Be Precise, when necessary.
Convention: Please, do not write or put an article on a page with an ambiguously-named title as though that title had no other meanings!
A reader may have found your article with a search, with Recent Changes or accidentally, or in some other way that robs him of the context, so do him a favor and name your articles precisely. If a word or phrase is ambiguous, and your article concerns only one of the meanings of that word or phrase, you should probably--not in all cases, but in many--use something more precise than just that word or phrase. For example, use Apollo program, Nirvana (band), smoking pipe; rather than simply Apollo, Nirvana, Pipe. See disambiguation for more details on that. This is not to say that pages should be constantly disambiguated; often, there is a tendency to include artists and their albums at disambiguated pages, even when there is no need. The basic rule is that, unless you are absolutely sure that a related usage deserves or has an article, no disambigutation is necessary.
Name your pages precisely. If you want to discuss a particular version of realism -- for example, Platonic realism -- then don't call your page realism; call it Platonic realism or even Platonic theories of universals. Notice that Platonism is also ambiguous.
Only a very few famous philosophers can be referred to by a single name. Socrates, Plato are fine; but compare James Mill and John Stuart Mill, or R. W. Sellars and Wilfrid Sellars. Remember that there are famous non-philosophers who might have the name in question, about whom we might eventually want to have articles! Best to do a Google (http://www.google.com) search first.
See also: Ireland Information Guide:Disambiguation