Introductory Logic



by William J. Kilgore

Summary by Luke Setzer

This page is posted by me, Luke Setzer, as a courtesy to those who have an interest in applying logic for mental self-defense and long-term prosperity and happiness.

In his book An Introductory Logic, William J. Kilgore details the most common informal fallacies of logic used in everyday speech, along with examples of those fallacies. This web page tabulates those fallacies and examples for easy application in everyday life. Master thinker Ayn Rand has stated that logic can be simply defined as "the art of making non-contradictory identifications of objective reality." Human beings require an accurate mental map of reality in order to live and prosper happily. When an error is made in an argument and the conclusion is widely accepted, only long-term harm to human beings can result.

Why would people use these fallacious maneuvers when the results can be so harmful? Generally, only two reasons exist:

1. The person has made a honest error in logic
2. The person has deliberately sidestepped logic in order to satisfy his or her own ego

The first reason can generally be handled with little fanfare. Simply point out the error in thinking, and guide the person to the correct line of thinking while allowing the person to save face. This sort of disagreement can sometimes be refreshing, allowing new insights and mental connections not previously made.

When fallacies are used for the second reason, I like to call these fallacies slick maneuvers. Why? Because they are frequently used to garner support for statements or actions that inflate the person's ego at the long-term expense of others.

Dealing with people who use slick maneuvers can be emotionally trying because they often exhibit characteristics of neurotics who do not have the first clue about what sound reasoning is. One of the common traits of neurotics is the unrealistic desire to control and manipulate others, and slick maneuvers provide a verbal arsenal for achieving that end. Regardless of your situation, you will find some people around you attempting to apply these slick maneuvers to get their way regardless of the harm they cause others.

These Slick Maneuver Identification Tables will help you to identify readily the slick verbal maneuvers used by different people in just about any situation. No matter how good their arguments sound, if you detect one or more of these fallacies, the whole argument can come into question. Once the argument comes into question, it becomes imperative for you to trace thoroughly the opponent's line of reasoning that leads to the asserted conclusion. If your opponent can fill apparent gaps in logic with hard evidence and sound reasoning, then you have earned the right to feel confident about the conclusion. Otherwise, you have the right to challenge the conclusion vociferously by exposing and attacking the fallacy.

Slick Maneuver Identification Table #1

Fallacies of Oversimplification

Special Pleading or Card-Stacking: Stacks the deck of evidence to facilitate a desired outcome. "During a period of war sales increase, prices rise, and greater profits are made. Therefore wars are brought about by persons who profit financially from them."
Genetic Fallacies: Attempt to reduce the significance of a movement or a state of affairs merely to a proposed account of its origins or earliest antecedents. "Our nation cherishes freedom today, since many of the founders of the republic were men who prized freedom more than life itself."
False Cause: Oversimplifies the relevant antecedents of a given series of events. "Rome fell because its leaders quarreled among themselves."
False Analogy: Takes two or more objects which are similar in some ways and makes an unwarranted inference about the additional ways in which such objects could be similar. "Minds, like rivers, can be broad. The broader the river, the shallower it is. Therefore, the broader the mind, the shallower it is."
Black-and-White Fallacy: Overlooks both gradations and additional alternatives between extreme positions. "All politicians are either highly efficient or completely inept."
Accident: Applies a general principle to an exceptional case without critical examination or regard to context. "If it is wrong to break into a cabin, then a cabin should not entered to save a party from freezing even though they are caught in a blizzard."
Converse Accident: Generalizes from an exceptional case to a proposed general principle. "Since it is permissible for a student to delay handing in his assignment if he is called home on an emergency, it is permissible for a student to delay handing in an assignment whenever he chooses to do so."
Hasty Generalization: Reaches a generalized conclusion on the basis of too limited a range of examples. "Smith, Jones, and Brown are members of labor unions and each of them is interested in gaining the maximum pay with the least amount of work. Therefore, all members of labor unions are interested only in gaining the highest wage for the least work."

Slick Maneuver Identification Table #2

Fallacies of Misuse of Appeal to Emotions

The Misuse of Appeal to Laughter: Diverts attention from the central issues and stifles serious thought and analysis. "Anyone who accepts the conclusions of my opponent would also be forced to accept the view that the tail wags the dog."
The Appeal to Pity (Argumentum Ad Misericordiam): Replaces relevant evidence for a conclusion with a bid for the sympathy of an audience. "John deserves a 'C' in this class since his parents have sacrificed to send him to college and he will not graduate if he receives a lower grade."
The Appeal to Reverence: Replaces relevant evidence for a conclusion with a bid for respect for traditions. "We must beware of foreign entangling alliances since Washington, the founder of our nation, warned us against taking such a course of action."
The Bandwagon Fallacy: Appeals to an interest in following the crowd and doing as they do rather than to adequate evidence justifying a conclusion. "You ought to buy a small European sports car as all members of the smart crowd now own one of these cars."
The Common-Folks Appeal: Appeals to attempts to secure acceptance of a conclusion by the speaker's identification with the everyday concerns and feelings of an audience rather than on the basis of adequate evidence. "I'm sure that you will recognize that I am more competent than my opponent. When I was in high school I had to get up at four-thirty every morning to deliver papers. In college I was barely able to make C's and had to do janitorial work in order to make ends meet to put myself through school. Therefore, I would make a better Congressman."
Appeal to the Gallery (Argumentum Ad Populum): Seeks acceptance of a point of view by an emotional reaffirmation of a speaker's support of values, traditions, interests, prejudices, or provincial concerns shared widely by members of an audience. "As you union members know, I am a champion of the labor movement, and seek to eliminate exploitation of the common worker by big business. Therefore, you know you can trust my judgment when I say that this agricultural legislation will be good for the country."

Slick Maneuver Identification Table #3

Fallacies of Involved or Complex Assumptions

Begging the Question (Petitio Principii): Assumes what needs to be proven and offers this assumption as evidence for a conclusion that only particularizes the assumption or that restates an equivalent form of the original assumption. "All the events in nature are determined. Human events are part of the events in nature. Therefore, human events are determined."
Arguing in a Circle: Uses a premise as evidence to establish a conclusion, and this conclusion is used as evidence to establish the original premise. "Democracy is desirable because it promotes freedom of inquiry. But why is freedom of inquiry desirable? Because it promotes democracy."
Name-Tagging: Assumes the attachment of labels to persons or things constitute evidence for conclusions about the objects to which the labels are applied. "This application is easy to use. Look at its label, 'Easy Applicator.'"
Poisoning the Wells: Discredits the source of proposed evidence, so that the evidence is ruled out prior to any consideration of its merits. "Anything that you say would be influenced by your interest in civil rights. You may make your statement, but we shall know beforehand that it will be distorted and unreliable."
Complex Question: Assumes or presupposes a certain state of affairs, so that any answer involves the granting of the assumption. "Have you stopped telling lies?"
Leading Question: "Plants" a proposed answer to a question by the manner in which the question is asked. "You do believe that longer vacations are desirable, do you not?"
Contradictory Assumptions: Attempts to make two or more contradictory assumptions, thus violating the Aristotelian rule of "either-or." "What would happen if an irresistible force met an immovable object?"

Slick Maneuver Identification Table #4

Fallacies of Imprecision in the Use of Language

The Misuse of Vague Expressions: Occurs if a conclusion not justified by evidence is attributable to the misinterpretation of a vague expression. "You claim that you believe in free enterprise, yet you accept socialistic practices of government like the War on Poverty and Medicare. The American way of life has never endorsed a policy of providing something for nothing."
The Fallacy of Simple Ambiguity: Results from an effort to establish a conclusion by interpreting a statement in a manner not justified by the context. "We cannot expect John to come since he said, 'Nothing will deter me from coming.'"
The Fallacy of Equivocation: Changes or shifts the meaning of a key expression in the middle of an argument. "Everything subject to law is subject to a lawgiver. The natural order is subject to a law. Therefore, the natural order is subject to a lawgiver."
The Fallacy of Amphibole: Occurs if a conclusion not justified by evidence is based upon ambiguity attributed to the syntax of a sentence. "No cat has nine tails. Any cat has one more tail than no cat. Therefore, any cat has ten tails."
The Fallacy of Ambiguity of Significance: Occurs in the drawing of an improper conclusion by misinterpretation of the significance of a statement. "A period of higher unemployment is developing, since there was a one percent increase in the rate of unemployment in January."
The Fallacy of Accent: Occurs when improper emphasis is placed upon a word, phrase, or a sentence and on this basis a conclusion is inferred. A theme was returned to a student with the notation, "Some parts of this theme are good and other parts interesting. The interesting parts are inaccurate and the good parts were copied." The student wrote his parents, "The grader wrote that my theme was 'good' and 'interesting.'"
The Fallacy of Division: Infers that the property of an organized whole also characterizes the parts of the whole. "Since surgeons have spent many years in perfecting appendectomies, Dr. James Doe, the new surgeon in our town, has spent many years in perfecting his technique in performing appendectomies."
The Fallacy of Composition: Infers that the qualities or characteristics of parts of a whole must also characterize the whole itself. "Since the members of this team are the best players of their respective positions in the conference, a team composed of these players would be the best team in the conference."

Slick Maneuver Identification Table #5

Fallacies of Irrelevance

Fallacies Misusing Appeals to Authoritative Sources: Support a conclusion by appeals to documents, generally held beliefs, or the opinions of well-known persons that are not particularly germane or qualified to deal with the point at issue. "Man must be immortal because this belief has tended to be present in such widely differing societies in highly divergent circumstances over such a long span of history."
The Appeal to Force (Argumentum Ad Baculum): Substitutes force or the threat of its use for rational evidence in the support of a conclusion. "You should accept the view that our protection society can strengthen the sales of your product. Otherwise you might find that your machinery has been damaged and that your labor troubles increase."
The Appeal to the Man (Argumentum Ad Hominem): Seeks to prove a conclusion false by attacking the character, reputation, associations, or social situations of the person proposing it. "The statement of this witness cannot be accepted as reliable, since he participated in a protest demonstration against the United States' foreign policy when he was a student in college."
The Argument from Intimidation: Asserts arbitrarily that a person's idea is false and then uses the assertion as proof of that person's immorality. This fallacy was identified by Ayn Rand in The Virtue of Selfishness. "John asserts that no man is his brother's keeper. This is a false idea. Therefore, John is immoral."
The Appeal to Ignorance (Argumentum Ad Ignorantium): Advances the position that if one conclusion in an argument cannot be established convincingly, then the opposing view can be accepted. "Since you cannot disprove that there are flying saucers, you should accept as reliable the reports of those claiming to have seen such objects."
The Fallacy of an Irrelevant Conclusion or of "Missing the Point of the Evidence" (Ignoratio Elenchi): Stresses factors that may support a conclusion other than the one proposed. "Any high school graduate should be admitted to any university supported by taxes in his state, since he should be assured of all privileges of citizenship guaranteed to him by the Constitution, his family also pays taxes in that particular state, and he can get a better job if he is a graduate of a university."
The Argumentative Leap (Non Sequitur): Jumps to a conclusion with no immediate basis for drawing the proposed conclusion provided internally within the argument. "The electoral college is subject to extreme criticism. Therefore, presidential candidates should be nominated by popular votes rather than by political conventions."
Post Hoc, Ergo Propter Hoc (After This, Therefore Because of This): Suggests that because one event follows another, the former must have caused the latter, without showing a causal link. "John had a cold. John took large doses of vitamin C. The cold subsided. Therefore, the large doses of vitamin C caused the cold to subside."


Controverting Objectionable Arguments

  1. Controverting an Argument by Indicating a Formal or an Informal Fallacy
    1. Appeal to a formal fallacy
    2. Appeal to an informal fallacy
  2. Controverting an Argument by Claiming Grounds for Rejecting One or More Premises Offered as Evidence
    1. Appeal to unsatisfactory evidence offered as premises
    2. Appeal to inconsistent premises
    3. Appeal to inconsistency with previous positions
    4. Appeal to internal self-refutation
  3. Controverting an Argument by Attacking Inadequate Conceptualization
    1. Appeal to unsatisfactory categorical structure
    2. Appeal to meaningless statements
    3. Appeal to distinctions
  4. Controverting an Argument by Criticism of Methods Used in Formulating Arguments
    1. Appeal to faulty sources
    2. Appeal to methodological deficiencies
    3. Appeal to a faulty model
  5. Controverting an Argument by Appeal to Its Consequences
    1. Appeal to similar consequences
    2. Appeal to disparity between proposed consequences and probable consequences
  6. Controverting an Argument by Establishing an Alternative Conclusion
    1. Appeal to a counterargument
    2. Appeal to a different argument
    3. Appeal to the greater simplicity of an alternative argument
  7. Controverting an Argument by Appeal to Irrational Positions Found Within It
    1. Appeal to the absurdity of an argument
    2. Appeal to circularity
    3. Appeal to an infinite regress


Objectivism 101
Objectivism 101