#Flaw, #Prediction

Question

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According to a prediction of the not-so-distant future published in 1940, electricity would revolutionize agriculture. Electrodes would be inserted into the soil, and the current between them would kill bugs and weeds and make crop plants stronger.

Which of the following, if true, most strongly indicates that the logic of the prediction above is flawed?

(Because of copyrights, the complete official question is not copied here. You can access the question here: GMAT Club)

Solution

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The Story

According to a prediction of the not-so-distant future published in 1940, electricity would revolutionize agriculture. – There was a prediction that electricity would revolutionize agriculture. (I’m wondering how it would do that. Perhaps the answer will follow.)

Electrodes would be inserted into the soil, and the current between them would kill bugs and weeds and make crop plants stronger. – Electrodes would be used to kill bugs and weeds and make crop plants stronger. (Aha. This statement indeed explains how electricity would revolutionize agriculture.)

Prediction’s logic:
It was predicted that electricity would revolutionize agriculture.
How? Electrodes would be inserted into the soil. Current will be passed between them. This current would kill bugs and weeds, making crop plants stronger.

Gaps in logic:
What if electricity harms the crop plants as well?

Question Stem

Which of the following, if true, most strongly indicates that the logic of the prediction above is flawed?

Framework:
What is the prediction?
That electricity will revolutionize agriculture.

What’s the logic?
Electrodes would be used to kill bugs and weeds and, thereby, make crops stronger. So, fewer bad things (bugs and weeds) and a good thing (stronger crop plants). That’s how electricity will revolutionize agriculture.

We have to look for something that will indicate a flow in the logic. Essentially, something that indicates that even if electrodes are used, electricity would not revolutionize agriculture.

Prediction:
Electricity will harm the crop plants too.

Answer choice analysis

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Additional Notes

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1. The question stem asks us to find an answer choice that ”most strongly indicates that the logic of the prediction above is flawed”. We need to find a flaw in the logic, and not find an alternate reason for why electricity might not revolutionize agriculture. If using electricity in agriculture requires additional work (option E), I might start doubting whether electricity will revolutionize agriculture (the prediction). The option does not, however, indicate a flaw in the logic of the prediction.

e.g.,

John is driving an expensive car. Therefore, John is rich.

A. John lives in a very poor community.
Does this option highlight a flaw in the argument’s logic? No. The argument is not based on where John lives.
Does it weaken the argument? Yes. Now I believe less that I did before that John is rich.

B. John does not own the car.
Does this option highlight a flaw in the logic? Yes. The argument’s logic was based on the assumptions that anyone driving an expensive car perhaps owns it. And anyone who owns an expensive car is rich.
Does it weaken the argument? Yes. Now I believe less that I did before that John is rich because this answer choice attacks the logic.

2. One could argue that option D contradicts the passage and is therefore wrong.

Here’s how:

In the last sentence there’s a prediction that the current between the inserted electrodes would
a. kills bugs and weeds
b. and make crop plants stronger

Option D states that ”electricity would affect weeds in the same way as it would affect crop plants”. So, presumably electricity would kill weeds as well as crop plants. Thus the current between the inserted electrodes will not make crop plants stronger.

So, one could argue that “since we’re given that the current would make crop plants stronger, whereas this option indicates that the current would kill crop plants, this option is wrong.”

Such reasoning is wrong.

Firstly, the question stem includes the phrase ”if true”. So, our job is not to check the validity of the answer choices. Rather, we have to accept them as true and then check whether they answer the question.

Secondly, notice that the last sentence of the passage is also a prediction. Predictions always have inherent assumptions. E.g., you might be thinking “I will prepare for GMAT for at least one more hour today.”
Can you be sure though? While hopefully nothing happens to break your rhythm, can you be 100% certain that you will prepare for at least one more hour today? No, right? You might get an important work call, you might have a family issue that needs to be dealt with immediately, you might have a friend call you and ask for urgent help, you might just feel lazy.

Predictions have an inherent assumption that all things will go according to plan. And that assumption can be challenged.

If you have any doubts regarding any part of this solution, please feel free to ask in the comments section.