Chapter 3: Speech Ethics

Using Sound Reasoning

Every public speaker has a responsibility to provide well-reasoned support for his or her points. Fallacious reasoning is faulty (and thus unsound) reasoning, in which the link between a claim and its supporting material is weak. Unfortunately, fallacious reasoning is all too common in speeches, even if it’s often unintentional. When public speakers intentionally misuse logic to deceive their audience, their actions are profoundly unethical. Four common ways in which a speaker might misuse logic include the following:

Hasty generalization: Making a claim about all members of a group from information based on a limited part of the group
Post hoc fallacy: Wrongly identifying the cause of one event as the event that immediately preceded it
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Ad hominem (personal attack) fallacy: Attempting to weaken someone’s argument by making unsubstantiated claims about her or his character
Ad populum (bandwagon) fallacy: Believing that an argument is true simply because other people believe it

We will discuss these and other logical fallacies in more depth in Chapter 18, Methods of Persuasion.