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Confusing sufficiency with necessity on GMAT Critical Reasoning



Confusing sufficiency with necessity on GMAT Critical Reasoning

Confusing Sufficiency with Necessity on CR


In GMAT critical reasoning, there are several different types of questions that you will encounter. In this short article, we will cover the characteristics of questions wherein the trap involves confusing sufficient conditions for necessary conditions.

Confusion between sufficiency and necessity


This error is said to occur when an argument confuses a “sufficient” condition with a “necessary” condition; in other words, this fallacy is the result of assuming that because a condition is enough to produce a particular outcome, the condition must produce the outcome.

Please take a look at the following example to better understand this concept.

Example 1: Statement: All Olympic athletes maintain a healthy body mass index.
Inference: One must be an Olympic athlete to maintain a healthy body mass index.
Inference: If one maintains a healthy body mass index, one is an Olympic athlete.

Here, “oxygen” has been given as a necessity for human survival. However, we cannot, on the basis of this information, state that oxygen is the only thing needed for human survival. Thus, oxygen is a necessity but not a sufficiency, meaning drawing such a conclusion would be confusing necessity with sufficiency. This statement is thus, of course, incorrect.

Now, let’s take a look at a more GMAT-like example. Please try to solve the question before reading further.

Example 2: Although many scholars dismiss Nietzscheism as a pseudo-philosophy, it is, in fact, a branch of philosophical thought, for it utilizes philosophical disciplines such as systemic examination and evaluation of opinions on metaphysics and morality to realize cognitive and eudemonic goals.

The most serious flaw in the argument is that…?

Here, we have a passage followed by a question stem.

Step 1 – Read the question stem.
Step 2 – Read the argument.
Step 3 – Come up with a broad expectation from the correct answer choice.

The flaw here is that the conclusion of the argument, that Nietzscheism is a branch of philosophical thought, has been reached on the basis of the information that it utilizes philosophical disciplines to realize cognitive and eudemonic goals, but whether anything that does so is a branch of philosophical thought has not been established; it is an assumption that the argument makes.

Take a look at the following answer choice.

Option 1: It assumes that any field of study that employs philosophical disciplines is a branch of philosophical thought.

Thus, this answer choice is correct.

This article has deliberately been kept brief; for a more elaborate explanation, please refer to the Experts’ Global Stage One Critical Reasoning videos.

Covered by…