Lesson 7.2: Finding the Argument's Gap

Introduction

Welcome, students. In this lesson, we will explore how to identify the logical gap between evidence and conclusion in critical reasoning questions. Understanding this gap is crucial for effectively analyzing arguments and responding to various question types you may encounter on the GMAT.

Learning Objectives

By the end of this lesson, you will be able to:

Locate the logical gap between evidence and conclusion.
Identify common reasoning flaws: causation versus correlation, sampling issues, and scope shifts.
Pre-think before reading answer choices in critical reasoning questions.
Identify the central gap or flaw in an argument.
Formulate an expectation of the answer before reviewing choices.

Understanding Logical Gaps

What is a Logical Gap?

A logical gap occurs when there is a disconnect between the evidence presented in an argument and the conclusion drawn. This gap can lead to flawed reasoning, making it essential to identify it in critical reasoning tasks.

To illustrate, consider the following example:

Example 1: "Many studies have shown that people who exercise regularly live longer. Therefore, to increase longevity, it’s best to start an exercise program."

Analysis:

Evidence: Many studies indicate that regular exercisers have longer lifespans.
Conclusion: Therefore, starting an exercise program is the best way to live longer.
Logical Gap: The gap here is that while exercise correlates with longevity, it does not directly imply that starting an exercise program will increase lifespan. Other factors may contribute, such as diet or genetic predispositions.

Common Reasoning Flaws

Understanding common reasoning flaws will bolster your ability to identify logical gaps.

Causation vs. Correlation

When two variables are correlated, it does not imply that one causes the other. For instance:

Example 2: "Cities with more ice cream vendors have higher rates of violent crime. Thus, ice cream vendors increase violence in cities."

Here, the correlation does not indicate causation. In reality, both correlations could stem from another factor, such as the summer season, when more people are out and crime rates naturally rise, alongside increased ice cream sales.

Sampling Issues

Flaws can also arise from inaccurate samples used to support conclusions.

Example 3: "A survey of 100 people in a small town found that 90% wanted a new park. Therefore, the entire community wants a new park."

Analysis: The sample size is too small and localized to generalize about the entire community's desires. Here, the gap lies in assuming the sample's desires reflect the whole population.

Scope Shifts

Scope shifts occur when the argument's conclusion extends beyond what the evidence supports.

Example 4: "All dogs can be trained to fetch. Therefore, all animals can be trained to fetch."

In this case, the conclusion improperly expands the assertion beyond dogs to all animals, showcasing a clear gap.

Pre-Thinking Before Reading Answer Choices

One effective strategy for critical reasoning is pre-thinking, which involves forming an expectation of the answer before reviewing the provided options. This process increases your chances of identifying the logical gap based on your understanding of the argument.

How to Pre-Think: Steps

Read the Argument Carefully: Identify evidence, conclusion, and any assumptions.
Analyze for Gaps or Flaws: Assess whether the argument makes logical sense and identify any flaws or assumptions that underpin it.
Formulate Your Answer: Based on your analysis, come up with a potential answer that resolves the logical gap.

Example 5:

"The new study indicates that students who study late at night achieve better grades. Therefore, to improve grades, students should study late at night."

After identifying evidence and conclusion, you might realize that studying conditions, personal habits, or morning productivity could be influencing factors.
You may conclude that an answer addressing these factors—perhaps suggesting that study habits tailored to individual preferences could improve grades—would effectively bridge the gap.

Identifying Central Gaps and Flaws

Identifying central gaps involves discerning the main point of failure in the argument. It allows you to focus on the most pertinent aspects when considering your answer choices.

Example 6:

"A new law in Country X decreased youth crime rates by 40%. Thus, the new law is effective at reducing crime in all age groups."

Central Flaw: The argument assumes that a decrease in youth crime rates is indicative of overall crime reduction without evidence that the law impacts all demographics equally. The gap lies in generalizing from a specific group to a broader context.

Pre-Thinking Conclusion and Answer Review

Once you identify the logical gap, return to the answer choices with your pre-thought conclusions in mind. Compare each option against the gap you have identified rather than rushing to choose based on familiar wording.

Recap of the Steps

Identify Evidence and Conclusion: What is the core of the argument?
Determine the Gap or Flaw: What assumptions are made? What is misrepresented?
Formulate an Expectation: What answer addresses the gap?
Review Answer Choices with Intention: Look for options that align with your prethought conclusion rather than instinctive choices.

Conclusion

In this lesson, students, you have learned about finding the logical gap between evidence and conclusion in critical reasoning. We discussed common reasoning flaws like causation versus correlation, sampling issues, and scope shifts, as well as techniques for pre-thinking and identifying central gaps.

As you prepare for the GMAT, remember that the ability to identify these gaps will significantly enhance your critical reasoning skills, allowing you to approach each question methodically and effectively.

Study Notes

A logical gap connects evidence to the conclusion.
Causation vs. correlation is a common reasoning flaw.
Sampling sizes can affect the validity of conclusions.
Scope shifts extend an argument beyond its evidence.
Pre-thinking helps to clarify expectations before reviewing answer choices.
Focus on the central gap or flaw to guide your answer selection process.