Page 242 - Between One and Many The Art and Science of Public Speaking

Chapter 8 Supporting Your Message 209

Exhibit 8.4
Supporting a Claim
Grounds: Claim: The claim “I should take
It is cloudy Warrant: Clouds and I should take an umbrella” is supported
and windy. wind are signs of rain. an umbrella.
by appropriate grounds
and a warrant.

diet, however, that doesn’t prove it will work for us. Unfortunately, celebrities
often persuade people even though they don’t have expertise in the area. In
our speeches, we try to make sure the authorities we cite not only are credible
to the audience but also are knowledgeable about the topic. When we cite our
own opinion, we need to be particularly careful to explain to the audience why
we have the authority to speak on the topic. Authority warrants are subject to
tests of whether the authority is truly an expert, has accurate information, and
is unbiased.
Tips and Tactics
Using Authority Warrants

• Make sure the authority is an expert in the area being discussed.
• Make sure the authority is acting on reliable information.
• Use only unbiased authorities.

An example of reasoning from an authority warrant is shown in Exhibit 8.5.
Based on the grounds (the doctor tells you that the best way to lose weight is to
go on the NutriSystem diet) and the warrant (the doctor is an expert in treating
obesity), you decide to accept the claim (and go on the NutriSystem diet).
To test the validity of this reasoning, we must know whether the doctor is
an expert in the area of treating obesity, whether she has reliable information
about the state of your health and the effectiveness of the NutriSystem diet, and
whether she is biased. If the doctor is a dermatologist, for example, there is no
reason to believe she is competent to advise patients on what diet is best. Fur-
ther, suppose the only information she has about the NutriSystem diet is what
she’s read in the popular press rather than in medical journals. And fi nally, sup-
pose it turns out she gets a referral fee from the sponsors of the diet for sending
them a customer. In such a case, that expert opinion would be unreliable on all
three counts.
As speakers, we are wise to tell our audiences specifi cally why the experts
we quote are reliable and that they have no axe to grind. Otherwise, a skeptical
audience may reject our claims. generalization
warrant
A statement that either
Generalization Warrants establishes a general rule
or principle or applies an
A generalization warrant is a statement that either establishes a general established rule or prin-
rule or principle or applies an established rule or principle to a specifi c case. ciple to a specifi c case.
Warrants involving generalizations are used in two ways. Some warrants take

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