GMAT Critical Reasoning questions: know your conclusion

Posted by Alexander V. on 6/10/20 11:00 AM

Statistical Mediation & Moderation in Psychological Research (15)For many people, Critical Reasoning are among the toughest verbal questions on the GMAT.

The Critical Reasoning arguments on the GMAT can get pretty convoluted! We are presented with a series of statements and assumptions, followed by some conclusion. Then, we are asked to either strengthen the argument, weaken the argument, or consider any unstated assumptions that may underpin the argument. To break down an intricate argument and five equally complicated answer choices in two minutes is an understandably daunting task. How do we work quickly and efficiently without getting bogged down by details?

Most arguments consist of two key components.

Most Critical Reasoning questions will have a premise and a conclusion. A premise is typically a true fact or piece of evidence used to draw a conclusion. The conclusion is typically a claim, prediction, or plan of action that follows from the premise. Let us consider the following case:

Many students in a certain high school report that listening to music while studying helps them to better retain information on exams. In response to these reports, the high school will institute a new policy, allowing students to listen to music during study periods in the hope that they will perform better academically.

This argument really boils down to two parts:

Screen Shot 2020-06-09 at 9.32.15 AM

The Premise: Listening to music helps many students better retain information.
The Conclusion: Allowing students to listen to music during study periods will result in better academic performance.

This conclusion is really a prediction based on the premise – since many students find music helpful for retention, allowing students to listen to music during study periods will lead to better academic performance. We may then be asked to strengthen the argument (what makes this conclusion even more likely?), weaken the argument (what calls this conclusion into question?), or identify underlying assumptions in the argument (what must be true for the argument to hold?).

The conclusion is the MOST important part to identify.

Critical Reasoning arguments are not limited to a single premise and conclusion, however. There may be multiple premises, intermediate conclusions, and counterarguments that also factor into the argument. It is not always obvious where to focus, and it can all be a little overwhelming!

We should always start by carefully reading the whole argument once, taking mental note of each statement. There is little point in reading and re-reading the same argument three or four times. We can always refer to some of the details later (if we even need to).

If nothing else, be sure to identify the primary conclusion. Write it down! For most Critical Reasoning questions, the conclusion will be the most important factor in determining the best answer. Let us consider a few examples:

Example 1: Official Guide 2018: Critical Reasoning #592 from p. 522 of GMAT Official Guide 2018 (copyright 2017 by the Graduate Management Admission Council, published by John Wiley & Sons, Inc., Hoboken, NJ)

Many industrialized nations are trying to reduce atmospheric concentrations of carbon dioxide, a gas released by the burning of fossil fuels. One proposal is to replace conventional cement, which is made with calcium carbonate, by a new “eco-cement.” This new cement, made with magnesium carbonate, absorbs large amounts of carbon dioxide when exposed to the atmosphere. Therefore, using eco-cement for new concrete building projects will significantly help reduce atmosphere concentrations of carbon dioxide.

Which of the following, if true, most strengthens the argument?

(A) The cost of magnesium carbonate, currently greater than the cost of calcium carbonate, probably will fall as more magnesium carbonate is used in cement manufacture.

(B) Eco-cement is strengthened when absorbed carbon dioxide reacts with the cement.

(C) Before the development of eco-cement, magnesium-based cement was considered too susceptible to water erosion to be of practical use.

(D) The manufacture of eco-cement uses considerably less fossil fuel per unit of cement than the manufacture of conventional cement does

(E) Most building-industry groups are unaware of the development or availability of eco-cement.

Okay, so there is a lot of information here. First, I like to create something called a conclusion map:

Screen Shot 2020-06-09 at 9.33.43 AM

This map essential states the crux of the argument: since eco-cement absorbs CO2, using this eco-cement will results in reductions of CO2 in the atmosphere. I now need to strengthen this conclusion ­– in other words, I must find something that makes these CO2 reductions even more likely.

Two types of incorrect answer choices may show up: those that weaken the argument and those that are outside of the scope. Remember, we need to show that the use of eco-cement will be able to effectively reduce CO2 in the atmosphere. Let us examine the options:

(A) The cost of magnesium carbonate, currently greater than the cost of calcium carbonate, probably will fall as more magnesium carbonate is used in cement manufacture. (the cost does not impact whether we effectively reduce CO2)

(B) Eco-cement is strengthened when absorbed carbon dioxide reacts with the cement. (that eco-cement is strengthened does not indicate whether it will do a better job of reducing CO2 than did the old cement)

(C) Before the development of eco-cement, magnesium-based cement was considered too susceptible to water erosion to be of practical use. (the former practicality of magnesium-based cement does not impact whether eco-cement will be effective at reducing CO2)

(D) The manufacture of eco-cement uses considerably less fossil fuel per unit of cement than the manufacture of conventional cement does (hmm… does less fossil fuel mean less CO2? We will come back to this one)

(E) Most building-industry groups are unaware of the development or availability of eco-cement. (lack of awareness does not impact whether this eco-cement will be effective at reducing CO2)

We eliminated (A), (B), (C), and (E) as out of scope, since none of them really indicate that eco-cement will be more effective at reducing CO2 levels.

To prove that (D) is the answer, we need to show that reduced fossil fuel usage will lead to reductions in CO2 levels. Let us revisit the premises. In the first sentence, we find,

“…carbon dioxide, a gas released by the burning of fossil fuels.”

This is what we needed! If eco-cement uses less fossil fuel, and if fossil fuels are what cause the release of CO2, then it follows that eco-cement will lead to lower CO2 levels than before. The answer is (D)!

Example 2: Official Guide 2018: Critical Reasoning #574 from p. 517 of GMAT Official Guide 2018 (copyright 2017 by the Graduate Management Admission Council, published by John Wiley & Sons, Inc., Hoboken, NJ)

People who do regular volunteer work tend to live longer, on average, than people who do not. It has been found that “doing good,” a category that certainly includes volunteer work, releases endorphins, the brain’s natural opiates, which induce in people a feeling of well-being. Clearly there is a connection: Regular releases of endorphins must in some way help to extend people’s lives.

Which of the following, if true, most seriously undermines the force of the evidence given as support for the hypothesis that endorphins promote longevity?

(A) People who do regular volunteer work are only somewhat more likely than others to characterize the work they do for a living as “doing good.”

(B) Although extremely high levels of endorphins could be harmful to health, such levels are never reached as a result of the natural release of endorphins.

(C) There are many people who have done some volunteer work but who do not do such work regularly.

(D) People tend not to become involved in regular volunteer work unless they are healthy and energetic to begin with.

(E) Releases of endorphins are responsible for the sense of well-being experienced by many long distance runners while running.

As we did before, we will create our conclusion map

Screen Shot 2020-06-09 at 9.40.53 AM

So our conclusion is that the higher levels of endorphins are going to increase people’s lifespans. We need to show that this is not necessarily true. “Weakeners” come in two forms:

  • Refute the conclusion: Perhaps, a study shows that endorphins have no effect on lifespan or even shorten lifespans.
  • Provide an alternative explanation: these increased lifespans are caused, not by endorphins, but by something else.

Let us examine the answer choices again:

(A) People who do regular volunteer work are only somewhat more likely than others to characterize the work they do for a living as “doing good.” (nothing about endorphins or their effect on lifespans)

(B) Although extremely high levels of endorphins could be harmful to health, such levels are never reached as a result of the natural release of endorphins. (this statement just tells us that endorphins will not kill us, not whether endorphins will help us live longer)

(C) There are many people who have done some volunteer work but who do not do such work regularly. (The mere existence of people who occasionally volunteer has nothing to do with endorphins increasing lifespans)

(D) People tend not to become involved in regular volunteer work unless they are healthy and energetic to begin with. (This one is interesting – it does not bring up endorphins or lifespan, but it does claim that people doing volunteer work are already healthy. Could this be why they are living longer?)

(E) Releases of endorphins are responsible for the sense of well-being experienced by many long distance runners while running. (Great. Runners feel a better sense of well-being. But, we do not know whether or not they are living longer).

We eliminated (A), (B), (C), and (E), since these answer choices did not draw any connection between endorphins and longer lifespans.

Answer choice (D) did not explicitly state that endorphins are unlikely to help us live longer, but it did provide an alternative explanation for why regular volunteers have longer lifespans. Regular volunteers live longer because they are more likely to already be healthy. This alternative explanation is enough to weaken our conclusion that the endorphins are what cause longer lifespans. The answer is (D).

The takeaway

Critical reasoning questions tend to bombard us with information – often too much information! Isolating and understanding the conclusion is the best way to avoid getting bogged down by details. In some cases, we may need to refer back to the premises to distinguish between two answer choices, but generally, focusing on the wording of the conclusion can get us pretty far on this question type.

In conclusion

To do well on GMAT Critical Reasoning, we want to make sure we really understand the crux of each argument. Some arguments will be very straightforward, and some of them will be very dense and complicated. At any rate, we should focus on the conclusion and on the task. Are we trying to strengthen the argument? Weaken it?

Do the best you can to eliminate answer choices that seem irrelevant to the argument. In the end, if you get stuck, and the question is taking too long, your best bet may be to guess and move on! Generally speaking though, by knowing exactly what the conclusion is, we can greatly increase our odds of selecting the right answer.

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Planning on taking the GMAT in 2020-21? Check out some of Alexander V.'s other helpful blog posts below!:

That Fine Line between Pure Algebra and Testing Numbers on the GMAT 

GMAT Tip: Look for Dangling Modifiers!

Work/Rate/Time Problems on the GMAT

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