Logical Fallacies

LogFall

A practical logical-fallacies reference with clear explanations, usable examples, and teaching tools.

Family

Linguistic/Definition Fallacy

The problem is driven by wording, ambiguity, definitions, or verbal framing rather than sound reasoning.

Entries

15 fallacies in this family.

Quick family question

What shift in wording, meaning, or definition is doing the hidden work?

Family vs. category

A family is the broad umbrella that gives a fallacy its main home. Categories are the narrower diagnostic tags, so the same fallacy can appear in multiple categories while still belonging to one family.

Contextomy

Occurs when words are selectively excerpted from their original context in a way that changes or distorts what the speaker meant.

TacticalLinguistic
Intermediate High school

Definist fallacy

Occurs when a substantive question is illegitimately 'solved' by defining one contested concept into another.

LinguisticConceptual
Intermediate High school

Equivocation

Occurs when a key word or phrase slides between different meanings inside the same argument, creating the illusion of support.

Linguistic
Foundational Middle school+

Equivocation fallacy

Occurs when a broad or harmless sense of a word is used to insinuate a narrower, stronger, or more loaded sense of the same word.

Linguistic
Intermediate High school

Etymological fallacy

Occurs when a word's original or historical meaning is treated as if it controlled the word's present meaning.

Linguistic
Intermediate High school

Fallacy of many questions

Occurs when a question smuggles in one or more assumptions that have not been established, then pressures the listener to answer as if those assumptions were already sett...

Tactical
Foundational Middle school+

If-by-whiskey

Occurs when someone uses strategically shifting language that seems to support both sides by quietly changing the meaning of the key term to suit the audience.

Tactical
Foundational Middle school+

Intentional fallacy

Occurs when the creator's intended meaning is treated as irrelevant in contexts where that intention is actually important to understanding the work or statement.

PerspectivalLinguistic
Intermediate High school

Judgmental language

Occurs when pejorative, loaded, or insulting language is used to steer judgment in place of actual support for the conclusion.

Tactical
Foundational Middle school+

No True Scotsman

Occurs when someone protects a generalization from counterexamples by redefining the group with an ad hoc 'real' or 'true' membership test.

ConceptualLinguistic
Foundational Middle school+

Proof by verbosity

Occurs when a claim is protected by an avalanche of words, side points, jargon, or branching assertions that overwhelm reasonable scrutiny and create the illusion of dept...

TacticalLinguistic
Intermediate High school

Semantic pixelization

Occurs when a fuzzy, graded, or probabilistic position is forced into unnaturally sharp categories so it becomes easier to attack.

Linguistic
Intermediate High school

Suppressed correlative

Occurs when one term in a meaningful contrast is redefined so broadly or so narrowly that its opposing term can no longer do any work.

ConceptualLinguistic
Intermediate High school

Thought-terminating cliché

Occurs when a familiar slogan or stock phrase is used to stop inquiry, deflect scrutiny, or create the feeling that an issue has already been settled.

Tactical
Foundational Middle school+

Vague insulators

Occurs when vague, elastic, or undefined terms are chosen so that a position sounds meaningful while resisting clear testing or criticism.

Tactical
Foundational Middle school+