Logic Over Content (II)

by on December 5th, 2012

Last week’s post was devoted to the importance of focusing on logic rather than on content in Reading Comprehension questions. Today’s article continues the same subject; however, this time we will look at the principle of “Logic over Content” in the Critical Reasoning part of the Verbal section.

I am sure most test-takers realize that Critical Reasoning questions check our ability to extract the structure of an argument without being distracted by difficult wording. And yet, quite often test-takers will fall into the trap of allowing themselves to be overwhelmed by the technical and scientific jargon used in a question.

The resulting panicky feeling leads them to think they won’t be able to solve the question correctly, since they don’t understand every single word. However, the truth is that we don’t really need to be familiar with all the terms used in CR questions. Even if we are not familiar with the subject matter in a question – be it microbiology, chemistry, or banking -, we should be able to see how the argument is constructed. What helps us establish the logic behind the reasoning presented in argument n is the basic procedure of breaking it down into premises, assumptions and conclusions, and deciphering the logical relationships between them.

Consider the following question taken from the latest edition of the Official Guide:

Traverton’s city council wants to minimize the city’s average yearly expenditures on its traffic signal lights and so is considering replacing the incandescent bulbs currently in use with arrays of light-emitting diodes (LEDs) as the incandescent bulbs burn out. Compared to incandescent bulbs, LED arrays consume significantly less energy and cost no more to purchase. Moreover, the costs associated with the conversion of existing fixtures so as to accept LED arrays would be minimal.

Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
(B) Whether any cities have switched from incandescent lights in their traffic signals to lighting elements other than LED arrays
(C) Whether the company from which Traverton currently buys incandescent bulbs for traffic
signals also sells LED arrays
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
(E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffic signals know how to convert the existing fixtures so as to accept LED arrays

The above question seems really complex and difficult because of the technical jargon it uses. Let’s try to break it down:

Premise 1 – the city council wants to minimize the spending on traffic lights

Conclusion – they are thinking of replacing X bulbs with LEDs

Premise 2 – X bulbs burn out

Premise 3 – LEDs cost the same as X bulbs do and the costs of the replacement would not be high

As you have probably noticed, the argument becomes much simpler to understand, if we get rid of complicated terms like “incandescent bulbs” and “light-emitting diodes”, and replace them with much less confusing “X bulbs” and “LEDs.” Therefore, when dealing with a seemingly complicated question you should always minimize the use of jargon when dissecting the argument into smaller chunks.

Now, let’s analyze the answers. We need to find a choice that will be the most useful to know in order to determine whether switching from incandescent bulbs – let’s continue calling them X bulbs – to LEDs could help minimize costs. Answer A is relevant to the subject of the argument. If LEDs don’t last as long as X bulbs do, they will be more expensive and, therefore, the costs will not be minimized. This choice seems to be the right one but we need to go through all the remaining answers in order to make sure whether there isn’t a better one.

Answer B does not really talk about LEDs but about changing into other types of lighting and thus it is irrelevant. Choice C speaks about the producers of X bulbs and LEDs. It is of no importance to us who produces both types of lighting. What is significant are the costs of X bulbs and LEDs. Thus answer C is also out of scope. Let’s have a look at the last two choices. Answer D speaks about the possible increase in the number of traffic lights in the city. It is true that the more traffic lights there will be, the higher expenses the city will need to bear. However, the costs related to lighting will increase regardless of the fact whether we use X bulbs or LEDs. More traffic lights will mean the increased demand for  both types of lighting. Therefore, answer D is not useful for the evaluation of the conclusion. Finally, answer E speaks about crews that install lighting. Again, it is of no importance which crew is going to service the traffic lights. We know that the costs of installing LEDs are similar to the ones related to installing X bulbs. So we can dismiss this choice as well.

Phew, we have made sure that all choices but A are out of scope. Thus Answer A is the best choice.

Key takeaways:

  1. Critical Reasoning questions are not about content but about logic.
  2. Don’t worry if you are not familiar with the topic of the question. You should focus on its underlying logical structure and ignore the distracting language.
  3. Minimize the use of difficult wording when you are dissecting a CR question. When you take notes on the argument use symbols, letter or abbreviations to substitute for difficult words. Focus on premises, assumptions, conclusions and how they’re all connected.

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