What I’m after here is not a dictionary of the fallacies with perfect definitions, but rather, by placing like with like, a systematisation of them, as far as this is possible. I try not to contradict anything done by established experts. I’d like to have good definitions and examples too, time permitting. update 26/04/2011
Something interesting to me is that in manipulating these categories diagrammatically, under multiple constraints, an insight “fell out” of the process – the grouping below False Dilemma, which I will soon change to an overall term of “Bifurcation” – as fallacies, they all play upon, or maybe even prey upon, the tendency of the human mind to think in opposites. 30/04/2011
Fallacies – Informal – an informal fallacy, as opposed to a formal fallacy, is a type of fallacy in which the content of the argument is relevant to its fallaciousness, or which is fallacious for epistemological, dialectical, or pragmatic reasons.
FALLACIES OF PRESUMPTION unsound arguments involving unfounded or unproven assumptions contained within the premises. Includes begging the question, argument from ignorance, false cause, generalisation, complex question and ignoratio elenchi.
petitio principii (begging the question). This is the fallacy of assuming, when trying to prove something, what it is that you are trying prove. For all practical purposes, this fallacy is indistinguishable from circular argumentation.
circulus in demonstrando (circular argument). Circular argumentation occurs when someone uses what they are trying to prove as part of the proof of that thing.
circular argument circulus in demonstrando
circulus in probando circulus in demonstrando
vicious circle begging the question
begging the question also known as petitio principii, circulus in probando, circular argument, vicious circle
question-begging analogy an analogical argument begs the question when the strength of the analogy depends upon some controversial point at issue.
False Analogy relates to metaphor
false analogy A is like B. B has property P. Therefore, A has property P. (Where the analogy between A and B is weak.)
weak analogy false analogy
faulty analogy false analogy
questionable analogy false analogy
Generalisation relates to synecdoche
dicto simpliciter A dicto simpliciter ad dictum secundum quid. Sweeping generalisation.
sweeping generalisation A dicto simpliciter ad dictum secundum quid
hasty generalisation fallacy committed when a person draws a conclusion about a population based on a sample that is not large enough
converse accident hasty generalisation
biased sample fallacy committed when a person draws a conclusion about a population based on a sample that is biased or prejudiced in some manner
unrepresentative sample biased sample
misleading vividness a fallacy in which a very small number of particularly dramatic events are taken to outweigh a significant amount of statistical evidence
spotlight committed when a person uncritically assumes that all members or cases of a certain class or type are like those that receive the most attention or coverage in the media
Volvo fallacy when the vividness of a recent memory, or the strikingness of an unusual event, leads one to overestimate the probability of events of that type occurring, especially if you have better evidence
fallacy of significance an assertion which seems to have an importance to the point at issue, but which does not.
fallacy of accident
False Cause relates to metonymy
non causa pro causa false cause
false cause non causa pro causa. This is the most general fallacy of reasoning to conclusions about causality.
cum hoc ergo propter hoc (with this, therefore because of this). This is the familiar fallacy of mistaking correlation for causation — i.e., thinking that because two things occur simultaneously, one must be a cause of the other.
post hoc ergo propter hoc (after this, therefore because of this). This is the fallacy of assuming that A caused B simply because A happened prior to B.
post hoc a fallacy with the following form: A occurs before B. Therefore A is the cause of B.
confusing cause and effect a fallacy that has the following general form: A and B regularly occur together. Therefore A is the cause of B.
ignoring a common cause fallacy having the following general structure: A and B are regularly connected (but no third, common cause is looked for). Therefore A is the cause of B.
questionable cause this fallacy has the following general form: A and B are associated on a regular basis. Therefore A is the cause of B.
argumentum ad ignorantiam (argument to ignorance). This is the fallacy of assuming something is true simply because it hasn’t been proven false.
argument from ignorance also known as Argumentum ad Ignorantiam. There is no evidence against p. Therefore, p.
Burden of Proof a fallacy in which the burden of proof is placed on the wrong side
black-and-white fallacy a fallacy in which a person uses the following pattern of “reasoning”: Either claim X is true or claim Y is true (when X and Y could both be false). Claim Y is false. Therefore claim X is true.
black-or-white fallacy black-and-white fallacy
either / or fallacy black-and-white fallacy
false dilemma a fallacy in which a person uses the following pattern of “reasoning”: Either claim X is true or claim Y is true (when X and Y could both be false). Claim Y is false. Therefore claim X is true.
bifurcation black-or-white fallacy
slippery slope a slippery slope fallacy is an argument that says adopting one policy or taking one action will lead to a series of other policies or actions also being taken, without showing a causal connection between the advocated policy and the consequent policies.
argument of the beard slippery slope
thin end of the wedge slippery slope
Middle Ground fallacy committed when it is assumed that the middle position between two extremes must be correct simply because it is the middle position
argumentum ad temperantiam
plurium interrogationum many questions
many questions plurium interrogationum: “many questions”, Latin complex question
complex question a complex question is a question that implicitly assumes something to be true by its construction
loaded question complex question
FALLACIES OF AMBIGUITY relates to language / puns
fallacy of ambiguity as a logical fallacy, ambiguity occurs when linguistic ambiguity causes the form of an argument to appear validating when it is not. Includes equivocation, amphiboly, composition and division.
ambiguous middle any valid form of categorical syllogism with an ambiguous middle term.
equivocation based on ambiguity of a word or phrase (lexical rather than grammatical)
amphiboly / amphibology ambiguity resulting from ambiguous grammar. The fallacy of Amphiboly occurs when a bad argument trades upon grammatical ambiguity to create an illusion of cogency
accent ambiguity by accents used to indicate pronunciation
fallacy of emphasis or accent incorrect emphasis of the words in a sentence. Improper stress is placed on some portion of a premise or conclusion so the meaning of the argument is distorted.
scope fallacy ambiguity based on scope. Logical terms such as “not” have a scope, that is, a part of the proposition in which they occur that they affect logically.
vagueness the fallacy of vagueness occurs only when the appearance of soundness in an argument depends upon vagueness in its terms.
FALLACIES OF RELEVANCE / EMOTIONAL APPEALS
relates to example and emotional
argumentum ad populum (argument or appeal to the public). This is the fallacy of trying to prove something by showing that the public agrees with you.
argumentum ad numerum (argument or appeal to numbers). This fallacy is the attempt to prove something by showing how many people think that it’s true
bandwagon fallacy the bandwagon fallacy is committed whenever one argues for an idea based upon an irrelevant appeal to its popularity.
argument by consensus bandwagon fallacy
authority of the many bandwagon fallacy
appeal to belief a fallacy that has this general pattern: Most people believe that a claim, X, is true. Therefore X is true.
appeal to common practice a fallacy with the following structure: X is a common action. Therefore X is correct/moral/justified/reasonable, etc.
argumentum ad verecundiam (argument or appeal to authority). This fallacy occurs when someone tries to demonstrate the truth of a proposition by citing some person who agrees, even though that person may have no expertise in the given area.
ipse dixit (“He, himself, said it”, Latin) Appeal to misleading authority
argumentum ad antiquitatem (the argument to antiquity or tradition). This is the familiar argument that some policy, behaviour, or practice is right or acceptable because “it’s always been done that way.”
appeal to novelty a fallacy that occurs when it is assumed that something is better or correct simply because it is new
naturalistic fallacy this is the fallacy of trying to derive conclusions about what is right or good (that is, about values) from statements of fact alone.
appeal to nature this is the fallacy of assuming that whatever is “natural” or consistent with “nature” (somehow defined) is good, or that whatever conflicts with nature is bad.
relativist fallacy committed when a person rejects a claim by asserting that the claim might be true for others but is not for him/her
argumentum ad consequentiam arguing that a proposition is true because belief in it has good consequences, or that it is false because belief in it has bad consequences is often an irrelevancy.
appeal to consequences of a belief X is true / false because if people accept / do not accept X as being true / false then there will be positive / negative consequences. Also includes wishful thinking.
wishful thinking as a logical fallacy, wishful thinking is an argument whose premise expresses a desire for the conclusion to be true.
argumentum ad baculum appeal to force. The name “argumentum ad baculum” alludes to the use of a stick, or club, to beat someone.
argument from force a technique of distraction which occurs when force, or the threat of force, is used to “win” a debate. More frequently, it is used to cover up the fact that the threatener is losing.
argumentum ad nauseam (argument to the point of disgust; i.e., by repetition). This is the fallacy of trying to prove something by saying it again and again.
emotional appeal a type of argument which attempts to arouse the emotions of its audience in order to gain acceptance of its conclusion
appeal to emotion a fallacy with the following structure: Favorable emotions are associated with X. Therefore, X is true.
argumentum ad metum appeal to fear. A fallacy with the following pattern: Y is presented (a claim that is intended to produce fear). Therefore claim X is true (a claim that is generally, but need not be, related to Y in some manner).
appeal to fear argumentum ad metum
argumentum ad odium appeal to hatred
argument from hatred also known as Argumentum ad Odium
argumentum ad misericordiam argument or appeal to pity
appeal to spite a fallacy in which spite is substituted for evidence when an “argument” is made against a claim
argumentum ad superbium appeal to pride
argument from pride also known as Argumentum ad Superbium
appeal to flattery a fallacy of the following form: Person A is flattered by person B. Person B makes claim X. Therefore X is true.
argumentum ad invidiam argument from envy.
argument from envy also known as Argumentum ad Invidiam
appeal to ridicule a fallacy in which ridicule or mockery is substituted for evidence in an “argument.”
Argumentum ad Hominem
genetic fallacy a line of “reasoning” in which a perceived defect in the origin of a claim or thing is taken to be evidence that discredits the claim or thing itself, or origin as evidence for the claim
argumentum ad hominem (argument directed at the person). This is the error of attacking the character or motives of a person who has stated an idea, rather than the idea itself.
circumstantial ad hominem a fallacy in which one attempts to attack a claim by asserting that the person making the claim is making it simply out of self interest
personal attack when a person substitutes abusive remarks for evidence when attacking another person’s claim or claims
poisoning the well trying to discredit what a person might later claim by presenting unfavorable information (be it true or false) about the person
guilt by association a fallacy in which a person rejects a claim simply because it is pointed out that people she dislikes accept the claim
bad company fallacy guilt by association – the attempt to discredit an idea based upon disfavored people or groups associated with it.
the company that you keep fallacy guilt by association
tu quoque (ad hominem tu quoque) (“you too”). This is the fallacy of defending an error in one’s reasoning by pointing out that one’s opponent has made the same error.
two wrongs make a right a fallacy in which a person “justifies” an action against a person by asserting that the person would do the same thing to him/her, when the action is not necessary to prevent B from doing X to A
special pleading a fallacy in which a person applies standards, principles, rules, etc. to others while taking herself (or those she has a special interest in) to be exempt, without providing adequate justification for the exemption
Straw Man this is the fallacy of refuting a caricatured or extreme version of somebody’s argument, rather than the actual argument they’ve made.
ignoratio elenchi (“ignorance of refutation”, Latin) red herring
red herring introducing irrelevant facts or arguments to distract from the question at hand
irrelevant thesis ignorantio elenchi, red herring
loaded language / words a word or phrase is “loaded” when it has a secondary, evaluative meaning in addition to its primary, descriptive meaning.
question-begging epithets loaded language / words
one-sidedness a one-sided case presents only evidence favouring its conclusion, and ignores or downplays the evidence against it.
one-sided assessment one-sidedness
suppressed evidence one-sidedness. ignoring the counterevidence
slanting one-sidedness. related to bias.
card stacking ignoring the counterevidence; one-sidedness
Quoting out of Context
quoting out of context to quote out of context is to remove a passage from its surrounding matter in such a way as to distort its meaning.
abstraction quoting out of context
gambler’s fallacy a fallacy committed when a person assumes that a departure from what occurs on average or in the long term will be corrected in the short term
Monte Carlo fallacy gambler’s fallacy
regression / regressive fallacy the regression fallacy occurs when one mistakes regression to the mean for a causal relationship.
Texas Sharpshooter fallacy this fallacy occurs when someone jumps to the conclusion that a cluster in some data must be the result of a cause, usually one that it is clustered around.
Composition relates to synecdoche
composition a fallacy committed when a conclusion is drawn about a whole based on the features of its constituents when, in fact, no justification is provided for the inference
division a fallacy committed when a person infers that what is true of a whole must also be true of its constituents and justification for that inference is not provided
false precision this fallacy occurs when an argument treats information as more precise than it really is.
misplaced precision false precision
fake precision false precision
spurious accuracy false precision