Unit 15: Using Persuasive
(Chapter 17)
“Speech is power; Speech is to persuade,
to convert, to compel.”
-- Ralph Waldo Emerson
“…is the process of adjusting ideas to
people and people to ideas.”
-- Donald C. Bryant, rhetoric scholar
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Establishing Credibility
Also known as ethos.
 Audience’s perception of the speaker
 Various dimensions:
 Competence
- knowledge & skill
 Trustworthiness - believability & honesty
 Dynamism - energy level
 Charisma - charm, talent & magnetism
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Enhancing Your Credibility
Well-stressed values and concerns
shared with audience.
 Well-documented evidence,.
 Well-organized ideas.
 Well-managed delivery.
Using Logic and Evidence to
Logos -- formal system of rules to reach
a conclusion
 Aristotle: “Always prove what you state.”
 Reasoning: drawing a conclusion from
the evidence.
Types of Reasoning
 Deductive
 Causal
Inductive Reasoning
Using specific examples or instances to
reach a general or probable conclusion.
 Used when one can claim that an
outcome is probably true because of
specific evidence.
Testing Inductive Reasoning
Are there enough specific instances to
support the conclusion?
 Are the specific instances typical?
 Are the instances recent?
Inductive Reasoning Example
Students are sneezing in dorms and
Professors are cancelling classes.
Campus clinic has long waiting lines.
Conclusion: there must be flu on our
Deductive Reasoning
Opposite of induction.
 Conclusion is more certain than
 The more value the outcome, the more
certain the conclusion.
 Start with widely accepted general
claim, then move toward specific
conclusion illustrating general claim.
Structure of Deductive
Syllogism -- three part argument
Major Premise: widely accepted general
2. Minor Premise: specific statement that
applies to the major premise.
3. Conclusion: logical outcome, minor
premise exemplifies major premise.
The more value the major premise, the
more value the deduction.
Testing the Validity of
Deductive Reasoning
Is the major premise (general
statement) true?
 Is the minor premise (specific instance)
Deductive Reasoning
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Deductive Reasoning: An
All tough drug laws introduced in
medium-sized communities result in
diminished drug-related crimes.
(generally accepted statement)
2. San Marcos, Texas is a medium-sized
community. (specific case supporting
general statement)
Conclusion: San Marcos should institute
tough drug laws.
Causal Reasoning
Relating to events to show connection.
 To conclude that one or more events
caused another event.
 Can move from cause to effect.
 Can move from effect to cause.
Causal Reasoning
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Causal Reasoning
Cause to Effect
1. Interest rates have increased this
2. The Dow Jones will decrease.
From a known fact to a predicted result.
Causal Resining
Effect to Cause
1. A major earthquack has occurred.
2. The cause was a shift in a fault line.
From a known result to a predicted cows.
Supporting Your Reasoning
with Evidence
Use facts
 Use value true examples
 Use opinions that enhance credibility
 Use sound & reliable statistics
 Use reluctant testimony -- shows that
someone has been convinced
 Use new and specific evidence
 Use evidence to tell a story
Avoid Faulty Reasoning
Be ethical & appropriate with evidence
& reasoning.
 Fallacy: False reasoning when
someone attempts to persuade without
adequate evidence, or with arguments
that are irrelevant or inappropriate.
Faulty Reasoning
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Avoid Faulty Reasoning
Causal -- Hurricanes are caused by war
(connection not related)
Bandwagon -- Everyone knows cell
phones are safe. (popularity appeals)
Either-Or -- Either you’re with us or you’re
against us. (only 2 choices)
Hasty Generalization -- Since my niece is
failing, city schools are bad. (quick
Avoid Faulty Reasoning
Ad Hominem -- What does a divorced man
know about parenting? (personal attack)
Red Herring -- Let’s not focus on the lawsuit
against me; let’s talk about…”
(changing the topic to distract)
Misplaced Authority -- Jessica Simpson says
McMillan trucks are best. (not a true expert)
Non Sequitur -- Support me for Hongress - I
have 3 children. (ideas do not follow)
Use Emotion to Persuade
Can make people feel pleasure or
 Can make people feel energized
 Can make people feel dominance
Using Emotion
Use concrete examples
 Use emotion-arousing words
 Use nonverbal behavior
 Use visual images
 Use metaphors and similes
 Use appropriate fear appeals
 Use appeals to a variety of emotions
 Tap shared beliefs
Organizing Persuasive
State your strongest arguments first
 Do not bury key arguments in the
 Save action calls for the end
 Consider presenting both sides of an
 State and refute counterarguments
Strategies for Organizing
Persuasive Messages
Problem -- Solution
 Refutation
 Cause and Effect
 Motivated Sequence
 Attention
 Need
 Satisfaction
 Visualization
 Action
Persuading the Receptive
Identify with the audience
 Clearly state your objective
 Tell your audience what you want them
to do
 Ask listeners for an show of support
 Use emotional appeals
 Make it easy for the audience to act
Persuading the Neutral
Capture listeners’ attention early
 Refer to common beliefs
 Relate topic to listeners’ loved ones
 Be realistic about what can be
Persuading the Unreceptive
Don’t immediately announce you will
change their minds
 Begin by noting common ground
 Don’t expect a major change in attitude
 Acknowledge their points of view
 Establish credibility
 Consider aiming for understanding
rather than action