Argument Structure Passages: Issues in Causality
Credit: XKCD
To succeed at Argument Structure Passages on the GRE — short “Reading Comp” passages that are really logic problems — it helps to know a bit about the study of logic, because most mistakes in logic have been made many times before, even over thousands of years.
Many of the logical mistakes made on the GRE are really just the same logical mistakes Aristotle (the founder of the study of logic) complained about in the 4th century, B.C.
Similarly, the same mistakes and argument patterns can occur repeatedly on the GRE, just dressed up in different clothes. For instance:
EXAMPLE 1: People who eat diets rich in tropical fruits rate higher in surveys of happiness. Therefore, a diet rich in tropical fruit is a cause of happiness.
EXAMPLE 2: Company X implemented a new time-tracking system and profits went up 10%. Therefore, the time tracking system has caused the company to profit.
Initially, it may seem as though these arguments are about totally different things “ tropical fruit and time tracking. However, the arguments share a common pattern:
PATTERN: Two things happened at roughly the same time. Therefore, one of them caused the other one.
Now that we put it that way, it sounds a bit ridiculous, doesn’t it? (Just like in the cartoon!)
Using this pattern, we could also say:
EXAMPLE 3: I have a runny nose and a stomachache. Therefore, the runny nose caused the stomachache.
EXAMPLE 4: All of the cancer patients in our hospital drank soda. Therefore, soda causes cancer.
EXAMPLE 5: People who eat more ice cream have more heart attacks. Therefore, a genetic predisposition to heart attacks causes a love of ice cream.
These examples are getting even more absurd. But why are they so absurd, and how can we recognize this mistake when the examples are dressed up in boring, respectable clothes (like the example about time tracking)?
Let’s break this down a little more. In all of the examples given, the causality given by the arguer could be true “ it is possible that tropical fruit causes happiness, or soda causes cancer. But the arguer has not given us enough reason to believe that this is the case.
There are a lot of things that could go wrong in between two things happening at the same time and one thing causing the other thing. For instance:
- Maybe the causality runs in reverse. This certainly seems likely in the case of ice cream and heart attacks: it is very likely that eating the ice cream is contributing to heart attacks, rather than the opposite.
- Maybe both things are caused by a separate, outside cause. This is probably the case with the runny nose and the stomachache. It is very likely that neither the runny nose nor the stomachache is causing the other, but rather that an outside cause “ the flu, for instance “ is causing both symptoms. It is also very likely that this is what is happening in the case of the tropical fruit “ people who eat a lot of tropical fruit probably live in tropical climates. Maybe the weather or the culture of such tropical places has something to do with happiness.
- Maybe it’s all just a coincidence. This is probably the case with the soda and the cancer patients. Almost everybody drinks soda. Some people get cancer. Maybe it doesn’t mean anything at all, as in the case, Murderers breathe air. Therefore, air causes murder. Ridiculous, right? The case of the time tracking software and the increase in profits “ while less ridiculous sounding “ may also be a case of a mere coincidence. Perhaps many changes occurred in the company around the same time, or perhaps the fluctuation in profits was simply due to the holiday shopping season, etc.
While this logical flaw may seem transparent (at least after reading the above), it occurs all the time in real life, especially in pop-cultural articles about health and medicine. A study of villagers in a remote corner of the Amazon jungle has shown a high consumption of Brazil nuts and a low rate of Alzheimer’s. Therefore, we should all eat Brazil nuts. This correlation, while perhaps providing an opening for further study, by itself proves nothing.
Fortunately, as GRE test takers, we don’t have to try to figure out what the real story is. It’s the job of the arguer to demonstrate it to us, by building a sound argument backed by appropriate evidence. Our job is simply to recognize flaws and omissions.
We don’t mean to imply that all logical flaws on the GRE are about causality; this is just one fallacy of many that occur. Watch out for more posts here on the blog about Argument Structure Passages.