Informal Fallacies
When Arguments go Bad

Definition: 'Fallacy' refers to any argument which is compromised by an error either in form or content other than a false premise.

  1. Two Types of Fallacies:

    1. Formal Fallacies - (Deductive Arguments) an error in the form (or structure) of the argument


      All cats are animals. T
      All pigs are animals. T
      Therefore, all pigs are cats. F

      Any business that overcharges its customers is unethical. T
      Some unethical businesses are owned by investors. T
      Therefore, there are some investor-owned businesses that overcharge their customers. T/F

    2. Informal Fallacies - (Inductive Arguments) an error in the content of the argument


    Governments are like ships at sea.
    Sailors are not allowed to question the orders of their captain.
    Likewise, citizens should always obey the will of the government.

    Everyone I know is opposed to the legalization of marijuana.
    Therefore, most people are against the legalization of marijuana.

  2. The Types of Informal Fallacies:

    1. Fallacies of Relevance - the evidence provided is irrelevant to the conclusion

    2. Fallacies of Weak Induction - the evidence provided is insufficient or of the wrong type to warrant the conclusion

    3. Fallacies of Presumption and Ambiguity - the conclusion depends on evidence not introduced, or depends on a misunderstanding of the evidence

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