Logical Argumentation: Avoiding Logical Fallacies


Emotionally Loaded Terms, or Argument to the People (Appeal to Stirring Symbols)--using emotionally charged words; words with positive connotations (e.g., "family values") are intended to sway readers to the author's point of view; words with negative connotations (e.g., "paying the price") try to sway readers away from an opposing point of view. This is similar to Equivocation: an assertion that falsely relies on the use of a term in two different senses: Faulty--We know this is a natural law because it feels natural. [In the first use, natural means "derived from nature or reason"; when used again, it means "easy or simple because of being in accord with one's own nature."]

Appeal to Tradition--Possibly the most common way to shift an issue is to appeal to the cultural conditioning of a group—the traditions, the customs, the common heritage. That is, something should be done a certain way simply because it has been done that way in the past: Faulty--We should not forbid fraternity hazings because they continue to be a memorable part of the pledge process. [Times change; what was considered good practice in the past is not necessarily considered acceptable now.]

Ad Hominem Argument (Attacking the Character of the Arguer Rather than the Argument Itself)--the writer rejects opposing views by attacking the person who holds them. A common form of ad hominem attack is guilt by association. In this ploy, a speaker or writer tries to associate someone with an idea or with another person that the audience finds distasteful. You should judge an opponent's position on its own strength and not resort to smear tactics.

Faulty Cause and Effect (post hoc, ergo propter hoc ["after this, therefore because of this"]) (Assuming that Event X Causes Event Y Because Event X Preceded Event Y)--the fact that one event precedes another in time does not mean that the first event has caused the second. The origins of an event are usually complex and are not always traceable to a single cause. So you must carefully examine cause-and-effect reasoning when you find a writer using it. Sometimes post hoc reasoning neglects a common cause and assumes a cause and effect relationship between two events that actually have another cause. The way to avoid this kind of logical fallacy is to learn as much as possible, given the time allowed, about the subject under discussion.

Either/Or Reasoning, or False Dilemma (Oversimplifying a Complex Issue So That Only Two Choices Appear Possible)—if in analyzing a problem an author artificially restricts the range of possible solutions by offering only two courses of action, and then rejects the one that he opposes, he cannot logically argue that the remaining course of action, which he favors, is therefore the only one that makes sense. Usually, several other options (at least) are possible. Faulty--We must either build more nuclear power plants or be completely dependent on foreign oil. [Other possibilities exist.]; “America—Love It or Leave It," implying that to live in this country requires unqualified approval of everything that takes place here. Writers can also fall into this trap, oversimplifying an issue to include only two possible choices. For example, universities must either have open-admissions policies or enroll only the children of the rich.

Hasty Generalization (Making a Broad Generalization on the Basis of Too Little Evidence) --drawing conclusions from too little evidence or from unrepresentative evidence.

     1. Pars pro toto/Mistaking the part for the whole (assuming that what is true for a part will be true for the whole).

     2. Supposed Evidence (withholding contradictory or unsupportive evidence so that only favorable evidence is presented to an audience).

     Faulty--Ellen is a poor student because she failed her first history test. [Her performance may improve in the weeks ahead or be good in all her other subjects.]

False Analogy (Claiming that Because X Resembles Y in One Regard, X Will Resemble Y in All Regards)—this error occurs in comparisons when the differences between the two things are more significant than their similarities, and conclusions drawn from one may not necessarily apply to the other. False analogy is the assumption that because two things are alike in some ways, they must be alike in others: Faulty--The United States lost credibility with other nations during the war in Viet Nam, so we should not get involved in the Middle East, or we will lose credibility again. [The difference between the war in Southeast Asia in the 1960s and 1970s and the current conflict in the Middle East may well be greater than their similarities.]

Begging the Question (Supporting a Claim with a Reason That Is Really a Restatement of the Claim in Different Words)--assuming as proven fact the very claim being argued. Since the fallacy is merely repeating the claim in different words, it is also known as circular reasoning. Faulty--We need to fire corrupt officials in order to reduce the city's crime rate. [If there are corrupt officials in city government, this point needs to be established.]

Bandwagon, or Appeal to Popularity--"Everyone's doing or saying or thinking this, so you should too": Faulty--Everyone drives over the speed limit, so why shouldn't we raise the limit? [The majority is not always right.] Alert readers will reject evidence that shifts, support from legitimate proof to the numbers of proponents.

Non Sequitur ("it does not follow"): Making a Claim That Doesn't Follow Logically from the Premises, or Supporting a Claim with Irrelevant Premises. Thus, in sense, any fallacy could be called a non sequitur. Usually, however the term refers to a fallacy in an argument based on deduction--an argument in which a person deduces a conclusion from accepted premises.

          a. A completely illogical leap

          b. A clear gap in the chain of reasoning

          c. Use of irrelevant reasons to support a claim

     Faulty--Eddie is smart; therefore, he'll do well in college. [This assertion is based on the faulty assumption that all smart people do well in college.]

Oversimplification, or Strawperson (Greatly Oversimplifying an Opponent's Argument to Make it Easier to Refute or Ridicule, or, worse, deliberately altering the opposing view to make it easier to attack [Straw Man Position])--offering easy solutions to complicated problems. Oversimplification is a statement or argument that leaves out relevant considerations in order to imply that a complex problem has a single cause or solution: Faulty--We can eliminate unwanted pregnancies by teaching birth control and abstinence. [Teaching people about birth control and abstinence does not guarantee the elimination of unwanted pregnancies.] People frequently oversimplify cause when they do not fully understand an issue.

Red Herring (Shifting the Audience's Attention from a Crucial Issue to an Irrelevant One)--sometimes called ignoring the question, means dodging the real issue by drawing attention an irrelevant one: Faulty--Why worry about violence in schools when we ought to worrying about international terrorism? [International terrorism has little if any direct relationship with school violence.] The name comes from an old hunting term that refers to dragging a herring across a trail to divert the hounds from their prey.

Slippery Slope Slippery slope is the assumption that if one thing is allowed, it will be the first step in a downward spiral: Faulty--Handgun control will lead to a police state. [Handgun control has not led to a police state in England.]

False authority is the assumption that an expert in one field can be credible in another: Faulty--We must stop sending military troops into Afghanistan, as Bruce Springsteen has argued. [Springsteen's expertise in music does not automatically qualify him as an expert in foreign policy.] Irrelevant Testimonial—just as advertisers frequently cite the testimony of a celebrity to support a claim, writers sometimes try to support an argument with quotations from inappropriate people—citing a popular novelist on a point of law, for example. You should reject this evidence and avoid this practice. Use only relevant testimonials: the knowledge and opinions of experts in the field in question.