Guide to Fallacy

If we’re going to argue, let’s do it well.

Below, you’ll find different types of fallacies. Use them to recognize when you’re dealing with someone whose statements lack logical soundness, or to help shape your own arguments.

Continues below…


The Anatomy of A Good Argument

A fallacy is an incorrect argument in logic and rhetoric which undermines an argument’s logical validity or logical soundness.

These are commonly-used styles of argument, where the focus is on communication and results rather than correctness. They may be used whether the point being advanced is correct or not.

Formal fallacies

A formal fallacy is an error in logic that can be seen in the argument’s form.

  • Anecdotal fallacy – using a personal example to generalize without a significant number of cases to form compelling evidence.
  • Appeal to probability – is a statement that takes something for granted because it would probably be the case (or might be the case).
  • Argument from fallacy – also known as “fallacy fallacy”, assumes that if an argument for some conclusion is fallacious, then the conclusion is false.
  • Base rate fallacy – making a probability judgment based on conditional probabilities, without taking into account the effect of prior probabilities.
  • Conjunction fallacy – assumption that an outcome simultaneously satisfying multiple conditions is more probable than an outcome satisfying a single one of them. What’s good for the goose is not always good for the gander.
  • Masked-man fallacy – the substitution of identical designators in a true statement can lead to a false one. Illegitimate substitution of identicals.

Propositional fallacies

A propositional fallacy is an error in logic that concerns compound propositions (think: compound sentences). The argument will have two or more parts and use connectors like: “and”, “or”, “not”, “only if”, “if and only if”.

For a compound proposition to be true, its parts also have to be logical and relevant. The following fallacies occur when the parts are not logical or relevant, which cannot guarantee the conclusion is true:

  • The fallacy of the alternative – making the false assumption that when presented with an either/or possibility, that if one of the options is true that the other one must be false. Ex: “A or B means either A and not B, or B and not A.”
  • Affirming the consequent – the first part is claimed to be true because the second part is true. Ex: “if A, then B; B, therefore A.”
  • Denying the antecedent – the first part is claimed to be false because the second part is false. Ex: “if A, then B; not A, therefore not B.” They don’t HAVE to go together.

Quantification fallacies

A quantification fallacy happens when the parts of the premise contradict the conclusion. Committed when two universal premises (“all”) are used to arrive at a particular (“some”) conclusion. Valid: if the two premises are universal, then the conclusion must also be universal. (“all”, “none”, and “some”)

Types of Quantification fallacies:

  • Existential fallacy – an argument that has a universal premise and a particular conclusion.

Syllogistic fallacies

Syllogistic fallacies can occur when a conclusion is drawn from two given or assumed premises, each of which shares a term with the conclusion, and shares a common or middle term not present in the conclusion. Ex: all dogs are animals; all animals have four legs; therefore all dogs have four legs.

Types of syllogistic fallacies

  • Affirmative conclusion from a negative premise – when a categorical syllogism has a positive conclusion, but at least one negative part. Aka: illicit negative.
  • Fallacy of exclusive premises – a categorical syllogism that is invalid because both of its premises are negative.
  • Fallacy of four terms – a categorical syllogism that has four terms.
  • Illicit major – a categorical syllogism that is invalid because its major term is not distributed in the major premise but distributed in the conclusion.
  • Illicit minor – a categorical syllogism that is invalid because its minor term is not distributed in the minor premise but distributed in the conclusion.
  • Negative conclusion from affirmative premises – when a categorical syllogism has a negative conclusion but affirmative premises.
  • Fallacy of the undistributed middle – the middle term in a categorical syllogism is not distributed.

Informal fallacies

Informal fallacies are arguments that are fallacious for reasons other than structural (formal) flaws and usually require examination of the argument’s content.

  • Appeal to the stone – dismissing a claim as absurd without demonstrating proof for its absurdity.
  • Argument from ignorance – assuming that a claim is true because it has not been or cannot be proven false, or vice versa.
  • Argument from incredulity – an appeal to common sense; “I cannot imagine how this could be true, therefore it must be false.”
  • Argument from repetition – signifies that it has been discussed extensively until nobody cares to discuss it anymore; sometimes confused with proof by assertion.
  • Argument from silence – where the conclusion is based on the absence of evidence, rather than the existence of evidence.
  • Argument to moderation – assuming that the compromise between two positions is always correct. Aka: false compromise, middle ground.
  • Begging the question – providing what is essentially the conclusion of the argument as a premise.
  • Shifting the burden of proof – “I need not prove my claim, you must prove it is false.”
  • Circular reasoning – when the reasoner begins with what he or she is trying to end up with; sometimes called assuming the conclusion.
  • Circular cause and consequence – where the consequence of the phenomenon is claimed to be its root cause.
  • Continuum fallacy – improperly rejecting a claim for being imprecise. Aka: fallacy of the beard, line-drawing fallacy.

Correlative-based fallacies

Arguments dealing with the relationship or association of two things.

  • Correlation proves causation – a faulty assumption that because there is a link between two variables that one caused the other. Aka: post hoc ergo propter hoc.
  • Suppressed correlative – a type of argument that tries to redefine one of two mutually-exclusive options so that one alternative encompasses the other, making one alternative impossible.
  • Divine fallacy – arguing that, because something is so incredible/amazing/unfathomable, it must be the result of superior, divine, or paranormal forces. Aka: argument from incredulity.
  • 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 – the misleading use of a term with more than one meaning (by glossing over which meaning is intended at a particular time).
  • Ambiguous middle term – a common ambiguity in syllogisms in which the middle term is fudged, or equivocated.
  • Definitional retreat – changing the meaning of a word to deal with an objection raised against the original wording.
  • Ecological fallacy – when inferences about the nature of specific individuals are based solely on statistics collected for the group to which those individuals belong.
  • Etymological fallacy – which reasons that the original or historical meaning of a word or phrase is necessarily similar to its actual present-day usage.
  • Fallacy of accent – a specific type of ambiguity that arises when the meaning of a sentence is changed by placing an unusual emphasis, or when it’s left unclear which word the emphasis was supposed to fall on.
  • Fallacy of composition – assuming that something true of part of a whole must also be true of the whole.
  • Fallacy of division – assuming that something true of a thing must also be true of all or some of its parts.
  • False attribution – an advocate appeals to an irrelevant, unqualified, unidentified, biased or fabricated source in support of an argument.
  • Fallacy of quoting out of context – refers to the selective excerpting of words from their original context in a way that distorts the source’s intended meaning.
  • False authority – using an expert of dubious credentials or using only one opinion to sell a product or idea. Aka: single authority.
  • False dilemma – two alternative statements are held to be the only possible options, when there are more. Aka: false dichotomy, fallacy of bifurcation, black-or-white fallacy.
  • False equivalence – describing a situation of logical and apparent equivalence, when in fact there is none.
  • Fallacy of many questions – someone asks a question that presupposes something that has not been proven or accepted by all the people involved. This fallacy is often used rhetorically, so that the question limits direct replies to those that serve the questioner’s agenda. Aka: loaded question.
  • Fallacy of the single cause – it is assumed that there is one, simple cause of an outcome when in reality it may have been caused by a number of only jointly sufficient causes. Aka: causal oversimplification.
  • Furtive fallacy – outcomes are asserted to have been caused by the malfeasance of decision makers.
  • Gambler’s fallacy – the incorrect belief that separate, independent events can affect the likelihood of another random event. If a fair coin lands on heads 10 times in a row, the belief that it is due to the number of times it had landed on tails before is incorrect.
  • Historian’s fallacy – occurs when one assumes that decisionmakers of the past viewed events from the same perspective and having the same information as those subsequently analyzing the decision. (Not to be confused with presentism, which is a mode of historical analysis in which present-day ideas, such as moral standards, are projected into the past.)
  • Historical fallacy – where a set of considerations is good only because a completed process is read into the content of the process which conditions this completed result.
  • Homunculus fallacy – where a “middle-man” is used for explanation, this sometimes leads to regressive middle-men. Explains without actually explaining the real nature of a process. Instead, it explains the concept in terms of the concept itself, without first defining or explaining the original concept. Explaining thought as something produced by a little thinker, a sort of homunculus inside the head, merely explains it as another kind of thinking (as different, but really the same).
  • Inflation of conflict – The experts of a field of knowledge disagree on a certain point, so the scholars must know nothing, and therefore the legitimacy of their entire field is put to question.
  • If-by-whiskey – an argument that supports both sides of an issue by using terms that are emotionally sensitive.
  • Incomplete comparison – insufficient information is provided to make a complete comparison.
  • Inconsistent comparison – different methods of comparison are used, leaving one with a false impression of the whole 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 Ex: 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.
  • Irrelevant conclusion – an argument that may, in itself, be valid, but does not address the issue in question. Aka: missing the point.
  • Kettle logic – using multiple, jointly inconsistent arguments to defend a position.
  • Ludic fallacy – the belief that the outcomes of non-regulated random occurrences can be encapsulated by a statistic; a failure to take into account unknown unknowns in determining the probability of events taking place.
  • McNamara fallacy – making a decision based only on quantitative observations, discounting all other considerations. Aka: quantitative fallacy.
  • Moral high ground fallacy – in which one assumes a “holier-than-thou” attitude in an attempt to make oneself look good to win an argument.
  • Moralistic fallacy – inferring factual conclusions from purely evaluative premises in violation of fact–value distinction. Ex: a real man is one who holds the door open for a woman, only because (according to tradition) men ought to do that. Moralistic fallacy is the inverse of naturalistic fallacy [defined below].
  • Moving the goalposts – an argument in which evidence presented in response to a specific claim is dismissed and some other (often greater) evidence is demanded. Aka: raising the bar.
  • Naturalistic fallacy – inferring evaluative conclusions from purely factual premises in violation of fact–value distinction. For instance, inferring “ought” from “is”.
  • Nirvana fallacy – when solutions to problems are rejected because they are not perfect. Aka: perfect solution fallacy.
  • Onus probandi – a particular case of the argumentum ad ignorantiam fallacy, here the burden is shifted on the person defending against the assertion.
  • Proof by assertion – a proposition is repeatedly restated regardless of contradiction; sometimes confused with argument from repetition.
  • Proof by verbosity – submission of others to an argument too complex and verbose to reasonably deal with in all its intimate details. Aka: proof by intimidation.
  • Prosecutor’s fallacy – a low probability of false matches does not mean a low probability of some false match being found.
  • Proving too much – using a form of argument that, if it were valid, could be used to reach an additional, undesirable conclusion.
  • Psychologist’s fallacy – an observer presupposes the objectivity of his own perspective when analyzing a behavioral event.
  • Red herring – a speaker attempts to distract an audience by deviating from the topic at hand by introducing a separate argument the speaker believes is easier to speak to.
  • Referential fallacy – assuming 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 or that the meaning of words often comes from how we use them.
  • Regression fallacy – assigns cause where none exists. The flaw is failing to account for natural fluctuations. It is frequently a special kind of the post hoc fallacy.
  • Reification – a fallacy of ambiguity, when an abstraction (abstract belief or hypothetical construct) is treated as if it were a concrete, real event or physical entity. In other words, it is the error of treating something that is not a real thing as a “real thing”. Aka: the fallacy of misplaced concreteness.
  • Retrospective determinism – the argument that, because an event has occurred under some circumstance, the circumstance must have made its occurrence inevitable.
  • Shotgun argumentation – the arguer offers such a large number of arguments for a position that the opponent can’t possibly respond to all of them. (See “Argument by verbosity”)
  • Special pleading – where a proponent of a position attempts to cite something as an exemption to a generally accepted rule or principle without justifying the exemption.
  • Wrong direction – cause and effect are reversed. The cause is said to be the effect and vice versa.

Faulty Generalizations

Faulty generalizations reach a conclusion from weak premises, or there is a defect in inducing the conclusion. Unlike fallacies of relevance, in fallacies of defective induction, the premises are weakly related to the conclusions. A faulty generalization is thus produced.

  • Accident – an exception to a generalization is ignored.
  • No true Scotsman – makes a generalization true by changing the generalization to exclude a counterexample.
  • Cherry picking – act of pointing at individual cases or data that seem to confirm a particular position, while ignoring a significant portion of related cases or data that may contradict that position. Aka: suppressed evidence, incomplete evidence.
  • Survivorship bias – when a small number of survivors of a given process are actively promoted while completely ignoring a large number of failures.
  • False analogy – an argument by analogy in which the analogy is poorly suited.
  • Hasty generalization – basing a broad conclusion on a small sample. Aka: fallacy of insufficient sample, fallacy of the lonely fact, leaping to a conclusion, hasty induction.
  • Inductive fallacy – A more general name to some fallacies, such as hasty generalization. It happens when a conclusion is made of premises that lightly support it.
  • Misleading vividness – involves describing an occurrence in vivid detail, even if it is an exceptional occurrence, to convince someone that it is a problem.
  • Overwhelming exception – an accurate generalization that comes with qualifications that eliminate so many cases that what remains is much less impressive than the initial statement might have led one to assume.
  • Thought-terminating cliché – a commonly used phrase, sometimes passing as folk wisdom, used to quell cognitive dissonance, conceal lack of thought-entertainment, move on to other topics, or otherwise end the debate with a cliché—not a point.

Red Herring Fallacies

A red herring fallacy, one of the main subtypes of fallacies of relevance, is an error in logic where a proposition is, or is intended to be, misleading in order to make irrelevant or false inferences.

  • Red herring – argument given in response to another argument, which is irrelevant and draws attention away from the subject of argument. (See also irrelevant conclusion.)
  • Ad hominem – “to person”; attacking the arguer instead of the argument.
  • Poisoning the well – a subtype of ad hominem presenting adverse information about a target person with the intention of discrediting everything that the target person says.
  • Abusive fallacy – a subtype of ad hominem that verbally abuses the opponent rather than arguing about the originally proposed argument.
  • Appeal to motive – a subtype of ad hominem that dismisses an idea by questioning the motives of its proposer.
  • Tone policing – a subtype of ad hominem focusing on emotion behind a message rather than the message itself as a discrediting tactic.
  • Traitorous critic fallacy – a subtype of ad hominem where a critic’s perceived affiliation is seen as the underlying reason for the criticism and the critic is asked to stay away from the issue altogether.
  • Appeal to authority – where an assertion is deemed true because of the position or authority of the person asserting it.
  • Appeal to accomplishment – where an assertion is deemed true or false based on the accomplishments of the proposer.
  • Appeal to consequences – the conclusion is supported by a premise that asserts positive or negative consequences from some course of action in an attempt to distract from the initial discussion.
  • Appeal to emotion – where an argument is made due to the manipulation of emotions, rather than the use of valid reasoning.
  • Appeal to fear – a specific type of appeal to emotion where an argument is made by increasing fear and prejudice towards the opposing side.
  • Appeal to flattery – a specific type of appeal to emotion where an argument is made due to the use of flattery to gather support.
  • Appeal to pity – an argument that attempts to induce pity to sway opponents.
  • Appeal to ridicule – an argument is made by presenting the opponent’s argument in a way that makes it appear ridiculous.
  • Appeal to spite – a specific type of appeal to emotion where an argument is made through exploiting people’s bitterness or spite towards an opposing party.
  • Wishful thinking – a specific type of appeal to emotion where a decision is made according to what might be pleasing to imagine, rather than according to evidence or reason.
  • Appeal to nature – wherein judgment is based solely on whether the subject of judgment is ‘natural’ or ‘unnatural’.
  • Appeal to novelty – where a proposal is claimed to be superior or better solely because it is new or modern.
  • Appeal to poverty – supporting a conclusion because the arguer is poor (or refuting because the arguer is wealthy).
  • Appeal to tradition – a conclusion supported solely because it has long been held to be true.
  • Appeal to wealth – supporting a conclusion because the arguer is wealthy (or refuting because the arguer is poor).
  • Argumentum ad baculum – an argument made through coercion or threats of force to support position. Aka: appeal to the stick, appeal to force, appeal to threat.
  • Argumentum ad populum – where a proposition is claimed to be true or good solely because many people believe it to be so. Aka: appeal to widespread belief, bandwagon argument, appeal to the majority, appeal to the people.
  • Association fallacy – arguing that because two things share (or are implied to share) some property, they are the same. Aka: guilt by association and honor by association.
  • Bulverism – inferring why an argument is being used, associating it to some psychological reason, then assuming it is invalid as a result. It is wrong to assume that if the origin of an idea comes from a biased mind, then the idea itself must also be a falsehood. Aka: psychogenetic fallacy.
  • Chronological snobbery – where a thesis is deemed incorrect because it was commonly held when something else, clearly false, was also commonly held.
  • Fallacy of relative privation – dismissing an argument or complaint due to the existence of more important problems in the world, regardless of whether those problems bear relevance to the initial argument. Saying something is “not as bad as” other things. Ex: “First World problems”
  • Genetic fallacy – where a conclusion is suggested based solely on something or someone’s origin rather than its current meaning or context.
  • Judgmental language – insulting or pejorative language to influence the recipient’s judgment.
  • Naturalistic fallacy (is–ought fallacy) – claims about what ought to be on the basis of statements about what is.
  • Pooh-pooh – dismissing an argument perceived unworthy of serious consideration.
  • Straw man fallacy – an argument based on misrepresentation of an opponent’s position.
  • Texas sharpshooter fallacy – improperly asserting a cause to explain a cluster of data.
  • Appeal to hypocrisy – the argument states that a certain position is false or wrong or should be disregarded because its proponent fails to act consistently in accordance with that position. Aka: Tu quoque, I’m rubber and you’re glue.
  • Two wrongs make a right – occurs when it is assumed that if one wrong is committed, an “equal but opposite” wrong will cancel it out.
  • Vacuous truth – A claim that is technically true but meaningless. For example, claiming that no mobile phones in the room are on when there are no mobile phones in the room at all.
  • Appeal to self-evident truth – A claim that a proposition is self-evidently true, so needs no further supporting evidence. If self-evidence is actually the basis for the claim, it is arbitrary and the opposite (a contradictory or contrary statement) is equally true. In many cases, however, the basis is really some kind of unstated and unexamined observation or assumption.

Conditional or Questionable Fallacies

  • Broken window fallacy – an argument that disregards lost opportunity costs (typically non-obvious, difficult to determine or otherwise hidden) associated with destroying property of others, or other ways of externalizing costs onto others. For example, an argument that states breaking a window generates income for a window fitter, but disregards the fact that the money spent on the new window cannot now be spent on new shoes.
  • Definist fallacy – involves the confusion between two notions by defining one in terms of the other.
  • Naturalistic fallacy – attempts to prove a claim about ethics by appealing to a definition of the term “good” in terms of either one or more claims about natural properties or “God’s will”.
  • Slippery slope – asserting that a relatively small first step inevitably leads to a chain of related events culminating in some significant impact/event that should not happen, thus the first step should not happen. It is, in its essence, an appeal to probability fallacy. Aka: thin edge of the wedge, camel’s nose.