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Common Logical Fallacies

The following are commonly used elements of argumentation that tend to weaken arguments by diverging from logical approaches to the support of claims (i.e., the use of evidence). Note, however, the Fallacy FallacyJust because an argument contains a fallacy does not necessarily mean that the argument’s claim is invalidated. Many of the following fallacies represent argumentative tactics that can be effective, but not necessarily in isolation.

Ad Hoc Rescue
Explaining away a challenge to a claim or belief without presenting evidence or thorough reasoning supporting the defense; modifying a belief “on the fly.”

Ad Hominem Attack
Aggressive behavior against the opposition’s identity instead of argument concerning the issue under discussion.

Affirming the Consequent
Assuming a phenomenon has a cause with which you are familiar.

Appeal to Authority
Suggesting that because someone in authority says it, it must be true.

Appeal to Fear
Suggesting threat in order to manipulate the hearer’s emotions toward your side.

Appeal to Novelty
Suggesting that because something is new, it must be better or true.

Appeal to Personal Bias
Highlighting things about a subject that activate your audience’s liking or disliking, but are separate from the issue under discussion.

Appeal to Pity
Highlighting things about a subject that activate the audience’s humanistic emotions, eclipsing logical and/or ethical elements of the decision making process.

Appeal to Ridicule
Avoiding challenges to rationale by simplistically characterizing opposing viewpoints as absurd.

Appeal to Tradition
Suggesting that because it has been done/believed for a long time, it must be good/true.

Bandwagon Fallacy
Suggesting that because many do/believe it, the audience should, too.

Burden of Proof Fallacy
Deflecting responsibility for providing supporting evidence by suggesting that the opposition is responsible for providing challenging evidence instead.

Circular Reasoning
The process of concluding that something is true depends on already believing that thing to be true.

Confirmation Bias
Information challenging a desired conclusion is ignored in the information gathering process; information confirming the conclusion is privileged.

Cum Hoc Ergo Propter Hoc
Suggesting that because two phenomena occurred at the same time and/or place, one must have caused the other.

False Dichotomy
Suggesting there are only two sides to an issue.

False Equivalence
Suggesting opposing sides are equally right/wrong or guilty/not guilty of error.

Ecological Fallacy
Suggesting that because the group appears to display an attribute, the members must also display that attribute, or vice versa.

Gambler’s Fallacy
Suggesting that phenomena will occur again because they have occurred in the past.

Genetic Fallacy
Suggesting a claim is true/untrue merely because of its source.

Perfection Fallacy
Rejecting a policy or argument because it does not address problems perfectly.

Post Hoc Ergo Propter Hoc
Suggesting that because one event followed another, it must have been caused by the prior event.

Slippery Slope Fallacy
Suggesting a current observed phenomenon can only grow in intensity.

Straw Man Argument
Arguing against a simplified version of the opposition’s argument.

Two Wrongs Don’t Make A Right
Suggesting that because your opponent committed an error, it gives you a pass to commit the same error.