Chapter summary image

The natural human practice of reasoning with a friend or colleague to seek the truth reveals how in argument making and reason giving, four important presumptions support the expectations and responsibilities that make that practice work in real life. The reasons we give should be true. The arguments we use should be logical. The reason given should be the relevant basis for accepting the truth of the claim. And the claim should not be used to lend support or credence to the reason. These four conditions ground the application of four straightforward tests to determine whether an argument is worthy of being accepted. The four are the Test of Truthfulness, Test of Logical Strength, Test of Relevance, and Test of Non-Circularity. The tests, which are to be applied in a particular order, must all be passed if an argument is to be worthy of acceptance as a demonstration that its conclusion is true or is very probably true.

To help with the application of the Test of Relevance, we examined seven common fallacies of relevance. Arguments that manifest these fallacious approaches to presenting reasons and claims often beguile and mislead us. In the next chapter we will explore in greater detail the application of the Test of Logical Strength with special attention to deductive reasoning and inductive reasoning. There we will expand the discussion of fallacies as well, for there are some that masquerade as valid deductive arguments and others that masquerade as strong inductive arguments.


good argument (or worthy argument)

is an argument that merits being accepted as a proof that its conclusion is true or very probably true.

sound argument

is an argument with true premises that also passes the Test of Logical Strength.


are deceptive arguments that appear logical, but upon closer analysis, fail to demonstrate their conclusions.



What if we discovered that we could manipulate the voting public more effectively by the use of fallacious arguments than by the use of worthy arguments? Consider the political impact of the 'death panels' issue described under the Straw Man Fallacy on pages 104-105. The entire episode generated more heat than light. And, yet, it may have achieved its political purpose. Many who heard and believed that the proposed legislation envisioned a eugenics program akin to that advanced by Nazi Germany, showed up at town meetings to vent their anger and voice their objections. If the goal was to delay or derail the Democratic legislative agenda, then the strategy succeeded. This is only one example of using one's skills at argument making to achieve one's goals. Defense attorneys who get juries to acquit criminals is another, as are prosecuting attorneys who get juries to convict innocent people accused of crimes. The ethical question for all critical thinkers is: To what purposes ought I to put my powerful critical thinking skills? This question is analogous to the question: to what purposes ought I to put my college education? These are in part ethical questions and in part questions about one's sense of how to make the meaning of one's life. And what are your answers? Why?


Each member of the group, having seen the 60 Minutes video and worked on the exercise on page 104, will have thoroughly considered the issue of homicidal DUI as murder. But for this project, you must first set aside your own individual opinions on this matter. This project involves interviewing people for whom this issue is much more than a textbook's abstraction. So you and the other members of your group need to focus on what you hear in the interviews without letting your personal opinions get in the way.

Your group will conduct four sets of interviews. You must always have at least two members of your group participate in each interview. This is so that you can help each other remember what the person being interviewed said.

First set of interviews: Locate at least one person--two or three if possible--who has been arrested for DUI, even if not for homicide while under the influence of alcohol or drugs. Find out what that person or those people think. Listen to their arguments, and then write them down and evaluate those arguments. Be objective and fair-minded in your evaluation, regardless of whether you agree or disagree with the person's position.

Second set of interviews: Locate at least one person who is a former drinker but who no longer drinks. Perhaps you can find someone who will talk with you by contacting AA. Interview that person the same way. Get his or her views on the matter; write down the person's arguments, and evaluate those arguments objectively and fair-mindedly.

Next, contact MADD or some other volunteer organization that is known for its stance on issues relating to drunk driving. Follow the same drill. Get that organization's arguments down and evaluate them.

Finally, contact the office of your local prosecuting attorney, or the state police and, again, conduct your interview and evaluate the arguments you hear.

Having talked directly with people who are close to this issue, your group must now assemble all the arguments that came forward in the various interviews. In light of these perspectives, take a stance individually and as a group on whether or not homicide by DUI should be prosecuted as murder. Write out the group's opinion and give the reasons.

Annotated Links

Thinking Critically: The Name of the Rose

In The Name of the Rose, a classic mystery story about the murder of a monk in a fourteenth-century monastery, the detective is played by Sean Connery. His character is a Franciscan scholar who visits the monastery and early in the film is told by the abbot that the brothers living in the monastery believe that perhaps the monk was killed by the devil. Watch this scene, which is 9 minutes and 15 seconds into the film. The abbot's argument that the devil did it begins with 'We found the body after a hailstorm,' and it is only a few lines.

Transcribe the abbot's argument so that you can have the language in front of you. Evaluate it for logical strength. Can you think of how the monk might have died other than at the hand of the devil, given the information you have at that point in the story? Is there a set of circumstances such that all the premises of the abbot's argument could remain true but the claim still be false? How plausible or implausible are those circumstances?

As you watch the film, key information is presented visually rather than in dialogue. For example, the director gives us a shot looking up a steep ravine at the abbey. The building wraps around the crest of the hills above the ravine. There appear to be two towers. This information enables the viewer and the detective to spot the logical flaw in the abbot's argument. 'No devil needed,' says Connery. He explains his reasoning to his young apprentice, played by Christian Slater. Go 6 minutes and 29 seconds further into the movie and view this short scene. Transcribe Connery's alternative explanation. Map it, and after reading the chapter, evaluate it for logical strength.

Thinking Critically: The Practice--Wrongful Termination

In an episode of The Practice called 'The Battlefield' that aired October 15, 1998, the owner of a small dry-cleaning business is being sued by his former employee. The former employee, a smart and competent Iranian woman, alleges that her former employer fired her in violation of anti-discrimination laws. Her lawyer claims that she was fired because of her national origin. This is called a wrongful termination civil suit, and, if she wins, she would be entitled to financial compensation for lost income and additional payments for punitive damages. Her former employer would have to pay if he loses. But he might win because his defense attorney's strategy is to argue to the jury that they would have made the same decision, were they in her former employer's shoes. Watch the episode and transcribe the arguments presented by the defense attorney. Identify fallacies of relevance as may be included in that attorney's arguments. The jury's decision in this case is unexpected, as is the judge's final response. This episode of The Practice asks us to think about whether our fears should be permitted to override our rights.

Thinking Critically: Should DUI Homicide be Prosecuted as Murder? (60 Minutes)

A prosecuting attorney in New York is bringing charges of murder against individuals who have killed other people while driving under the influence. The attorney argues that everyone understands that driving while under the influence poses risks for the driver and for other people, including the risk of a fatal accident. The statutes provide for charges of 'depraved indifference' when one's behavior results in the unintended but foreseeable death of another human being. Defense attorneys argue, among other things, that the laws pertaining to murder were never intended to be applied in this way. The debate was captured by CBS's 60 Minutes in a segment that aired on August 2, 2009. Review that segment and map out the reasoning for both sides of this debate. Evaluate the reasoning using the four tests for evaluating arguments. After completing your evaluation, present your own reasoned views on the matter.