Critical Reasoning

Recently, a beatthegmat member asked me to post some tips on causal arguments...sorry but this one's going to be loooong.

The causal argument is likely the most common form of argument structure on GMAT CR. Certainly, it is very common in strengthen and weaken questions. Given that strengthen and weaken questions together account for well over half of all CR questions, mastering the causal argument can translate into quick and plentiful points on test day.

Identifying causal arguments

Analysis of causal arguments begins with identifying when you do (and when you don't) have a causal argument.

First, we can look out for "causal" language. For examples, when the author asserts that x is responsible for y, or that x led to y, or that x is to be blamed or credited for y, we have a causal argument on our hands.

However, an arguer can advance a causal argument without using any causal language. That is, an author can imply causation. For example: "Ever since I started jogging at night, I've been waking up with headaches. So, I'm going to stop jogging at night." Certainly, this author thinks that jogging at night caused his headaches even though he did not use any causal language.

We should also be able to recognize quickly "explain the phenomenon" arguments (more on that below).

Correlation vs Causation

Often, an author will proceed from a correlation between two variables to the assertion that there is a causal relationship between them. In abstract:

"Because x came before y, x caused y"
"Because I took the tylenol before my headache went away, the tylenol must have caused my relief".
Here, the arguer is proceeding from a chronological correlation (x/tylenol came BEFORE y/relief) to a causal assertion.

But we can also have:

"Because x and y happened at the same time, x caused y"
"Subjects with diminished premotor cortex activity are more likely to be hyperactive. Thus, hyperactivity is caused by diminished premotor cortex activity".
Here, the arguer is proceeding from a simultaneous correlation to a causal assertion.

Explaining the phenomenon

In a GMAT argument, whether or not you recognize a correlation, if the author is advancing an explanation for a phenomenon, you are dealing with a causal argument. ("Explanation" is the same as "cause" while "phenomenon" is the same as "effect".)

It is very important to recognize when a GMAT argument is throwing a "phenomenon" at you. Basically, while you're reading the first couple of sentences of an argument, if you see there's some fact (or set of facts) that needs to be explained, you know that's a phenomenon, and that the author will likely complete the argument by advancing an explanation for that phenomenon. Phenomena could be things like: the company's revenues declined, key information has begun disappearing from air traffic controller's computers, or the fish have abnormally low levels of reproductive hormones. Possible explanations (or causes) the author may assert, respectively, for each of these could be: the company hired a new president, air traffic control towers have installed new untested software, and the factory is dumping more pollutants in the river.

Attacking causal arguments

In all causal arguments the author makes one or more of the following assumptions:

1) there are no other causes/explanations (most commonly tested one)
2) that the correlation was not just a coincidence
3) causality is not reversed (least commonly tested one, and not applicable to chronological correlation).

We weaken by attacking assumptions. So, if you have to weaken a causal argument, number one on your hit list is looking for a choice that suggests an alternative cause. For example, a weakener for the "tylenol" argument (above) could be a choice that suggests that the headache was due to dehydration (this would suggest that it was the water you drank with the tylenol and not the tylenol itself that caused relief from the headache). And, we can strengthen by backing up this assumption; so, a choice that eliminates an alternative explanation strengthens.

We can also weaken by targetting assumption number 2. A choice that suggests that the headache would have gone away on its own suggests that the correlation between taking tylenol and relief from headahce was merely a coincidence.

Finally, we can weaken by targetting assumption number 3. It might not be the case that diminished premotor cortex causes hyperactivity. Instead, diminished premotor cortex activity might be caused by hyperactivity. Or: It's not that because he gets good grades, the teachers like Govi. Instead, its because the teachers like Govi that Govi gets good grades.