PHI 111 Chap 3
What is the term designating a valid argument with true premises? A strong argument with true premises?
"A valid argument with true premises" is a sound (deductive) argument (74). "A strong argument with true premises" is a cogent (inductive) argument (73).
What kind of premises must a moral argument have?
A moral argument must have at least one moral premise and one nonmoral premise. "A nonmoral premise is also necessary in a moral argument. . . . The conclusion of a typical moral argument is a moral judgment, or claim, about a particular kind of action. The moral premise is a general moral principle, or standard, concerning a wider category of actions. Be we cannot infer a statement (conclusion) about a particular kind of action from a moral statement (premise) about a broad category of actions unless we have a nonmoral premise to link the two. . . . The role of the nonmoral premise, then, is to affirm that the general moral principle does indeed apply to the particular case" (61).
What is the best method for evaluating moral premises?
The counterexample method (63).
Explain the method for locating implied premises.
"The easiest way to identify implied premises in a moral argument is to treat it as deductive. Approaching moral arguments this way helps you not only find implied premises but also assess the worth of all the premises" (61). If we discover that the argument "needs a premise that can bridge the gap between the current premise and the conclusion . . . we should ask, 'What premise can we add that will be plausible and fitting and make the argument valid?' . . . trying to make [the argument] valid . . . help[s] us find at least one premise that might work. Moreover, if we know that the argument is valid, we can focus our inquiry on the truth of the premises. . . . If there is something wrong with a valid argument (that is, if the argument is not sound), we know that the trouble is in the premises—specifically, that at least one premise must be false. Consider the pro-gun slogan: "Guns don't kill people. People kill people." This is presented as an argument to show why gun control laws are unnecessary. But as we try form a deductive syllogism from it, we quickly see that there are a number of missing parts, not just premises but even the conclusion: "Therefore, gun control laws are unnecessary." The slogan consists of two Minor Premises: specific facts about guns and people. To evaluate the argument, we need to provide or create the Major Premise and a Conclusion. This is how the syllogism might look: Major Premise: Since inanimate objects like guns can't harm anyone unless a person uses them, we should have no laws restricting how people use inanimate objects. Minor Premise: Guns are inanimate objects. Conclusion: Therefore, we should have no laws restricting how people use guns. This argument quickly falls apart using the counterexample method. We have many laws restricting how people can use inanimate objects: cars, asbestos, uranium, buildings, septic systems, alcohol, cigarettes, hypodermic needles, etc. And most of us would agree that those laws are necessary. There may be sound and cogent arguments opposing gun control laws, but this slogan isn't one of them.
Is the following argument form valid or invalid?
If p, then q. If p, then r. Therefore, if p, then r. Yes, this argument form is valid. It is called a "hypothetical syllogism" (55).
Is the following argument form valid or invalid?
If p, then q. p. Therefore, q. Yes, this argument is valid. "it has a name, modus ponens, or 'affirming the antecedent.'" The first premise is conditional . . . and the second premise affirms the antecedent of that conditional. . . . This form is always valid: if the premises are true, the conclusion has to be true" (54).
Are all persuasive arguments valid? Recount a situation in which you tried to persuade someone of a view by using an argument.
No, not all persuasive arguments are valid. "To persuade someone of something is to influence her opinion by any number of means, including emotional appeals, linguistic or rhetorical tricks, deception, threats, propaganda, and more. Reasoned argument does not necessarily play any part at all in persuasion" (50). I recently tried to convince my cousin that she should wear a mask in public to help prevent the spread of COVID-19. She said that she didn't care if she contracted the disease, that we all had to die of something. I argued that the reason we wear masks is not to protect ourselves but to protect others. We should wear masks for the same reason that we drive slowly in school zones, to keep others safe. An argument is any two statements in which one statement supports (tries to convince the listener or reader to accept or believe) the other statement. The statements do not need to be complete sentences; in English, one sentence can make two or more "statements." "We should go to the park because the weather is nice" is an argument. Statement 1: "we should go to the park." Statement 2: "because the weather is nice." Statement 2 supports Statement 1.
What is the counter example method?
The counterexample method is a way to evaluate moral premises. "If we want to test a moral premise (a variety of universal generalization), we can look for counterexamples" (63). If counterexamples exist "in which the principle seems false" (63) then the premise is false or "at least dubious" (63). This method quickly pokes holes in most absolutist principles. If someone (like Kant) says that it's "always wrong to tell a lie," all we need to do is find one example where telling a lie is the right thing to do (like when my wife asks, "do these pants make me look fat?") to prove the statement false. And if the Premise is false, then the argument is invalidated and can be dismissed. Most arguments that have "always" or "never" as part of the Major Premise are vulnerable to the counterexample method because we just have to fine one exception to prove the argument false. Consider these examples: We must never prohibit free speech. Abortion is always wrong. The right to bear arms must never be infringed. In each case it is fairly easy to find a counterexample. By removing or hedging the absolutist terms, we can make the arguments stronger: We should rarely prohibit free speech. Abortion is almost always unnecessary. The right to bear arms should rarely be infringed.
Can a valid deductive argument ever have false premises?
Yes, it can. "The validity or invalidity of an argument is a matter of its form, not its content. The structure of a deductive argument renders it either valid or invalid, and validity is a separate matter from the truth of the argument's statements. Its statements (premises and conclusion) may be either true or false, but that has nothing to do with validity" (52). Before we can even begin to evaluate whether or not an argument is a "good" argument it has to at least have the correct form. For instance, if someone showed you a shoe and asked, "what do you think of this house," you'd dismiss them instantly. It wouldn't matter how good the quality of the construction of the shoe was, how nice the materials were, or how perfectly it fit on your foot: a shoe is not a house. It has the wrong form. However, having the correct form does not necessarily make a good house (or a sound argument). A Fisher-Price doll house has the form of a house, but you can't live in it. Consider this argument: Major Premise: If eating ice cream makes us smarter, we should eat more ice cream. Minor Premise: Eating ice cream makes us smarter. Conclusion: Therefore, we should eat more ice cream. This argument is "valid"; it has the correct form. However, the Minor Premise is false, and even the Major Premise is questionable (it's possible that even if eating ice cream made us smarter, it might have so many negative side effects that it still wouldn't be worth it). Like the toy house, the argument has the correct form, but it is not a "sound" argument.
Are the premises of a cogent argument always true? Is the conclusion always true?
Yes, they are always true. By definition, a "cogent argument [is] a strong argument with true premises" (73). No, the conclusion is not necessarily true. A cogent argument is an inductive argument, and inductive arguments are "intended to provide probable, not decisive, support to the conclusion. That is, the argument is intended to show only that, at best, the conclusion is probably true. With any inductive argument, it is possible for the premises to be true and the conclusion false" (52). Unfortunately, most arguments about complex issues are inductive in nature. The conclusions are probably true, but they are not certain. Consider an inductive argument like going to the doctor. If you go to the doctor because you have a fever, cough, sinus congestion, and bodily aches and pains, the doctor's diagnosis will be an inductive argument: Major Premise: If a patient comes into the clinic with a fever, cough, sinus congestion, and bodily aches and pains, they probably have the flu because I've seen a thousand patients in the last week with these symptoms, and they all had the flu. Minor Premise: This patient has these symptoms. Conclusion: This patient probably has the flu. This argument is "strong" and "cogent"; however, it could be wrong. You could have Mononucleosis, or Lyme Disease, or any number of other conditions with similar symptoms (according to WebMD, you are almost certainly dying of brain cancer).
