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Logic and Argument

What is an Argument?

We've talked in depth about what constitutes an argument in What is an Academic Paper? Still, it's worth repeating the fundamental elements of argument here.

A good argument will have, at the very least:

If your paper has these essential features, then you've probably presented a sound argument. Of course, "probably" isn't good enough for the good writer and scholar. How can you be sure that your argument is sound?

Understanding Formal Logic

It's important to understand that an argument can be logical without necessarily being true. Consider, for example, the following:

Is this argument logical? Indeed, it is. The test for logic in this instance is not whether the statement is reasonable, but whether the argument follows the almost mathematical construction of the syllogism.

A syllogism, like the one above, is made up of three statements: the major premise, or general observation; the minor premise, or particular observation; and the conclusion, which is something that one might rightly deduce from the premises given.

Consider the following syllogism, and note how it differs from the one above:

What is the difference between the two syllogisms? It's very clear that in the first syllogism, the major premise is not true. Surely there are women in the world who are not brilliant. On the other hand, the major premise of the second syllogism we can accept as true. While there may in fact be people who have been exposed to this virus and lived, we have no record of them. On the other hand, every case of E-Boli that we've seen has resulted in death. Therefore, we can proceed confidently from our major premise to a conclusion that is sound.

Of course, in any syllogism all premises must be true (or considered true) if the argument is to stand. Consider the following syllogism:

In this case, it is the minor premise that is most open to challenge. Is abortion indeed murder? If the writer can convince his reader that it is, then the reader will accept his conclusion.

This way of arguing is called deduction. When one deduces, she moves from a general argument to a specific argument. The great detective Sherlock Holmes was famous for his deductive arguments. A crime might be solved, for example, along these lines:

Most detectives, however, use a different kind of reasoning when they try to solve a crime: inductive reasoning. When you reason inductively, you observe the specific(s) and move to the general. Detectives like Columbo and Kojak might gather their clues from specific observations. From these observations they then determine inductively who the murderer is.

It's important to note that many of the major premises used in syllogisms are often arrived at through inductive reasoning. For example, epidemiologists studying the E-Boli virus certainly had to observe the disease carefully before they could come to the general observation that E-Boli always kills. If we recall the early days of the AIDS virus, we will remember that researchers were initially stumped by the illness. Because so many cases in America involved gay men, researchers erroneously dubbed the disease, "Gay Cancer." When they began to gather more information about the disease, researchers were able to understand that the disease is a virus passed from one individual to another via bodily fluids. AIDS is not cancer. Nor is it a gay disease.

Reasoning inductively is perhaps more difficult than reasoning deductively, because it is easy to make a mistake in your observations. It is also possible that the evidence you have to work with isn't complete, making it difficult to draw persuasive conclusions.

Reviewing Your Argument's Evidence

So how do you create an argument with solid premises? You review your evidence, making sure that it is fair, objective, and complete.

Ask yourself the following questions about the evidence in your paper.

Avoiding Logical Fallacies

Logical fallacies are mistakes in reasoning. They may be intentional or unintentional, but in either case they undermine the strength of an argument. Some common fallacies are defined below.

  1. Hasty Generalization: A generalization based on too little evidence, or on evidence that is biased. Example: All men are testosterone-driven idiots. Or: After being in New York for a week, I can tell you: all New Yorkers are rude.
  2. Either/Or Fallacy: Only two possibilities are presented when in fact several exist. Example: America: love it or leave it. Or: Shut down all nuclear power plants, or watch your children and grandchildren die from radiation poisoning.
  3. Non Sequitur: The conclusion does not follow logically from the premise. Example: My teacher is pretty; I'll learn a lot from her. Or: George Bush was a war hero; he'll be willing to stand tough for America.
  4. Ad Hominem: Arguing against the man instead of against the issue. Example: We can't elect him mayor. He cheats on his wife! Or: He doesn't really believe in the First Amendment. He just wants to defend his right to see porno flicks.
  5. Red Herring: Distracting the audience by drawing attention to an irrelevant issue. Example: How can he be expected to manage the company? Look at how he manages his wife! Or: Why worry about nuclear war when we're all going to die anyway?
  6. Circular Reasoning: Asserting a point that has just been made. Sometimes called "begging the question." Example: She is ignorant because she was never educated. Or: We sin because we're sinners.
  7. False Analogy: Wrongly assuming that because two things are alike in some ways, they must be alike in all ways. Example: An old grandmother's advice to her granddaughter, who is contemplating living with her boyfriend: "Why should he buy the cow when he can get the milk for free?"
  8. Post Hoc, Ergo Propter Hoc: The mistake of assuming that, because event a is followed by event b, event a caused event b. Example: It rained today because I washed my car. Or: The stock market fell because the Japanese are considering implementing an import tax.
  9. Equivocation: Equates two meanings of the same word falsely. Example: The end of a thing is its perfection; hence, death is the perfection of life. (The argument is fallacious because there are two different definitions of the word "end" involved in the argument.)

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Written by Karen Gocsik
Last modified: Tuesday, 12-Jul-2005 11:27:37 EDT
Copyright © 2004 Dartmouth College
www.dartmouth.edu/~writing/materials/student/ac_paper/logic.shtml
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