List of fallacies

A fallacy is the use of invalid or otherwise faulty reasoning in the construction of an argument. All forms of human communication can contain fallacies.

Because of their variety, fallacies are challenging to classify. They can be classified by their structure (formal fallacies) or content (informal fallacies). Informal fallacies, the larger group, may then be subdivided into categories such as improper presumption, faulty generalization, error in assigning causation, and relevance, among others.

The use of fallacies is common when the speaker's goal of achieving common agreement is more important to them than utilizing sound reasoning. When fallacies are used, the premise should be recognized as not well-grounded, the conclusion as unproven (but not necessarily false), and the argument as unsound.^[1]

A formal fallacy is an error in the argument's form.^[2] All formal fallacies are types of non sequitur.

• Appeal to probability – taking something for granted because it would probably be the case (or might possibly be the case).^[3][4]
• Argument from fallacy (also known as the fallacy fallacy) – the assumption that, if a particular argument for a "conclusion" is fallacious, then the conclusion by itself is false.^[5]
• Base rate fallacy – making a probability judgment based on conditional probabilities, without taking into account the effect of prior probabilities.^[6]
• Conjunction fallacy – the assumption that an outcome simultaneously satisfying multiple conditions is more probable than an outcome satisfying a single one of them.^[7]
• Non sequitur fallacy – where the conclusion does not logically follow the premise.^[8]
• Masked-man fallacy (illicit substitution of identicals) – the substitution of identical designators in a true statement can lead to a false one.^[9]

Informal fallacies – arguments that are logically unsound for lack of well-grounded premises.^[14]

• Argument from incredulity – when someone can't imagine something to be true, and therefore deems it false, or conversely, holds that it must be true because they can't see how it could be false.^[15]
• Argument to moderation (false compromise, middle ground, fallacy of the mean, argumentum ad temperantiam) – assuming that a compromise between two positions is always correct.^[16]
• Continuum fallacy (fallacy of the beard, line-drawing fallacy, sorites fallacy, fallacy of the heap, bald man fallacy, decision-point fallacy) – improperly rejecting a claim for being imprecise.^[17]
• Correlative-based fallacies
  • Suppressed correlative – a correlative is redefined so that one alternative is made impossible (e.g., "I'm not fat because I'm thinner than John.").^[18]
• Definist fallacy – defining a term used in an argument in a biased manner (e.g., using "loaded terms"). The person making the argument expects that the listener will accept the provided definition, making the argument difficult to refute.^[19]
• Divine fallacy (argument from incredulity) – arguing that, because something is so phenomenal or amazing, it must be the result of superior, divine, alien or paranormal agency.^[20]
• Double counting – counting events or occurrences more than once in probabilistic reasoning, which leads to the sum of the probabilities of all cases exceeding unity.
• Equivocation – using a term with more than one meaning in a statement without specifying which meaning is intended.^[21]
  • Ambiguous middle term – using a middle term with multiple meanings.^[22]
  • Definitional retreat – changing the meaning of a word when an objection is raised.^[23] Often paired with moving the goalposts (see below), as when an argument is challenged using a common definition of a term in the argument, and the arguer presents a different definition of the term and thereby demands different evidence to debunk the argument.
  • Motte-and-bailey fallacy – conflating two positions with similar properties, one modest and easy to defend (the "motte") and one more controversial (the "bailey").^[24] The arguer first states the controversial position, but when challenged, states that they are advancing the modest position.^[25][26]
  • Fallacy of accent – changing the meaning of a statement by not specifying on which word emphasis falls.
  • Persuasive definition – purporting to use the "true" or "commonly accepted" meaning of a term while, in reality, using an uncommon or altered definition.
  • (cf. the if-by-whiskey fallacy)
• Ecological fallacy – inferring about the nature of an entity based solely upon aggregate statistics collected for the group to which that entity belongs.^[27]
• Etymological fallacy – assuming that the original or historical meaning of a word or phrase is necessarily similar to its actual present-day usage.^[28]
• Fallacy of composition – assuming that something true of part of a whole must also be true of the whole.^[29]
• Fallacy of division – assuming that something true of a composite thing must also be true of all or some of its parts.^[30]
• False attribution – appealing to an irrelevant, unqualified, unidentified, biased or fabricated source in support of an argument.
  • Fallacy of quoting out of context (contextotomy, contextomy; quotation mining) – selective excerpting of words from their original context to distort the intended meaning.^[31]
• False authority (single authority) – using an expert of dubious credentials or using only one opinion to promote a product or idea. Related to the appeal to authority.
• False dilemma (false dichotomy, fallacy of bifurcation, black-or-white fallacy) – two alternative statements are given as the only possible options when, in reality, there are more.^[32]
• False equivalence – describing two or more statements as virtually equal when they are not.
• Feedback fallacy – believing in the objectivity of an evaluation to be used as the basis for improvement without verifying that the source of the evaluation is a disinterested party.^[33]
• Historian's fallacy – assuming that decision-makers of the past had identical information as those subsequently analyzing the decision.^[34] This is not to be confused with presentism, in which present-day ideas and perspectives are anachronistically projected into the past.
• Historical fallacy – believing that certain results occurred only because a specific process was performed, though said process may actually be unrelated to the results.^[35]
  • Baconian fallacy – supposing that historians can obtain the "whole truth" via induction from individual pieces of historical evidence. The "whole truth" is defined as learning "something about everything", "everything about something", or "everything about everything". In reality, a historian "can only hope to know something about something".^[36]
• Homunculus fallacy – using a "middle-man" for explanation; this sometimes leads to regressive middle-men. It explains a concept in terms of the concept itself without explaining its real nature (e.g.: explaining thought as something produced by a little thinker – a homunculus – inside the head simply identifies an intermediary actor and does not explain the product or process of thinking).^[37]
• Inflation of conflict – arguing that, if experts in a field of knowledge disagree on a certain point within that field, no conclusion can be reached or that the legitimacy of that field of knowledge is questionable.^[38][39]
• If-by-whiskey – an argument that supports both sides of an issue by using terms that are emotionally sensitive and ambiguous.
• Incomplete comparison – insufficient information is provided to make a complete comparison.
• Intentionality fallacy – the insistence that the ultimate meaning of an expression must be consistent with the intention of the person from whom the communication originated (e.g. a work of fiction that is widely received as a blatant allegory must necessarily not be regarded as such if the author intended it not to be so).^[40]
• Kettle logic – using multiple, jointly inconsistent arguments to defend a position.
• Ludic fallacy – failing to take into account that non-regulated random occurrences unknown unknowns can affect the probability of an event taking place.^[41]
• Lump of labour fallacy – the misconception that there is a fixed amount of work to be done within an economy, which can be distributed to create more or fewer jobs.^[42]
• McNamara fallacy (quantitative fallacy) – making an argument using only quantitative observations (measurements, statistical or numerical values) and discounting subjective information that focuses on quality (traits, features, or relationships).
• Mind projection fallacy – assuming that a statement about an object describes an inherent property of the object, rather than a personal perception.
• Moralistic fallacy – inferring factual conclusions from evaluative premises in violation of fact–value distinction (e.g.: inferring is from ought). Moralistic fallacy is the inverse of naturalistic fallacy.
• Moving the goalposts (raising the bar) – argument in which evidence presented in response to a specific claim is dismissed and some other (often greater) evidence is demanded.
• Nirvana fallacy (perfect-solution fallacy) – solutions to problems are rejected because they are not perfect.
• Package deal – treating essentially dissimilar concepts as though they were essentially similar.
• Prevalent proof fallacy – Using consensus or majority vote as evidence of truthfulness, often without regard for expert opinion.
• Proof by assertion – a proposition is repeatedly restated regardless of contradiction; sometimes confused with argument from repetition (argumentum ad infinitum, argumentum ad nauseam).
• Prosecutor's fallacy – a low probability of false matches does not mean a low probability of some false match being found.^[43][44]
• Proving too much – an argument that results in an overly generalized conclusion (e.g.: arguing that drinking alcohol is bad because in some instances it has led to spousal or child abuse).
• Psychologist's fallacy – an observer presupposes the objectivity of their own perspective when analyzing a behavioral event.
• Referential fallacy^[45] – assuming that all words refer to existing things and that the meaning of words reside within the things they refer to, as opposed to words possibly referring to no real object (e.g.: Pegasus) or that the meaning comes from how they are used (e.g.: "nobody" was in the room).
• Reification (concretism, hypostatization, or the fallacy of misplaced concreteness) – treating an abstract belief or hypothetical construct as if it were a concrete, real event or physical entity (e.g.: saying that evolution selects which traits are passed on to future generations; evolution is not a conscious entity with agency).
• Retrospective determinism – believing that, because an event has occurred under some circumstance, the circumstance must have made the event inevitable (e.g.: because someone won the lottery while wearing their lucky socks, wearing those socks made winning the lottery inevitable).
• Slippery slope (thin edge of the wedge, camel's nose) – asserting that a proposed, relatively small, first action will inevitably lead to a chain of related events resulting in a significant and negative event and, therefore, should not be permitted.^[46]
• Special pleading – the arguer attempts to cite something as an exemption to a generally accepted rule or principle without justifying the exemption (e.g.: an orphaned defendant who murdered their parents asking for leniency).