Welcome to Evaluating Explanations!

In the Thinking Skills (9694) syllabus, evaluating evidence isn't just about deciding if a source is lying or telling the truth. Once we have the "facts" (the evidence), we need to figure out why those facts exist. People will often offer you a "reason" or an "explanation" for a set of data or an event. Your job as a critical thinker is to assess those explanations to see if they actually hold water.

This chapter is all about being a "logic detective." We aren't just looking at what happened; we are judging the story someone is telling us about why it happened. Don't worry if this feels a bit abstract—we will break it down into simple, repeatable steps!

1. What Does it Mean to "Assess an Explanation"?

In your exam, you will often be given a piece of evidence (like a graph showing rising ice cream sales) and a suggested explanation (like "Ice cream makes people happy"). To assess this, you have to judge its quality. Is it a strong explanation? Is it weak? Is it just plain unlikely?

Key Definition: An explanation is a statement that seeks to clarify how or why something is the case. It is different from an argument because it doesn't try to persuade you that something is true; it assumes it is true and tries to find the cause.


2. The Three Golden Rules of Assessment

When you are asked to assess how well an explanation fits the evidence, use these three criteria:

A. Plausibility (Does it make sense?)

Plausibility is about whether the explanation is believable based on our general knowledge of how the world works. Example: If a student is late for class, the explanation "I was stuck in traffic" is plausible. The explanation "I was abducted by time-traveling pirates" is implausible.

B. Consistency (Does it match everything else?)

An explanation must be consistent with all the known facts in the sources. If Source A says the crime happened at \( 9:00 \) PM, but the explanation for the suspect's behavior assumes the crime happened at noon, the explanation is inconsistent and should be rejected.

C. Sufficiency (Does it explain everything?)

A good explanation should account for all the evidence, not just a small part of it. If there are three weird things happening and the explanation only accounts for one, it is a weak or partial explanation.


3. Step-by-Step: How to Assess in the Exam

When you see a question asking you to "Assess the explanation provided in Source X," follow these steps:

Step 1: Identify the Evidence
What is the actual fact we are trying to explain? (e.g., "The bird population in the woods has dropped by \( 20\% \)").

Step 2: Identify the Proposed Explanation
What reason does the source give? (e.g., "The birds have all flown to a different forest because of the noise from a nearby factory").

Step 3: Look for "Gaps" or "Flaws"
Ask yourself: Does the factory noise explain why all the birds left, or just some? Are there other sources that say the factory is actually very quiet? If the factory is quiet, the explanation fails the consistency test.

Step 4: Reach a Judgment
State clearly if the explanation is strong, weak, likely, or implausible, and give your reason why.


4. Common Pitfalls to Avoid

Even the best students can get tripped up by these common mistakes:

  • Confusing Correlation with Causation: Just because two things happen at the same time doesn't mean one caused the other. If sales of sunglasses and sales of sunscreen both go up, an explanation saying "Sunglasses cause people to buy sunscreen" is a poor assessment. They are both caused by a third factor: the sun!
  • Ignoring Alternative Explanations: An explanation might be plausible, but if there is another explanation that is even more likely, the first one is weakened. (Note: You will learn more about "suggesting" these in the next chapter).
  • Being Too Certain: In Thinking Skills, we rarely say an explanation is \( 100\% \) "proven." Instead, use words like "This explanation is highly likely because..." or "This explanation is weakened by..."

5. Quick Review: The "Logic Checklist"

Before you move on, make sure you can answer these three questions about any explanation you encounter:

1. Is it possible? (Plausibility)

2. Does it contradict any other evidence? (Consistency)

3. Does it leave anything unexplained? (Sufficiency)


Key Takeaways

- Assessing means making an informed judgment about the quality of an explanation.

- Plausibility, Consistency, and Sufficiency are your primary tools for evaluation.

- Always refer back to the sources. Your judgment must be based on the evidence provided in the exam paper, not just your personal opinion.


Top Tip: In Paper 2, Section A, you are often asked to evaluate the evidence. If you notice that an explanation provided in one source is contradicted by a graph in another source, you have found a major weakness in the consistency of that explanation!


Cross-reference: To see how this fits with other skills, check out "Assess credibility of evidence" to judge the source, and "Suggest explanations for evidence" to come up with your own alternative theories.