Find The Assumption | The Critical Reasoning question type on the GMAT largely cares about a very crucial element of the arguments that it presents in its questions. This element, referred to as an assumption on which the logical flow of the argument strongly depends. The significance of this assumption is so very crucial that the entire argument could fall apart if it were to be flawed.
The Assumption Family, essentially the largest of the other two CR families (Structure family, Evidence family), encompasses five different varieties of questions, the first of which (Find the Assumption) will be discussed here.
First things first; an assumption is something that the author must believe to be true in order to draw a certain conclusion. However, the author does not state the assumption in the argument. You must bear in mind that this assumption need not be absolutely true in the real world; it’s just what the author believes to be true in order to logically make his/her argument. An assumption is just as essential as the four building blocks to put together a meaningful argument.
Assumptions fill at least part of a gap in the argument, within which if you insert a valid assumption, you are left with a better, more holistic argument.
Let’s diagrammatically demonstrate what this gap may look like, and how we can fill it with a good enough assumption.
As mentioned before, Find the Assumption questions ask you to find an assumption that the author must believe to be true in order to make the argument. The correct answer should make the argument possible, If the correct answer were not true, the argument would not be valid.
With these questions, your task is to figure out which answer choice represents something that must hold true according to the author. Remember that this assumption need only be true in the author’s mind, and not necessarily in the real world, so make sure you don’t get trapped by your own general knowledge and/or knowledge of any specific facts. Always go with the logical flow of the given argument.
These questions are usually easy to identify, because the question stem will use some form of the noun “assumption” or the verb “to assume”. Occasionally, the question may ask for a new premise, or a new piece of information, that is “required” or will help the conclusion be “more reasonably drawn”.
Let’s have a look at a few examples:
Gortland has long been narrowly self-sufficient in both grain and meat. However, as per capita income in Gortland has risen toward the world average, per capita consumption of meat has also risen toward the world average, and it takes several pounds of grain to produce one pound of meat. Therefore, since per capita income continues to rise, whereas domestic grain production will not increase, Gortland will soon have to import either grain or meat or both.
Which of the following is an assumption on which the argument depends?
(A) The total acreage devoted to grain production in Gortland will soon decrease.
(B) Importing either grain or meat will not result in a significantly higher percentage of Gortlanders’ incomes being spent on food than is currently the case.
(C) The per capita consumption of meat in Gortland is increasing at roughly the same rate across all income levels.
(D) The per capita income of meat producers in Gortland is rising faster than the per capita income of grain producers.
(E) People in Gortland who increase their consumption of meat will not radically decrease their consumption of grain.
Let’s break down the argument text:
Conclusion: “Therefore, since per capita income continues to rise, whereas domestic grain production will not increase, Gortland will soon have to import either grain or meat or both.”
Premise: “as per capita income in Gortland has risen toward the world average, per capita consumption of meat has also risen toward the world average, and it takes several pounds of grain to produce one pound of meat.”
So, we can see the following from the above argument:
Now, if we look at the premise closely, we’ll know that a considerable decrease in grain intake could help make up for the increased demand for meat. So, essentially, the basis for the problem that has arisen (the need to import meat) is possibly the fact that both meat and grain consumption have been on the rise.
With this information in mind, if we look at the answer choices, the closest matches we find are options C and E. But then, the argument involves only meat consumption in general, not its distribution by income level. Hence, we eliminate option C.
Option E is the answer.
Here’s another example:
A newly discovered painting seems to be the work of one of two seventeenth-century artists, either the northern German Johannes Drechen or the Frenchman Louis Birelle, who sometimes painted in the same style as Drechen. Analysis of the carved picture frame, which has been identified as the painting’s original seventeenth-century frame, showed that it is made of wood found widely in northern Germany at the time, but rare in the part of France where Birelle lived. This shows that the painting is most likely the work of Drechen.
Which of the following is an assumption that the argument requires?
(A) The frame was made from wood local to the region where the picture was painted.
(B) Drechen is unlikely to have ever visited the home region of Birelle in France.
(C) Sometimes a painting so resembles others of its era that no expert is able to confidently decide who painted it.
(D) The painter of the picture chose the frame for the picture.
(E) The carving style of the picture frame is not typical of any specific region of Europe.
Breaking it down,
Conclusion: ”…the painting is most likely the work of Drechen.”
Premise: “Analysis of the carved picture frame, which has been identified as the painting’s original seventeenth-century frame, showed that it is made of wood found widely in northern Germany at the time, but rare in the part of France where Birelle lived.”
So, we can see the following from the above argument:
If the assumption given above were to be considered plausible, it also makes sense to assume that the painter painted and eventually framed the picture in the same region.
Now, if we consider the answer choices, the closest answer that resembles our reasoning is option A. If, just to be sure, we consider the other choices, we need to analyse what would happen if each of the given options were NOT true.
Let’s look at each in turn:
A: If the frame were not made from wood local to the region where the picture was painted, then the given conclusion about who painted the picture would completely fall apart.
B: If Drechen visited the home region of Birelle, he could’ve still painted the picture whilst in Germany.
C: Even if an expert could not decidedly tell who painted a picture, he/she could still examine the wood to tell which region the frame belonged to.
D: The painter could’ve just painted the picture and left the task of framing the picture to someone else; possibly a local retailer and/or customer.
E: If this were untrue, the argument would in fact be strengthened, indicating that the wood can in fact belong to a specific region, i.e. Germany in this case.
Option A is the best answer.