THE LOGIC CLASSROOM
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study six: informal fallacy and definitions

Definition: Fallacy
A fallacy is a blunder in reasoning. It is "false" reasoning, that is to say, reasoning with illogical argument or misleading argument. Reasoning means drawing inferences or conclusions from known or assumed facts or premises. The premises and conclusions of arguments should qualify as propositions, i.e., the meanings of declarative sentences which possess the essential characteristic of being either true or false. Recall that an argument is defined as a series of connected declarative sentences (premises) in support of another statement (conclusion) or a position. A fallacy consists of invalid or unwarranted inference of a conclusion from premises, some of which may not qualify as propositions. Commands, exhortations, or exclamations, for instance, do not possess the quality of truth or falsity and must be reworded into propositions if they are to serve as either premises or conclusions.

Fallacies Classified
Fallacies may be broadly classified as either formal or non-formal. Formal fallacies are invalid inferences of conclusions from premises, the invalidity being due to the form of the argument. Non-formal, known as informal fallacy, as a category includes a multiplicity of mistakes in reasoning, some of which involve careless use of language. Informal fallacy may be thought of as counterfeit argument, i.e., a type of argument that may seem to be correct but which proves on examination not to be correct. Informal fallacies, unlike formal fallacies, are not fallacies of form. Extralogical or emotional appeals usually constitute one of the sources of persuasion. In other cases, informal fallacies are deceptive pieces of "bad" English or mistakes due to ambiguity or vagueness of a term or phrase, or an entire sentence. In any case, the pretense of logical relevance, we could say, is the source of fallacy.

Fallacies of Form
Fallacies of form render arguments invalid irrespective of the content of the argument or the truth or falsity of its propositions with the following qualification. If the form of an argument allows an inference of a false conclusion from all true premises, then we know the argument to be invalid, for a valid argument will never result in the deduction of a false conclusion from true premises. Indeed, if it so happens that the conclusion of a particular argument is known to be false and the argument is valid, then we know that at least one of the premises is false as well.

Informal Fallacies
In reasoning that "If X looks like a Z, walks like a Z, talks like a Z, and even reasons like a Z, well then, X must be a Z," one runs the risk of accepting a counterfeit for the real thing. Some, one could say, most informal fallacies are counterfeit deductive arguments. The language of informal fallacies may present the appearance or structure of a deductive argument with premises in-support-of a conclusion. But herein lies the possibility of error -- if one interprets the in-support-of as a necessary inference relation. While there is a relation between premises and conclusion in such "arguments," the relation is a psychological one consisting, in many instances, of emotional appeals to agree with or accept a conclusion.

Informal fallacies use language which is inherently confused, or to create a special effect in the listener conducive to agreement with a conclusion. The art of using language to persuade acceptance of a conclusion by appeal to feelings of attraction or aversion to an object or event has a long history. It can be traced back to the Garden of Eden and to God's Adam and Eve, our ancestors. And the methods of informal fallacy are with us still. Many commercials make use of attraction and/or aversion for things or circumstances to persuade one to avoid something by buying a product or to attain an attractive status by using a product. When their effect causes people to confuse an emotional appeal for a necessary inference, we can say that they make use of counterfeit argument to achieve acceptance of a conclusion. One should not ignore the context in determining whether a piece of language is functioning as counterfeit argument.

Informal fallacy classifications abound. Perhaps the simplest consists of two categories of the most common types: (1) fallacies of irrelevant conclusion; and (2) fallacies of ambiguity and vagueness. (Note: There is no systematic classification of informal fallacies. More than one may apply in some cases. Judge by that which fits the context best.)

Fallacies of Relevance
Fallacies of irrelevant conclusion are those for which the premises are not relevant to the truth of the conclusion. With such, the label non sequitur, meaning literally that the conclusion does not follow from the premises is often used. With these fallacies the premises are incapable of establishing the conclusion logically because they are irrelevant to the conclusion. Some of the more common informal fallacies have retained and are known by their Latin names.
Argumentum

Argumentum
ad hominem-abusive

AH

When irrelevancies of character, circumstances, the beliefs or prejudices of the person are used as a ploy to reject a position or conclusion.

Argumentum
ad baculum

AB

When one appeals to force or the threat of force instead of reason to cause acceptance of a conclusion.

Argumentum
ad misericordiam

AM

When one appeals to pity instead of sound reasoning to gain acceptance of a conclusion.

Argumentum
ad populum

AP

When one attempts to gain popular assent to a conclusion by arousing the feelings and enthusiasms of the multitude.

Appeals that one should accept a conclusion since everyone else or most people have accepted it.

Argumentum
ad verecundiam

AV

When instead of sound argument one appeals to the feeling of respect people may have for the famous to win assent to a conclusion.

Argumentum
ad ignorantiam

AI

Whenever it is argued that a proposition is true solely on the basis that it has not been proved false, or that it is false because it has not been proved true.

False Cause

FC

When one infers that because one event follows another, the first event caused the second. (post hoc ergo propter hoc or "after this, therefore because of this")

False Dilemma

FD

when one calls for a conclusion based on the assumption that two and only two mutually exclusive alternatives are possible, when in fact more than two are possible or the two are not mutually exclusive.

Accident

A

When an accidental or irrelevant factor is treated as the essential point in an argument.

Hasty  Generalization

HG

When in argument one considers only exceptional or too few cases and generalizes universally to a rule that fits them alone.

Circular Reasoning

CR

When one assumes as a premise for an argument the very conclusion that is intended to be proved. (petitio principii or "begging the question")

Complex Question

CQ

When in argument one treats a plurality of questions as if it were a simple one demanding a single answer.

 

For examples of Informal Fallacies of Ambiguity in a dialogue format, Click Here.
Fallacies of Ambiguity
Fallacies of ambiguity occur in formulations of argument that use ambiguous words or phrases. This is a smaller class of fallacies that include the fallacies of equivocation, amphibology, accent, composition, and division. Definitions follow.
Equivocation

 

Equivocation

EQU

When one confuses the different meanings a single word or phrase may have.

Amphibology

AMP

When a statement’s meaning is unclear because of the loose or awkward way in which the words are combined.

Accent

ACC

When words or phrases of a statement are stressed producing different meanings from the original.

Composition

COM

When one reasons fallaciously from the properties of the part or parts to the properties of the whole.

Division

DIV

When one reasons fallaciously that what is true of a whole must also be true of each of the whole’s parts.

 

It is not difficult to come up with examples of each of the above. Some uses are a mere play on words as in "Good steaks are rare these days, so don't order yours well-done" where the equivocation turns on the meanings of "rare." Other examples follow:
  • "The end of a thing is its perfection; death is the end of life. Therefore, death is the perfection of life." (EQU: Examine the meanings of "end.")
  • "Leaking badly manned by a starved and thirsty crew one infirmity after another overtakes the little ship." (AMP: The ambiguity lies in the structure or syntax of the sentence; the phrase "manned ... crew" needs to be relocated to achieve an unambiguous meaning.)

  • The statement, "We should not speak ill of our friends." when quoted as, "We should not speak ill of OUR FRIENDS" (ACC) stresses words not emphasized in the original, thereby conveying a different meaning(s) from the original.

Composition and division are closely related. For example, if one argues that based on the properties of the elements of NaCl, the compound must be highly toxic (COM), one might suspect that the person knows little or nothing about chemistry or does not know that the compound is table salt. On the other hand, if someone argued that since salt possesses a class of salutary properties; therefore, the salt's elements (sodium and chloride) must be salutary, instruction in chemistry and perhaps more, would seem to be necessary.

Avoiding Informal Fallacies
As we have already suggested, context should not be ignored in assessing fallacies. Likewise, context should not be ignored in determining when to label something as an informal fallacy. For example, when there is no attempt to disguise an emotional appeal as a necessary inference, there may be no point in accusing someone of using an informal fallacy. Or, when all logical appeals have failed to convince a perverse arguer who knowingly and willfully disregards truth for error, what else remains but ad hominem (not the abusive variety which is fallacious)? Silence? Perhaps. No doubt as well there are occasions where the use of blunt, even ad baculum language may be the only alternative; for example, as when a police officer is confronted by an armed felon.

For more on avoiding fallacy in reasoning and argumentation, Click Here.

Definitions
Among the best ways to avoid vagueness or ambiguity in the language of argument is to define key terms clearly. Much confusion, if not controversy, would be avoided if persons would take time to define their terms in unambiguous, precise language. If vague or ambiguous terms are used, it is not self-evident and should not be assumed that one's hearer will have in mind the same meaning as oneself. The use of emotively loaded terminology exacerbates the task of getting clear about the meanings of crucial terms.

To define a term means to state what it means or signifies. Definition is the clear determination of a word's outline or limits. In defining words we are primarily concerned with describing a term or phrase univocally.

Definitions are often classified according to the purposes one has in mind. Purposes include reporting the conventional meaning of a term (reportive or lexical); introducing a new term, or an old one with a new meaning (stipulative); reducing the vagueness of a term (precising); attempting to solve a theoretical problem or increase and systematize knowledge (theoretical); replace a longer expression by a shorter, more convenient one (abbreviative); and attempting to change attitudes (persuasive). The others may sometimes function persuasively if the purpose is to change attitudes toward a more or less favorable degree.

The following table contains brief descriptions for some of these more well known types of definition with an example of each.
TYPE

TYPE

PURPOSE

EXAMPLE

Lexical

To report the meaning of a term for increasing vocabulary or eliminating ambiguity; assessed as true or false. (real or reportive definition)

Unicorn is “an animal-like horse having a single straight horn projecting from its forehead.”

Stipulative

To introduce a new term (or a new use for an old one) for increasing vocabulary; proposal to use a word or phrase in a certain way; includes abbreviations or acronyms; not assessed as true or false. (nominal or verbal definition)

By hermeneut, I mean “one who is obsessed with one kind of interpretation – one’s own.”

Precising

To reduce the vagueness of a term going beyond lexical but faithful to established usage; applies to borderline cases; assessed as partially true or false.

In a correlation study of police height and job injuries, short means “a height of less than 5 feet 6 inches.”

Theoretical

To provide adequate characterization of the objects to which it is applied in order to increase and systematize knowledge useful in the solution of theoretical problems; takes some account of previous usage; assessed in terms of status of a theory. (analytic definition)

Justice may be defined as “getting what one is due.”

Persuasive

To influence or change attitudes by the emotive or evaluative use of language; assessed as successful or not in changing attitudes. (rhetorical definition)

Television news reporters constitute an unelected "kakistocracy" meaning “government by the worst available citizens.”

 

Definitions are often classified into two:  denotative and designative.  Denotative definitions make reference to objects; whereas designative (connotative) definitions point to the essential properties of what is being defined.  Designative definitions, in turn, consist of two sub-classes, one of which, the "analytic," has played important functions in theological and philosophical discussions.

For more on Analytic Defintions, click here.
Some useful questions to keep in mind when evaluating definitions follow:
  1. Does the definition avoid circularity, i.e., using the same word in the definiens that is being defined?
  2. Does the definition avoid the use of negative terms in the definiens?
  3. Is the definition either too narrow, or too broad, i.e., either excluding too much or including too much?
  4. Does the definition avoid obscure or figurative language, vague terms, or emotively loaded terminology?
  5. Does the definition serve the purpose for which it was intended?

Which of the numerous types of definitions is called for will depend, of course, on both subject matter and purpose. More could be written on the topic of definitions; however, for a primer in logic, perhaps this much on the subject will suffice. The importance of defining one’s key terms in communication cannot be overemphasized. Gordon Clark remarks on the necessity for good definitions this way:

“Strict definitions and strict adherence to them are essential to intelligible discussion. If one contender has one idea in mind – or perhaps no clear idea at all, while the other party to the debate entertains a different notion, or is equally vague – the result of the conversation is bound to be complete confusion." (Gordon Clark: God and Evil, p. 16)

Summary
Informal fallacies can be thought of as counterfeit argument. Counterfeit argument is a sub-class of a larger class known as propaganda or language used to create special effects. It should be clear that when the connection between premises and conclusion in a given context is obviously psychological, masquerading as a necessary inference, we are in the presence of counterfeit argument – informal fallacy.

In this short chapter two classes of informal fallacies were described: fallacies of relevance and fallacies of ambiguity. Fallacies of relevance, as the label suggests, are those in which the premises are not logically relevant to the truth of the conclusion. Some of the more common informal fallacies are known by and have retained their Latin names. Others may not have received either a Latin or English label, being less familiar. With these, the label non sequitur, meaning that the conclusion does not follow from the premises, is often used. Fallacies of ambiguity occur in formulations of argument that use ambiguous words or phrases. This is a smaller class of fallacies which include the fallacies of equivocation, amphibology, accent, composition, and division.

As to how one can halt the advance of an informal fallacy, it can be effective to ask for a clear definition of key terms. Articulating a clear understanding of crucial terms can serve to avoid the vagueness or ambiguity that feeds controversy based on misunderstanding or misinterpreted language. Nevertheless, even with all precautions, there is no certain way to avoid counterfeit arguments. The logical task requires practice, vigilance, and clear language:  (As Dr. Clark wrote: “,,,you must know what you mean. Otherwise you don’t know what you are talking about.” Gordon Clark, Logic, HC ed.,  p.21.)
Review
Suppose one is given the following definition of definition.

“Definition is a statement which captures the meaning, use, function, and essence of a concept, term or phrase.”
  1. Does it meet all of the requirements for an adequate definition listed in Table 7.6?
  2. Would you classify the definition as a denotative or connotative definition? Why?
  3. Does the definiens use terms that require definition?
  4. In what context would this definition be essential to intelligible discussion?
  5. Compare the above definition with your dictionary definition. How do the two differ?
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Exercise 6
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