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Encyclopedia > Regression fallacy

The regression (or regressive) fallacy is a logical fallacy. It ascribes cause where none exists. The flaw is failing to account for natural fluctuations. It is frequently a special kind of the post hoc fallacy. It has been suggested that this article or section be merged with fallacy. ... Post hoc ergo propter hoc is Latin for after this, therefore because of this. ...



Things like stock market prices, golf scores, and chronic back pain can fluctuate naturally and may regress towards the mean. The logical flaw is to make predictions that expect exceptional results to continue as if they were average. (See representativeness heuristic.) People are most likely to take action when variance is at its peak. Then after results become more normal they believe that their action was the cause of the change when in fact it was not causal. In statistics, regression toward the mean is a principle stating that of related measurements, the second is expected to be closer to the mean than the first. ... The representativeness heuristic is a heuristic wherein we assume commonality between objects of similar appearance. ...

The word ‘regression’ was coined by Sir Francis Galton in a study from 1885 called "Regression Toward Mediocrity in Hereditary Stature”. He showed that the height of children from very short or very tall parents would move towards the average. Sir Francis Galton F.R.S. (February 16, 1822 – January 17, 1911), half-cousin of Charles Darwin, was an English Victorian polymath, anthropologist, eugenicist, tropical explorer, geographer, inventor, meteorologist, proto-geneticist, psychometrician, and statistician. ... 1885 (MDCCCLXXXV) is a common year starting on Thursday of the Gregorian calendar (or a common year starting on Saturday of the 12-day slower Julian calendar). ...


When his pain got worse, he went to a witchdoctor, after which it subsided a little. Clearly, he benefited from the witchdoctor's powers.

The pain subsiding a little after it has gotten worse was more easily explained by regression towards the mean. Assuming it was caused by the witchdoctor is fallacious. (The same would be true if "witchdoctor" is replaced by "doctor" when improvemenet is more easily explained by regression towards the mean than by phamaceutical drugs whose effectiveness may in many casees be far from proven).

The student did exceptionally poorly last semester, so I punished him. He did much better this semester. Clearly, punishment is effective in improving students' grades.

Often exceptional performances are followed by more normal performances, so the change in performance might better be explained by regression towards the mean. Incidentally, tests[citation needed] have shown that people may develop a systematic bias for punishment and against reward because of reasoning analogous to this example of the regression fallacy.


The regression fallacy can be used to dismiss valid explanations. For example:

After the Western Allies invaded Normandy, creating a second major front, German control of Europe waned. Clearly, the combination of the Western Allies and the USSR drove the Germans back.

Given that the counterattacks against Germany occurred only after they had conquered the greatest amount of territory under their control, regression to the mean can explain the retreat of German forces from occupied territories as a purely random fluctuation that would have happened without any intervention on the part of the USSR or the Western Allies.

In essence, mis-application of regression to the mean can reduce all events to a "just so" story, without cause or effect. A just-so story is a term used in academic anthropology, biological sciences, and social sciences for a narrative explanation for a cultural practice or a biological trait or behavior of humans or animals which is unverifiable and unfalsifiable. ...

Informal fallacies
v  d  e
Special pleading | Red herring | Gambler's fallacy and its inverse
Fallacy of distribution (Composition | Division) | Begging the question | Many questions
Correlative-based fallacies:
False dilemma (Perfect solution) | Denying the correlative | Suppressed correlative
Deductive fallacies:
Accident | Converse accident
Inductive fallacies:
Hasty generalization | Overwhelming exception | Biased sample
False analogy | Misleading vividness | Conjunction fallacy
False precision | Slippery slope
Amphibology | Continuum fallacy | False attribution (Contextomy | Quoting out of context)
Equivocation (Loki's Wager | No true Scotsman)
Questionable cause:
Correlation does not imply causation | Post hoc | Regression fallacy
Texas sharpshooter | Circular cause and consequence | Wrong direction | Single cause
Other types of fallacy

In Philosophical logic, an informal fallacy is a pattern of reasoning which is false due to the falsity of one or more of its premises. ... Special pleading is a form of spurious argumentation where a position in a dispute introduces favorable details or excludes unfavorable details by alleging a need to apply additional considerations without proper criticism of these considerations themselves. ... It has been suggested that this article or section be merged into Red herring (disambiguation). ... The gamblers fallacy is a logical fallacy which encompasses any of the following misconceptions: A random event is more likely to occur because it has not happened for a period of time; A random event is less likely to occur because it has not happened for a period of... The inverse gamblers fallacy is a tempting mistake in judgments of probability, comparable to the gamblers fallacy whence its name derives. ... A fallacy of distribution is a logical fallacy occurring when an argument assumes there is no difference between a term in the distributive (referring to every member of a class) and collective (referring to the class itself as a whole) sense. ... A fallacy of composition arises when one infers that something is true of the whole from the fact that it is true of some (or even every) part of the whole. ... A fallacy of division occurs when someone reasons logically that something that is true of a thing must also be true of its constituents. ... In logic, begging the question, also known as circular reasoning and by the Latin name petitio principii, is an informal fallacy found in many attempts at logical arguments. ... Many questions, also known as complex question, presupposition, loaded question, or plurium interrogationum (Latin, of many questions), is a logical fallacy. ... In logic, correlative-based fallacies, also known as fallacies of distraction, are logical fallacies based on correlative conjunctions. ... The logical fallacy of false dilemma (in some sources falsified dilemma), which is also known as fallacy of the excluded middle, false dichotomy, either/or dilemma or bifurcation, involves a situation in which two alternative points of view are held to be the only options, when in reality there exist... The perfect solution fallacy is a logical fallacy that occurs when an argument assumes that a perfect solution exists and/or that a solution should be rejected because some part of the problem would still exist after it was implemented. ... The logical fallacy of denying the correlative is the opposite of the false dilemma, where an attempt is made at introducing alternatives where there are none. ... The logical fallacy of suppressed correlative is a type of argument which tries to redefine a correlative (two mutually exclusive options) so that one alternative encompasses the other, i. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The logical fallacy of accident, also called destroying the exception or a dicto simpliciter ad dictum secundum quid, is a deductive fallacy occurring in statistical syllogisms (an argument based on a generalization) when an exception to the generalization is ignored. ... The logical fallacy of converse accident (also called reverse accident, destroying the exception or a dicto secundum quid ad dictum simpliciter) is a deductive fallacy that can occur in a statistical syllogism when an exception to a generalization is wrongly called for. ... A faulty generalization, also known as an inductive fallacy, is any of several errors of inductive inference: Hasty generalization is the fallacy of examining just one or very few examples or studying a single case, and generalizing that to be representative of the whole class of objects or phenomena. ... Hasty generalization, also known as fallacy of insufficient statistics, fallacy of insufficient sample, fallacy of the lonely fact, leaping to a conclusion, hasty induction, law of small numbers, unrepresentative sample or secundum quid, is the logical fallacy of reaching an inductive generalization based on too little evidence. ... A biased sample is one that is falsely taken to be typical of a population from which it is drawn. ... False analogy is a logical fallacy applying to inductive arguments. ... The logical fallacy of misleading vividness involves describing some occurrence in vivid detail, even if it is an exceptional occurrence, to convince someone that it is a problem. ... The conjunction fallacy is a logical fallacy that occurs when it is assumed that specific conditions are more probable than general ones. ... Ambiguity is one way in which the meanings of words and phrases can be unclear, but there is another way, which is different from ambiguity: vagueness. ... This article or section does not cite its references or sources. ... In debate or rhetoric, the slippery slope is an argument for the likelihood of one event given another. ... Look up ambiguity in Wiktionary, the free dictionary. ... Amphibology or amphiboly (from the Greek amphibolia) is, in logic, a verbal fallacy arising from ambiguity in the grammatical structure of a sentence. ... Continuum fallacy, also called fallacy of the beard is a logical fallacy which abuses the paradox of the heap. ... The fallacy of a false attribution occurs when an advocate appeals to an irrelevant, unqualified, unidentified, biased or fabricated source in support of an argument. ... // Contextomy Contextomy refers to the selective excerpting of words from their original linguistic context in a way that distorts the source’s intended meaning, a practice commonly (and erroneously) referred to as the fallacy of quoting out of context. ... It has been suggested that Contextomy be merged into this article or section. ... Equivocation is a logical fallacy. ... Lokis Wager is a form of logical fallacy. ... It has been suggested that this article or section be merged with Special Pleading . ... Fallacies of questionable cause, also known as causal fallacies, non causa pro causa (non-cause for cause in Latin) or false cause, are informal fallacies where a cause is incorrectly identified. ... Correlation does not imply causation is a phrase used in statistics to indicate that correlation between two variables does not imply there is a cause-and-effect relationship between the two. ... Post hoc ergo propter hoc, Latin for after this, therefore because of this, is a logical fallacy which assumes or asserts that if one event happens after another, then the first must be the cause of the second. ... The Texas sharpshooter fallacy is a logical fallacy where a cluster of statistically non-significant data is taken from its context, and therefore thought to have a common cause. ... Circular cause and consequence is a logical fallacy where the consequence of the phenomenon is claimed to be its root cause. ... Wrong direction is a logical fallacy of causation where cause and effect are reversed. ... The fallacy of the single cause, also known as joint effect or causal oversimplification, is a logical fallacy of causation that occurs when 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...

External links

  Results from FactBites:
Logical fallacy - Wikipedia, the free encyclopedia (879 words)
A logical fallacy may mean nothing more than a fallacy or it may mean an error in deductive reasoning, i.e., a formal fallacy.
In the latter case, it is a flaw in the structure of a deductive argument as opposed to an error in the premises.
Recognizing fallacies in everyday arguments may be difficult since arguments are often embedded in rhetorical patterns that obscure the logical connections between statements.
  More results at FactBites »



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