Persuasive Speaking

 “We may convince others by our arguments,

but we can only persuade them by their own”

– Joseph Jouber.

Contrary to common sense most people are not convinced by logic neither words. People are more easily persuaded by emotions and pictures. Credibility plays a crucial role in persuasion, some speaker have credibility even before their speech is delivered, others have to present their credentials. According to Stephen E. Lucas a speaker’s credibility is affected by two factors. First, competence: how the audience regards a speaker’s intelligence, expertise, and knowledge of the subject. The second factor is character: how and audience regards a speaker’s sincerity, trustworthiness, and concern for the well-being of the audience.  

One way to enhance credibility is to establish common ground with your audience, show how your audience’s ideas relate to your ideas and use vivid language and evidence to connect emotionally to your audience.

According to Wayne Brockriede good arguers can be seen as lovers. Lovers differ radically from rapist and seducers in their attitudes toward co-arguers. Whereas the rapist and seducer see a unilateral relationship toward the victim, the lover sees a bilateral relationship with a lover. The lover wants power parity.

People use facts to support their emotions   

Scientist at Emory University studied a group of committed Democrats and Republicans during the three months before the 2004 presidential election.

In each test, subjects were given a reasoning task in which they had to evaluate information that was threatening to their own candidate, while functional magnetic resonance imaging recorded what parts of their brain were active.

“We did not see any increased activation of the parts of the brain normally engaged during reasoning,” said: Drew Western, director of the clinical psychology at Emory and lead author of the study.

“What we saw instead was a network of emotion circuits lighting up, including circuits hypothesized to be involved in regulating emotions, and circuits known to be involved in resolving conflicts,” he added.


Fallacies are errors of reasoning. They also refer to arguments which fail to provide adequate evidence for their conclusions. You should always be aware of them when speaking or when acting as member of an audience. Here there is a  list provided by professor Marianne Neuwirth at Stanford University. 

Ad hominem: This fallacy is committed when, instead of proving or disproving the  conclusion of an argument, the person who presents the argument is attacked. There are two types: Abusive and Circumstantial.

Abusive occurs when an attack is made on the character of the person presenting the argument.

Anyone who believes in capital punishment is immoral.

Circumstantial results when it is argued that a person’s circumstances make it impossible for him or her to be sincere or to tell the truth.

His interpretation can’t be right; he never even went to college.

Ad populum: This fallacy is committed whenever anyone appeals to the opinions or passions of the multitude to establish a conclusion.

Abortion is wrong; the overwhelming majority of intelligent people agree. (A bit of ad hominem here, too)

Reductio ad absurdum: (Latin: “reduction to the absurd”) is a form of argument in which a proposition is disproven by following its implications to a logical but absurd consequence.  This fallacy makes a potentially sound argument appear groundless by extending it to a point where it can be ridiculed.

If we pass the ERA, women and men will be political equals. Next its unisex hair and clothes, then coed restrooms. Pretty soon we won’t be able to tell each other apart.

Post hoc: This fallacy is committed when it is argued that A is a cause of B simply because A occurs earlier than B. This fallacy is the source of many superstitions. Also = confusing sequence with cause.

Every time the rooster crows, the sun comes up.

Circular reasoning (tautology): This fallacy assumes as one of its premises the very conclusion it sets out to establish. At the lowest level of tautologies, it is silly (but much practiced) to say,

“It is so because it is so”; “Boys will be boys,” “A rose is a rose is a rose.”

“When people are out of work, unemployment results,” “Where you are is where the world is today.”

“You can observe a lot just by watching” “It ain’t over till it’s over.”

“…all we need is to define disorder as a certain kind of differentiation and to define order as the absence of disorder.”

“Can’t get a job until you have experience; can’t get experience until you get a job.”

Hasty Generalization: This fallacy is committed whenever anyone generalizes an entire class on the basis of examples that are either not representative of the class, or are too few in number to support the conclusion.

It has rained for the last three weekends, so it will probably rain this weekend.
The savings and loan scandal proves every politician can be bought.

Ad Ignorantiam:  This fallacy is an appeal to ignorance. An argument is true because it has not been proven false, or an argument is false because it has not been proven to be true.

The planet was colonized by visitors from space. There’s a lot of evidence that has never been contradicted.

False dichotomy:   This fallacy is committed when reasoning is based on an either/or statement when the two alternatives are not really mutually exclusive, or when other alternatives exist.

Would you rather go out to dinner or see a movie?
Would you rather have a football program or a band and orchestra at our school?

Slippery SlopeThis assumes that once something happens, it will establish an irreversible trend leading to disaster.  It assumes that a relatively small first step inevitably leads to a chain of related events culminating in some significant impact, much like an object given a small push over the edge of a slope sliding all the way to the bottom.

“You can never give anyone a break.  If you do, they’ll walk all over you.”

Red Herring: This occurs when persuaders try to draw attention away from the real issues, usually with sensational claims about the other side.

Myth of the Mean:  Misuse of statistics.

Straw Figure: This is based on misrepresentation of an opponent’s position, when you set up a weak argument, attribute it to the opposing side, then proceed to discredit it.  To “attack a straw figure” is to create the illusion of having refuted a proposition by substituting a superficially similar proposition (the “straw figure”), and refuting it, without ever having actually refuted the original position.

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