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

      Examples

      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

    Examples:

    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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