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 .
A propositional fallacy is an error that concerns compound propositions. For a compound proposition to be true, the truth values of its constituent parts must satisfy the relevant logical connectives that occur in it (most commonly: [and], [or], [not], [only if], [if and only if]). The following fallacies involve relations whose truth values are not guaranteed and therefore not guaranteed to yield true conclusions.
Types of propositional fallacies:
A quantification fallacy is an error in logic where the quantifiers of the premises are in contradiction to the quantifier of the conclusion.
Types of quantification fallacies:
Syllogistic fallacies – logical fallacies that occur in syllogisms.
Informal fallacies – arguments that are logically unsound for lack of well-grounded premises. [14]
Faulty generalization – reaching a conclusion from weak premises.
Questionable cause is a general type of error with many variants. Its primary basis is the confusion of association with causation, either by inappropriately deducing (or rejecting) causation or a broader failure to properly investigate the cause of an observed effect.
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. This includes any logical inference based on fake arguments, intended to replace the lack of real arguments or to replace implicitly the subject of the discussion. [70] [71]
Red herring – introducing a second argument in response to the first argument that is irrelevant and draws attention away from the original topic (e.g.: saying "If you want to complain about the dishes I leave in the sink, what about the dirty clothes you leave in the bathroom?"). [72] In jury trial, it is known as a Chewbacca defense. In political strategy, it is called a dead cat strategy.
Ad hominem, short for argumentum ad hominem, refers to several types of arguments that are fallacious. Often currently this term refers to a rhetorical strategy where the speaker attacks the character, motive, or some other attribute of the person making an argument rather than the substance of the argument itself. This avoids genuine debate by creating a diversion often using a totally irrelevant, but often highly charged attribute of the opponent's character or background. The most common form of this fallacy is "A" makes a claim of "fact", to which "B" asserts that "A" has a personal trait, quality or physical attribute that is repugnant thereby going off-topic, and hence "B" concludes that "A" has their "fact" wrong – without ever addressing the point of the debate. Many contemporary politicians routinely use ad hominem attacks, some of which can be encapsulated to a derogatory nickname for a political opponent used instead of political argumentation.
A false dilemma, also referred to as false dichotomy or false binary, is an informal fallacy based on a premise that erroneously limits what options are available. The source of the fallacy lies not in an invalid form of inference but in a false premise. This premise has the form of a disjunctive claim: it asserts that one among a number of alternatives must be true. This disjunction is problematic because it oversimplifies the choice by excluding viable alternatives, presenting the viewer with only two absolute choices when, in fact, there could be many.
Argument from ignorance, also known as appeal to ignorance, is a fallacy in informal logic. The fallacy is committed when one asserts that a proposition is true because it has not yet been proven false or a proposition is false because it has not yet been proven true. If a proposition has not yet been proven true, one is not entitled to conclude, solely on that basis, that it is false, and if a proposition has not yet been proven false, one is not entitled to conclude, solely on that basis, that it is true. Another way of expressing this is that a proposition is true only if proven true, and a proposition is false only if proven false. If no proof is offered, then the proposition can be called unproven, undecided, inconclusive, an open problem or a conjecture. In debates, appealing to ignorance is sometimes an attempt to shift the burden of proof. The term was likely coined by philosopher John Locke in the late 17th century.
A syllogism is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true.
A fallacy is the use of invalid or otherwise faulty reasoning in the construction of an argument that may appear to be well-reasoned if unnoticed. The term was introduced in the Western intellectual tradition by the Aristotelian De Sophisticis Elenchis.
The genetic fallacy is a fallacy of irrelevance in which arguments or information are dismissed or validated based solely on their source of origin rather than their content. In other words, a claim is ignored or given credibility based on its source rather than the claim itself.
Appeal to tradition is a claim in which a thesis is deemed correct on the basis of correlation with past or present tradition. The appeal takes the form of "this is right because we've always done it this way", and is a logical fallacy. The opposite of an appeal to tradition is an appeal to novelty, in which one claims that an idea is superior just because it is new.
Appeal to consequences, also known as argumentum ad consequentiam, is an argument that concludes a hypothesis to be either true or false based on whether the premise leads to desirable or undesirable consequences. This is based on an appeal to emotion and is a type of informal fallacy, since the desirability of a premise's consequence does not make the premise true. Moreover, in categorizing consequences as either desirable or undesirable, such arguments inherently contain subjective points of view.
Argument from fallacy is the formal fallacy of analyzing an argument and inferring that, since it contains a fallacy, its conclusion must be false. It is also called argument to logic, the fallacy fallacy, the fallacist's fallacy, and the bad reasons fallacy.
The association fallacy is a formal logical fallacy that asserts that properties of one thing must also be properties of another thing if both things belong to the same group. For example, a fallacious arguer may claim that "bears are animals, and bears are dangerous; therefore your dog, which is also an animal, must be dangerous."
The formal fallacy of affirming a disjunct also known as the fallacy of the alternative disjunct or a false exclusionary disjunct occurs when a deductive argument takes the following logical form:
The fallacy of exclusive premises is a syllogistic fallacy committed in a categorical syllogism that is invalid because both of its premises are negative.
Reductio ad Hitlerum, also known as playing the Nazi card, is an attempt to invalidate someone else's argument on the basis that the same idea was promoted or practised by Adolf Hitler or the Nazi Party. Arguments can be termed reductio ad Hitlerum if they are fallacious. Contrarily, straightforward arguments critiquing specifically fascist components of Nazism like Führerprinzip are not part of the association fallacy.
Informal fallacies are a type of incorrect argument in natural language. The source of the error is not just due to the form of the argument, as is the case for formal fallacies, but can also be due to their content and context. Fallacies, despite being incorrect, usually appear to be correct and thereby can seduce people into accepting and using them. These misleading appearances are often connected to various aspects of natural language, such as ambiguous or vague expressions, or the assumption of implicit premises instead of making them explicit.
In logic and philosophy, a formal fallacy is a pattern of reasoning rendered invalid by a flaw in its logical structure that can neatly be expressed in a standard logic system, for example propositional logic. It is defined as a deductive argument that is invalid. The argument itself could have true premises, but still have a false conclusion. Thus, a formal fallacy is a fallacy in which deduction goes wrong, and is no longer a logical process. This may not affect the truth of the conclusion, since validity and truth are separate in formal logic.
Appeal to the stone, also known as argumentum ad lapidem, is a logical fallacy that dismisses an argument as untrue or absurd. The dismissal is made by stating or reiterating that the argument is absurd, without providing further argumentation. This theory is closely tied to proof by assertion due to the lack of evidence behind the statement and its attempt to persuade without providing any evidence.
The politician's syllogism, also known as the politician's logic or the politician's fallacy, is a logical fallacy of the form:
In argumentation theory, an argumentum ad populum is a fallacious argument which is based on claiming a truth or affirming something is good or correct because many people think so.
An argument from authority is a form of argument in which the opinion of an authority figure is used as evidence to support an argument.
For my purposes the desirable but only lightly defensible territory of the Motte and Bailey castle, that is to say, the Bailey, represents a philosophical doctrine or position with similar properties: desirable to its proponent but only lightly defensible. The Motte is the defensible but undesired position to which one retreats when hard pressed ...
Some people have spoken of a Motte and Bailey Doctrine as being a fallacy and others of it being a matter of strategic equivocation. Strictly speaking, neither is correct.
Bare assertion. The most basic way to distort an issue is to deny that it exists. This fallacy claims, 'That's just how it is.'