Logical Fallacies

Says something must be true because it has not been proved false, OR something must be false because it has not been proven true.

Appeal to ignorance

Assumes that one event will automatically lead to a chain of increasingly serious events, without enough evidence that the chain will actually occur.

Slippery slope

Presents only 2 choices when there are actually other possibilities.

We overlook the alternatives that exist between the extremes of two poles.

False alternatives; false dilemma

Makes a broad conclusion based too little evidence or too few examples (e.g. if we draw a conclusion based on an exceptional case, a very small sample, or a biased sample, we may have overgeneralized).

Hasty generalizations

Compares two things that are not similar enough for the comparison to support the conclusion.

Questionable analogies

No one has proven that animals dream, so they must not dream.

Appeal to ignorance

If one student gets an extension, soon everyone will want extensions and deadlines will stop mattering.

Slippery slope

Any experience that does not kill you will make you stronger.

False alternatives/false dilemma

Boys raised by single mothers are effeminate because that’s what happened to my cousin Michael.

Hasty generalizations

When you put a bridge girder under too much stress, it breaks. The same thing happens with people.

Questionable analogies

Attacking the source instead of addressing the evidence itself

Ad hominem

attacking a person's characteristics (calling them s…, insulting appearance, race, ethnicity, sexual orientation, etc.) instead of their argument.

Ad hominem–abusive

dismissing someone's argument because of their circumstances/self-interest (e.g., "she only says the policy is unfair to women because she'd benefit" — irrelevant to whether her reasons are good).

Ad hominem–circumstantial

Claiming a belief/practice is right because it has a long history

Appeal to tradition

Denying a general pattern/statistic based on one known counterinstance.

Fallacy of anecdotal evidence

Reformulating someone's argument into a more extreme, easier-to-attack version, then refuting that instead of their actual claim.

Straw man

Embedding a controversial, unproven assumption inside a question so that any direct answer confirms the assumption.

Complex question

A special case of false dilemma: rejecting a proposal because it won't achieve a perfect outcome — as if the only options are "perfect" or "nothing."

Perfectionist fallacy