|This page in a nutshell: A rationale used in discussions is that other, similar pages or contents exist and have precedential value. The rationale may be valid in some contexts but not in others: Other stuff sometimes exists according to consensus or policies and guidelines, sometimes in violation of them.|
In Wikipedia discussions, editors point to similarities across the project as reasons to keep, delete, or create a particular type of content, article or policy. These "other stuff exists" arguments can be valid or invalid.
When used correctly, these comparisons are important as the encyclopedia should be consistent in the content that it provides or excludes. For example, harmonizing file names of a set of images is a valid rationale for renaming files (to a lesser degree, this applies to article titles as well, although article naming is more complex). Trouble arises when legitimate comparisons are disregarded without thought or consideration of the Wikipedia:Five pillars.
As this essay tries to stimulate people to use sound arguments related to existing notability policies and guidelines in deletion discussions, and also to consider otherwise valid matters of precedent and consistency, it is important to realize that countering the keep or delete arguments of other people, or dismissing them outright, by simply referring them to this essay by name, and nothing else, is not encouraged. (For a similar issue, see Wikipedia:Arguments to avoid in deletion discussions.)
The claim of "other stuff exists" most often arises in article deletion debate, where it is often used in the following manner. Examples:
A variant of the "other stuff exists" argument is to cite a specific Featured article.
The nature of Wikipedia means that you cannot make a convincing argument based solely on what other articles do or do not exist, because there is nothing stopping anyone from creating any article (except for a salting). Even our basic inclusion rules, such as notability and the use of reliable sources, don't actually provide a mechanism to stop somebody from trying to create an article about a topic that fails them — those rules govern whether or not the article is allowed on Wikipedia once it's here, but they do not actually make it impossible for someone to start an article about a non-notable topic in the first place. And even when such an article does get created, the more responsible editors have to actually see it before it can get dealt with.
While these comparisons are not a conclusive test, they may form part of a cogent argument; an entire comment should not be dismissed because it includes a comparative statement like this. Plenty of articles exist that probably should not. Equally, a lot of articles do not exist that probably should. Therefore, just pointing out that an article on a similar subject exists does not prove that the article in question should also exist; it is quite possible that the other article should also be deleted but nobody has noticed it. However, threats to actually put these other articles forward for AfD after a debate closes may be interpreted as all-or-nothing reasoning. Sometimes arguments are made that other articles have been put forward for AfD and survived/deleted (the most famous example being the Pokémon test); these may be effective arguments, but even here caution should be used.
In general, these deletion debates should focus mainly on the nominated article. In consideration of precedent and consistency, though, identifying articles of the same nature that have been established and continue to exist on Wikipedia may provide extremely important insight into the general concept of notability, levels of notability (what's notable: international, national, regional, state, provincial?), and whether or not a level and type of article should be on Wikipedia. When an editor introduces a novel type of article in Wikipedia, it may be necessary, however, to consider whether such organization of material is compliant with core policies such as neutral point of view and no original research. Other editors may argue that a certain type of articles doesn't exist because of inherent violations of said policies; see WP:ATTACK for example. Dismissing such concerns simply by pointing to this essay is inappropriate.
Deletion debates can sometimes be faulty; even if the debate was correct, it can be hard to draw comparisons: would the fact that there is an article on every Grey's Anatomy character mean there necessarily should be an article on every character on The Office? Comparisons can be highly subjective, and so it is better to look at the debates in question and see what policies were cited and make an argument based on how they apply to the current debate than just say "x was kept so this should be too". However, a small number of debates do receive wide participation and result in a decision that is effectively final, until new evidence comes along. If you reference such a past debate, and it is clearly a very similar case to the current debate, this can be a strong argument that should not be discounted because of a misconception that this section is a blanket ban on ever referencing other articles or deletion debates.
Note as well that people have sometimes tried to raise "other stuff exists" arguments by comparing their article to a non-equivalent situation — for example, the fact that we have an article about Hillary Clinton, even though she did not win the 2016 United States presidential election, has actually been attempted more than once as an argument for why we would need to keep an article about a person notable only as a non-winning candidate for a smalltown city council. What these arguments miss is that Hillary Clinton already held several other notable political offices before running for president, and thus qualifies for an article regardless of her victory or defeat in one individual election. It is important, accordingly, to realize that if you're seeking to establish an article's includability by comparing it to what other articles do or don't exist, you need to look at equivalent topics: if your topic's most notable accomplishment is that she ran for city council and lost, then look to see if we have any significant number of articles about other losing city council candidates. (Spoiler alert: we don't.)
Wikipedia recognizes that it suffers from systemic bias (see WP:BIAS). Sometimes the nomination of one of a series of articles that have relatively equal merit would further the bias (e.g., deletion of Fooian this but not XYZian this if XYZian represents the culture of the majority on Wikipedia) – note that this argument differs from Fooian this vs. Fooian that or Fooian this vs. XYZian that.
When applied to creation of articles, this concept must demonstrate that articles of a similar nature and construct are included throughout Wikipedia. For instance:
Be wary of this logic, though, across topics of differing similarities. The same is not necessarily applicable to vastly different core topics or to every aspect of a topic. For example:
While the Wikipedia community discusses the concept of "inherent notability"—meaning that there is a class of subjects in which every subject in the class could have a stand-alone Wikipedia article—the concept is in limited practice through the use of precedent.
As an example, generally speaking, any television station is very likely to be deemed sufficiently notable for an article, but lower-level schools are generally not. While not a hard-and-fast rule, this is the status quo for Wikipedia inclusion and is consistently maintained through discussions of various schools, school districts, and their creatability and keepability (or lack thereof). Thus "inherent notability" is basically codification of "other stuff exists".
This essay is not a standard reply that can be hurled against anyone you disagree with who has made a reference to how something is done somewhere else. Though a lot of Wikipedia's styles are codified in policy, to a large extent minor details are not. In cases such as these, an "other stuff exists"–type of argument or rationale may provide the necessary precedent for style and phraseology.