                      List of Common Fallacies  

HONORS ETHICS and VALUES   PHILOSOPHY 205h   Spring, 1991  
Utah Valley Community College   Taught by Mark S. Gustavson

I.  INFORMAL LOGIC. These are fallacies of relevance, where the premises are logically irrelevant to, and therefore incapable of
                    establishing the truth of, their conclusions.

There are many major categories of these fallacies. They are:

     1. ARGUMENTUM ad BACULUM (Appeal to Force). This fallacy is committed when one appeals to force or to the threat of force to cause acceptance of a conclusion.

     Example: When a lobbiest reminds a legislator that a particular bill should be adopted for the reasons that, either, the lobbiest
contributed a lot of money to the campaign or that the legislator represents a very large constituency.

     2. ARGUMENTUM ad HOMINEM (abusive). This fallacy occurs when someone seeks to prove or disprove a proposition by attacking the person who utters the argument.

     Example: A Utah Legislator's political views are unreliable because she pleaded nolo contendre to a charge of shoplifting.

     Example: That a proposition is disreputable because it was uttered by: a Communist, a member of the John Birch Society,
a Democrat, a Republican, and so forth.

     3. ARGUMENTUM ad HOMINEM (circumstantial). This fallacy is committed when one argues that the truth or falsehood of a particular proposition can be established by appealing to the circumstances of the opponent.

     Example: A member of the Republican party may not argue for a certain idea because it is not entailed by the tenets of that party.

     Example: If debating with a clergyperson, a certain religious belief must be true (where the clergyperson disagrees) because
that religious belief it is compatible with Scripture.

     4. ARGUMENTUM ad IGNORATUM (argument from ignorance).  When one argues that a particular idea is true (or false) for the reason that it has never been proven false (or true). The problem here is that one is not entitled to conclude that any idea is true or false on the grounds that no one has been able to prove the converse of our beliefs.

     Example: Santa Claus exists because no one has been able to prove that jolly, fat, older men, who cavort with reindeer at the North Pole, and commit charitable acts for children every 365-odd days, don't exist.

     Example: A Christian is not entitled to conclude that the Prophet Mohammed did not exist because there is no definitive historical record to prove that the Prophet ever existed.

     5. ARGUMENTUM ad MISERICORDIAM (appeal to pity). When pity is cited for the sake of reaching a desired conclusion, this fallacy has occurred. The problem here is that citing the awful circumstances of any person does not prove or disprove any particular claims concerning that person.

     Example: When a youth was tried for the ugly murder of his parents, he pleaded for leniency on the grounds that he was now an orphan!

     Example: When any person argues that he/she ought to benefit from some social charity because, otherwise, they would starve. (While true, the supposed result is no argument for the act of charity).

     6. ARGUMENTUM ad POPULUM. Someone commits this fallacy when they argue for the truth of a proposition because so many people agree with that idea. When the enthusiasm and excitement of the crowd is aroused, with the goal of achieving a particular end, then this fallacy is also committed.

     Example: One ought to buy a Mustang GT because they are so popular with stock car racers.

     Example: One ought to adopt a particular idea because it is "progressive" and not "antiquated".

     Example: You ought to buy a certain perfume because you will be sexually irresistible.

     7. ARGUMENTUM ad VERECUNDIAM (appeal to authority). The feelings of respect for famous or notorious persons, as grounds for doing or thinking a particular thing, constitutes this fallacy.

     Example: Since Albert Einstein was a very smart physicist, his views on politics are trustworthy.

     Example: A religious leader is fully capable of counseling a sexually-abused youngster for the reason that the clergyperson
knows his/her religion.

     8. ACCIDENT When a general rule is applied to a particular case whose "accidental" circumstances render the rule inapplicable. What is true in general may not be true in particular for the reason that circumstances often change particular cases.

     Example: Since it is true that you should always tell the truth, you should tell the Nazis that you are hiding Jews in your attic.

     9. CONVERSE ACCIDENT (hasty generalization). In writing a general rule from particular cases, you should be sure that those particular cases be general ones (having mutual elements of consistency) and not atypical. Therefore, when one comes up with a generalized rule based upon exceptional cases, this fallacy is committed.

     Example: Since opiates are helpful when treating terminal cancer patients, everyone should ingest narcotics.

     Example: Since highly skilled drivers can safely (but not legally) drive at speeds in excess of 90 mph, all drivers should be able to drive at that speed.

     10. FALSE CAUSE (two varieties: post hoc ergo prompter hoc, and pro causa/non causa).

     POST HOC ERGO PROMPTER HOC: this fallacy is committed when one mistakes what is not the cause of a given effect for its real cause.

     Example: From the fact that one observes two stones thrown flying through the air with similar trajectories and similar points of impact, it must follow that they were both thrown by a machine (or by a person).

     PRO CAUSA / NON CAUSA: this fallacy occurs when one infers that one event is caused by the other from the sole fact that the first occurs earlier than the second.

     Example: Joe Shmow slammed a door and an earthquake occurred within ten minutes. Therefore, door-slamming causes earthquakes.

     Example: If I pay my tithes and offerings, and I get a new job that pays more than my previous job, it must he true that being a charitable person leads to personal wealth.

     11. PETITIO PRINCIPII (begging the question). This is committed when the conclusion was previously stated in the premises.

     Example: Billy Graham is a better preacher than Robert Schuller because people with religious education prefer Graham.  When asked how one identifies those with religious education, the reply is that those persons prefer Graham to Schuller.

     12. COMPLEX QUESTION: This fallacy is committed when a single answer is sought to a question containing two or more elements. alternatively, the question can have a "suppressed" inference in it.

     Example: Have you stopped abusing your spouse? No matter which way you go with the answer, you are in trouble.

     Example: Where did you hide the evidence? This question contains the inference that you actually hid the evidence, the location of which is now at issue.

     Example: Are you for Republican economic prosperity or not?

     Example: Do you want to go to heaven? (as the donations plate is being passed around).

     13. IGNORATIO ELENCHI (irrelevant conclusion). This fallacy occurs when an argument purporting to establish a particular conclusion is directed to proving a different conclusion.

     Example: When a particular piece of abortion legislation is under consideration by the U.S. Congress, a legislator may speak in favor of it and argue that only the preservation of a woman's right to control her body is acceptable.

     Example: In a closing argument in a criminal trial, the prosecutor may speak against the defendant by arguing that murder is a particularly awful crime.


II.  FALLACIES OF AMBIGUITY.

     1. EQUIVOCATION. When a single word is used in two different ways in an argument this fallacy has occurred. You must be sure here that the term under consideration is a non-relative word. (Confusion of definition of a word in the argument.)  For instance:

     Example: The end of a thing is its perfection; death is the end of life therefore, death is the perfection of life. Relative word here is "perfection".

     Example: Some cats have fuzzy paws. My cat has fuzzy paws. Therefore, my cat is some cat! (kind of silly, but it proves the point). What is the relative word here? "Some"

     Example: An african elephant is an animal. Therefore, a small african elephant is a small animal. The relative word here is "small".  However, this is valid: an elephant is an animal. Therefore, a gray elephant is a gray animal. "Gray" is a non-relative word.

     2. AMPHIBOLE. This fallacy occurs in arguing from premises whose formulations are ambiguous because of their grammatical construction. An amphibolous statement occurs when it may be true on one interpretation and false on another, hence the premise to an argument is interpreted as being true, and the conclusion is drawn from an interpretation of the lanauage which makes it false, then this fallacy has heen committed.

     Example: "If you go to war, a mighty kingdom will be destroyed." When the person who received that prediction, the king of a large country, was defeated, the palm reader would respond: "I didn't tell you which country would be destroyed!!"

     Example: "Save soap and waste paper". No comment.

     Example: Should we conclude that a woman was dressed immodestly when the newspaper story said: "...loosely wrapped in a newspaper, she carried three dresses".

     Example: "He murdered forty-three people and then committed suicide after saying a tearful farewell to his wife with a machine gun."

     3. ACCENT. This fallacy occurs when an argument is deceptive because of a change or shift in its meaning. That change may alter depending upon the ways in which a particular element, or another, in the argument is emphasized.

Examples:

"No one should say nasty things about their family."

     But, now look how the meaning changes when only certain words are emphasized:

"No one should say nasty things about their family."  What is heing implied here?

"No one should say nasty things ahout their family."  What is being implied here?

"No one should say nasty things about their family."  What is being implied here?

     4. COMPOSITION. This is a title applied to two major kinds of arguments which impute to a group the properties of particular items.

A.  First sort is where someone argues that since every part of a new Chevrolet is composed of rare earth metals, then the entire Chevy is composed of Americum.

B.  Second sort of this fallacy is where someone argues that since an F-16 uses more jet fuel than a Lear Jet, therefore all F-16 jets use more fuel than all Lear Jets.

     This fallacy is also explained by the observation that although college students may enroll in no more than six classes each semester, it is also true that college students (as a group) enroll in hundreds of different classes each semester.

     5. DIVISION.  This is just the flip side of the fallacy of COMPOSITION, where what is presumed true of a group of items is argued to be true of individual examples of that group of items. There are two basic categories of this fallacy:

     A. Arguing fallaciously that what is true of a whole must also be true of its parts. Example: "Since a certain Church is very important and because Ms. Jones is a lay clergyperson in that Church, therefore Ms. Jones is very important."

     Another example: Because College Woman Z lives in a large dormitory, she must have a large room in which to keep her things.

     B. The second part of this fallacy occurs when someone argues that the properties of a collection of elements apply to the properties of those elements themselves.

     Example: "Since College students study ethics and law, therefore each (or even any) college students study ethics and law." The first part of the sentence speaks of only a possible subset of all subjects that all college students commonly study, but the conclusion presumes that all college students must have studied ethics and law.

Note:  Some portions of this outline were taken from INTRODUCTION TO LOGIC, by Irving M. Copi, MacMillan Press, New York.