Page 246 - Between One and Many The Art and Science of Public Speaking

Chapter 8 Supporting Your Message 213

such as Florida and even Manhattan. On the other hand, we sometimes reason
from effect to cause, looking at why something has occurred. Gore also claims that
the once feared hole in the ozone layer has been reduced because of the nations
that banned the use of CFCs, once found in everything from hairspray to air
conditioners. Causal warrants are subject to tests of relatedness, other causes,
and side effects.
For example, we recall a student who wanted to convince her classmates to
avoid getting a tattoo. One of the effects she claimed that could be caused by im-
proper tattooing (with dirty needles) was hepatitis, a serious disease. She cited
experts who cautioned against tattooing and pointed out that among the unin-
tended side effects was the pain and expense of removing tattoos later in life.
She even offered another way to cause the desired effect of a tattoo—namely, a
technique called Mehndi, which creates body art that lasts only a few weeks.

Tips and Tactics
Using Causal Warrants

• Show how the cause is related to the alleged effect.
• Rule out other causes of the effect.
• Consider “side effects” in addition to the desired effect.

Sign Warrants

Perhaps you’ve heard someone say, “It’s going to rain. I can feel it in my bones.”
Or you’ve read a newspaper article stating that the economy is in a recovery
because the latest “leading economic indicators” are pointing upward. These are
examples of reasoning from sign. A sign warrant is reasoning in which the
sign warrant
presence of an observed phenomenon is used to indicate the presence of an un-
Reasoning in which the
observed phenomenon. In sign reasoning, the warrant asserts that the grounds
presence of an observed
provide a reliable sign that the claim is true. Some signs are infallible; most are phenomenon is used
merely probable. The absence of brain waves is considered legally as an infal- to in dicate the pres-
lible sign of death. On the other hand, no one would claim that the rise or fall of ence of an unobserved
stock prices is even close to an infallible sign of the state of the economy. Sign phenomenon.
warrants are subject to tests of reliability and confl icting signs.

Tips and Tactics
Using Sign Warrants
• Show that the signs are reliable indicators of the claim.
• Rule out confl icting signs.

A detective examines a crime scene for signs of forced entry, struggle, and
the like. Anyone who is a fan of Sherlock Holmes will recall that he often made
a case based on the most obscure signs. One small sign would point him to the
guilty suspect every time. Unfortunately, in real life such reliable signs are more

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