Formal Fallacies
Formal fallacies occur when the logical structure of an argument is flawed. These errors render the argument invalid, regardless of the truth or falsity of its premises. Let’s explore some common formal fallacies along with examples:
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Affirming the Consequent:
- Description: This fallacy arises from an invalid application of the modus ponens rule.
- Logical Form: “If A, then B. B is true. Therefore, A is true.”
- Example:
- Premise 1: “If it’s raining, the ground is wet.”
- Premise 2: “The ground is wet.”
- Conclusion: “Therefore, it’s raining.”
- Issue: The conclusion does not necessarily follow from the premises.
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Denying the Antecedent:
- Description: Similar to affirming the consequent, this fallacy misapplies the modus tollens rule.
- Logical Form: “If A, then B. A is false. Therefore, B is false.”
- Example:
- Premise 1: “If it’s raining, the ground is wet.”
- Premise 2: “It’s not raining.”
- Conclusion: “Therefore, the ground is not wet.”
- Issue: The conclusion is not necessarily true based on the premises.
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Fallacy of Composition:
- Description: This fallacy assumes that what is true for parts is true for the whole.
- Example:
- Premise: “Each player on the team is skilled.”
- Conclusion: “Therefore, the entire team is skilled.”
- Issue: The collective skill of individual players does not guarantee the team’s overall skill.
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Fallacy of Division:
- Description: The opposite of the fallacy of composition, this error assumes that what is true for the whole is true for its parts.
- Example:
- Premise: “The team is skilled.”
- Conclusion: “Therefore, each player on the team is skilled.”
- Issue: The team’s overall skill does not necessarily apply to every individual player.