Logical Fallacies and Concepts

Vocabulary practice cards identifying and defining common logical fallacies and reasoning errors.

Exclusivity (False Dilemma)

Assuming there are only two options (or explanations) when there might be a third.

Unique/Rare Assumption

A catch-all concept involving a specific assumption that bridges two unrelated or uncommon concepts in the stimulus with no stated connection between them.

Hasty Generalization

Drawing a broad conclusion about a group based on a small, biased, or unique sample.

Correlation for Causation

Assumes that because A and B happen together, A causes B, while ignoring coincidence or a third common cause.

Ad Hominem

Attacking the person making the argument, specifically their motives or character, rather than the argument itself.

Necessary vs. Sufficient

Treating a required condition (necessary) as if it were a guarantee (sufficient).

Numbers vs. Rates

Assuming a larger raw number means a larger percentage or likelihood, or vice versa.

Flawed Analogy

Comparing two things that are not alike in the way that matters for the conclusion.

Mistaken Reversal

An argument where, given $A \rightarrow B$, it is incorrectly concluded that $B \rightarrow A$.

Mistaken Negation

An argument where, given $A \rightarrow B$, it is incorrectly concluded that $\text{Not } A \rightarrow \text{Not } B$.

Argument from Ignorance

Reasoning that because a claim has not been proven true, it must be false, or that because it has not been proven false, it must be true.

Equivocation

Using a key word in two different ways with different definitions within the same argument.

Fallacy of Composition (Part → Whole)

Assuming that because the parts of something have a property, the whole must also have that property.

One-Sided Net Effect

Looking only at the pros or only the cons to make a decision, while ignoring the net outcome.

Fallacy of Division (Whole → Part)

Assuming that because a group or whole has a property, every member or part must have it as well.

Knowledge vs. Reality

Confusing what is known, believed, or opined with what is actually and factually true.

Quantifier Shift

Shifting the scope of a quantifier, such as moving from 'every individual has one' to 'there is one shared by all'.

Reversed Causality

Identifying a real relationship but getting the direction wrong by mistaking the effect for the cause.

Incomplete Cause

Attributing a result to one cause when that cause is not sufficient alone, thereby ignoring other necessary contributing factors.

Rejecting Conclusion (Bad Argument)

Assuming that because the argument given for a conclusion is bad, the conclusion itself must be false.

Straw Man

Distorting an opponent’s argument into a more extreme version to make it easier to attack.

Temporal Flaw

Assuming that what was true in the past will necessarily continue to be true in the future.

Misinterpreting Evidence

Misreading data or text to support a conclusion that the evidence does not actually support.

Exaggerating Conclusion

Stating a conclusion with more certainty than the evidence allows, such as treating a possibility as a definite fact.