Baronett, Logic (4 Ed.) Chapter Guide Chapter 4: Informal Fallacies
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Argumentation and Fallacies in Creationist Writings Against Evolutionary Theory Petteri Nieminen1,2* and Anne-Mari Mustonen1
Nieminen and Mustonen Evolution: Education and Outreach 2014, 7:11 http://www.evolution-outreach.com/content/7/1/11 RESEARCH ARTICLE Open Access Argumentation and fallacies in creationist writings against evolutionary theory Petteri Nieminen1,2* and Anne-Mari Mustonen1 Abstract Background: The creationist–evolutionist conflict is perhaps the most significant example of a debate about a well-supported scientific theory not readily accepted by the public. Methods: We analyzed creationist texts according to type (young earth creationism, old earth creationism or intelligent design) and context (with or without discussion of “scientific” data). Results: The analysis revealed numerous fallacies including the direct ad hominem—portraying evolutionists as racists, unreliable or gullible—and the indirect ad hominem, where evolutionists are accused of breaking the rules of debate that they themselves have dictated. Poisoning the well fallacy stated that evolutionists would not consider supernatural explanations in any situation due to their pre-existing refusal of theism. Appeals to consequences and guilt by association linked evolutionary theory to atrocities, and slippery slopes to abortion, euthanasia and genocide. False dilemmas, hasty generalizations and straw man fallacies were also common. The prevalence of these fallacies was equal in young earth creationism and intelligent design/old earth creationism. The direct and indirect ad hominem were also prevalent in pro-evolutionary texts. Conclusions: While the fallacious arguments are irrelevant when discussing evolutionary theory from the scientific point of view, they can be effective for the reception of creationist claims, especially if the audience has biases. Thus, the recognition of these fallacies and their dismissal as irrelevant should be accompanied by attempts to avoid counter-fallacies and by the recognition of the context, in which the fallacies are presented. -
CHAPTER XXX. of Fallacies. Section 827. After Examining the Conditions on Which Correct Thoughts Depend, It Is Expedient to Clas
CHAPTER XXX. Of Fallacies. Section 827. After examining the conditions on which correct thoughts depend, it is expedient to classify some of the most familiar forms of error. It is by the treatment of the Fallacies that logic chiefly vindicates its claim to be considered a practical rather than a speculative science. To explain and give a name to fallacies is like setting up so many sign-posts on the various turns which it is possible to take off the road of truth. Section 828. By a fallacy is meant a piece of reasoning which appears to establish a conclusion without really doing so. The term applies both to the legitimate deduction of a conclusion from false premisses and to the illegitimate deduction of a conclusion from any premisses. There are errors incidental to conception and judgement, which might well be brought under the name; but the fallacies with which we shall concern ourselves are confined to errors connected with inference. Section 829. When any inference leads to a false conclusion, the error may have arisen either in the thought itself or in the signs by which the thought is conveyed. The main sources of fallacy then are confined to two-- (1) thought, (2) language. Section 830. This is the basis of Aristotle's division of fallacies, which has not yet been superseded. Fallacies, according to him, are either in the language or outside of it. Outside of language there is no source of error but thought. For things themselves do not deceive us, but error arises owing to a misinterpretation of things by the mind. -
Proving Propositional Tautologies in a Natural Dialogue
Fundamenta Informaticae xxx (2013) 1–16 1 DOI 10.3233/FI-2013-xx IOS Press Proving Propositional Tautologies in a Natural Dialogue Olena Yaskorska Institute of Philosophy and Sociology, Polish Academy of Sciences, Warsaw, Poland Katarzyna Budzynska Institute of Philosophy and Sociology, Polish Academy of Sciences, Warsaw, Poland Magdalena Kacprzak Department of Computer Science, Bialystok University of Technology, Bialystok, Poland Abstract. The paper proposes a dialogue system LND which brings together and unifies two tradi- tions in studying dialogue as a game: the dialogical logic introduced by Lorenzen; and persuasion dialogue games as specified by Prakken. The first approach allows the representation of formal di- alogues in which the validity of argument is the topic discussed. The second tradition has focused on natural dialogues examining, e.g., informal fallacies typical in real-life communication. Our goal is to unite these two approaches in order to allow communicating agents to benefit from the advan- tages of both, i.e., to equip them with the ability not only to persuade each other about facts, but also to prove that a formula used in an argument is a classical propositional tautology. To this end, we propose a new description of the dialogical logic which meets the requirements of Prakken’s generic specification for natural dialogues, and we introduce rules allowing to embed a formal dialogue in a natural one. We also show the correspondence result between the original and the new version of the dialogical logic, i.e., we show that a winning strategy for a proponent in the original version of the dialogical logic means a winning strategy for a proponent in the new version, and conversely. -
Common Reasoning Mistakes
Common Fallacies (mistakes of reasoning) The fallacy fallacy • There is danger even in the study of fallacies. This study involves identifying certain patterns of reasoning as fallacies. Each pattern has a name. E.g. an argument that attacks a person is ad hominem. But ad hominem arguments are not always fallacies! • Rejecting an argument as a (named) fallacy, based on its pattern alone, is a fallacy that we might call the fallacy fallacy. • In general, an ad hominem is only legitimate when attacking an argument from authority. • But not all such attacks on authority are legitimate. They can be made on irrelevant grounds. Irrelevant ad hominem E.g. Einstein’s physics was attacked on the basis of Einstein being Jewish. Thomas Powers, Heisenberg’s War, p. 41 Fallacy? • Alliance leader Stockwell Day argues that Canada should increase its military expenditure now, by at least 20%, in order to continue to meet our NATO obligations five years from now. But Day is a fundamentalist who thinks the universe is only 6,000 years old! Clearly his view can be dismissed. • Mr. Wilson, in his letter of January 16, argues that it would be counter-productive to yield to the demands of the hostage takers. He does not, I take it, have a son or daughter among the hostages. As such a parent, I am repelled by his callous attitude. My daughter could well be the next innocent victim of these terrorists, but Wilson apparently doesn’t give a damn about this. 1. Comment on the following ad hominem (to the person) arguments, explaining why they are, or are not, reasonable. -
Explicit Examples of Logical Fallacies in Love Is a Fallacy by Max Shulman Foundations – Part of the Easy Peasy All-In-One Homeschool
Explicit examples of logical fallacies in Love is a Fallacy by Max Shulman Foundations – Part of the Easy Peasy All-in-One Homeschool A dicto simpliciter ("an argument based on an unqualified generalization") - the example given in the story is: Exercise is good. Therefore everybody should exercise. Hasty generalization (or "fallacy of insufficient sample") - example given in the story is “You can speak French, I can't speak French, Petey Burch can't speak French. I must therefore conclude that nobody at the University of Minnesota can speak French.” If most of the people the author (Dobie Gillis) knows cannot speak French he concludes that no one at the college can speak French. OR "My dear," I said, favoring her with a smile, "we have now spent five evenings together. We have gotten along, splendidly. It is clear that we are well matched." Post hoc ergo propter hoc ("after it, therefore because of it", or "confusing coincidental relationships with cause") - from the story: “Let's not take Bill on our picnic. Every time we take him out with us, it rains.” Contradictory Premises ("self-contradiction") - from the story: I do not see the contradictory premise in this story. The main contradiction would be that the author (Dobie Gillis) begins the story believing that love is logical and can be won through logic. However, the end of the story proves that love is not logical and Dobie’s original belief was a fallacy. Ad Misericordiam ("appeal to pity") - example given in the story: "A man applies for a job. When the boss asks him what his qualifications are, he replies the he has wife and six children at home, the wife is a helpless cripple, the children have nothing to eat, no clothes to wear, no shoes on their feet, there are no beds in the house, no coal in the cellar, and winter is coming." OR “Polly, I love you. -
334 CHAPTER 7 INFORMAL FALLACIES a Deductive Fallacy Is
CHAPTER 7 INFORMAL FALLACIES A deductive fallacy is committed whenever it is suggested that the truth of the conclusion of an argument necessarily follows from the truth of the premises given, when in fact that conclusion does not necessarily follow from those premises. An inductive fallacy is committed whenever it is suggested that the truth of the conclusion of an argument is made more probable by its relationship with the premises of the argument, when in fact it is not. We will cover two kinds of fallacies: formal fallacies and informal fallacies. An argument commits a formal fallacy if it has an invalid argument form. An argument commits an informal fallacy when it has a valid argument form but derives from unacceptable premises. A. Fallacies with Invalid Argument Forms Consider the following arguments: (1) All Europeans are racist because most Europeans believe that Africans are inferior to Europeans and all people who believe that Africans are inferior to Europeans are racist. (2) Since no dogs are cats and no cats are rats, it follows that no dogs are rats. (3) If today is Thursday, then I'm a monkey's uncle. But, today is not Thursday. Therefore, I'm not a monkey's uncle. (4) Some rich people are not elitist because some elitists are not rich. 334 These arguments have the following argument forms: (1) Some X are Y All Y are Z All X are Z. (2) No X are Y No Y are Z No X are Z (3) If P then Q not-P not-Q (4) Some E are not R Some R are not E Each of these argument forms is deductively invalid, and any actual argument with such a form would be fallacious. -
35. Logic: Common Fallacies Steve Miller Kennesaw State University, [email protected]
Kennesaw State University DigitalCommons@Kennesaw State University Sexy Technical Communications Open Educational Resources 3-1-2016 35. Logic: Common Fallacies Steve Miller Kennesaw State University, [email protected] Cherie Miller Kennesaw State University, [email protected] Follow this and additional works at: http://digitalcommons.kennesaw.edu/oertechcomm Part of the Technical and Professional Writing Commons Recommended Citation Miller, Steve and Miller, Cherie, "35. Logic: Common Fallacies" (2016). Sexy Technical Communications. 35. http://digitalcommons.kennesaw.edu/oertechcomm/35 This Article is brought to you for free and open access by the Open Educational Resources at DigitalCommons@Kennesaw State University. It has been accepted for inclusion in Sexy Technical Communications by an authorized administrator of DigitalCommons@Kennesaw State University. For more information, please contact [email protected]. Logic: Common Fallacies Steve and Cherie Miller Sexy Technical Communication Home Logic and Logical Fallacies Taken with kind permission from the book Why Brilliant People Believe Nonsense by J. Steve Miller and Cherie K. Miller Brilliant People Believe Nonsense [because]... They Fall for Common Fallacies The dull mind, once arriving at an inference that flatters the desire, is rarely able to retain the impression that the notion from which the inference started was purely problematic. ― George Eliot, in Silas Marner In the last chapter we discussed passages where bright individuals with PhDs violated common fallacies. Even the brightest among us fall for them. As a result, we should be ever vigilant to keep our critical guard up, looking for fallacious reasoning in lectures, reading, viewing, and especially in our own writing. None of us are immune to falling for fallacies. -
Better Thinking and Reasoning Chapter 11 Test Answer
Name ________________________________ Better Thinking and Reasoning Chapter 11 Test Page 1 Answer each question. 1. Define formal fallacy. an error in the form of reasoning (caught by using a truth table) 2. Define informal fallacy. an error in the relationship of the premises (caught by examining context) 3. When is a valid argument unsound? when it has a false premise 4. What should you always do after you have completed your essay? rewrite it and check it for logical fallacies Classify the informal fallacy in each deductive argument as accident, begging the question, composition, division, or equivocation. 5. Anyone who thrusts a knife into another person should be arrested on the grounds of attempted murder. Since surgeons regularly put knives into their victims, they should be arrested for attempted murder. accident 6. Every atom in this chair is invisible. Therefore, the chair is invisible. composition 7. Please be quiet. You are making far too much noise. begging the question 8. A watermelon is a fruit. Therefore, a small watermelon is a small fruit. equivocation 9. The average American family has 2.4 children. The Smiths are an average American family. Therefore the Smiths have 2.4 children. division Classify each deductive argument as displaying a false dichotomy or having one of these three formal fallacies: affirming the consequent, denying the antecedent, or improper negation. 10. If your pet is a whale or a dolphin, then your pet is a mammal. Judy is not a mammal. Therefore, Judy is not a whale or not a dolphin. improper negation 11. If Probst won the election, then we would have a Democrat for mayor. -
Inductive Arguments: Fallacies ID1050– Quantitative & Qualitative Reasoning Analyzing an Inductive Argument
Inductive Arguments: Fallacies ID1050– Quantitative & Qualitative Reasoning Analyzing an Inductive Argument • In an inductive argument, the conclusion follows from its premises with some likelihood. • Inductive arguments can be strong, weak, or somewhere between. • Ways to attack an inductive argument: • Introduce additional (contradictory) premises that weaken the argument. • Question the accuracy of the supporting premises. • Identify one (or more) logical fallacies in the argument. What is a Fallacy? • A logical fallacy is an error in reasoning in an argument. • Formal fallacy • A ‘formal fallacy’ is an error in the structure of an argument. • Formal fallacies are used to analyze deductive arguments for validity by means of symbolic logic. • Informal fallacy • An ‘informal fallacy’ is an error in the content of an argument. • This is the type of fallacy that will be discussed in this presentation. • An argument with a fallacy is said to be ‘fallacious’. Formal and Informal Fallacies • Formal fallacy example: • All humans are mammals. All dogs are mammals. So, all humans are dogs. • This argument has a structural flaw. The premises are true, but they do not logically lead to the conclusion. This would be uncovered by the use of symbolic logic. • Informal fallacy example: • All feathers are light. Light is not dark. So, all feathers are not dark. • The structure of this argument is actually correct. The error is in the content (different meanings of the word ‘light’.) It uses a fallacy called ‘Equivocation’. Lists of Fallacies • There are a great number of identified fallacies of the informal type. Following are some good websites that list them and provide definitions and examples. -
Alabama State University Department of Languages and Literatures
ALABAMA STATE UNIVERSITY DEPARTMENT OF LANGUAGES AND LITERATURES COURSE SYLLABUS PHILOSOPHY 201 LOGICAL REASONING (PHL 201) (Revised 10/20/04 – Dr. Daniel Keller.) I. Faculty Listing: PHL 201: Logical Reasoning (3 credit hours) II. Description: To satisfactorily complete the course, a student must earn a grade of “C.” The course is designed to help students assess information and arguments and to improve their ability to reason in a clear and logical way. The course concentrates specifically on helping students learn some of the various uses of languages, understand how different kinds of inferences are drawn, and learn to recognize fallacies of ambiguity, presumption, and relevance. III. Purpose: Many students do not reason soundly and do not distinguish correct from incorrect reasoning. Hence, the aim of this course is to give students experience in learning to recognize and evaluate arguments; it also aims at teaching them to construct arguments that are reasonable and defensible. It is designed as a basic course to improve the reasoning skills of students. After completing this course successfully, students should show improvements in reading comprehension, writing, and test- taking skills. IV. Course Objectives: 1. Comprehend concepts 1-9 on the attached list. a) Define each concept b) Identify the meaning of each concept as it applies to logic. 2. Comprehend how these concepts function in logical reasoning. a) Given examples from the text of each concept, correctly identify the concept. b) Given new examples of each concept, correctly identify the concept. 3. Comprehend concepts 10-16 on the attached list. a) Define the concepts b) Identify the meaning of the concept as it applies to logic. -
Fallacy: a Defect in an Argument That Arises from a Mistake in Reasoning Or the Creation of an Illusion That Makes a Bad Argument Appear Good
Fallacy: A defect in an argument that arises from a mistake in reasoning or the creation of an illusion that makes a bad argument appear good. There are two kinds of fallacy: • Formal fallacy: Detectable by analyzing the form of an argument • Informal fallacy: Detectable only by analyzing the content of an argument Fallacies of Relevance: The premises are not relevant to the conclusion: • Appeal to force: Arguer threatens the reader/ listener. • Appeal to pity: Arguer elicits pity from the reader/ listener. • Appeal to the people (Ad Populum): Arguer incites a mob mentality ( direct form) or appeals to our desire for security, love, or respect ( indirect form). This fallacy includes appeal to fear, the bandwagon argument, appeal to vanity, appeal to snobbery, and appeal to tradition. • Argument against the person (Ad hominems): -Arguer personally attacks an opposing arguer by verbally abusing the opponent ( ad hominem abusive) – Presenting the opponent as predisposed to argue as he or she does ( ad hominen circumstantial), or by – Presenting the opponent as a hypocrite ( tu quoque). For ad hominem to occur, there must be two arguers. • Accident: A general rule is applied to a specific case it was not intended to cover. • Straw man: Arguer distorts an opponent’s argument and then attacks the distorted argument. N ote: For this fallacy to occur, there must be two arguers. • Missing the point: Arguer draws a conclusion different from the one supported by the premises. N ote: Do not cite this fallacy if another fallacy fits. • Red herring: Arguer leads the reader/ listener off the track. Fallacies of Weak Induction: The premises may be relevant to the conclusion, but they supply insufficient support for the conclusion: • Appeal to unqualified authority: Arguer cites an untrustworthy authority. -
Formal Fallacies
First Steps in Formal Logic Handout 16 Formal Fallacies A formal fallacy is an invalid argument grounded in logical form. Validity, again: an argument is valid iff the premises could not all be true yet the conclusion false; or, a rule of inference is valid iff it cannot lead from truth to falsehood, i.e. if the infer- ence preserves truth. The semantic turnstile ‘⊧’ indicates validity, so where P is the set of premises and C is the conclusion, P ⊧ C. We can also say that C is a ‘logical consequence’ of, or follows from, P. In a fallacious argument, this may seem to be the case, but P ⊭ C. There are also many informal fallacies (e.g., begging the question: petitio principii) that do not preserve truth either, but these are not grounded in logical form. Fallacies of Propositional Logic (PL) (1) Affirming the Consequent: φ ⊃ ψ, ψ ⊦ φ Examples: (a) ‘If Hume is an atheist, then Spinoza is an atheist too. Spinoza is an atheist. So, Hume is an atheist.’ (b) ‘If it rains, the street is wet. The street is wet. So it rains.’ (2) Denying the Antecedent: φ ⊃ ψ, ~φ ⊦ ~ψ Examples: (a) ‘If Locke is a rationalist, then Spinoza grinds lenses for a living. But Locke is not a rationalist. So, Spinoza does not grind lenses for a living.’ (b) ‘If it rains, the street it wet. It does not rain. So the street is not wet.’ Affirming the consequent and denying the antecedent are quite common fallacies. They ignore that the material implication lacks an intrinsic connection between antecedent and consequent.