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0091 logic10 fallacies


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0091 logic10 fallacies

  1. 1. FALLACIESHow to detect erroneous statementsand arguments
  2. 2. FALLACY (…meaning)• 7.0. Fallacy – errorin reasoning; aproduct of one’sfailure to think orargue correctly
  3. 3. Categories...• Categories of Fallacy:7.1.Fallacy of Relevance:• 7.1.1. Appeal to Force/ Staff(argumentum ad baculum) -- someonein a position of power threatens tobring down unfortunate consequencesupon anyone who dares to disagreewith a proffered proposition. (Ex. If youdo not agree with my political opinions,you will receive a grade of F for thiscourse.)
  4. 4. Cont’n• 7.1.2. Appeal to Pity (argumentumad misericordiam) -- tries to winacceptance by pointing out theunfortunate consequences thatwill otherwise fall upon thespeaker and others, for whom wewould then feel sorry.• (Example: I am a single parent,solely responsible for the financialsupport of my children; If you giveme this traffic ticket, I will lose mylicense and be unable to drive towork.)
  5. 5. Cont’n• 7.1.3. Appeal to Emotion(argumentum ad populum) --relies upon emotively chargedlanguage to arouse strongfeelings that may lead anaudience to accept itsconclusion
  6. 6. Cont’n• 7.1.4. Appeal to Authority (argumentumad verecundiam) --involves the mistakensupposition that there is someconnection between the truth of aproposition and some feature of theperson who asserts or denies it; theopinion of someone famous oraccomplished in another area ofexpertise is supposed to guarantee thetruth of a conclusion. As a pattern ofreasoning, this is clearly mistaken: noproposition must be true because someindividual (however talented orsuccessful) happens to believe it.
  7. 7. Fallacy cont’n…• 7.1.5. Ad Hominem Argument -- we areencouraged to reject a proposition becauseit is the stated opinion of someone regardedas disreputable in some way• 7.1.6. Appeal to Ignorance (argumentum adignoratiam) -- proposes that we accept thetruth of a proposition unless an opponentcan prove otherwise. (Example: No one hasconclusively proven that there is nointelligent life on the moons of Jupiter.Therefore, there is intelligent life on themoons of Jupiter.)
  8. 8. Cont’n…• 7.1.7. Irrelevant Conclusion(ignoratio elenchi) -- tries toestablish the truth of a propositionby offering an argument thatactually provides support for anentirely different conclusion.(Example:All children should haveample attention from their parents;Parents who work full-time cannotgive ample attention to theirchildren; Therefore, mothers shouldnot work full-time)
  9. 9. Fallacies of Ambiguity• 7.2.1. Equivocation -- trades upon theuse of an ambiguous word or phrase inone of its meanings in one of thepropositions of an argument but alsoin another of its meanings in a secondproposition. Example: Really excitingnovels are rare; But rare books areexpensive; Therefore, expensive thingsare really exciting novels.
  10. 10. Cont’n• 7.2.2. Amphiboly -- can occur evenwhen every term in an argument isunivocal, if the grammaticalconstruction of a sentence createsits own ambiguity. (Example: Areckless motorist Thursday struckand injured a student who wasjogging through the campus in hispickup truck. Therefore, it is unsafeto jog in your pickup truck).
  11. 11. Cont’n• 7.2.3. Accent -- the fallacy ofaccent arises from an ambiguityproduced by a shift of spoken orwritten emphasis (Ex. Desert –double meaning).
  12. 12. Cont’n• 7.2.4. Composition -- involves aninference from the attribution ofsome feature to every individualmember of a class (or part of agreater whole) to the possessionof the same feature by the entireclass (or whole). [Ex.: "Myphilosophy course was well-organized; therefore, collegecourses are well-organized."]
  13. 13. Cont’n• 7.2.5. Division -- involves aninference from the attribution ofsome feature to an entire class (orwhole) to the possession of thesame feature by each of itsindividual members (or parts).(Example: Tamaraws are now dyingout; Kolokoy is a Tamaraw;Therefore, Kolokoy is now dyingout)
  14. 14. Exercises (1-10)• What fallacies are involved in the ff?:• 1) The suspect was begging forforgiveness after he was apprehended bythe police in the snatching incident lastweek along the University belt.2) A certain Barbara Fields was arrestedinside a mall after she was identified asthe culprit after the victim told thesecurity guards that the person who tookher cell phone was wearing jeans andblack shirt..
  15. 15. Cont’n• 3) The Barangay Captain was givena stern warning by the Mayor ofthe town not talk about the brawlinvolving the latter’s two sonsduring the town fiesta.4) Manny Pacquiao would neverwin in any Congressional electionbecause he is not highly educatedcompared to his political rivals.
  16. 16. Cont’n• 5) Where did the Governors bring themoney given them by the President duringthe visit in the Palace?• 6) All the apostles are faithful followers ofthe Lord. Therefore, Judas Iscariot is afaithful follower of the Lord being anapostle.• 7) The reason why the Bar topnotcher gotthe plum was because she took herundergraduate course from the Jesuituniversity known for its excellent education.
  17. 17. Cont’n• 8) Some Filipinos are servants ordomestic helpers in foreign lands.Therefore, all Filipinos are servantsor domestic helpers.• 9) She failed to win the World’s QuizBee because she missed to pray thenovena to St. Jude.• 10) The head of the state was mad athis critics after the former read inthe news he was the butt of joke inthe latter’s party conventionEND OF THETOPIC