• Students should be familiar with    Additional Fallacies  not in our text
• Students should be familiar with the term fallacy, and understand the distinction between a deductive argument and an inductive argument   

What is a fallacy?
Fallacies are defects in an argument - other than false premises - which cause an argument to be invalid, unsound or weak. Many were identified be Renaissance and Medieval logicians, and their Latin names still survive. 

They usually reflect an appeal based on emotion rather than reason and divert attention away from real issues.

What are the two general groups of fallacies?

A formal fallacy is a defect  in logic. It is an error in the formal structure. It involves  invalid deductive rules. It can be identified by looking at the illogical structure of an argument,  rather than any specific statements.

An informal   fallacy has defects which can be identified only through an analysis of the actual content of the argument rather than through its structure. It is a mixed bag of unreliable strategies, such as vague language, ambiguities, irrelevancies. Fallacies have often misled the unwary and gullible.  See below:   

Syllogism:____________________________________________________
 A syllogism is the classical style of a deductive argument.  It is a formal logical argument of three sentences. Its conclusions follow necessarily from its premise
1. All men are mortal
2. Socrates is a man
3. Therefore, Socrates is mortal

Playing my instrument makes me happy
I am playing my instrument.
Conclusion.  I am happy.

An inductive argument infers a  general statement from a class of specific  instances. The premises are intended to support the conclusion. Technically it cannot lead to 100% certainty but just probability.
1. Socrates was Greek. (premise)
2. Most Greeks eat fish. (premise)
3. Socrates probably ate fish. (conclusion) http://atheism.about.com/library/glossary/general/bldef_inductive.

Yesterday I was happy when I was playing my instrument
Last week I was happy when I was playing my instrument.
Conclusion: Playing my instrument makes me happy

Ad Hominem Argument:___________________________________

• Latin Root: "Directed to or against the person"
• Definition: An attack on the opponent's character rather than on the opponent's argument
• Commentary: 
  • Very persuasive because people are concerned with ethical character
  • Often used in politics
  • The point is to have someone's opinion disregarded because of his character
  • We are asked the believe the opposing viewpoint of the person being attacked
  • The flaw is that personality bears no direct relationship to truth.
  • Rather than listening to or rationally debating an idea, one listens to a personal attack on another (slander).
• Example:  discounting
  • a furrier's views of animal rights
  • a divorcee's qualifications as a marriage counselor
  • a carouser's or alcoholic's view on any topic
  • a drug user's views on the legalization of marijuana for medicinal purposes

Appeal to Ignorance  _____________________________________

• Latin:  "argumentum ad ignorantiam"
• Definition: Drawing a specific conclusion from a lack of information and knowledge.
• comment: the absence of evidence is not proof in and of itself. It could still be so.
• Examples:
  • UFOs must be real, because skeptics have never been able to prove that they don't exist; therefore UFOs are real
  • No one has conclusively proven that there is no plant life on Pluto; therefore there is plant life on the Pluto
  • Global warming is (not) a threat because no one has proved that it is (not) a threat.

Begging the Question_____________________________________

• Definition:  The truth is presented as what is supposed to be proven in the argument.
  "Assuming as a premise what you want to prove"
• Comment: One begs the question, like a beggar, to get something for nothing from the reader. The writer  simply asserts  a premise as a fact  while giving no evidence for what must first be proven & argued i.e. that pornography is dangerous.
• Examples:
  • Dangerous pornography should be banned
  • Unfair laws  (like bill 69) should be  banned
  • Useless laws (life bill 13) should be banned
  • Affirmative Action opponents are racist for if they weren't, they wouldn't oppose it.

Equivocation___________________________________________

• Latin root:   equi (equal) and vox (voice). When a term is used univocally in an argument, it always has the same meaning. But, when it is use equivocally, more than one meaning is given equal voice.
• Definition: Implicit reliance on two different meanings of the same word to reach a conclusion;  a term being used with two or more meanings.

   

  • Example:  The Preamble to the Constitution: "all men are created equal" this does not include women.
  • Tommy is a turkey (meaning not too bright).  Turkeys gobble. therefore, Tommy eats fast (another meaning of gobble).  the conclusion does not follow.

Faulty Analogy____________________________________________

• Definition: Analogy refers to finding a likeness or similarity between two otherwise dissimilar objects or concepts.  this is fine in and of itself.  A faulty analogy, takes the analogy too far: weak similarities are used to infer other, stronger similarities which are simply not justified. 
• Comment: A faulty analogy would say if 2 things are alike in one sense, they MUST be alike in the sense I am arguing. Wyrich reminds us that compelling analogies may suggest similarities, but they cannot prove anything, like sex education is analogous to taking an alcoholic to a bar.
• Example: our text states both tigers &  hard-core pornography are similar in that they are harmful.  The faulty analogy would occur when we conclude that both should be banned from private homes.
• Example from advertising: Coke is like family. You can never have enough.   always coca cola.  Coke and family  are not similar enough to draw these conclusions
• If physicians can look in a text, why can't medical students who are taking a test do the same?

Hand Waving____________________________________________

• Definition: Claiming that something is true because everyone knows so.  
• Example from text  We don't need evidence to prove capital punishment is a better deterrent to crime than life imprisonment because everyone knows so; it's just common sense.
• Further Example:  Everyone knows women has a natural instinct for taking care of children and are better day care providers.

Hasty Generalization______________________________________

• Definition:  Reaching a general conclusion from too small a sample
• Example:  Surveying athletes & determining they are held to higher academic standards and that "college students want the bulk of general fund monies spent on an athletic complex."

Post Hoc Ergo Propter Hoc_________________________________

• Latin: "after this, therefore because of this"
• Definition: Mistaking a temporal connection for a causal relationship.  Confusing correlation with sausation.  In plain English, assuming that because one event follows another in time, that the first event caused the second event.
• Examples:
  • Walking under a ladder causes bad luck
  • Politicians take credit for whatever good thing occurs after they take credit (as they caused it

Questionable Authority    (argumentum ad verecundiam)__________________

• Definition: Supporting a conclusion by depending on the judgment of someone who is no a reliable authority on the subject
• Comment:  Questionable authority involves a mistaken supposition that there is a connection between  the authority and the truth of the proposition. Having fame or expertise in one area guarantees the truth. Even expertise in one area doesn't guarantee the truth.
• Examples:
  • Athletes endorsing cereals
  • Cheryl Tiegs endorsing cameras
  • Heyward (NFL Running Back) zest soap
  • The Vice President said tarantulas are insects; therefore tarantulas are insects.

Red Herring____________________________________________

• Definition:  an irrelevant issue introduced to distract attention from the issue at hand
• Comment:  the term originates from escaping prisoners  who dragged a smoked herring (strong smelling)  across their trail to confuse tracking dogs.
• Example:
  • Blaming someone for never taking turns to take out the garbage & diverting the issue by saying, "I've been helping you with school work."

Slippery Slope___________________________________________

• Definition: One action will lead to an unwanted action
• Example from text: Having sex with an individual will lead one to be a streetwalker

Straw Man______________________________________________

• Definition: Arguing against a position which the other person does not actually hold. Distorting and refuting  the opponent's actual position and claiming victory as if the real position were also refuted.
• Example from text: Arguing a regulation is too expensive with a come back that the opponent want to poison the children. Arguing for better support of endangered species  with the come back that owls are more important than people.
• Example:  A famous example occurred in 1952 When Nixon was accused of misappropriating his campaign funds when his 6-year old daughter received a dog named Checkers from a Texas supporter. Nixon spoke at length about this rather than addressing $18,000 in missing campaign funds.

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Great Links:

Logical Fallacies: Sources and Resources - ... By Leo Groarke, from the Stanford Encyclopedia of Philosophy . ... of the place of fallacies in informal ... An interesting example of the Ad Hominem Fallacy, together ...  http://gncurtis.home.texas.net/resource.

• Max Shulman, "Love is a Fallacy"
  
• An interesting example of the Ad Hominem Fallacy, together with an explanation of how different theories explain what is wrong with it.
• A fascinating example of fallacious visual argument in an advertisement.
• Fallacies of Relevance

http://www.aros.net/~wenglund/Logic101a.htm  index of fallacies

http://www.vuse.vanderbilt.edu/~jgray/funny.html

http://www.vuse.vanderbilt.edu/~jgray/funny.html

 http://atheism.about.com/library/glossary/indexes/blglossary_logic.htm

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Informal Fallacies

Assessing the legitimacy of arguments embedded in ordinary language is rather like diagnosing whether a living human being has any broken bones. Only the internal structure matters, but it is difficult to see through the layers of flesh that cover it. Soon we'll begin to develop methods, like the tools of radiology, that enable us to see the skeletal form of an argument beneath the language that expresses it. But compound fractures are usually evident to the most casual observer, and some logical defects are equally apparent.

The informal fallacies considered here are patterns of reasoning that are obviously incorrect. The fallacies of relevance, for example, clearly fail to provide adequate reason for believing the truth of their conclusions. Although they are often used in attempts to persuade people by non-logical means, only the unwary, the predisposed, and the gullible are apt to be fooled by their illegitimate appeals. Many of them were identified by medieval and renaissance logicians, whose Latin names for them have passed into common use. It's worthwhile to consider the structure, offer an example, and point out the invalidity of each of them in turn.

Link:
 Said OK fallacy