Tu Quoque Fallacy

The tu quoque fallacy is committed when it is assumed that because someone else has done a thing there is nothing wrong with doing it. This fallacy is classically committed by children who, when told off, respond with “So and so did it too”, with the implied conclusion that there is nothing wrong with doing […]

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Subjectivist Fallacy

There are two types of claim: objective and subjective. Objective claims have the same truth-value for everyone. For example, the claim that the Earth is cuboid is an objective claim; it’s either true for everyone or false for everyone. It isn’t possible for the Earth to be cuboid for me, spherical for you, but flat […]

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Sweeping Generalization Fallacy

A sweeping generalization applies a general statement too broadly. If one takes a general rule, and applies it to a case to which, due to the specific features of the case, the rule does not apply, then one commits the sweeping generalization fallacy. This fallacy is the reverse of a hasty generalization, which infers a […]

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Slippery Slope Fallacy

Slippery slope arguments falsely assume that one thing must lead to another. They begin by suggesting that if we do one thing then that will lead to another, and before we know it we’ll be doing something that we don’t want to do. They conclude that we therefore shouldn’t do the first thing. The problem […]

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Post Hoc Fallacy

The Latin phrase “post hoc ergo propter hoc” means, literally, “after this therefore because of this.” The post hoc fallacy is committed when it is assumed that because one thing occurred after another, it must have occurred as a result of it. Mere temporal succession, however, does not entail causal succession. Just because one thing […]

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No True Scotsman Fallacy

The no true scotsman fallacy is a way of reinterpreting evidence in order to prevent the refutation of one’s position. Proposed counter-examples to a theory are dismissed as irrelevant solely because they are counter-examples, but purportedly because they are not what the theory is about. Example The No True Scotsman fallacy involves discounting evidence that […]

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Hasty Generalization Fallacy

A hasty generalisation draws a general rule from a single, perhaps atypical, case. It is the reverse of a sweeping generalisation. Example (1) My Christian / atheist neighbour is a real grouch. Therefore: (2) Christians / atheists are grouches. This argument takes an individual case of a Christian or atheist, and draws a general rule […]

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False Dilemma / Bifurcation Fallacy

The bifurcation fallacy is committed when a false dilemma is presented, i.e. when someone is asked to choose between two options when there is at least one other option available. Of course, arguments that restrict the options to more than two but less than there really are are similarly fallacious. Examples (1) Either a Creator […]

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Cum Hoc Fallacy

The cum hoc fallacy is committed when it is assumed that because two things occur together, they must be causally related. This, however, does not follow; correlation is possible without causation. This fallacy is closely related to the post hoc fallacy. Example As the graph below (taken from the Church of the Flying Spaghetti Monster […]

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Complex Question Fallacy

The complex question fallacy is committed when a question is asked (a) that rests on a questionable assumption, and (b) to which all answers appear to endorse that assumption. Examples “Have you stopped beating your wife?” This is a complex question because it presupposes that you used to beat your wife, a presupposition that either […]

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Begging the Question / Circular Reasoning

An argument is circular if its conclusion is among its premises, if it assumes (either explicitly or not) what it is trying to prove. Such arguments are said to beg the question. A circular argument fails as a proof because it will only be judged to be sound by those who already accept its conclusion. […]

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Arguing from Ignorance

Arguments from ignorance infer that a proposition is true from the fact that it is not known to be false. Not all arguments of this form are fallacious; if it is known that if the proposition were not true then it would have been disproven, then a valid argument from ignorance may be constructed. In […]

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Affirming the Consequent

The fallacy of affirming the consequent is committed by arguments that have the form: (1) If A then B (2) B Therefore: (3) A The first premise of such arguments notes that if a state of affairs A obtained then a consequence B would also obtain. The second premise asserts that this consequence B does […]

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Appeal to Wealth

The appeal to wealth fallacy is committed by any argument that assumes that someone or something is better simply because they are wealthier or more expensive. It is the opposite of the appeal to poverty. In a society in which we often aspire to wealth, where wealth is held up as that to which we […]

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Appeal to Poverty

The appeal to poverty fallacy is committed when it is assumed that a position is correct because it is held by the poor. The opposite of the appeal to poverty is theappeal to wealth. There is sometimes a temptation to contrast the excesses, greed, and immorality of the rich with the simplicity, virtue, and humility […]

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Appeal to Popularity

Appeals to popularity suggest that an idea must be true simply because it is widely held. This is a fallacy because popular opinion can be, and quite often is, mistaken. Hindsight makes this clear: there were times when the majority of the population believed that the Earth is the still centre of the universe, and […]

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Appeal to Pity

An appeal to pity attempts to persuade using emotion—specifically, sympathy—rather than evidence. Playing on the pity that someone feels for an individual or group can certainly affect what that person thinks about the group; this is a highly effective, and so quite common, fallacy. This type of argument is fallacious because our emotional responses are […]

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Appeal to Novelty

An appeal to novelty is the opposite of an appeal to antiquity. Appeals to novelty assume that the newness of an idea is evidence of its truth. They are thus also related to the bandwagon fallacy. That an idea is new certainly doesn’t entail that it is true. Many recent ideas have no merit whatsoever, […]

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Appeal to Force

An appeal to force is an attempt to persuade using threats. Its Latin name, “argumentum ad baculum”, literally means “argument with a cudgel”. Disbelief, such arguments go, will be met with sanctions, perhaps physical abuse; therefore, you’d better believe. Appeals to force are thus a particularly cynical type of appeal to consequences, where the unpleasant […]

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Appeal to Consequences

An appeal to consequences is an attempt to motivate belief with an appeal either to the good consequences of believing or the bad consequences of disbelieving. This may or may not involve an appeal to force. Such arguments are clearly fallacious. There is no guarantee, or even likelihood, that the world is the way that […]

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Appeal to Authority

An appeal to authority is an argument from the fact that a person judged to be an authority affirms a proposition to the claim that the proposition is true. Appeals to authority are always deductively fallacious; even a legitimate authority speaking on his area of expertise may affirm a falsehood, so no testimony of any […]

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Appeal to Antiquity / Tradition

An appeal to antiquity is the opposite of an appeal to novelty. Appeals to antiquity assume that older ideas are better, that the fact that an idea has been around for a while implies that it is true. This, of course, is not the case; old ideas can be bad ideas, and new ideas can […]

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Straw Man Fallacy

A straw man argument is one that misrepresents a position in order to make it appear weaker than it actually is, refutes this misrepresentation of the position, and then concludes that the real position has been refuted. This, of course, is a fallacy, because the position that has been claimed to be refuted is different […]

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Equivocation Fallacy

The fallacy of equivocation is committed when a term is used in two or more different senses within a single argument. For an argument to work, words must have the same meaning each time they appear in its premises or conclusion. Arguments that switch between different meanings of words equivocate, and so don’t work. This […]

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Accent Fallacies

Accent fallacies are fallacies that depend on where the stress is placed in a word or sentence. The meaning of a set of words may be dramatically changed by the way they are spoken, without changing any of the words themselves. Accent fallacies are a type of equivocation. Example Suppose that two people are debating […]

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Weak Analogy

Arguments by analogy rest on a comparison. Their logical structure is this: (1) A and B are similar. (2) A has a certain characteristic. Therefore: (3) B must have that characteristic too. For example, William Paley’s argument from design suggests that a watch and the universe are similar (both display order and complexity), and therefore […]

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Red Herring

The red herring is as much a debate tactic as it is a logical fallacy. It is a fallacy of distraction, and is committed when a listener attempts to divert an arguer from his argument by introducing another topic. This can be one of the most frustrating, and effective, fallacies to observe. The fallacy gets […]

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Naturalistic Fallacy

There are two fundamentally different types of statement: statements of fact which describe the way that the world is, and statements of value which describe the way that the world ought to be. The naturalistic fallacy is the alleged fallacy of inferring a statement of the latter kind from a statement of the former kind. […]

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Moralistic Fallacy

The moralistic fallacy is the opposite of the naturalistic fallacy. The naturalistic fallacy moves from descriptions of how things are to statements of how things ought to be, the moralistic fallacy does the reverse. The moralistic fallacy moves from statements about how things ought to be to statements about how things are; it assumes that […]

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Irrelevant Appeals

Irrelevant appeals attempt to sway the listener with information that, though persuasive, is irrelevant to the matter at hand. There are many different types of irrelevant appeal, many different ways of influencing what people think without using evidence. Each is a different type of fallacy of relevance. Examples For example, an appeal to authority seeks […]

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Genetic fallacy

The genetic fallacy is committed when an idea is either accepted or rejected because of its source, rather than its merit. Even from bad things, good may come; we therefore ought not to reject an idea just because of where it comes from, as ad hominem arguments do. Equally, even good sources may sometimes produce […]

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Fallacy of Division

The fallacy of division is the reverse of the fallacy of composition. It is committed by inferences from the fact that a whole has a property to the conclusion that a part of the whole also has that property. Like the fallacy of composition, this is only a fallacy for some properties; for others, it […]

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Fallacy of Composition

The fallacy of composition is the fallacy of inferring from the fact that every part of a whole has a given property that the whole also has that property. This pattern of argument is the reverse of that of the fallacy of division. It is not always fallacious, but we must be cautious in making […]

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Fallacist’s Fallacy

The fallacist’s fallacy involves rejecting an idea as false simply because the argument offered for it is fallacious. Having examined the case for a particular point of view, and found it wanting, it can be tempting to conclude that the point of view is false. This, however, would be to go beyond the evidence. It […]

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Appeal to force (Argumentum ad baculum)

Argumentum ad baculum (Latin for “argument to the cudgel” or “appeal to the stick”), also known as appeal to force, is an argument where force, coercion, or the threat of force, is given as a justification. It is a specific case of the negative form of anargument to the consequences. For this reason, it is […]

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Circular reasoning

Circular reasoning (Latin: circulus in probando, “circle in proving”; also known as circular logic) is a logical fallacy in which the reasoner begins with what they are trying to end with. The components of a circular argument are often logically valid because if the premises are true, the conclusion must be true. Circular reasoning is not […]

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ad hominem

An ad hominem (Latin for “to the man” or “to the person”), short for argumentum ad hominem, means responding to arguments by attacking a person’s character, rather than addressing the content of their arguments. When used inappropriately, it is a fallacy in which a claim or argument is dismissed on the basis of some irrelevant […]

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Logical Fallacy

A logical fallacy is an error in logical argumentation (e.g. ad hominem attacks, slippery slopes, circular arguments, appeal to force, etc.). A cognitive bias, on the other hand, is a genuine deficiency or limitation in our thinking — a flaw in judgment that arises from errors of memory, social attribution, and miscalculations (such as statistical […]

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Hot-hand fallacy

The “hot-hand fallacy” (also known as the “hot hand phenomenon” or “hot hand”) is the fallacious belief that a person who has experienced success with a random event has a greater chance of further success in additional attempts. The concept has been applied to gambling and sports, such as basketball. While a previous success at a skill-based athletic task, such as making a shot in basketball, can change […]

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Planning fallacy

The planning fallacy is a tendency for people and organizations to underestimate how long they will need to complete a task, even when they have experience of similar tasks over-running. The term was first proposed in a 1979 paper by Daniel Kahneman and Amos Tversky. Since then the effect has been found for predictions of a wide variety of tasks, including […]

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Conjunction fallacy

The conjunction fallacy is a formal fallacy that occurs when it is assumed that specific conditions are more probable than a single general one. The most often-cited example of this fallacy originated with Amos Tversky and Daniel Kahneman: Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of […]

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Appeal to spite

An appeal to spite (also called argumentum ad odium) is a fallacy in which someone attempts to win favor for an argument by exploiting existing feelings of bitterness, spite, or schadenfreude in the opposing party. It is an attempt to sway the audience emotionally by associating a hate-figure with opposition to the speaker’s argument. Fallacious ad […]

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Magical thinking

Magical thinking is the attributing of causal relationships between actions and events where scientific consensus says that there are none. In religion, folk religion, and superstition beliefs, the correlation posited is often between religious ritual, prayer, sacrifice, or the observance of a taboo, and an expected benefit or recompense. In clinical psychology, magical thinking can […]

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Informal fallacy

An informal fallacy is an argument whose stated premises fail to support its proposed conclusion. The problem with an informal fallacy often stems from a flaw in reasoning that renders the conclusion unpersuasive. In contrast to a formal fallacy of deduction, the error is not merely a flaw in logic.

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Post-purchase rationalization

Post-purchase rationalization, also known as Buyer’s Stockholm Syndrome, is a cognitive bias whereby someone who has purchased an expensive product or service overlooks any faults or defects in order to justify their purchase. It is a special case of choice-supportive bias. Expensive purchases often involve a lot of careful research and deliberation, and many consumers […]

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Gambler’s fallacy

The gambler’s fallacy, also known as the Monte Carlo fallacy or the fallacy of the maturity of chances, is the mistaken belief that if something happens more frequently than normal during some period, then it will happen less frequently in the future (presumably as a means of balancing nature). In situations where what is being […]

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Nirvana fallacy

The nirvana fallacy is the informal fallacy of comparing actual things with unrealistic, idealized alternatives. It can also refer to the tendency to assume that there is a perfect solution to a particular problem. A closely related concept is the perfect solution fallacy. By creating a false dichotomy that presents one option which is obviously […]

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Quoting out of context

The practice of quoting out of context, sometimes referred to as “contextomy“, is a logical fallacy and a type of false attribution in which a passage is removed from its surrounding matter in such a way as to distort its intended meaning. Contextomies are stereotypically intentional, but may also occur accidentally if someone misinterprets the meaning […]

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Masked man fallacy

In philosophical logic, the masked man fallacy (also known as the intensional fallacy and the epistemic fallacy) is committed when one makes an illicit use of Leibniz’s law in an argument. Leibniz’s law states that, if one object has a certain property, while another object does not have the same property, the two objects cannot […]

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Proof by example

Proof by example (also known as inappropriate generalization) is a logical fallacy whereby one or more examples are claimed as “proof” for a more general statement. This fallacy has the following structure, and argument form: Structure: I know that X is such. Therefore, anything related to X is also such. Argument form: I know that […]

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