Fallacies of weak induction
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FALLACIES OF WEAK INDUCTION. CONNECTION: Connection between premises and conclusion is not strong enough to support the conclusion. SHRED OF EVIDENCE: PREMISES premises provide at least a shred of evidence in support of the conclusion. FALLACIES OF WEAK INDUCTION.

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Fallacies of weak induction
FALLACIES OF WEAK INDUCTION

  • CONNECTION:

    • Connection between premises and conclusion is not strong enough to support the conclusion.

  • SHRED OF EVIDENCE: PREMISES

    • premises provide at least a shred of evidence in support of the conclusion


Fallacies of weak induction1
FALLACIES OF WEAK INDUCTION

  • APPEAL TO UNQUALIFIED AUTHORITY (ARGUMENTUM AD VERECUNDIAM)

  • APPEAL TO IGNORANCE (ARGUMENTUM AD IGNORANTIAM)

  • HASTY GENERALIZATION (CONVERSE ACCIDENT)

  • FALSE CAUSE

  • SLIPPERY SLOPE

  • WEAK ANALOGY


ARGUMENTUM AD VERECUNDIAM: appeal to misplaced/unqualified authority

  • Based on the prestige or fame of the person endorsing the view

  • We question the credibility of the speaker regarding his statements that are not his specialization



Fallacy of weak induction
FALLACY OF WEAK INDUCTION true! That’s what our gardener said!

2. ARGUMENTUM AD IGNORANTIAM (Appeal to Ignorance)

  • Something true =

    • On the basis that it has not been proven false,

  • Something false =

    • On the basis that it has not been proven true.


    • When we lack evidence for or against a claim, it is best to suspend judgment and to admit that we don’t know!



    Argumentum ad ignorantiam
    ARGUMENTUM AD IGNORANTIAM true! That’s what our gardener said!

    • Nobody has proven that God doesn't exist; therefore God exists.

    • Nobody has proven that God exists;

      therefore God doesn't exist.

    • Nobody has proven that I am not a virgin; therefore I am a virgin!


    • drawing a conclusion about a population based on a sample that is not large enough!

    • size of the sample is too small to support the conclusion.

    • basing broad conclusions regarding the statistics of a survey from a small sample group that fails to sufficiently represent an entire population


    • After true! That’s what our gardener said!only one year the alternator went out in Mr. O’Grady’s new Aveo. Mrs. Dodson’s Cruzedeveloped a transmission problem after six months. The obvious conclusion is that cars made by General Motors are just a pile of junk these days.


    Hasty generalization
    HASTY GENERALIZATION true! That’s what our gardener said!

    • Six Arab fundamentalists were convicted of bombing the World Trade Center in New York City. The message is clear: Arabs are nothing but a pack of religious fanatics prone to violence.


    FALSE CAUSE FALLACY true! That’s what our gardener said!

    "after this, therefore because of this"


    • EFFECT = true! That’s what our gardener said!presuming the wrong cause/ disregarding the possible real cause


    • " true! That’s what our gardener said!Just because succeeding events occur one after the other in a sequence does not mean that they are usually related.


    False cause
    FALSE CAUSE true! That’s what our gardener said!

    • "Every time that I forget my umbrella, it rains, therefore I cause the rain by leaving my umbrella at home, and I can guarantee a nice day by bringing my umbrella. "


    • Suppose you get a 100% in Logic quiz every time you take a bath; you may be tempted to conclude that one event (taking a bath) has some influence on the other event (getting a 100% in the quiz). As a result, you may continue to take a bath with the thought that it is the one giving you a perfect score.


    5. bath; you may be tempted to conclude that one event (taking a bath) has some influence on the other event (getting a 100% in the quiz). As a result, you may continue to take a bath with the thought that it is the one giving you a perfect score.SLIPPERY SLOPE

    • variety of the false cause fallacy

    • conclusion of an argument rests upon an alleged chain reaction and there is not sufficient reason to think that the chain reaction will actually take place

    • E.g.

    • 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 in the end to the total collapse of civilization.


    6. WEAK ANALOGY bath; you may be tempted to conclude that one event (taking a bath) has some influence on the other event (getting a 100% in the quiz). As a result, you may continue to take a bath with the thought that it is the one giving you a perfect score.

    • conclusion depends on the existence of a similarity between two things or situations.

    • E.g.

    • Harper’s new car is bright blue, has leather upholstery, and gets excellent gas mileage. Crowley’s new car is also bright blue and has leather upholstery. Therefore, it probably gets excellent gas mileage, too.


    Weak analogy
    WEAK ANALOGY bath; you may be tempted to conclude that one event (taking a bath) has some influence on the other event (getting a 100% in the quiz). As a result, you may continue to take a bath with the thought that it is the one giving you a perfect score.

    • The flow of electricity through a wire is similar to the flow of water through a pipe. Obviously a large-diameter pipe will carry a greater flow of water than a pipe of small diameter. Therefore, a large-diameter wire should carry a greater flow of electricity than a small-diameter wire.


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