Mergism is the philosophy that minor topics should be merged into the relevant main article(s). Users who adhere to this philosophy are called mergists and are opposed to separatists who tend to split minor topics off into their own articles.
Mergism is grounded in the centre of the inclusionism-deletionism spectrum. Rather than taking to extreme sides in the quest for a better Wikipedia, mergists believe that while much information may warrant inclusion somewhere, very little of it probably warrants its own article.
While it is true that Wiki is not paper, and this enables it to host a vast variety of topics and information, superfluous articles containing information that could easily be merged into other articles make Wikipedia harder to navigate and more difficult to organize. Critics argue that articles can become too complex, when everything is merged into one. When there are many articles on narrow, closely related topics, such as objects in a fictional universe, each remains small and each must establish the context anew without the benefit of reference to prior discussion or simultaneous viewing of related items. Mergists maintain that while the articles may merit deletion (or redirection) the information contained therein often deserves to be preserved. This, of course, does not apply to patent nonsense and/or gibberish, but even in the case of vanity pages, advertising and/or self-promotion there may be important information that could be preserved elsewhere while the article itself is removed.
Mergism is positively correlated with making redirects for neighbour (or closely related) notions and synonymical terms; see implicit merger for expanded view of such kind of mergism. Furthermore, some mergists also believe that rampant inclusionism and deletionism are both harmful to Wikipedia and, as a whole, accomplish very little other than to muddy the water.
The formal organization for Mergists is the AMW. Membership is open to anybody that wishes to add their name to the association's page. The AMW gives Mergists a place to gather and discuss their ideas, beliefs, or anything else that may interest them.
In June 2006, users on English Wikipedia began a project that embraces Mergist philosophy as a focused cleanup effort.