Common logical fallacies and reasoning errors - Circular rea...

Learning Outcomes

After reading this article, you will be able to define circular reasoning, identify it within LSAT argument stimuli, and explain why it is a major flaw. You will learn effective strategies for detecting circularity and understand how circular logic affects argument validity on the LSAT. You will practice distinguishing circular errors from other common flaws and know how to eliminate circular answers.

LSAT Syllabus

For LSAT, you are required to understand and analyse common logical flaws in arguments, including circular reasoning. For your revision, focus on:

• Recognising when an argument’s reasoning is circular or assumes its own conclusion
• Understanding how circular reasoning invalidates the argument
• Distinguishing circular reasoning from closely related flaws (such as begging the question)
• Applying flaw-identification strategies to LSAT-style multiple choice questions

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. Which of the following best defines circular reasoning?
   1. An argument that uses irrelevant evidence
   2. An argument where the conclusion repeats a premise
   3. An argument based on analogy
   4. An argument that ignores the question

2. True or false? Circular reasoning always guarantees a valid conclusion.

3. In which of the following LSAT scenarios might you see circular reasoning?
   1. The conclusion is restated as evidence
   2. The argument uses studies as proof
   3. The premise provides an alternative explanation to the conclusion
   4. The argument examines trends over time

Introduction

For LSAT Logical Reasoning, you must recognise arguments that fail because they assume as evidence exactly what they set out to prove—a classic logical error known as circular reasoning. Understanding this flaw is critical for both flaw identification questions and for quickly eliminating faulty answer choices.

Key Term: circular reasoning
An argument is circular if it takes for granted the truth of the conclusion in one of its premises or uses a premise that presupposes what the conclusion claims.

Recognising Circular Reasoning

Circular reasoning involves using the very claim that needs to be proven as part of the supporting evidence. Rather than proving a point, the argument goes in a logical circle, failing to give independent support for the conclusion.

Key Term: premise
A statement or claim offered as evidence in support of a conclusion.

Key Term: conclusion
The main point an argument aims to establish, supported by its premises.

Spotting the Flaw

LSAT arguments featuring circular reasoning:

• Often restate the conclusion in different words as a premise
• Might rely on terms like "because," "as everyone knows," or "since this is so"—but the “proof” simply assumes the conclusion is true
• Provide no new or independent evidence

In flaw questions, typical answer stems include:

• "presupposes what it sets out to prove"
• "the argument assumes its conclusion"
• "the reasoning is circular"

Worked Example 1.1

A stimulus reads:
"Success is guaranteed because successful people always achieve their goals, and achieving your goals means you are successful."

Question: What is the flaw in this argument?

Answer:
The argument is circular; it defines being successful as achieving one’s goals, and then uses that definition to "prove" that success is guaranteed—simply by assuming that the definition itself is proof.

Why Circular Reasoning Is Invalid

Circular reasoning fails basic logical standards:

• No new or independent support is introduced for the conclusion.
• Anyone inclined to doubt the conclusion would not be convinced, since the premises depend on the truth of the conclusion.
• The overall effect: the argument proves nothing and cannot persuade a reasonable critic.

Revision Tip

If a conclusion feels like a restatement of a premise, check whether the argument is simply rephrasing its own claim as support. This may signal circularity.

Distinguishing Circular Reasoning from Other Flaws

Circular reasoning can sometimes be confused with similar flaws:

• Begging the Question: Sometimes used interchangeably, but technically "begging the question" is a broader category. Circularity is one way to beg the question, by repeating the conclusion as evidence.
• Irrelevant Premises: In circular reasoning, the evidence is not irrelevant; it is insufficient because it relies on what it is supposed to establish.

Worked Example 1.2

"Abortion is immoral because it is always wrong to end a human life by abortion."

Answer:
This is circular. The premise that it is "always wrong to end a human life by abortion" simply asserts what the conclusion claims ("abortion is immoral") without independent justification.

LSAT Flaw Questions: Spotting Circular Reasoning

Many LSAT flaw questions ask you to find the error in reasoning. Commonly, one answer choice will refer to circular flaws, especially in logical reasoning sections.

Key Term: flaw question
A question that requires you to identify an error in the reasoning provided by the argument.

Exam Warning

Circular reasoning is rarely the correct answer unless the argument truly repeats its conclusion as a premise. Do not pick this answer if the argument introduces any independent reason, even if the case is weak or unsound.

Strategies to Avoid Selection Errors

• Always check if the "evidence" is simply a reworded version of the claim.
• Look for logical movement: does the premise provide a genuine reason for the conclusion, or just assert the conclusion again?
• Compare the premise and conclusion word by word for overlap and repetition.

Worked Example 1.3

The stimulus states:
"We know the new traffic policy is effective because it is the best approach for reducing congestion, and an effective policy always reduces congestion."

Which flaw is present?

Answer:
The argument is circular. The premise "an effective policy always reduces congestion" simply assumes the point to be proven ("the policy is effective") rather than providing independent evidence.

Summary

Circular reasoning is a major LSAT flaw in which an argument’s conclusion is assumed in its premises. This logical error means the argument offers no support and cannot persuade a critical reader. LSAT flaw questions will frequently test your ability to spot this mistake.

Key Point Checklist

This article has covered the following key knowledge points:

• Circular reasoning repeats the conclusion as evidence, making the argument logically invalid
• The flaw is exposed when the premise and conclusion restate each other
• Circular reasoning is a common LSAT flaw and regularly appears in flaw-identification questions
• “Presupposes what it sets out to prove” and similar answer stems are signals for circularity
• Do not confuse circularity with arguments that present some independent evidence, even if weak

Key Terms and Concepts

• circular reasoning
• premise
• conclusion
• flaw question