" 'Contrariwise', continued Tweedledee, 'If it was so, it might be; and if it were so, it would be; but as it isn't, it ain't. That's logic.' "
— Lewis Carroll, Through The Looking Glass, Ch. IV.

These fallacies are well-known and can be avoided, for the most part, using Aristotelian logic. However, some fallacies are best avoided using the 'logic' of general semantics, applying non-allness, non-identity and self-reflexivity. Most fallacies can be avoided with some knowledge of science and epistemology that the practice of general semantics helps to convey.

Fallacies of Distraction
Appeals to Motives in Place of Support
Changing the Subject
Inductive Fallacies
Causal Fallacies
Missing the Point
Fallacies of Ambiguity
Category Errors
Non Sequitur
Syllogistic Errors
Fallacies of Explanation
Fallacies of Definition

Fallacies of Distraction

• False Dilemma: two choices are given when in fact there are three options or more. A special form is
  • Argument from Ignorance (ad ignorantiam): because a proposition is not known to be true/false it is aserted to be false/true
• Middle Ground: asserting that the 'middle' position between two extremes is correct
• Slippery Slope: a series of increasingly unacceptable consequences is drawn
• Wicked alternative: attempting to support one proposition by denouncing another, when the second is not opposite of the first.
• Complex Question (plurium interrogationum): two unrelated points are conjoined as a single proposition. It is the interrogative form of "Begging the Question" fallacy
• Red Herring (ignoratio elenchi): an irrelevant topic is presented in order to divert attention from the original issue
• Trivial Objections: attacking an opponent's position by focusing critical attention on some point less significant than the main point or basic thrust of the argument.
• Argumentum ad nauseam: incorrect belief that an assertion is more likely to be true, or is more likely to be accepted as true, the more often it is heard
• Nothing but objections (ad infinitum): continually raising objections as a means of avoiding the issue.
• Quoting out of context: manipulating a quote either from an authority, or from one's opponent, in such a way that the original meaning of the statement is altered

Appeals to Motives in Place of Support

• Appeal to Force/Fear (ad baculum), Bandwagon, Appeal to Tradition (ad antiquitatem), Appeal to Novelty (ad novitatem): the reader is persuaded to agree by force/fear/psychological pressure/tradition/novelty
• Appeal to Emotion/Prejudicial Language, with some special cases being
  • Appeal to Pity (ad misericordiam), Appeal to Flattery, Appeal to Humor/Ridicule, Appeal to Spite: the reader is persuaded to agree by pity//flattery/humour/ridicule/spite
  • Appeal to Consequences (ad consequentiam): the reader is warned of unacceptable consequences. Includes wishful thinking
  • Appeal to Wealth/Poverty (ad crumenam/ad Lazarum): believing that wealth/poverty is a criterion of correctness
  • Self-righteousness: confusing good intentions with actual good or truth
• Improper Use of a Cliché: using an aphorism or cliché in place of relevant evidence for a claim
• Appeal to Popularity/Belief (ad populum, ad numerum), Appeal to Common Practice: a proposition is argued to be true because it is widely held to be true/widely believed/widely practiced as a justification for the exemption
• Guilt by Association: a person rejects a claim simply because it is pointed out that people she dislikes accept the claim
• Fallacy of Opposition: those who disagree with you must be wrong and not thinking straight
• Argument by Innuendo: directing one's listeners to a particular, usually derogatory, conclusion, by a skillful choice of words or the careful arrangement of sentences, which implicitly suggests but does not assert that conclusion. The force of the fallacy lies in the impression created that some veiled claim is true, although no relevant evidence is presented to support such a view.

Changing the Subject

• Attacking the Person (ad hominem): attacks on the person, subdivided into
  • Abusive Ad Hominem: the person's character is attacked
  • Circumstantial Ad Hominem: the person's circumstances are noted or
  • Ad Hominem Tu Quoque: the person does not practise what is preached. A special form is:
    • Two Wrongs Make a Right, by which a person "justifies" an action against another by asserting that the person would do the same thing to him/her
• Appeal to Authority (ad verecundiam): the authority is not an expert in the field, or experts in the field disagree, or the authority was joking, drunk, etc. A special form of it is:
  • Anonymous Authority: the authority in question is not named. Includes Hearsay
• Style Over Substance: the manner in which an argument (or arguer) is presented is felt to affect the truth of the conclusion
• Occam's razor fallacy: "less is more, and more is less", "plurality should not be posited without necessity", or "the simpler the explanation the better"
• Misuse of etymology: asserting that words should remain close to their etymological roots, and using such to come to a certain conclusion
• Allness: belief that one can say everything there is to say about something (in order to achieve some kind of ideal perfection, scientific precision, etc.) A special form is
  • Overprecision: rejecting a concept as unusable because it has borderline cases or because the definition, phrasing, syntax, grammar, or structure of the proposition or argument is not perfect

Inductive Fallacies

• Hasty Generalization (audiatur et altera pars): the sample is too small to support an inductive generalization about a population. Special forms of it are:
  • Accident (dicto simpliciter): a generalization is a applied because of recent personal events when circumstances suggest that there should be an exception
  • Spotlight: all members or cases of a certain class or type are like those that receive the most attention or coverage in the media
  • Converse Accident: an exception is applied in circumstances where a generalization should apply
  • Gambler's Fallacy: an independent event is expected to be more probable to happen because other events happened before
  • Unrepresentative/Biased Sample: the sample is unrepresentative of the whole/biased compared to the whole
• False Analogy: the two objects or events being compared are relevantly dissimilar
• Illegitimate Difference: attempting to defend an action or point of view as different from some other one, with which it is allegedly confused, by means of a very careful distinction of language. In reality, however, the action or position defended is no different in substance from the one from which it is linguistically distinguished.
• Slothful Induction: the conclusion of a strong inductive argument is denied despite the evidence to the contrary.
• Exclusion/Concealed Evidence: evidence which would change the outcome of an inductive argument is excluded from consideration
• Casual Oversimplification: oversimplifying the relevant casual antecedents of an event by introducing factors insufficient to account for the event in question or by overemphasizing the role of one or more of those factors
• Fallacy Fallacy (ad logicam): arguing that a proposition is false because it has been presented as the conclusion of a fallacious argument. Remember always that fallacious arguments can arrive at true conclusions
• Fake Precision: making a claim with the kind of mathematical precision that is impossible to obtain

Causal Fallacies

• Questionable Cause (non causa pro causa):
  • Post Hoc Ergo Propter Hoc: because one thing follows another, it is held to cause the other
  • Confusing Cause and Effect: the direction between cause and effect is reversed
  • Joint Effect (cum hoc ergo propter hoc): one thing is held to cause another when in fact they are both the joint effects of an underlying cause
  • Genuine but Insignificant Cause: one thing is held to cause another, and it does, but it is insignificant compared to other causes of the effect
  • Complex Cause: the cause identified is only a part of the entire cause of the effect

Missing the Point

• Begging the Question (petitio principii): the truth of the conclusion is assumed by the premises. A special form of it is:
  • Argument from Design: assigning a purpose to a fact and drawing a conclusion of the existence of a creator of that purpose
• Irrelevant Conclusion: an argument in defense of one conclusion instead proves a different conclusion
• Straw Man: the author attacks an argument different from (and weaker than) the opposition's best argument
• Rationalization: making excuses instead of addressing the issue

Fallacies of Ambiguity

• Equivocation: the same term is used with two different meanings
• Amphiboly: the structure of a sentence allows two different interpretations
• Accent: the emphasis on a word or phrase suggests a meaning contrary to what the sentence actually says

Category Errors

• Composition: because the attributes of the parts of a whole have a certain property, it is argued that the whole has that property. It is a special case of identification
• Division: because the whole has a certain property, it is argued that the parts have that property. It is a special case of identification

Non Sequitur

• Affirming the Consequent: any argument of the form: If A then B, B, therefore A. When stated in conditional form ("If A then B, therefore if B then A"), it is called "Converting a Conditional"
• Denying the Antecedent: any argument of the form: If A then B, Not A, thus Not B. When stated in conditional form ("If A then B, therefore if Not-A then Not-B"), it is called "Improper Transposition"
• Inconsistency: asserting that contrary or contradictory statements are both true
• Divine Fallacy: drawing an irrelevant conclusion from some fact

Syllogistic Errors

• Fallacy of Four Terms: a syllogism has four terms
• Undistributed Middle: two separate categories are said to be connected because they share a common property
• Illicit Major: the predicate of the conclusion talks about all of something, but the premises only mention some cases of the term in the predicate
• Illicit Minor: the subject of the conclusion talks about all of something, but the premises only mention some cases of the term in the subject
• Exclusive Premises: a syllogism has two negative premises
• Drawing an Affirmative Conclusion From a Negative Premise: as the name implies
• Drawing a Negative Conclusion From Affirmative Premises: as the name implies
• Existential Fallacy: a particular conclusion is drawn from universal premises

Fallacies of Explanation

• Subverted Support: the phenomenon being explained doesn't exist
• Non-support: evidence for the phenomenon being explained is biased
• Untestability: the theory which explains cannot be tested, or verification lie somewhere in the future
  • Relativist/Subjectivist Fallacy: a claim might be true/false for others but false/true for the author based on individual perception or whim
  • Paradigm: taking one's own encapsulated world view, or system of thought (paradigm), or culture, as the standard by which all other paradigms may be judged
• Limited Scope: the theory which explains can only explain one thing
• Limited Depth: the theory which explains does not appeal to underlying causes
• Ad hoc hypothesis: hypothesis used to explain away facts that seem to refute one's theory. A special form of it is:
  • "No true Scotsman. . .": an argument that takes the form of: "no Scotsman puts sugar on his porridge", which is countered with "my friend Angus likes sugar with his porridge", but is followed by the rejoinder, "Ah yes, but no true Scotsman puts sugar on his porridge"
• Identifications:
  • Idiosyncratic language: charging words with personal meaning which alter their usual meanings
  • Lip service: verbal agreement unsupported in action or true conviction
  • Inference from a Label: assuming that the evaluative or identifying words or phrases attached to people or things constitute a sufficient reason for the drawing of conclusions about the objects to which such labels are attached. See non-identity for a general description of identification.
  • Word Magic (ad lapidem): assume word means existence, bare assertion, no evidence, no argument
  • Reification-Hypostatization (objectification): reification occurs when an abstract concept is treated as a concrete thing
  • Personification: attributing human traits to other creatures or reading purpose into inanimate configurations

Fallacies of Definition

• Too Broad: the definition includes items which should not be included
• Too Narrow: the definition does not include all the items which should be included
• Failure to Elucidate: the definition is more difficult to understand than the word or concept being defined
• Circular Definition (a contrario proof of the existence of undefined terms): the definition includes the term being defined as a part of the definition
• Conflicting Conditions: the definition is self-contradictory

1. The Nizkor Project: Fallacies
2. Stephen Downes' Guide to Logical Fallacies
3. The Atheism Web: Logic and Fallacies
4. Logical Fallacies: The Fallacy Files
5. The Skeptic's Dictionary: Fallacies

Bibliography:

1. Bergmann, Merrie, James Moor, and Jack Nelson. The LogicBook. Second Edition. McGraw-Hill, 1990.
2. Barker, Stephen F. The Elements of Logic. Fifth Edition.McGraw-Hill, 1989.
3. Boolos, George, and Jeffrey, Richard. Computability andLogic. Second Edition. Cambridge University Press, 1980.
4. Bergmann, Merrie, James Moor, and Jack Nelson. The LogicBook. Second Edition. McGraw-Hill, 1990.
5. Cederblom, Jerry and Paulsen, David. Critical Reasoning. 5th Edition, Jerry Cederblom University of Nebraska, Omaha, David Paulsen The Evergreen State College, Published by Wadsworth Publishing
6. Copi, Irving M. and Cohen, Carl. Introduction to Logic. Eighth Edition, Macmillan, 1990.
7. Engel, S. Morris. With Good Reason: An Introduction to Informal Fallacies. 5th Edition, St. Martin's Press, 1994.
8. Gianelli, A.P. Meaningful Logic. Bruce PublishingCompany, 1962.
9. Haack, Susan. Philosophy of Logics. Cambridge University Press, 1978.
10. Huff, Darrell. How to Lie With Statistics. W.W. Norton, 1954.
11. Hughes, G.H., and Cresswell, M.J. An Introduction to Modal Logic. Methuen and Co. Ltd., 1968.
12. Jason, Gary. Introduction to Logic. Jones and Bartlett,1994.
13. Jager, Ronald. Essays in Logic From Aristotle to Russell. Prentice-Hall, 1963.
14. Jeffrey, Richard. Formal Logic: Its Scope and Limits.McGraw-Hill, 1981, 1967.
15. Kelly, David. The Art of Reasoning. W.W. Norton, 1988.
16. Pospesel, Howard. Introduction to Logic: PropositionalLogic. Second Edition. Prentice-Hall, 1984.
17. Purtill, Richard L. Logic for Philosophers. Harperand Row, 1971.
18. Thomason, Richmond. Symbolic Logic: An Introduction.Collier-Macmillan, 1970.
19. Weston, Anthony. A Rulebook for Arguments. Hackett, 1987.