380 17.2 Using PersUasive strategies
Conclusion: If Mega-Low-Mart is permitted to open a store in
our town, the merchants in the downtown area will
lose business, and the city will lose tax revenue.
The strength of Ann’s argument rests on whether or not her major premise
is true. Does the arrival of a large discount chain store always, in fact, result in
a loss of business for and tax revenue from merchants in small towns? In con-
structing arguments for your persuasive messages, assess the soundness of the
major premise on which you build your argument. Likewise, when listening to a
persuasive pitch from someone using a deductive argument, critically evaluate
the accuracy of the major premise, using the questions in the How To box.
Although we have identified inductive and deductive reasoning as separate
types of reasoning, they are related; the general premise in deductive argument
is often reached by noting several examples that support the general premise.^8
Identifying whether you are using inductive or deductive reasoning can help
you better analyze and assess your arguments.
Causal reasonIng A third type of reasoning is called causal reasoning.
When you reason by cause, you relate two or more events in such a way as to
conclude that one or more of the events caused the others. For example, you
might argue that having unprotected sex causes the spread of sexually trans-
mitted diseases. When reasoning from cause, you suggest that one thing actu-
ally caused the other thing to occur. There are two ways to structure a causal
argument:- From cause to effect. One approach is to move from a known fact to a pre-
dicted result. You know, for example, that interest rates have increased in
Test the Truth of a Deductive Argument
• Is the major premise (general statement) true? The power of deductive reasoning hinges in
part on whether your generalization is true. In our example about communication professors,
is it really true that all communication professors have excellent teaching skills? What evidence
do you have to support this statement?
• Is the minor premise (the particular statement) also true? A syllogism can also collapse if your
minor premise is false. In our example, it is easy enough to verify that John Smith is a commu-
nication professor. But not all minor premises can be verified as easily. For example, it would
be difficult to prove the minor premise in this example:
All gods are immortal.
Zeus is a god.
Therefore, Zeus is immortal.
We can accept the major premise as true, because immortality is part of the definition of a
god. But proving that Zeus is a god would be very difficult.How To