Wikipedia:Verifiability

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The threshold for inclusion in Wikipedia is verifiability, not truth. This means that we only publish material that is verifiable with reference to reliable, published sources.

Wikipedia:Verifiability is one of Wikipedia's three content-guiding policy pages. The other two are Wikipedia:No original research and Wikipedia:Neutral point of view. Jointly, these policies determine the type and quality of material that is acceptable in the main namespace. The three policies are complementary, non-negotiable, and cannot be superseded by any other guidelines or by editor's consensus. They should therefore not be interpreted in isolation from one other, and editors should try to familiarize themselves with all three.

The policy

1. Articles should contain only material that has been published by reputable sources. 2. Editors adding new material to an article should cite a reputable source, or it may be removed by any editor. 3. The obligation to provide a reputable source lies with the editors wishing to include the material, not on those seeking to remove it.

Verifiability, not truth

One of the keys to writing good encyclopedia articles is to understand that they should refer only to facts, assertions, theories, ideas, claims, opinions, and arguments that have already been published by a reputable publisher. The goal of Wikipedia is to become a complete and reliable encyclopedia, so editors should cite reliable sources so that their edits may be verified by readers and other editors.

"Verifiability" in this context does not mean that editors are expected to verify whether, for example, the contents of a New York Times article are true. In fact, editors are strongly discouraged from conducting this kind of research, because original research may not be published in Wikipedia. Articles should contain only material that has been published by reliable sources, regardless of whether individual editors view that material as true or false. As counter-intuitive as it may seem, the threshold for inclusion in Wikipedia is verifiability, not truth.

A good way to look at the distinction between verifiability and truth is with the following example. Suppose you are writing a Wikipedia entry on a famous physicist's Theory X, which has been published in peer-reviewed journals and is therefore an appropriate subject for a Wikipedia article. However, in the course of writing the article, you contact the physicist and he tells you: "Actually, I now believe Theory X to be completely false." Even though you have this from the author himself, you cannot include the fact that he said it in your Wikipedia entry.

Why not? Because it is not verifiable in a way that would satisfy the Wikipedia readership or other editors. The readers don't know who you are. You can't include your telephone number so that every reader in the world can call you for confirmation. And even if they could, why should they believe you?

For the information to be acceptable to Wikipedia, you would have to persuade a reputable news organization to publish your story first, which would then go through a process similar to peer review. It would be checked by a reporter, an editor, perhaps by a fact-checker, and if the story were problematic, it might be checked further by the lawyers and the editor-in-chief. These checks and balances exist to ensure that accurate and fair stories appear in the newspaper.

It is this fact-checking process that Wikipedia is not in a position to provide, which is why the no original research and verifiability policies are so important.

If the newspaper published the story, you could then include the information in your Wikipedia entry, citing the newspaper article as your source.

Sources

Further information: Wikipedia:Reliable sources

Articles should rely on credible, third-party sources with a reputation for fact-checking and accuracy. For academic subjects, the sources should preferably be peer-reviewed. Sources should also be appropriate to the claims made: outlandish claims beg strong sources.

English-language sources should be given whenever possible, and should always be used in preference to foreign-language sources, so that readers can easily verify that the source material has been used correctly.

Citing sources

Further information: Wikipedia:Citing sources

The burden of evidence lies with the editors who have made an edit or wish an edit to remain. Editors should therefore provide references. If an article topic has no reputable sources, Wikipedia should not have an article on that topic. Any edit lacking a source may be removed, but do not remove large tracts of Wikipedia without first giving people a chance to provide references to support their inclusion. If you doubt the accuracy or origin of an unsourced statement that has been in an article for a long time, delete it or move it to the talk page. Alternatively, you may tag the article by adding the {{fact}}, {{not verified}} or {{unsourced}} templates. If the article has many unsourced statements that have been there a long time, you may request sources on the talk page before removing them, unless the article or information is about a living person, in which case remove the unsourced information. When removing information be very careful to do so politely and with civility.

Sources of dubious reliability

In general, sources of dubious reliability are sources with a poor reputation for fact-checking, or with no fact-checking facilities.

Sometimes a statement can only be found in a publication of dubious reliability, such as a tabloid newspaper. If the statement is relatively unimportant, remove it. If it is important enough to keep, attribute it to the source in question. For example: "According to the British tabloid newspaper The Sun ..."

Self-published sources

Anyone can create a website or pay to have a book published, and then claim to be an expert in a certain field. For that reason, self-published books, personal websites, and blogs are largely not acceptable as sources. Exceptions may be when a well-known, professional researcher in a relevant field, or a well-known professional journalist, has produced self-published material. In some cases, these may be acceptable as sources, so long as their work has been previously published by credible, third-party publications. However, exercise caution: if the information on the professional researcher's blog is really worth reporting, someone else will have done so.

Self-published sources in articles about themselves

Self-published sources and other published sources of dubious reliability may be used as sources in articles about themselves. For example, the Stormfront website may be used as a source about itself in an article about Stormfront, so long as the information is notable, not unduly self-aggrandizing, and not contradicted by other published sources.

A Wikipedia article about an unreliable newspaper should not — on the grounds of needing to give examples of their published stories — repeat any claims the newspaper has made about third parties, unless the stories have been repeated by credible third-party sources.

Other comments

Just because some information is verifiable, doesn't mean that Wikipedia is the right place to publish it. See what Wikipedia is not. And just because information is true, doesn't mean that it meets our verifiability requirements - information has to be sourced if it is to have a place in Wikipedia (although, of course, if information is true, you should be able to find a ready reputable source for it). Another effect of this policy is that as original research will not be supported by reputable sources, it cannot be included. See Wikipedia:No original research.

See also

• WikiProject Fact and Reference Check
• Forum for Encyclopedic Standards
• Stable versions
• Wikipedia:Biographies of living persons