The following is a proposed Wikipedia policy, guideline, or process. The proposal may still be in development, under discussion, or in the process of gathering consensus for adoption.

All material published by Wikipedia must be attributable to a reliable published source. This means that all facts, opinions, ideas, and arguments may only be included in articles if they have already been published by a reliable source.

“

Proposing as I do to follow the consentient testimony of historians, I shall give the differences in their narratives under the writers' names. — Tacitus ^[1]

”

Not all material must actually be attributed to a source. "The sun will rise in the east tomorrow" does not require a source. However, it is a fact that is capable of attribution; that is, there are published sources who could be cited in its support if necessary. In other words, it is not a Wikipedian's original research.

Editors should provide attribution for any material that is challenged or likely to be challenged. The burden of evidence lies with the editor wishing to add material.

Wikipedia:Attribution is one of Wikipedia's two core content policies. The other is Wikipedia:Neutral point of view. Jointly, these policies determine the type and quality of material that is acceptable in the main namespace. Because the policies are complementary, they should not be interpreted in isolation from one another.

Some key terms

Original research refers to material for which no reliable published source could be found; that is, it refers to material that is not attributable to a reliable source. It includes unpublished arguments, concepts, data, ideas, statements, and theories. It also includes any unpublished analysis or synthesis of published material that appears to advance a position. Wikipedia does not publish original research.

Reliable sources are people or documents generally regarded as trustworthy or authoritative regarding the subject we're writing about. All Wikipedia articles must be based on reliable sources. There is no firm definition, and how reliable a source is depends on context. In general, the most reliable sources are books and journals published by universities; mainstream newspapers; magazine and journals published by known publishing houses. What these have in common is that there are usually large numbers of people standing between the writer and the act of publication. As a rule of thumb, the greater the number of people employed by a publisher to check facts, to check for legal problems, and to check the writing, the more reliable the publication. Material that is self-published is generally not regarded as reliable, because nothing stands between the writer and the act of publication, but see below for exceptions.

Primary sources are documents or people very close to the situation you are writing about. An eyewitness account of a traffic accident is a primary source. The Bible is a primary source. The White House's summary of a George Bush speech is a primary source. Primary sources that have been published by a reliable source may be used for the purposes of attribution in Wikipedia, but only with care, because it's easy to misuse primary sources; for example, anyone could try to use the Bible as evidence that God said homosexuality was a sin. For that reason, edits that rely on primary sources should only make descriptive claims that can be checked by anyone without specialist knowledge. Any interpretation of primary source material requires a secondary source.

Secondary sources are documents or people who summarize other material, usually primary source material. They are academics, journalists, and other researchers, and the papers and books they produce. A journalist's account of a traffic accident is a secondary source. A theologian's account of what the Bible says is a secondary source. The New York Times account of a George Bush speech is a secondary source. Wikipedia articles should rely on reliable, published secondary sources wherever possible. This means that we're publishing the opinions of reliable authors, and not the opinions of Wikipedians who have read the primary source material for themselves. We want to know what Professor Smith, the theologian, says about the Bible and homosexuality. We don't want to know what User:Smith says about it, even though both are relying on the same source.

What does this policy exclude?

Editors may not use Wikipedia to publish:

their personal opinions;
unpublished facts, theories, arguments, or ideas;
unpublished neologisms;
any analysis or synthesis of published facts, ideas, opinions, or arguments that builds a case favored by the editor, unless that precise analysis or synthesis can be attributed to a reliable, preferably secondary, published source.

Requesting sources

For how to format citations, see Wikipedia:Citing sources

If an article topic has no reliable sources that can be cited, it isn't notable enough to have a Wikipedia entry.

Any edit lacking attribution may be removed in principle, but bear in mind that not all edits need a source, and this policy should never be used to cause disruption by removing material for which reliable sources could reasonably be found.

Usually, you should give people a chance to provide attribution. If you want to request a source for an unsourced statement, consider moving it to the talk page; tag the sentence by adding the ((fact)) template; or tag the whole article by adding ((not verified)) template. You can also make the unsourced sentences invisible by adding <nowiki> after it, until the material is attributed. Always leave a note on the talk page explaining what you're doing. If no source has been provided within a reasonable time — and how long that is will depend on the context — then you may remove it.

Be careful not to err too far on the side of not upsetting other editors by leaving unsourced information in articles for too long, or at all in the case of information about living people. Jimmy Wales has said of this: "I can NOT emphasize this enough. There seems to be a terrible bias among some editors that some sort of random speculative 'I heard it somewhere' pseudo information is to be tagged with a 'needs a cite' tag. Wrong. It should be removed, aggressively, unless it can be sourced. This is true of all information, but it is particularly true of negative information about living persons." ^[2]^[3]

As with all Wikipedia policies, use your common sense when applying this policy.

Biographies of living persons

Biographies of living people need special care because they could negatively affect someone's life and could have legal consequences. Remove unattributed material about living persons immediately if it could be viewed as criticism, ^[2]^[3] and do not move it to the talk page. This also applies to material about living persons in other articles.

Citing yourself

If you're a subject expert, you may cite your own publications just as you'd cite anyone else's, although make sure your material is relevant and that you're regarded as a reliable source for the purposes of Wikipedia.

Questionable sources

For the purposes of this policy, questionable sources are sources with a poor reputation for fact-checking, or with no fact-checking process or editorial oversight. This category includes websites and publications that express political or religious views that are widely acknowledged as extremist: for example, the website of Stormfront.

Sources of questionable reliability should only be used in articles about themselves. Even those articles should not – on the grounds of needing to give examples of the source's work – repeat any potentially defamatory claims the source has made about third parties. For example, if the online satirical magazine London's Gossip! publishes that the baby of Actress X was fathered by Y and not by Mr. Actress X, that story must not be repeated in a Wikipedia article about London's Gossip! on the grounds that the article needs to give examples of their stories. This does not apply, of course, if the story has also been published by reliable sources.

Self-published sources

A self-published source is a published source, online or on paper, that has not been subject to any form of independent fact-checking, or where no one stands between the writer and the act of publication. 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 usually not acceptable as reliable sources.

There are two exceptions:

1. When a professional or academic researcher writing in his or her area of expertise, or a well-known professional journalist or commentator, produces self-published material, we can rely on it so long as the writer would normally be regarded as a reliable source. For example, if the journalist Seymour Hersch were to publish material on his blog, we could use that material as a source because Hersch is regarded as a reliable source no matter where he publishes.

However, exercise caution: if the material is really worth reporting, someone else is likely to have done so. If there is reasonable doubt about the reliability of the source or the relevance of the material to the subject matter, err on the side of caution and don't use the self-published material.

2. The second exception is where self-published sources, online or on paper, are used in articles about themselves. This is allowed so long as:

The material is relevant to the person's or organization's notability;
It is not contentious;
It is not unduly self-serving;
It does not involve claims about third parties, or about events not directly related to the subject;
There is no reasonable doubt as to who wrote it.

Synthesis of material serving to advance a position

Material can often be put together in a way that constitutes original research even if its constituent parts have been published by reliable sources. If you have reliable sources for the edits you want to make, be careful that you're not analysing the material in a way that produces a new idea or argument of your own. Just because A is published by a reliable source, and B is published by a reliable source, doesn't necessarily mean that A and B can be joined in order to advance position C.

An example from a Wikipedia article, with the names changed. The article was about Jones:

Smith says that Jones committed plagiarism in Jones's Flower-Arranging: The Real Story by copying references from another book. Jones denies this, saying he had learned about the references in that book, and it's acceptable scholarly practise to use other people's books to find new references."

So far, so good. The article tells us what Smith said, and then what Jones said, and both edits were sourced to reliable publications. Now comes the unpublished synthesis of published material:

If Jones's claim that he always consulted the original sources is false, this would be contrary to the practice recommended in the Chicago Manual of Style, which requires citation of the source actually consulted. The Chicago Manual of Style does not call violating this rule "plagiarism." Instead, plagiarism is defined as using a source's information, ideas, words, or structure without citing them.

This entire paragraph is original research, because the editor's synthesis of published material is being used to support the editor's opinion. The paragraph is putting forward the editor's view that, given the Chicago Manual of Style's definition of plagiarism, Jones did not commit it. For this paragraph to be acceptable, the editor would have to find a reliable source that specifically commented on the Smith and Jones dispute and made the same point about the Chicago Manual of Style. In other words, that precise analysis must have been published by a reliable source before it can be published in Wikipedia.

A final thought: Tacitus' recommendation

Nos consensum auctorum secuturi, quae diversa prodiderint sub nominibus ipsorum trademus.		Proposing as I do to follow the consentient testimony of historians, I shall give the differences in their narratives under the writers' names.
Tacitus, Annals XIII, 20 – Church/Brodribb translation

Notes

^ Annals XIII, 20 – Church/Brodribb translation.
^ ^a ^b Wales, Jimmy. "Zero information is preferred to misleading or false information", WikiEN-l, May 16, 2006.
^ ^a ^b "Zero information is preferred to misleading or false information", WikiEN-l, May 19, 2006.