Critical Reasoning: Assumptions on GMAT

Many previous GMAT aspirants have reported that critical reasoning is an especially complex portion of the exam. The key to overcoming this complexity and tackling these questions is to approach them in a systematic manner. It is especially important to handle critical reasoning questions, systematically, as a failure to do so will not only lead to a lower score, in this section, but also take up much of your valuable time. Here, we will cover the best approach for you to take on the GMAT critical reasoning questions.

The Missing Link Approach

At Experts’ Global, we call this strategy the missing link approach. To understand this highly organized approach, you must begin by understanding the the nature of the GMAT critical reasoning passages. Each passage will include a "premise" and a "conclusion"; however, the “conclusion” will not logically follow the “premise”. They key to solving these questions is to identify the gap between the "premise" and "conclusion", which we call the “missing link”.

Although, you should note that there is no need for you to fill in the missing link. You only need to identify it, so that you can use it to identify the correct answer choice. Please go through the step-by-step guide, provided below, to understand this approach.

1. Read the question, before reading the passage. Doing so will allow you to understand exactly what type of question it is, strengthening, weakening, etc., and approach the passage, accordingly.

2. Read the passage very carefully and make a mind-map rather than taking note, to save time.

3. Identify the missing link by seeing where the gap in the passage's reasoning is. The missing link is whatever information is needed to connect the premise of the passage to its conclusion that is not provided.

4. Have an idea of what you are going to search for in the answer choices. This step is quite important.

5. Finally, use the "grid" to eliminate four answer choices. Remember, it is not about finding the one correct answer choice; it's about finding the best among the five answer choices. When you eliminate four answer choices, the one that is left is the correct answer choice.

When it comes to GMAT critical reasoning questions, understanding the nature of assumptions is vital to getting a good score. Assumptions are central to critical reasoning, and we will now cover what their exact nature and role on the GMAT are.

Characteristics of an Assumption

The key to solving GMAT critical reasoning questions is identifying the missing link, the gap between the premise and conclusion that make up the critical reasoning argument.

The defining features of a correct assumption are that it fills the missing link and is necessarily true. Please do keep in mind that both of the features must be present for a statement to be an assumption. Not everything that fills a missing link is an assumption; an assumption must also be necessarily true for the argument to hold. Thus, assumptions always lend strength to an argument and if made negative, void it. You might find this concept to be somewhat complex. Please go through the following example, for clarity.

Example 1 - Consider the following argument:
The GDP of Xitora has grown by 15% during the tenure of the current political party. Hence the political party has done a good job and deserves a second term.

The missing link in this passage is the link between the 15% GDP growth and the performance of the political party.

Now, take a look at this answer choice:

- GDP growth is an important factor in deciding the performance of a political party.

The only factor that the conclusion considers is GDP growth, and this answer choice suggests that GDP growth is important in determining the performance of a political party. Moreover, we can safely say that this answer choice must be true if the argument is to hold. If the answer choice was reversed to state that GDP growth did not matter in determining the performance of a political party, the argument would become void because it hinges on the idea that GDP is important in determining a political party's performance.

Thus, this statement is a good example of an assumption, as it is necessarily true and fills the missing link.

Now let us take a look at another potential answer choice, for the same passage:

Example 2 - GDP growth is the most important factor in determining the performance of a political party.
Example 2 is not a correct assumption. Although it does fill in the missing link, it is not necessarily true. Even if the GDP growth is not the single most important factor in determining the party’s performance, instead being the second, third, or fourth most important, the argument would still hold. Thus, this answer choice is not necessarily true, and while it may be a good strengthening statement, it is not an assumption.

Here, we will cover how to employ the assumption negation test on GMAT critical reasoning questions. Since assumptions must fill the missing link between the premise and conclusion and be necessarily true for an argument to hold, they always strengthen arguments and when made negative, void the argument.Utilizing this property, you can test for valid assumptions on the GMAT; this is called the assumption negation test.

The Assumption Negation Test

We will now use a live example, to explain how to conduct this test.

Example 1 - Consider the following argument:
The GDP of Xitora has grown by 15% during the tenure of the current political party. Hence the political party has done a good job and deserves a second term.

The missing link in this passage is the link between the 15% GDP growth and the performance of the political party, and the conclusion is that the party has done a good job and should stay in power.

Now, consider this answer choice:

- GDP growth is an important factor in deciding the performance of a political party.

If you are having difficulty deciding whether this qualifies as an assumption, , invert this statement and apply it to the argument. If the argument is now void, the statement is an assumption. Inverted, the statement becomes “GDP growth is not an important factor in deciding the performance of a political party.” If this statement is true, the argument is voided, as the conclusion hinges upon the idea that high GDP growth is an important determining factor in the party's performance. Thus, this answer choice is an assumption.

Let us now take a look at another answer choice, for the same passage and missing link.

Example 2 - GDP growth is the most important factor in determining the performance of a political party.
When negated, this statement becomes “GDP growth is not the most important factor in determining the performance of a political party.”This statement does not void the argument because even if GDP growth is not the most important factor, it can still be an important determining factor. Thus, Example 2 is not an assumption.

Now let us go through one, final, example.

Example 3 - During the tenure of no previous government did the GDP grow by more than 10%.
This answer choice suggests that the previous governments did not manage to achieve GDP growth, as high as the current one’s. When inverted, the answer choice would state that some of the previous governments did manage to achieve a higher GDP growth. This statement does not invalidate the argument as the 15% rise in GDP being the highest ever is not necessary for the argument to hold. Once again, this answer choice qualifies as a strengthening statement but it is not an assumption.

As we have mentioned above, GMAT critical reasoning questions include an argument that consists of a premise and a conclusion. Within this argument, there will usually be a logical gap between the premise and conclusion, called the missing link. Identifying this missing link is the key to solving GMAT critical reasoning questions. Another aspect of the missing link that we have mentioned on this page is how “strengthening statements” and “assumptions” affect missing links. Here, we will cover the difference between these two elements, in greater detail.

Strengthening Statements and Assumptions

The defining trait of a strengthening statement is that it fills in the missing link by providing information that can bridge the gap between the premise and conclusion. The difference between an assumption and a strengthening statement is that the former serves the same function as the latter, but it must also necessarily be true. Therefore, we can say that assumptions are a subset of strengthening statements, and strengthening questions are easier versions of assumption questions. In summary, any statement that can fill the missing link is a strengthening statement, and if it must be true for the argument to hold, it is an assumption.

Please consider the following example, to understand this concept better.

Example 1 - Consider the following argument:
The GDP of Xitora has grown by 15% during the tenure of the current political party. Hence the political party has done a good job and deserves a second term.

The missing link in this passage is the link between the 15% GDP growth and the performance of the political party, and the conclusion is that the party has done a good job and should stay in power.

Now, consider the following answer choice:

- GDP growth is an important factor in deciding the performance of a political party.

This answer choice is an assumption. This statement bridges the gap between the premise and conclusion, by suggesting that GDP is an important factor in determining how well a political party performed. This answer choice is also an assumption, as it must be true for the argument to hold.

To further our understanding of this concept, we will now take up another example, with the same passage and the same reasoning but a different answer choice.

Example 2 - GDP growth is the most important factor in determining the performance of a political party.
Example 2 is only a strengthening statement, not an assumption. While it does fill the missing link very well, it need not be true for the argument to hold. To elaborate, even if GDP were the second most, third most, or even merely an important factor, the argument would still make sense.

By studying this example, you should be able to understand the distinction between strengthening statements and assumptions, quite well. So, make sure to do so as the sooner you understand this distinction, the easier your life on the GMAT critical reasoning will be.

Now, please consider one final example; once again, with the same passage and missing link.

Example 3 - During the tenure of no previous government did the GDP grow by more than 10%.
Again, this example is a good strengthening statement but not an assumption. The 5% gap indicates that this government improved upon the GDP growth. However, the statement does not have to be true for the argument to hold.