FALLACIES CHAPTERS 8 & 9. DEDUCTIVE REASONING From general to specific; have a law, premise, or principle Insert a specific fact or event regarding that.

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Presentation transcript:

FALLACIES CHAPTERS 8 & 9

DEDUCTIVE REASONING From general to specific; have a law, premise, or principle Insert a specific fact or event regarding that law Come to a conclusion about that specific fact or event Stated in the form of SYLLOGISM

FORMAT OF SYLLOGISM Major premise = statement of law or principle Minor premise = application of law to specific facts Conclusion = derived from premises

DEDUCTIVE SYLLOGISMS DENYING THE CONSEQUENT AFFIRMING THE ANTECEDENT DISJUNCTIVE SYLLOGISM APPLYING A GENERALIZATION APPLYING AN EXCEPTION TRANSITIVITY RELATIONSHIP (HYOTHETICAL SYLLOGISM) REFLEXIVITY RELATIONSHIP IDENTITY RELATIONSHIP

DENYING THE CONSEQUENT Major Premise: If A then B Minor Premise: Not B Conclusion: Therefore, not A If Richard graduate with honors, then Richard maintained a GPA of 3.2 or higher. Richard did not maintain a GPA of 3.2 or higher Richard did not graduate with honors

AFFIRMING THE ANTECEDENT Major Premise: If A then B Minor Premise: A Conclusion: Therefore, B If you are eligible to graduate with honors, you will get a Registrar’s notification You are eligible to graduate with honors So you will get a Registrar’s notification If the sun shines on the far side of the moon, then carrier pigeons are raised in Denver The sun shines on the far side of the moon Therefore, carrier pigeons are raised in Denver.

DISJUNCTIVE SYLLOGISM Either A or B Not A Therefore, B Either Romney won the presidency in 2012 or Obama did. Romney didn’t win. Therefore, Obama did win.

APPLYING A GENERALIZATION Major Premise: Every member of F is a member of G. Minor Premise: Individual object X is a member of F. Conclusion: So, X is a member of G. Every student in this class is a Medical Assisting Major. Janelly is in this class. So Janelly is a Medical Assisting major.

APPLYING AN EXCEPTION Major Premise: Every F is a G. Minor Premise: The object X is not a G. Conclusion: So X is not an F. Attic insulation installers run the risk of lung disease. Angela and Jennifer do not run the risk of lung disease. So Angela and Jennifer do not install attic insulation.

TRANSITIVITY RELATIONSHIP (HYPOTHETICAL SYLLOGISM) If A then B If B then C If A then C If I do not wake up, then I cannot go to work. If I cannot go to work, then I will not get paid. Therefore, if I do not wake up, then I will not get paid. Tom is taller than John. John is taller than Mark. So Tom is taller than Mark. All men are mortal Socrates is a man Therefore Socrates is mortal.

REFLEXIVITY RELATIONSHIP If X has a reflexive relationship to Y Then Y has the same reflexive relationship to X. Meryl Streep played Julia Child in the film Julie and Julia The actress who played Julia child in that film was nominated for an Oscar. Therefore Meryl Streep received an Oscar nomination for her performance in that film.

IDENTITY RELATIONSHIPS If X has a reflexive relationship to Y Then Y has the same reflexive relationship to X. If all bachelors are unmarried males, then all unmarried males are bachelors.

DEDUCTIVE FALLACIES Affirming the Consequent Denying the Antecedent False Classification Composition Division False Reference

AFFIRMING THE CONSEQUENT (THE HOUSE M.D. FALLACY) Major Premise: If A then B Minor Premise: B Conclusion: Therefore, A If we put a human on Mars, then we have a successful space program. We have a successful space program. Therefore we have put a human on Mars. All dogs eat meat. Bob (a human) eats meat. Therefore, Bob is dog.

DENYING THE ANTECEDENT Major Premise: If A then B Minor Premise: Not A Conclusion: Therefore, not B If we see a light in the window then someone is home. No light is in the window. Therefore, no one is home. If all college students drank red wine the wine industry would be booming. The wine industry is booming. Therefore, all college students drink red wine

FALSE CLASSIFICATION FALLACY Major Premise: A has quality X Minor Premise: B has quality X Conclusion: Therefore, A is B. Criminals enjoy mafia movies Cassandra enjoys mafia movies. Therefore, Cassandra is a criminal. See P. 159 for more examples

COMPOSITION AND DIVISION FALLACIES Mistaking a whole for the part: Attributing characteristics to the whole which are true for the part. See page 160.

FALSE REFERENCE FALLACY My Cousin Vinny: Vinny gets arrested for confessing to murder when he thought he was confessing to shoplifting a can of tuna fish. “I lost hope.” I hear that the Tour de France winter used banned performance enhancing drugs. I also heard that Cadel Evans won the 2011 Tour de France. Therefore, Evans used banned performance enhancing drugs.

EVALUATING ARGUMENTS Page 163