Understanding Causal Arguments
One of the most difficult tasks on the GMAT verbal section can be finding the assumption in a critical reasoning section. The difficulty of the task is compounded by the fact that three of the most common critical reasoning question types, assumption, weaken and strengthen, rely on assumptions as the basis for getting a correct answer.
This article will address one common pattern of reasoning, the causal argument. It describes how a causal argument is constructed, how to find the conclusion and the premises and most importantly how the test constructs answers that can confuse test takers. If you can identify an argument as causal during your first read, you can cut down on the confusion associated with them and spot the typical types of answers, thus improving your verbal score.
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Causal argument comes to the conclusion that one thing is caused by another thing. Most commonly the premise is that one thing happened before the other, therefore the earlier even caused the latter. For instance an argument might read “The baby started crying loudly one minute before his brother woke up. Since the baby and his brother share a room, it is clear that the baby’s crying woke his brother.” This argument concludes that there is a causal relationship between the two events – that the crying caused the brother to wake up. This relationship seems quite reasonable, we have all had some experience with noise waking people up. Yet the fact that it could happen is not enough to prove causality. For instance, if you claim that you washed your car today and then it rained, therefore washing your car must have caused the rain, the relationship is revealed as logically inconsistent. It is this very logical inconsistency that the test writers use to trick students.
Causal Assumptions
When the argument claims that one thing caused another because one happened before the other or that the two events happened at the same time, the assumption is either that the proposed cause actually caused the effect or that there was no other intervening cause. For example in the argument:
In the last 20 years, there has been a significant increase in coffee consumption. During this same time period, there has been an increasing number of public coffee shops in urban areas. Therefore, the increase in the number of public coffee shops must have caused the increase in coffee consumption.The author assumes the causal relationship without actually establishing it as fact. Therefore, a correct answer to an assumption question would be one that establishes that having the public coffee houses did indeed cause the increase in coffee consumption or that there was no other cause for the increase in the consumption of coffee.
Weakening Causal Arguments
In order to weaken this type of argument, the GMAT requires you to find a reason why the cause/effect relationship is not established. One way to do this is to establish that there was an
alternate or intervening cause for the result. This type of correct answer is often difficult to spot because it brings in new information that does not seem connected to the argument. Thus, an answer choice that says “in the past 20 years, people have been made increasingly aware of the health benefits of coffee” would weaken the argument because it introduces a possible alternate cause and thus shows a break in the causal relationship the author wishes to establish.
Similarly, an answer choice that
reverses the causal relationship will weaken the argument. An answer choice such as “public coffee houses have been increasing as a result of the increase in consumption of coffee” gives a fact that shows that the relationship is the reverse of what the author concludes, and thus it weakens the argument. These types of answers can be easier to spot, but, unfortunately, they, are less common.
Strengthening Causal Arguments
Strengthening a causal argument can be a very difficult task. One way to strengthen an argument is to state the assumption. Thusly, an answer that says “the public coffee houses are the only cause of increase in coffee consumption” would be correct. However most test takers will not choose this answer because they believe it to be a restatement of facts in the paragraph. On careful inspection the addition of the word only give the reader new information, which eliminates all other possible causes for the increase. In this way, the answer would strengthen the argument.
However, eliminating all possible causes is not necessary for an answer to a strengthen question. Simply
eliminating other possible causes also serves to strengthen the argument, albeit much less than eliminating all possible causes. Thus an answer choice that eliminates another possible cause is often the answer to some of the most difficult strengthen questions. For instance, an answer that reads “The price of coffee has not dramatically decreased in the past 20 years” would strengthen the argument. At first glance, cost seems completely out of scope, but it is relevant. Cost is one factor that affects peoples’ purchases, and, if the cost of an item decreases dramatically, it can cause consumption to rise, Thus, the fact that the price has not risen, eliminates this as a possible cause and strengthens the argument. Eliminating a possible other cause is a common way the GMAT answers this type of question, and because the possible cause is off topic and the answer choice says it did not happen, students often have a difficult time choosing the answer. Thus, opening up to the possibility of this type of answer, and recognizing the relevance will help to improve your accuracy on the Critical Reasoning Section.