Introduction: Playing the "Devil’s Advocate"

Welcome! In this chapter, we are going to learn one of the most important skills in Critical Thinking: Suggesting a challenge to an inference. While earlier chapters taught you how to draw conclusions from evidence, this chapter teaches you how to look at someone else’s conclusion and say, "Wait a minute—is there another way to look at this?"

Think of yourself as a detective. Just because a suspect's fingerprints are on a vase doesn't automatically mean they stole the jewelry inside. To "suggest a challenge" is to find a logical reason why the evidence might not lead to the conclusion being claimed.

Note: This chapter focuses on "Using Evidence." If you want to learn how to judge a challenge that someone else has already made, see our chapter on "Assess challenges to inferences made from evidence."

1. What is an Inference? (A Quick Refresher)

Before we can challenge an inference, we must understand what it is. An inference is a "logical leap" we take from a piece of evidence to a conclusion.

The Formula:
Evidence (The Fact) + Reasoning (The Logic) = Inference (The Conclusion)

Example:
Evidence: Your friend is soaking wet.
Inference: It is raining outside.

To challenge this, you need to show that even though the evidence is true (your friend is wet), the inference (it is raining) might be wrong.

2. How to Suggest a Challenge

When the exam asks you to "suggest a challenge," it wants you to provide a plausible reason why the inference might be weak or incorrect. Here are the three most effective strategies:

A. Suggest an Alternative Explanation

This is the most common way to challenge an inference. You accept that the evidence is true, but you offer a different reason for why it happened.

Example:
Evidence: "Sales of umbrellas increased by \(50\%\) last month."
Inference: "Therefore, it must have rained more than usual last month."
Your Challenge: "Perhaps a major fashion influencer started a trend of using umbrellas as sunshades, causing sales to rise regardless of the weather."

B. Point Out a "Coincidence" (Correlation vs. Causation)

Sometimes two things happen at the same time, and we wrongly infer that one caused the other. Challenging this means suggesting that the two events are unrelated.

Example:
Evidence: "Since the city built a new library, local crime rates have dropped."
Inference: "The library is causing people to be more law-abiding."
Your Challenge: "The drop in crime might actually be due to the increased police patrols that were introduced at the same time the library was built."

C. Identify Missing Information (The "What If?")

An inference is often weak because it ignores a "hidden factor." You can challenge it by suggesting what that factor might be.

Example:
Evidence: "The new 'Super-Grow' fertilizer was used on Farm A, and their crops grew twice as fast as Farm B."
Inference: "Super-Grow is a highly effective fertilizer."
Your Challenge: "The inference is challenged if Farm A is located in a sunnier region with better soil than Farm B; the fertilizer may have had no effect at all."

Quick Review: To challenge an inference, don't call the evidence a lie. Instead, show that the evidence could point to a different conclusion.

3. Step-by-Step: How to Write Your Answer

In Paper 2, you may be asked to "Suggest one challenge to the inference drawn from Source X." Follow these steps:

  1. Identify the Inference: What is the author trying to prove with this evidence?
  2. Ask "What Else?": Brainstorm one other reason why that evidence might exist.
  3. Use the "Could be" phrasing: Start your answer with phrases like "It could be that..." or "The evidence does not account for..."

Example Scenario:
"A study shows that students who eat breakfast get higher grades. Therefore, eating breakfast makes you smarter."

Weak Challenge (Avoid): "I don't think this is true because I don't eat breakfast and I'm smart." (This is a personal anecdote, not a logical challenge).

Strong Challenge (Use): "It could be that students who eat breakfast come from wealthier families who can also afford private tutors; it is the tutoring, not the breakfast, that leads to higher grades."

4. Common Mistakes to Avoid

Don't worry if this feels tricky at first! Many students make these common errors:

  • Attacking the Source instead of the Inference: Saying "The scientist who wrote this is biased" is a challenge to credibility, not the inference. A challenge to an inference must address the logic of the leap itself.
  • Simply denying the conclusion: Saying "I disagree, breakfast doesn't help" is just an opinion. You must provide a reason why the evidence might be misleading.
  • Confusing "Inconsistent" with "Challenge": Inconsistency means the evidence contradicts the conclusion. A challenge means the evidence is consistent with the conclusion, but it's also consistent with something else.

5. Helpful Phrases for Your Exam

Use these "power phrases" to structure your thoughts:

  • "While the evidence shows \(X\), it does not necessarily mean \(Y\) because..."
  • "An alternative explanation for this data is..."
  • "This inference assumes that there are no other factors, but..."
  • "The data could also be explained by..."

Did you know?
In the 2028 syllabus edition, the command word Suggest means you need to apply your knowledge to make proposals or put forward considerations. You are being asked to be creative but logical!

Key Takeaways

- A challenge is a reason why an inference might be wrong, even if the evidence is true.
- Alternative explanations are your best friend when suggesting a challenge.
- Focus on the "leap" between the fact and the conclusion, and try to find a "tripwire" that makes that leap fail.
- Avoid personal opinions; stay focused on logical possibilities.