Chapter 16 Persuasive Speaking 479Logos
Many persuasive speeches focus on issues that require considerable thought.
Should the United States adopt a national health care plan? Are certain television
programs too violent for children? When an audience needs to make an impor-
tant decision or reach a conclusion regarding a complicated issue, appeals to
reason and logic are necessary. Aristotle used the term logos to refer to persuasive
appeals directed at the audience’s reasoning on a topic.
Reasoning is the line of thought we use to make judgments based on facts
and inferences from the world around us. This basic human capability lies at the
heart of logical proof: when we offer our evidence to our audience in hopes that
our listeners will reach the same logical conclusions as we have, we are appealing
to their reason. There are two types of reasoning: inductive and deductive.
Inductive reasoning occurs when you draw general conclusions based on spe-
cific evidence. When you reason inductively, you essentially start by gathering the
specific examples, incidents, cases, or statistics and draw them into a conclusion
that ties them all together. For example, if you work at an animal shelter and have
been bitten or snapped at several times by small dogs but never by a large dog, then
you might conclude inductively that small dogs are more vicious than large dogs.
Deductive reasoning, by contrast, proceeds from the general principle to
the specific examples. You begin with a general argument or hypothesis and then
see how it applies it to specific cases, incidents, and locations. The most popular
way to argue deductively is with a syllogism, a three-line deductive argument
that draws a specific conclusion from two general premises (a major and a minor
premise). Consider this syllogism:
Major premise: All cats are mammals.
Minor premise: Fluffy is a cat.
Conclusion: Therefore, Fluffy is mammal.The speaker starts with a proposed conclusion or argument and then tests that
argument by gathering facts and observations and evidence. Applied to a speech,
you might use a syllogism in the following ways:
Major premise: Regular cleanings and visits to the dentist will help keep
your teeth in excellent condition and reduce your chances of developing
costly medical complications.
Minor premise: The proposed student dental insurance plan is affordable
and provides for two free cleanings per year and additional coverage on or-
thodontics and dental procedures.
Conclusion: Therefore, adopting the proposed student dental insurance plan
will keep your teeth in excellent condition and help you avoid costly medi-
cal complications.The extent to which your syllogism is persuasive depends on how well the audi-
ence accepts the major premise of your case. If the people in your audience do
accept your major premise that regular cleanings and visits to the dentist will
Think about the last major
purchase you made. Now
consider the information you
had prior to the purchase
(advertisements, reviews in
the media, advice from oth-
ers). Did you rely primarily on
emotional appeals, ethical
appeals, or logical appeals?AND YOU?