Deletionism is a term used to describe theminimalist idea that removal of material is a productive mode of editing, and that doing such regularly, primarily, or solely, rather than adding material, is sufficient to call oneself an editor. The main claim is that thewiki mode of editing is 'too quick', and that there are too many of them (contributors, of some nominal spectrum of skill), and that culling is therefore an art.

Conversely, Wikipedians who have beliefs ranging from less strict to no standards barring an article from Wikipedia are said to subscribe toinclusionism. Few editors would explicitly describe themselves as "deletionists", rather the term is often used in a derogatory manner, as self-deprecating humor, or simply used to expose contrast with people describing themselves as inclusionists.

Wikipedians who subscribe to a conservative inclusion philosophy are likely to request removal of an article they believe does not meet standards. Many editors' inclusion philosophies are dependent on the subject area. For example, some people have more expansive views about removing or deleting unsourced/poorly sourced biographies of living people from the Wikipedia project, because of the increased risk of harm these articles can represent.

The narrower viewpoint on inclusion does not usually insist that useful information should bedeleted. Rather, the decision to keep or eliminate an article is viewed by many as a tool for organizing the information that the project retains. Most often, people promoting the deletion of an article support moving the most important information from that article into a larger parent article on the subject and leaving a redirect to the relevant section.

On most articles in Wikipedia, there is little disagreement between editors of either persuasion. Most Wikipedians would agree that articles such asDwight D. Eisenhower andEvolution have a clear place in the encyclopedia, just as many Wikipedians want extremely poor content to be excluded from Wikipedia. Disagreements usually arise, however, with relatively poorly written articles, or articles pertaining to a specialized subject, especially those whose subjects are fictional in nature (such as characters from a work of fiction) or narrow in scope.

For example, some editors may hold that a short, poorly sourced article on an elementary school in an obscure location does not merit a page of its own in the encyclopedia. They may cite concerns about adequatereferences andverification of claims made in the article. They are more likely to suggest that it is unnecessary to create individual articles on topics that are difficult or impossible to reliably expand in adherence to the verifiability and citation policies of the encyclopedia. Inclusionists often suggest that such articles be kept, especially if verifiability and adequate references are believed can be found. In this sense, inclusionism shares attributes ofeventualism, whereas deletionism has similarities withimmediatism andexclusionism.

Some argue that labeling positions as "deletionism" and "inclusionism" only leads tofactionalism, which makes it difficult to foster cooperation and endangers the understanding of mutual positions. Instead of doing so, Wikipedians should try to develop meaningful policies inconsensus which can be applied to resolve questionable cases. This can be done by building on existing policy, that is, by examining previous cases of deletions. Others argue that tensions can be reduced by recognizing this difference of tendency rather than denying it to create a false harmony, and instead setting policy and designing the software so that it allows the two tendencies to work with less conflict. And then there are those who consider it irrelevant whether there is an atmosphere of conflict or of co-operation, of tension or of harmony. They point out thatWikipedia is not a social club, and that the only important things here are the articles and the mechanisms that make their writing possible.

It is sometimes proposed thattechnological de-escalation such as output filtering could resolve the conflict completely, but deletion itself is simply output filtering: The mediawiki software never actually deletes anything. "Deletion" merely hides the content from public view. Proposals to add additional levels of deletion, e.g. logged in users only for content which is below the threshold which can be well maintained and referenced, have not gained any traction.

It is inaccurate to label Wikipedians simply deletionists or inclusionists: There is a range of views, and many Wikipedians judge articles on their individual merits, forming conclusions that may be ascribed to different "philosophies" by others. An individual's standards for keeping or dropping an article may require a two or three dimensional representation to be accurately described, instead of a one-dimensional continuum. For example, a Wikipedian may be quite happy to keep stubs, provided that they are on-topic, but desire to delete (or move) large but off-topic articles.

An essay written on English Wikipedia long ago and subsequently deleted by its author, but which eloquently reflects the tension here, states:

• Wikipedia can protect itself against legal threats by removinglibelous orcopyright-infringing articles.
• Some articles complicate indexing. For example, having articles on the many unnoteworthy individuals namedJohn Anderson makes it difficult for readers to find the article about the notable U.S. presidential candidate with that name.
• Similarly, the presence of obscure subjects in lists and timelines makes it more difficult for readers to find key people and events.
• Some articles cover topics too obscure for the wiki process to work. For example, a topic where only a few dozen people have firsthand knowledge (or any knowledge at all) is unlikely to see expansion or error correction by anyone but the original author. If these articles are retained Wikipedia may gather larger amounts of incorrect information. It is arguably better to find no result in Wikipedia or an obviously incomplete result than outright incorrect information.
• Some believe that the presence of uninformative articles damages the project's usefulness and credibility, particularly when casual visitors encounter them through Internet search engines or Wikipedia's "random page" or "recent changes."
• Some argue that allowing small, uninformative articles to remain promotes poorly written "drive-by" articles, and that by deleting them writers will be more likely to make informative, well-written articles, a kind ofbroken windows theory.
• Articles on obscure topics, even if they are in principle verifiable, tend to be very difficult to verify. Usually, the more obscure, the harder to verify. Actually verifying such articles, or sorting out verifiable facts from exaggeration and fiction, takes a great deal of time. Not verifying them opens the door to fiction and advertising. This also leads to a de facto collapse of the "no original research policy", which is one of the fundamental Wikipedia policies. Empirically, there have beena number of hoax articles which were difficult to prove to be hoaxes but which could have easily been deleted by a sufficiently strict notability policy.
• For many subjects related to fictional characters or works, it's very difficult to ensure that an article would portray the subject from a real-world perspective. The most high-profile example of this was that at one time Wikipedia had an article for every single individualPokémon, even though most of them exist as little more than minor actors in video games: that's because it is easy to write whole articles from the perspective of a video game guide, or from an in-universe perspective which treats plot elements of a TV show as real. Because of this, some Wikipedians argue that the content itself simply isn't appropriate for an encyclopedia, whereas an external wiki which had different rules on how to present content from a fictional universe would be ideal.
• Less notable articles (minor concepts,South Park episodes, etc.) are more likely to result in articles that are mostly full of original research.
• Less notable articles may distract attention from improving important topics (big things in history for example) because energy is devoted to maintaining popular but fairly insignificant fandom.
• BecauseWikipedia is not paper it can utilize things like section redirects and search to cover even the most obscure subjects without giving each its own free-standing article.
• Poorly sourced articles can result incitogenesis, as incorrect or unsourced information on Wiki (e.g., information that is the product of original research) is then repeated outside Wiki and eventually works its way into a publication that is normally regarded as a reliable source.
• Less notable stubs are much less likely to improve to better, more informative articles.

• Notability of articles is sometimes very subjective. For some,John Anderson the US presidential candidate might be a noted person; others who don't live in the United States might feel thatJohn Anderson the Scottish scientist is more prominent.
• First-time contributors tend to be disheartened if the article(s) that they have started are deleted without (in their opinion) a good reason. In their view, at least, the subject matter is noteworthy.
• Instead of deleting the article altogether, it should be merged with another one (seeMergism).
• Rather than deleting it, why not simply add to it?
• Deleting a well-written, well-sourced article on the basis of notability can reduce the total information of Wikipedia.
• It can be frustrating for a reader to come to Wikipedia for information and inside find that the relevant article existed at one point but has been deleted. This discourages both Wikipedia readership and authorship.
• Deleting an article on the basis of notability both reduces Wikipedia to the level of traditional encyclopedias (which won't cover topics that Wikipedia will for various reasons, including notability), but also doesn't provide the oversight that a traditional encyclopedia has to justify it trimming articles. Part of the reason people use Wikipedia is that it is a vibrant source of obscure knowledge, especially about obscure topics that aren't covered in a more traditional encyclopedia. Other methods of ensuring quality, such as labeling a page "In Need of Editing and Sources", are more than enough to correct problems.
• Search, categorization, and other technical measures for organization can diminish the difficulty in finding information even when there are many articles about insignificant subjects.

• Inclusionism
• Constructionism and reductionism
• Association of Exclusionist Wikipedians
• Association of Inclusionist Wikipedians
• Association of Mergist Wikipedians
• Association of Wikipedians Who Dislike Making Broad Judgements About the Worthiness of a General Category of Article, and Who Are In Favor of the Deletion of Some Particularly Bad Articles, but That Doesn't Mean They are Deletionist
• Closing projects policy
• Wikimedia fundraiser highlights webcomic community's frustration with Wikipedia guidelines
• AFD is evil (essay)

• c2:WikiReductionist
• Nicholas Carr on longer term implications of Deletionism vs. Inclusionism
• Watching Wikipedia's Extinction Event From A Distance
• 40% of Wikipedia is under threat from deletionists

• Wikipedia philosophy
• Deletions