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Anecdotal evidence (or anecdata [1] ) is evidence based on descriptions and reports of individual, personal experiences, or observations, [2] [3] collected in a non-systematic manner. [4]
The word anecdotal constitutes a variety of forms of evidence. This word refers to personal experiences, self-reported claims, [3] or eyewitness accounts of others, [5] including those from fictional sources, making it a broad category that can lead to confusion due to its varied interpretations.
Anecdotal evidence can be true or false but is not usually subjected to the methodology of scholarly method, the scientific method, or the rules of legal, historical, academic, or intellectual rigor, meaning that there are little or no safeguards against fabrication or inaccuracy. [2] However, the use of anecdotal reports in advertising or promotion of a product, service, or idea may be considered a testimonial, which is highly regulated in some jurisdictions. [6]
The persuasiveness of anecdotal evidence compared to that of statistical evidence has been a subject of debate; some studies have argued for the presence a generalized tendency to overvalue anecdotal evidence, whereas others have emphasized the types of argument as a prerequisite or rejected the conclusion altogether. [7] [8] [9] [10] [11]
In science, definitions of anecdotal evidence include:
Anecdotal evidence may be considered within the scope of scientific method as some anecdotal evidence can be both empirical and verifiable, e.g. in the use of case studies in medicine. Other anecdotal evidence, however, does not qualify as scientific evidence, because its nature prevents it from being investigated by the scientific method, for instance, in that of folklore or in the case of intentionally fictional anecdotes. Where only one or a few anecdotes are presented, there is a chance that they may be unreliable due to cherry-picked or otherwise non-representative samples of typical cases. [16] [17] Similarly, psychologists have found that due to cognitive bias people are more likely to remember notable or unusual examples rather than typical examples. [18] Thus, even when accurate, anecdotal evidence is not necessarily representative of a typical experience. Accurate determination of whether an anecdote is typical requires statistical evidence. [19] Misuse of anecdotal evidence in the form of argument from anecdote is an informal fallacy [20] and is sometimes referred to as the "person who" fallacy ("I know a person who..."; "I know of a case where..." etc.) which places undue weight on experiences of close peers which may not be typical.
Anecdotal evidence can have varying degrees of formality. For instance, in medicine, published anecdotal evidence by a trained observer (a doctor) is called a case report, and is subjected to formal peer review. [21] Although such evidence is not seen as conclusive, researchers may sometimes regard it as an invitation to more rigorous scientific study of the phenomenon in question. [22] For instance, one study found that 35 of 47 anecdotal reports of drug side-effects were later sustained as "clearly correct." [23]
Anecdotal evidence is considered the least certain type of scientific information. [24] Researchers may use anecdotal evidence for suggesting new hypotheses, but never as validating evidence. [25] [26]
If an anecdote illustrates a desired conclusion rather than a logical conclusion, it is considered a faulty or hasty generalization. [27]
In any case where some factor affects the probability of an outcome, rather than uniquely determining it, selected individual cases prove nothing; e.g. "my grandfather smoked two packs a day until he died at 90" and "my sister never smoked but died of lung cancer". Anecdotes often refer to the exception, rather than the rule: "Anecdotes are useless precisely because they may point to idiosyncratic responses." [28]
In medicine, anecdotal evidence is also subject to placebo effects. [29]
In the legal sphere, anecdotal evidence, if it passes certain legal requirements and is admitted as testimony, is a common form of evidence used in a court of law. Often this form of anecdotal evidence is the only evidence presented at trial. [30] Scientific evidence in a court of law is called physical evidence, but this is much rarer. Anecdotal evidence, with a few safeguards, represents the bulk of evidence in court.
The legal rigors applied to testimony for it to be considered evidence is that it must be given under oath, that the person is only testifying to their own words and actions, and that someone intentionally lying under oath is subject to perjury. However, these rigors do not make testimony in a court of law equal to scientific evidence as there are far less legal rigors. Testimony about another person's experiences or words is called hearsay and is usually not admissible, though there are certain exceptions. However, any hearsay that is not objected to or thrown out by a judge is considered evidence for a jury. This means that trials contain quite a bit of anecdotal evidence, which is considered as relevant evidence by a jury. Eyewitness testimony (which is a form of anecdotal evidence) is considered the most compelling form of evidence by a jury. [31]
Pseudoscience consists of statements, beliefs, or practices that claim to be both scientific and factual but are incompatible with the scientific method. Pseudoscience is often characterized by contradictory, exaggerated or unfalsifiable claims; reliance on confirmation bias rather than rigorous attempts at refutation; lack of openness to evaluation by other experts; absence of systematic practices when developing hypotheses; and continued adherence long after the pseudoscientific hypotheses have been experimentally discredited. It is not the same as junk science.
Persuasion or persuasion arts is an umbrella term for influence. Persuasion can influence a person's beliefs, attitudes, intentions, motivations, or behaviours.
The phrase "correlation does not imply causation" refers to the inability to legitimately deduce a cause-and-effect relationship between two events or variables solely on the basis of an observed association or correlation between them. The idea that "correlation implies causation" is an example of a questionable-cause logical fallacy, in which two events occurring together are taken to have established a cause-and-effect relationship. This fallacy is also known by the Latin phrase cum hoc ergo propter hoc. This differs from the fallacy known as post hoc ergo propter hoc, in which an event following another is seen as a necessary consequence of the former event, and from conflation, the errant merging of two events, ideas, databases, etc., into one.
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.
Testimony is a solemn attestation as to the truth of a matter.
Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. Such evidence is expected to be empirical evidence and interpretable in accordance with the scientific method. Standards for scientific evidence vary according to the field of inquiry, but the strength of scientific evidence is generally based on the results of statistical analysis and the strength of scientific controls.
A faulty generalization is an informal fallacy wherein a conclusion is drawn about all or many instances of a phenomenon on the basis of one or a few instances of that phenomenon. It is similar to a proof by example in mathematics. It is an example of jumping to conclusions. For example, one may generalize about all people or all members of a group from what one knows about just one or a few people:
Cherry picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position while ignoring a significant portion of related and similar cases or data that may contradict that position. Cherry picking may be committed intentionally or unintentionally.
Inductive reasoning is any of various methods of reasoning in which broad generalizations or principles are derived from a body of observations. This article is concerned with the inductive reasoning other than deductive reasoning, where the conclusion of a deductive argument is certain given the premises are correct; in contrast, the truth of the conclusion of an inductive argument is at best probable, based upon the evidence given.
An anecdote is "a story with a point", such as to communicate an abstract idea about a person, place, or thing through the concrete details of a short narrative or to characterize by delineating a specific quirk or trait.
Rigour or rigor describes a condition of stiffness or strictness. These constraints may be environmentally imposed, such as "the rigours of famine"; logically imposed, such as mathematical proofs which must maintain consistent answers; or socially imposed, such as the process of defining ethics and law.
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.
Persuasive writing is a set of written arguments to convince, motivate, or move readers into a particular point of view or opinion on your topic. This argument is typically presented with reasoned opinions backed and explained by evidence that supports the thesis. A wide variety of writings, such as criticisms, reviews, reaction papers, editorials, proposals, advertisements, and brochures, utilize different persuasion techniques to influence readers. In some forms of persuasive writing, especially in formal and academic works, the knowledge of both sides of the argument, one in favor and one against is essential to distinguish and minimize the significance of the counterargument to convince the audience.
Evidence of absence is evidence of any kind that suggests something is missing or that it does not exist. What counts as evidence of absence has been a subject of debate between scientists and philosophers. It is often distinguished from absence of evidence.
Evidence for a proposition is what supports the proposition. It is usually understood as an indication that the proposition is true. The exact definition and role of evidence vary across different fields. In epistemology, evidence is what justifies beliefs or what makes it rational to hold a certain doxastic attitude. For example, a perceptual experience of a tree may serve as evidence to justify the belief that there is a tree. In this role, evidence is usually understood as a private mental state. In phenomenology, evidence is limited to intuitive knowledge, often associated with the controversial assumption that it provides indubitable access to truth.
The invincible ignorance fallacy, also known as argument by pigheadedness, is a deductive fallacy of circularity where the person in question simply refuses to believe the argument, ignoring any evidence given. It is not so much a fallacious tactic in argument as it is a refusal to argue in the proper sense of the word. The method used in this fallacy is either to make assertions with no consideration of objections or to simply dismiss objections by calling them excuses, conjecture, anecdotal, etc. or saying that they are proof of nothing, all without actually demonstrating how the objections fit these terms. It is similar to the ad lapidem fallacy, in which the person rejects all the evidence and logic presented, without providing any evidence or logic that could lead to a different conclusion.
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.
An argument from anecdote is an informal logical fallacy, when an anecdote is used to draw an improper logical conclusion. The fallacy can take many forms, such as cherry picking, hasty generalization, proof by assertion, and so on.
Math on Trial: How Numbers Get Used and Abused in the Courtroom is a book on mathematical and statistical reasoning in legal argumentation, for a popular audience. It was written by American mathematician Leila Schneps and her daughter, French mathematics educator Coralie Colmez, and published in 2013 by Basic Books.
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: CS1 maint: others (link)Testimonial and anecdotal evidence can be quite useful in the early stages of scientific investigation. Nevertheless, such evidence is almost always much more helpful in the context of discovery (i.e., hypothesis generation) than in the context of justification (i.e., hypothesis testing [...]).