The document discusses evaluating the strength of evidence used to support factual claims. It emphasizes that factual claims require evidence to be considered dependable. When assessing evidence, readers should consider the quality, quantity, and consistency of the evidence. Common knowledge claims and conclusions well-supported by research require less scrutiny than opinions or disputed claims with little supporting evidence. Readers are advised to critically examine sources of evidence and ask how reliable they are before accepting factual claims as true.

1. Chapter 8
How Good Is the Evidence:
Intuition, Personal Experience,
Case Examples, Testimonials,
and Appeals to Authority.

2. The Need for Evidence
▪ Almost all reasoning we encounter includes beliefs, about the
way the world was, is or going to be, that the communicator
wants us to accept as facts.
▪ These can be conclusions, reasons, or assumptions
▪ These beliefs are factual claims

3. Questions You Should Ask about Factual Claims
▪ Why should I believe it? ▪ Does the claim need
evidence to support it?
▪ If yes, and there is not
evidence, it is just a mere
assertion!!!
▪ If there is evidence, you
need to ask yourself “How
good is the evidence?”

4. WHAT SEPARATES OPINION FROM FACT
▪ It is impossible to find absolute truth
▪ We have to go by what is dependable
▪ We want to ask “Can we count on these beliefs?”
▪ The greater the quality and quantity of evidence, the more we
can depend on it.

5. example
George Washington was our first
president.
Bottled water is safer to drink than
tap.

6. How do We Determine the Dependability of
persuasive material? Ask the Following:
▪ What is your proof?
▪ Where’s the evidence?
▪ Are you sure that’s true?
▪ How do you know that’s true?
▪ Why do you believe that?
▪ Can you prove it?

7. Then ask: How good is the evidence?
When we ask these questions, we may
realize that many beliefs lack sufficient
evidence to support or refute the claim.

8. Much evidence supports the idea the if you
take an aspirin a day, reduces the risk of a
heart attack; however, some evidence
disputes it.
Example

9. We encounter factual claims as
▪ Descriptive conclusions
▪ Reasons used to support descriptive or prescriptive
conclusions
▪ or descriptive assumptions

10. Locating Factual Claims
Let us look at the examples

11. Sources of Evidence: When Should we Accept a
Factual Claim as Dependable?
▪ When the claim appears to be undisputed common
knowledge, such as the claim “weight lifting increases
muscular body mass”
▪ When the claim is the conclusion from a well researched
argument
▪ When the claim is adequately supported by solid evidence in
the same communication or by other evidence that we know

12. What is evidence?
▪ Explicit information shared by the communicator that is used
to back up or justify the dependability of a factual claim.
▪ In prescriptive arguments, evidence will be needed to support
reasons that are factual.
▪ In descriptive arguments, evidence will be needed to directly
support a descriptive conclusion.

13. Before we begin, we need
to revisit descriptive and
prescriptive arguments.