Generally, we may write about whatever we like in the Citizendium. There are, however, at least three basic constraints on the choice of article topic:
- Encyclopedia topics. Topics should be plausible as encyclopedia article topics. This excludes, for example, topics expressing personal opinions (e.g., "Why I think God does not exist"), or highly complicated topics that reflect original research (e.g., "Fruit production in France, Turkmenistan, and Australia").
- Redundancy. If one topic is quite similar to another--for example, is just a variant on the name--then the less common topic name should in many cases be redirected to the more common topic name. Thus, for example Great War redirects to World War I.
- Maintainability. There are certain classes of articles that are unlikely to ever be complete, high-quality, and well-maintained. The reason for this is simply that the Citizendium will never have an adequate number of contributors to do the work. The "class" of article here depends on certain types that are in many cases fairly easy to spot. For example, we should not write an article about an undistinguished, perfectly ordinary school unless we can write articles about all schools; we should not write an article about a county in Connecticut unless we can write articles about all counties in the United States; and so forth. An example of a class of article that it seems we will never have the contributors to maintain is: all named roads. What the future has in store could surprise us, however, so it is important not to be dogmatic here. See maintainability.
Unlike in Wikipedia, there is no requirement on the Citizendium that article topics be "notable." That is, we do not exclude topics solely on the ground that their topics do not strike contributors as being significant or important. We recognize that what may completely trivial to one person might in fact be quite important to another, and that as a criterion "notability" is too vague to admit of consistent use.