This document discusses different types of evidence used to support claims, including facts, statistics, surveys, examples, and testimony from experts. It notes that facts and statistics can change over time or be manipulated. Surveys can also contain biases in their wording or context. The document cautions that evidence should be carefully evaluated based on the reputation of its source, whether personal experiences or observations are relevant, and if conclusions drawn from the evidence are warranted.

1. Evaluating Evidence
Chapter 8 Lecture
Read 142
Angela Henderson

2. Evidence defined
 Any information or support used to back up a
claim

3. Facts & Statistics
 Facts change
 Alcohol kills brain
cells.
 New study: dendrites
can grow in adulthood.
 Alcohol does damage
dendrites.
 Statistics
 Can be manipulated

4. Surveys & Poll Results
 Surveys are used to measure
people’s attitudes and beliefs.
 Need to be answered
honestly.
 Many survey questions are
ambiguous in their wording.
 Surveys contain many built-in
biases that make them even
more suspect:
 biased wording
 biased context

5. A Conclusion based on a Recent Poll
 A U.S. Congressman
sent a questionnaire
to his constituents
and received the
following results:
92% were against
government-
supported child-care
centers.
 Survey Question: Do
you believe the
federal government
should provide child-
care centers to assist
parents in rearing
their children?

6. Leading Words in Poll Questions
 Do you believe the federal government
should provide child-care centers to assist
parents in rearing their children?
Versus
Do you believe the federal government
should provide child-care centers to assist
parents who are unable to find alternative
child care while they are working?

7. Do we throw the baby out
with the bath water?
 Do not generalize further than warranted
 Know the reputation of the surveying
company
 Examine survey procedures before
accepting the results
 Generate your own qualified
generalizations

8. Examples and Illustrations
 Taken from observation, personal
experience or reading
Is the author an authority?
Is the personal experience valid?
Is the observation relevant to the claim?
Is it sufficient to persuade you to accept the
claim?

9. Good Reasons
 Cause & Effect
Pattern
 Remote cause

10. Testimony of Experts &
Authorities in the field
 Subjective
 Clear criteria
 Relevance to the
claim
 Accuracy

11. Analogy
 Analyze the
comparison for
validity and relevance

12. The Refutation
 Examination of one or
two of the
opposition’s strongest
arguments
 Disproves or finds
faulty with them
 Forms
 Concession
 Statistics
 Myths