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This module introduces students to the foundational skills of evaluating evidence. By the end of the lesson, students will be able to critically assess the credibility of evidence by examining its source, context, and reliability.
Key Terms
Key Terms
Credibility - How believable a sources is. Does the source consist of aspects that might make a wise person more or less likely to believe it to be true. Credibility includes reliability.
Reliability - Qualities of the source that make it more or less worthy of trust
Representative - Does the evidence reflect the whole picture? Is the sample size large enough? Is it diverse? Or is it cherry-picked?
Presentation - How is the evidence being framed? Are statistics being used honestly? Are visuals misleading? Is language emotionally loaded?
Plausibility - How believable something is based on logic, context, or prior knowledge.
Corroboration - is additional evidence from an independent source which supports a claim
Consistent - is when two or more claims are possible to be true
Inconsistent - is when it is not possible for multiple claims to be true
Imagine you're reading an article that says:
“90% of people prefer Brand X over Brand Y!”
Sounds convincing, right? But what if you found out the survey only asked 10 people, all of whom work for Brand X? This is where your thinking skills come in. How do to spot weak evidence and ask the right questions?
A study claims that “Teenagers who play video games score higher on memory tests.”
Before we accept this, ask yourself:
Who conducted the study?
How many teenagers were tested?
What kind of memory test was used?
Could there be other explanations?
In this class we will use R.A.V.E.N. as a way to remember how to determine how credible and reliable a source is.
TS: Credibility RAVEN.pdfAccess whether the reputation of each statement is reduced or increased
Access whether the reputation of each statement is reduced or increased
Betty believes that maintaining good relationships has the highest priority. Her friends and relatives know that if they ask her opinion, she tells them what she thinks will please them most.
The Orange Rat Company has been convicted on many occasions for making false claims in its advertising.
Stephen believes in encouraging his students. So he always tells them their work is good, even when it is not. But the students know this.
Ajab is a devoutly religious young man, who is renowned for always speaking the exact truth, even when it is in his interests to lie.
Examples of Vested Interest
Examples of Vested Interest
People who have committed a crime have a vested interest to lie or to conceal part of the truth, in order to avoid being punished.
Employees who have made a mistake or acted dishonestly have a vested interest to conceal the truth, in order to avoid being disciplined or dismissed.
Suspects being tortured have a vested interest to tell the torturers whatever they want to hear (whether it is true or not), in order to avoid further pain.
Companies have a vested interest to exaggerate the benefits of their products, in order to increase sales.
Newspapers have a vested interest to sensationalize stories, in order to increase sales.
Assessing reliability
Assessing reliability
The fact that someone's reliability is weak does not mean that their evidence is necessarily untrue, but it does mean that we should be rather skeptical towards it. A source is not 100% reliable or 100% unreliable. You have to access it using all parts of R.A.V.E.N. Some aspects will strengthen it's reliability and some will weaken it.
Assessing Reliability Practice
Assessing Reliability Practice
Use the source to evaluate the reliability of Dr. Aihara's evidence.
Suggest one factor which strengthens the reliability of Dr. Aihara's evidence. Briefly explain your answer.
Suggest one factor which weakens the reliability of Dr. Aihara's evidence. Briefly explain your answer.
Understanding Plausibility in Evaluating Evidence
Understanding Plausibility in Evaluating Evidence
But here’s where it gets interesting: sometimes, plausibility and source reliability can conflict.
Take miracles, for example. The philosopher David Hume argued that while miracles aren’t impossible, they’re so unlikely that it’s usually more reasonable to believe the witness is mistaken or lying than to believe the miracle actually happened. So if someone tells you they saw a miracle, you have to weigh:
How unlikely the event is (its low plausibility), against
How trustworthy the person is (their high reliability).
This kind of balancing act is at the heart of critical thinking.
When we assess the credibility of evidence, we often start by asking: Is the source reliable? But that’s only part of the picture. We also need to consider the plausibility of the claim itself.
Plausibility refers to how likely or believable a claim seems on its own, even before we consider who said it. A claim that fits with what we already know about the world—something that seems reasonable and doesn’t raise red flags—is considered more plausible, and therefore often more credible.
Evaluating How Evidence Relates:
Evaluating How Evidence Relates:
When you're presented with two or more pieces of evidence on the same topic, it's important to think critically about how they relate. There are three main possibilities:
1. ✅ Corroboration
Two pieces of evidence corroborate each other when they support the same conclusion and make each other more believable—especially if they come from independent sources.
🧠 Example:
Two people, interviewed separately, describe the same event in similar detail—without having spoken to each other. Their agreement strengthens the credibility of both accounts.
⚠️ But be careful:
If one person copied the other’s story, or if they had a reason to support each other (like being friends or having the same bias), then their evidence does not truly corroborate—because it’s not independent.
2. 🤝 Consistency
Two pieces of evidence are consistent if they don’t contradict each other—they could both be true—but they don’t necessarily make each other more likely to be true.
🧠 Example:
One witness says they saw a red car leave the scene. Another says they heard tires screeching. These details don’t conflict, so they’re consistent—but they don’t directly confirm each other either.
3. ❌ Inconsistency
Evidence is inconsistent when the two pieces cannot both be true at the same time. This creates a conflict that needs to be resolved.
🧠 Example:
One person says the event happened at 10 a.m., another says it happened at 2 p.m. Both can’t be right—so the evidence is inconsistent.
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