The most important flaws to pay attention to on the GMAT are those that relate to the connection between the premises and the conclusions. Spotting those flaws will help you with critical reasoning assumption questions, strengthen, weaken and, of course, flaw questions. It will also help you with the analytical writing assessment, as you will need to write an essay explaining an argument’s flaws.
These flaws are often very subtle and difficult to find if you are not looking for them. To look for them, you should be critical of shifts in languages between the premises and the conclusion. Think to yourself, “is there a way for the premises to be true, but the conclusion to be false?” Therefore, knowing what types of flaws are most common will make it easier to spot them. Here are three common flaws and how to catch them.
Flaw #1: A is better than B, therefore A is the best
The GMAT test makers, often try to trick people by having the premises prove that that something is better than the other, but then the conclusion tries to assert that that thing is the best. Just because one thing is better than the other, doesn’t mean that it is the best. Look at this example:
A survey of customers at a Joe’s Café revealed that more people bought orange juice than tea. Therefore, orange juice is the most popular beverage at Joe’s Café.
Just because orange juice is more popular than tea, doesn’t mean that orange juice is the most popular beverage. That could be coffee or soda or water. We have absolutely no way of no way of knowing what is the most popular beverage. All we know is that more people buy orange juice over tea.
Because of this, you should always be cautious when you see extreme language, like: best, most, all, only…etc. This type of language doesn’t always mean something is wrong, but it does mean you need to check to make sure the language in the premises warrants a strong conclusion. In the case of Joe’s Café, it does not.
Flaw #2: Correlation means causation
In no circumstances does correlation mean causation. While it might imply causation, there is no way to prove it without other evidence. Let’s look an example to further demonstrate this point:
A study revealed that the more sleep per night students get on average, the better they perform in school. Therefore, if you want to do well in school, sleep as much as you can.
This argument assumes that because there is a certain correlation (more sleep and higher grades) that one (sleep) causes the other (higher grades). However, we have no way to know if the more sleep, causes the grades. The higher grades could cause more sleep. For example, the studying required to achieve top marks could be very energy consuming and cause people to sleep more. There also could be a third thing that causes both. For example, the more disciplined a person is, the more they sleep and the more they study, therefore they get higher grades.
Flaw #3: Equating a subset to the general population
A very subtle shift in language that demonstrates a GMAT flaw is when the premises prove something is true for a subset of a population and then the conclusion is about that entire population. Take a look at this example:
The solution to our company’s marketing problems can only be solved through the board voting to hire a marketing manager. Since the board can only vote during an official meeting, and the next official meeting isn’t for another 6 months and cannot be rescheduled, our company will not be able to solve most of our problems for 6 months.
This may seem like a pretty airtight argument, because there is a lot of extreme language, such as the word only. However there is one subtle language shift between the premises and the conclusion that makes the conclusion impossible to prove.
While the premises do create an airtight argument that the company cannot solve any of their marketing problems, the conclusion is about the companies problems in general. For example, it could be true that the company has 100 problems and only 4 of them are marketing problems. If the rest of their problems are solvable without the board’s vote, then it could be true that the company can solve its most of its problems before the board meeting.
Language is really important while trying to spot GMAT flaws. If there is a subtle shift in language, it will likely create some sort of flaw. As a GMAT test taker, you have to be very critical about the words on the page. While all the premises must be accepted as true, you need to be critical about how they connect to the conclusion and if there is a way for the conclusion to be false, even with the premises being true. This will help you catch these GMAT flaws.