Classic argumentation and Formal Logic

Classic argumentation and Formal Logic Part 1 – Discovery or Invention Inventio

Inventio (Discovery or Inventions) • Given a topic, the orator had to find arguments to support his point of view. Inventio is a system for finding those arguments, and the orator had to make some carefully prescribed choices: • Emotional appeal: an analysis and understanding of the common emotions • Ethical appeal: gaining the audience’s trust and admiration through high moral standards. • Rational appeal: an appeal to reason through induction or deduction

Pathos or Emotional Appeal • Writing that appeals only to the emotions of the audience is generally ineffective. • However, if one chooses language (figurative language or personal anecdotes) that engages the emotions of the audience, pathos can add an important addition. • Connotation versus denotation • Using words that have an emotional meaning that is strong to the reader references connotation. Denotation is the traditional dictionary definition of the word. • I would appeal to an audience by saying words like grand, honored, and blessing in a thank you speech instead of nice and thank you.

Ethos or Ethical Appeal (sometimes called Moral appeal) • Speakers who appeal to ethos demonstrate that they are credible or trustworthy. • If giving a speech about alcohol and children, for example, a speaker may be • A concerned parent • A psychologist specializing in alcoholism and adolescence behavior • Or recovering alcoholics themselves. • It is important to note here that the ethos appeal is not an argument concerning the ethics of the claim one is making. • For example, I am not arguing that alcoholism is morally or ethically wrong. • Instead it is the speakers expertise and knowledge, experience, training sincerity, or a combination of these that gives the audience a reason to listen.

Logos or Logical Appeal • Logos is an appeal to reason or logic. • It offers clear, rational ideas.(remember that your idea must be logical) • It must have a thesis or main idea, • Specific details • Examples, facts, statistical data, and/or expert testimony (as support) • Logos is often used to acknowledge a counterargument (anticipating objections or opposing viewpoints)

Logos – the Counterargument • While it may seem raising a counterargument will weaken your point, you’ll actually seem more vulnerable if you ignore others’ ideas. • You acknowledge you concede (agree) that an opposing argument may be true but… • You then refute (deny) the validity of all or part of the argument. • This concession and refutation strengthens your argument by appealing to logos, which shows you considered your subject carefully before making your argument.

Types of Logos • Logos uses two types logical appeal: • Induction • involves the compiling of evidence /reasons/examples that support an argument: the amassing of reasons. The more evidence, the better the argument, but often three good reasons or examples will do. • Deduction • involves premises—statements upon which all parties agree, which, when considered logically, lead to a strong conclusion. (Getting all parties to agree on the premises is often the cause of debate, however.)

Induction • When arguing inductively, you should ask these questions: • Are the examples sufficient in number? (Do you have enough of them?) • Are the examples truly representative of the issue? (Are they relevant?) • Do the examples come from a reliable authority or from logic?

Example of Induction • Nearly 80% of the ocean pollution comes from runoff. • Runoff pollution can make ocean water unsafe for fish and people. • Drinking water can be contaminated by runoff.More than one third of shellfish growing in waters in the United States are contaminated by runoff. • Each year, millions of dollars are spent to restore polluted areas. • There is a casual relationship because of agricultural runoff and waterborne organisms that damage fish.

Deduction • When arguing deductively, you should ask these questions: • Are the premises themselves valid or resulting from strong inductive evidence? • Does the conclusion follow logically?

Examples of Deduction • Major Premise: All good students get financial aid. • Minor Premise: Sara is a good student. • Conclusion: Therefore, Sarah should get financial aid.

Examples of Deduction • Major Premise: When a government oppresses people, the people have a right to abolish that government. • Minor Premise: The government of England is oppressing the American people. • Conclusion: Therefore, the American people have the right to abolish that government.

How it applies? • We will be discussing this further as the year progresses. Meanwhile, you should know some background on argumentation as a formal study that the ancient Romans called “rhetoric.”

Induction • As we’ve learned, inductioninvolves the compiling of evidence/reasons/examples that support an argument: the amassing of reasons. • If one is arguing inductively, she may say: • “Wow! My dog smells terrible! She was outside all night, and around midnight I smelled skunk at the back of the house. I heard her barking loudly, too. That’s definitely a skunky smell on her. She must have tangled with that skunk.” • This person has amassed sufficient, relevant, and reliable evidence to draw her conclusion.

Deduction • We also recall that deduction involves premises – statements upon which all parties agree, which when considered logically, lead to a strong conclusion. (Getting all parties to agree is often the cause of debate) • Syllogism • The formal statement of a deductive proof. • It contains a major premise, a minor premise, and a conclusion.

Syllogism • Major Premise: A generalization or all-encompassing statement. • Minor Premise: A statement of a specific instance of the generalization. • Conclusion A statement of conclusion which follows the premises.

Syllogism • The classic example is • All human beings are mortal. • Socrates is a human being. • ∴Socrates is mortal. • ∴ means therefore.

Syllogism • Syllogisms are seldom found in their pure form but instead appear in the form of enthymemes.

Enthymeme • An enthymeme is a syllogism with one or two parts of its argument – usually the major premise – missing. • In everyday life, we often leave out part of the arguments – most of the time because we think they are so obvious (or clearly implied) that they don’t need to be stated. • Many enthymemes are presented as a conclusion plus a reason.

Enthymeme • The enthymeme can be understood as an abbreviated syllogism because • It resembles the syllogism in that it employs logic. • It has as its starting pont an assumption, statement, or proposition that the writer/speaker presumes the audience accepts. • We recognize that part of the argument goes unstated.

Enthymeme • One way of explaining the strategy of the enthymeme is this: • “Statements may be strategically excluded in an enthymeme because they are too obvious or because revealing them might damage the force of the argument. Yet another reason to exclude a premise or conclusion is to let the audience infer it. The idea here is hat audiences who have to draw out premises or conclusions for themselves are more likely to be persuaded by the overall argument.:” – americanrhetoric.com

Enthymeme • Enthymeme : Robert has lied, so he cannot be trusted. • In the statement above, the minor premise and conclusion are stated, but the major premise is only implied. • Major Premise: People who lie cannot be trusted. • Minor Premise: Robert has lied. • Conclusion: Therefore, Robert cannot be trusted.

Enthymeme • Enthymeme : Robert cannot be trusted. • In the statement above, the major premise and minor premise are implied, and only the conclusion is stated.. • Major Premise: People who lie cannot be trusted. • Minor Premise: Robert has lied. • Conclusion: Therefore, Robert cannot be trusted.

Enthymeme • It is important to identify enthymemes in arguments you read because some writers, knowing that readers often accept enthymemes uncritically, use them intentionally to unfairly influence readers. • Enthymeme: Because Liz receives a tuition grant, she should work. • Major Premise: All students who receive a tuition grant should work. • Minor Premise: Liz received a tuition grant. • Conclusion: Therefore, Liz should work. • How is this enthymeme oversimplifying the issue?

Enthymeme • Bumper Sticker Thinking • Self-Control beats birth control. • Peace is patriotic. • A woman’s place is in the White House. • Ban cruel traps. • It’s never too late to have a happy childhood. • No one needs a mink coat except a mink. • Celebrate diversity.

Enthymeme vs. Syllogism • A fully stated syllogism where both premises are accepted as universally true, leads us to necessary conclusion based on its proven validity. • But • An enthymeme, where the implied premise can be stated either of two was, leads us to a tentative conclusion based only on probable premises, which therefore may be arguable.

Classic argumentation and Formal Logic