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Logical Fallacies FAQ

Alphabetical Index

• Logical Fallacies
• Alphabetical Index
• Fallacies of Analogy
• Fallacies of Ambiguity
• Fallacies of Relevance
• Fallacies of Presumption
• Appeals to Emotion
• Ad Hominem Fallacies
• Appeals to Authority

• Skepticism FAQs
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Fallacies are defects in an argument - other than false premises - which cause an argument to be invalid, unsound, or weak. In a deductive argument, the existence of a fallacy means that the argument is not valid. Because of this, even if the premises are true, the conclusion might still be false. Nevertheless, the existence of a fallacy does not guarantee that it is false; a fallacious argument merely fails to provide a good reason to believe the conclusion, even if that conclusion is correct.

In an inductive argument, the existence of a fallacy weakens it. Inductive arguments, no matter how strong, cannot guarantee the truth of a conclusion in the same way that deductive arguments can. No matter how weak an inductive argument is, the conclusion might still be true - but if it is weak, you have little reason to believe that conclusion.

Fallacies can be separated into two general groups: formal and informal. A formal fallacy is a defect which can be identified merely be looking at the logical structure of an argument rather than any specific statements. Informal fallacies are defects which can be identified only through an analysis of the actual content of the argument rather than through its structure.

Below is a list of all of the fallacies, formal and informal, which are cataloged and explained on this site. More are added regularly, so keep checking back over time.

Abusive ad hominem
Ambiguity (index)
Age, Appeal to
Authority, Appeals to (4 types)
Authority, Legitimate Appeal to
Ad Hominem (5 types)
Begging the Question
Circumstantial ad hominem
Complex Question
Correlation vs. Causation
Emotion and Desire, Appeals to (5 types)
False Dilemma
Flatter, Appeal to
Force / Fear, Appeal to (Argumentum ad Baculum)
Genetic Fallacy
Illicit Observation
Novelty, Appeal to
No True Scotsman
Numbers, Appeal to
Money, Appeal to
Oversimplification and Exaggeration
Pity, Appeal to (Argumentum ad Misercordiam)
Poisoning the Well
Poverty, Appeal to
Quantifier Fallacy
Quoting out of Context
Reification / Hypostatization
Fallacies of Relevance (index)
Scope Fallacy
Suppressed Evidence
Tradition, Appeal to
Tu Quoque (two wrongs don't make a right)
Unqualified Authority, Appeal to


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