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Fallacies of Weak Induction
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Fallacies of Weak Induction

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Fallacies of Weak Induction Fallacies of Weak Induction Presentation Transcript

  • Fallacies of Weak Induction Wali Memon1 Wali Memon
  • Overview Fallacies of Weak Induction Appeal to Unqualified Authority Appeal to Ignorance Hasty Generalization False Cause Slippery Slope Weak Analogy2 Wali Memon
  • Introduction The key characteristic of these fallacies is that the connection between the premises and conclusion is not strong enough to support the conclusion.3 Wali Memon
  • Appeal to Unqualified Authority: Definition This fallacy occurs when the appeal is made to an authority or witness that is not trustworthy or is not qualified in that particular area.4 Wali Memon
  • Appeal to Unqualified Authority: Example We should all accept the claim that the moon is made of green cheese. After all, Dr. Ray says it is, and he’s a recognized authority in English. Comment: Ray is not qualified in the area of astronomy.5 Wali Memon
  • Appeal to Unqualified Authority: Key Question Does the arguer appeal to an authority who is actually not qualified in that area for support of his/her conclusion?6 Wali Memon
  • Appeal to Ignorance: Definition This fallacy occurs when the premises of an argument state that nothing has been proved one way or the other about something, and the conclusion then makes a definite assertion about that thing.7 Wali Memon
  • Appeal to Ignorance: Example Example: People have been trying for centuries to disprove the claims of astrology, and no one has ever succeeded. Therefore, we must conclude that the claims of astrology are true. Comment: The only justified conclusion is that we don’t know.8 Wali Memon
  • Appeal to Ignorance: Key Question Does the arguer claim something is true because no one has disproved it or that something is false because no one has proved it to be true?9 Wali Memon
  • Hasty Generalization: Definition This fallacy occurs in inductive generalizations where there is a reasonable likelihood that the sample is not representative of the group.10 Wali Memon
  • Hasty Generalization: Example Four white youths were convicted of fire bombing several historically Black churches in Alabama. The message is clear: Young white men are nothing but a pack of racist fanatics prone to violence. Comment: This draws a conclusion about a whole group on the basis of one incident.11 Wali Memon
  • Hasty Generalization: Key Question Does the speaker/author draw an inductive conclusion based on a sample that is too small or too unrepresentative?12 Wali Memon
  • False Cause: Definition This fallacy occurs whenever the link between premises and conclusion depends on some imagined causal connection that probably does not exist. Also known as Post Hoc fallacy. The name of this fallacy comes from the Latin phrase, Post Hoc, Ergo Propter Hoc, which translates as “after this, therefore caused by this.”13 Wali Memon
  • False Cause: Example During the past two months, every time that the cheerleaders have worn blue ribbons in their hair, the basketball team has been defeated. Therefore, to prevent future defeats, the cheerleaders should get rid of those blue ribbons. Comment: There’s no reason to believe wearing the ribbons caused the defeats.14 Wali Memon
  • False Cause: Key Question Does the conclusion maintain that one thing caused another when it probably did not?15 Wali Memon
  • Slippery Slope: Definition This fallacy occurs when the conclusion rests on an alleged chain reaction and there is not sufficient evidence to believe that the chain reaction will actually occur.16 Wali Memon
  • Slippery Slope: Example “Immediate steps should be taken to outlaw pornography once and for all. The continued manufacture and sale of pornographic material will almost certainly lead to an increase in sex-related crimes such as rape and incest. This in turn will gradually erode the moral fabric of society and result in an increase in crimes of all sorts. Eventually a complete disintegration of law and order will occur, leading to the the total collapse of civilization.” Comment: It’s not proved that legal pornography leads to these consequences.17 Wali Memon
  • Slippery Slope: Key Question Does the speaker/author claim that a single step will eventually lead to disastrous consequences when there is little evidence that this will actually occur?18 Wali Memon
  • Weak Analogy: Definition This fallacy occurs in some arguments from analogy in cases where the arguer ignores important differences between the types of cases used in the analogy.19 Wali Memon
  • Weak Analogy: Example “Political dissent is like a cancer in the body politic. And we all know what the best treatment for cancer is: radical surgery. So when we see dissidents, we should cut them out of society as fast as possible before they spread!” Comment: This ignores important differences between cancer and political dissent, especially: people have rights, cancer cells don’t.20 Wali Memon
  • Weak Analogy: Key Question Does the arguer introduce an analogy but ignore important differences between the two classes of things being compared?21 Wali Memon
  • Fallacies of Weak Induction Review: Appeal to Unqualified Authority Appeal to Ignorance Hasty Generalization False Cause Slippery Slope Weak Analogy22 Wali Memon