question which states (and I am paraphrasing): "Lower currency is shown to cause increase in exports". However, the answer to this question suggests that "Higher currency is shown to cause decrease in exports".
Basically A-> B in this case does mean ~A -> ~B

Be careful here! I think you may be reading the word "cause" into your paraphrase of the conclusion. Making a conclusion about Causation would present a problem here, but I suspect the original wording was really more about correlation ("When A is low, B is high"). In fact, it would be great if you could post the original text for verification.

The comparatives imply some other state: When the currency is lower than what? A higher original currency. Then the exports are increased from what? A lower original export level.

Even if the premise was about causation, you can conclude that higher currency correlates with lower export level simply by considering the original levels of both currency and exports.
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In contrast, the Rain example is binary: rain vs. not rain. Go to the beach vs. not go to the beach. There are two reasons you can't infer notA --> notB from A--> B:
(1) Conclusions about Cause-and-effect are tricky. There are plenty of examples where only "positive" (something happens) cause creates an effect, while "negative" cause does nothing at all, let alone the reverse of that effect!
(2) Binary possibilities A/notA and B/not B are more rigid than questions of "how much A?" or "how much B?"