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Fallacies Part 1 Critical Thinking

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1 Fallacies Part 1 Critical Thinking

2 Contents Page 3 – Definition of a Fallacy
Page 4 - Video Introduction to Fallacies Pages 5 to 11 - Informal and Formal Fallacy Pages 12 to 19 - Material Fallacies Pages 20 to 23 - Verbal Fallacies Pages 24 - You Tube Introduction to Fallacies Pages 25 – Ad Hominem Page 26 – Irrelevant Authority Page 27 – Genetic Fallacy Page 28 – Hasty Generalisation Page 29 – Argument from Ignorance Page 30 – Equivocation Pages 31 to 32 – Affirming the Consequent Page 32 - Denying the Antecedent Page 33 - Bibliography

3 Fallacies A fallacy is a component of an argument which, being demonstrably flawed in its logic or form, renders the whole argument invalid (except in the case of 'begging the question' fallacy).

4 YOUTUBE Video on fallacies-An introduction to Fallacies
Click on the image to the left. You will need to be connected to the internet to view this presentation. Enlarge to full screen

5 Fallacies In logical arguments, fallacies are either formal or informal. Because the validity of a deductive argument depends on its form, a formal fallacy is a deductive argument that has an invalid form, whereas an informal fallacy is any other invalid mode of reasoning whose flaw is not in the form of the argument.

6 Fallacies Beginning with Aristotle, informal fallacies have generally been placed in one of several categories, depending on the source of the fallacy. There are fallacies of relevance, fallacies involving causal reasoning, and fallacies resulting from ambiguities (or equivocations).

7 Fallacies Recognizing fallacies in actual arguments may be difficult since arguments are often structured using rhetorical patterns that obscure the logical connections between assertions. Fallacies may also exploit the emotional or intellectual weaknesses of the interlocutor. Having the capability of recognizing logical fallacies in arguments reduces the likelihood of such an occurrence.

8 A different approach to understanding and classifying fallacies is provided by argumentation theory; see for instance the van Eemeren, Grootendorst reference below. In this approach, an argument is regarded as an interactive protocol between individuals which attempts to resolve a disagreement. The protocol is regulated by certain rules of interaction, and violations of these rules are fallacies. Many of the fallacies in the list below are best understood as being fallacies in this sense.

9 Fallacious arguments involve not only formal logic but also causality
Fallacious arguments involve not only formal logic but also causality. Others may involve psychological ploys such as use of power relationships between proposer and interlocutor to establish necessary intermediate (explicit or implicit) premises for an argument. Fallacies often have unstated assumptions or implied premises in arguments that are not always obvious at first glance.

10 Note that providing a critique of an argument has no relation to the truth of the conclusion. The conclusion could very well be true, while the argument as to why the conclusion is true is not valid.

11 Fallacies Note that providing a critique of an argument has no relation to the truth of the conclusion. The conclusion could very well be true, while the argument as to why the conclusion is true is not valid.

12 Material Fallacies Affirming the Consequent--draws a conclusion from premises that do not support that conclusion by assuming Q implies P on the basis that P implies Q (e.g., If a person runs barefoot, then his feet hurt. Socrates' feet hurt. Therefore, Socrates ran barefoot. Other things, such as tight sandals, can result in sore feet.)

13 Material Fallacies Denying the antecedent--draws a conclusion from premises that do not support that conclusion by assuming Not P implies Not Q on the basis that P implies Q (e.g., If I have the flu, then I have a sore throat. I do not have the flu. Therefore, I do not have a sore throat. Other illnesses may cause sore throat.)

14 Material Fallacies Begging the question (also called Petitio Principii, Circulus in Probando--arguing in a circle, or assuming the answer)-- demonstrates a conclusion by means of premises that assume that conclusion (e.g., Paul must be telling the truth, because I have heard him say the same thing many times before. Paul may be consistent in what he says, but he may have been lying the whole time.)

15 Material Fallacies Fallacy of Accident (also called destroying the exception or a dicto simpliciter ad dictum secundum quid)--makes a generalization that disregards exceptions (e.g., Cutting people is a crime. Surgeons cut people. Therefore, surgeons are criminals.)

16 Material Fallacies Converse Fallacy of Accident (also called reverse accident, destroying the exception, or a dicto secundum quid ad dictum simpliciter)--argues from a special case to a general rule (e.g., Every swan I have seen is white, so it must be true that all swans are white.)

17 Material Fallacies Irrelevant Conclusion (also called Ignoratio Elenchi)--diverts attention away from a fact in dispute rather than address it directly. This is sometimes referred to as a "red herring". Subsets include: purely personal considerations (argumentum ad hominem), popular sentiment (argumentum ad populum-- appeal to the majority), fear (argumentum ad baculum), conventional propriety (argumentum ad verecundiam--appeal to authority)

18 Material Fallacies Fallacy of False Cause or Non Sequitur (Latin for "it does not follow")--incorrectly assumes one thing is the cause of another (e.g., Our nation will prevail because God is great.) A special case of this fallacy also goes by the Latin term post hoc ergo propter hoc--the fallacy of believing that temporal succession implies a causal relation. Another special case is given by the Latin term cum hoc ergo propter hoc -- the fallacy of believing that happenstance implies causal relation (aka as fallacy of causation versus correlation: assumes that correlation implies causation).

19 Material Fallacies Fallacy of Many Questions (Plurium Interrogationum)--groups more than one question in the form of a single question (e.g., Is it true that you no longer beat your wife? A yes or no answer will still be an admission of guilt to wife-beating.) Example The following argument is posited: Cake is food. Food is delicious. Therefore, cake is delicious. This argument claims to prove that cake is delicious. This particular argument has the form of a categorical syllogism. Any argument must have premises as well as a conclusion. In this case we need to ask what the premises are—that is, the set of assumptions the proposer of the argument can expect the interlocutor to grant. The first assumption is almost true by definition: cake is a foodstuff edible by humans. The second assumption is less clear as to its meaning. Since the assertion has no quantifiers of any kind, it could mean any one of the following: All food is delicious. One particular type of food is delicious. Most food is delicious. To me, all food is delicious. Some food is delicious.

20 Verbal fallacies Equivocation consists in employing the same word in two or more senses, e.g. in a syllogism, the middle term being used in one sense in the major and another in the minor premise, so that in fact there are four not three terms ("All heavy things have a great mass; this is heavy fog; therefore this fog has a great mass.")

21 Verbal fallacies Amphibology is the result of ambiguity of grammatical structure, e.g. of the position of the adverb "only" in careless writers ("He only said that," in which sentence, the adverb has been intended to qualify any one of the other three words).

22 Verbal fallacies Fallacy of Composition "From Each to All". Arguing from some property of constituent parts, to the conclusion that the composite item has that property e.g. "all the band members (constituent parts) are highly skilled, therefore the band (composite item) is highly skilled". This can be acceptable (i.e., not a fallacy) with certain arguments such as spatial arguments e.g. "all the parts of the car are in the garage, therefore the car is in the garage"

23 Verbal fallacies Proof by verbosity, sometimes colloquially referred to as argumentum verbosium - a rhetorical technique that tries to persuade by overwhelming those considering an argument with such a volume of material that the argument sounds plausible, superficially appears to be well-researched, and it is so laborious to untangle and check supporting facts that the argument might be allowed to slide by unchallenged.

24 YOUTUBE Video on fallacies-An introduction to Fallacies
Click on the image to the right. You will need to be connected to the internet to view this presentation. Enlarge to full screen

25 Personal Attack/Ad Hominem
When an arguer rejects a person’s argument or claim by attacking the person’s character rather than examining the worth of the argument or claim itself. Example: Professor Doogie has argued for more emphasis on music in our F2F classes to facilitate creativity. But Doogie is a selfish bigheaded fool. I absolutely refuse to listen to him. 1. X is a bad person. 2. Therefore X's argument must be bad. Pattern

26 Argument from an Irrelevent Authority
Citing a witness or authority that is untrustworthy. Example: My dentist told me that aliens built the lost city of Atlantis. So, it’s reasonable to believe that aliens did build the lost city of Atlantis. Authority Assessment Is the source an authority on the subject at issue? Is the source biased? Is the accuracy of the source observations questionable? Is the source known to be generally unreliable? Has the source been cited correctly? Does the source’s claim conflict with expert opinion? Can the source’s claim be settled by an appeal to expert opinion? Is the claim highly improbable on its face? Tips

27 Genetic Fallacy Genetic Fallacy To attack the argument not in terms of its content but in terms of its origins. Example: All claims of the Freemasons can be safely ignored. The Freemasons are just an ancient trade union movement warmed up for modern times. Arguing with – A is wrong because it has origins which Should be ignored. No reason is given. Reason

28 Drawing a general conclusion from a sample that
Hasty Generalization Hasty Generalization Drawing a general conclusion from a sample that is biased or too small. Example: Norwegians are lazy. I have two friends who are from there, and both of them never prepare for class, or do their homework. 1. A biased sample is one that is not representative of the target population. 2. The target population is the group of people or things that the generalization is about. 3. Hasty generalizations can often lead to false stereotypes. Pattern

29 Argument from Ignorance
Claiming that something is true because no one has proven it false or vice versa. Example: Yoda must exist. No one has proved that he doesn’t exist. Agree I do! “Not proven, therefore false” If such reasoning were allowed, we could prove almost any conclusion. Remember

30 Equivocation Equivocation When an arguer uses a key word in an argument in two (or more) different senses. Example: In the summer of 1940, Londoners were bombed almost very night. To be bombed is to be intoxicated. Therefore, in the summer of 1940, Londoners were intoxicated almost every night. Fallacies of Equivocation can be difficult to spot because they often appear valid, but they aren’t. Remember

31 Affirming the Consequent and Denying the Antecedent
Any argument that takes the following form is a non sequitur If A is true, then B is true. B is stated to be true. Therefore, A must be true. Even if the premises and conclusion are all true, the conclusion is not a necessary consequence of the premises. This sort of non sequitur is also called affirming the consequent. An example of affirming the consequent would be: If I am a human (A) then I am a mammal. (B) I am a mammal. (B) Therefore, I am a human. (A) "I" could be another type of mammal without being a human. While the conclusion may be true, it does not follow from the premises. This argument is still a fallacy even if the conclusion is true. It is a non sequitur.

32 Affirming the Consequent and Denying the Antecedent
Another common non sequitur is this: If A is true, then B is true. A is stated to be false. Therefore B must be false. While the conclusion can indeed be false, this cannot be linked to the premise since the statement is a non sequitur. This is called denying the antecedent. An example of denying the antecedent would be: If I am in Tokyo, I am in Japan. I am not in Tokyo. Therefore, I am not in Japan. Whether or not the speaker is in Japan cannot be derived from the premise. He could either be outside Japan or anywhere in Japan except Tokyo.

33 Bibliography Aristotle, On Sophistical Refutations, De Sophistici Elenchi. William of Ockham, Summa of Logic (ca. 1323) Part III.4. John Buridan, Summulae de dialectica Book VII. Francis Bacon, the doctrine of the idols in Novum Organum Scientiarum, Aphorisms concerning The Interpretation of Nature and the Kingdom of Man, XXIIIff. The Art of Controversy | Die Kunst, Recht zu behalten - The Art Of Controversy (bilingual), by Arthur Schopenhauer (also known as "Schopenhauers 38 stratagems") John Stuart Mill, A System of Logic - Raciocinative and Inductive. Book 5, Chapter 7, Fallacies of Confusion. C. L. Hamblin, Fallacies. Methuen London, 1970. Fearnside, W. Ward and William B. Holther, Fallacy: The Counterfeit of Argument, 1959. Vincent F. Hendricks, Thought 2 Talk: A Crash Course in Reflection and Expression, New York: Automatic Press / VIP, 2005, ISBN D. H. Fischer, Historians' Fallacies: Toward a Logic of Historical Thought, Harper Torchbooks, Douglas N. Walton, Informal logic: A handbook for critical argumentation. Cambridge University Press, 1989. F. H. van Eemeren and R. Grootendorst, Argumentation, Communication and Fallacies: A Pragma-Dialectical Perspective, Lawrence Erlbaum and Associates, 1992. Warburton Nigel, Thinking from A to Z, Routledge 1998. T. Edward Damer. Attacking Faulty Reasoning, 5th Edition, Wadsworth, ISBN Sagan, Carl, "The Demon-Haunted World: Science As a Candle in the Dark". Ballantine Books, March 1997 ISBN pgs hardback edition: Random House, ISBN X, xv+457 pages plus addenda insert (some printings). Ch.12. Wikipedia-Fallacies- Zaid Ali Allsagoff- Fallacies -

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