I think the Nupedia software is written so that articles in a subject area are not displayed unless a subject is "active." So, none of the philosophy articles are displayed, because there is no philosophy editor and therefore the subject area is "inactive."
This is just a bug, not a requested feature. Whether it can and will be fixed--don't know!
Of course, if we were to implement the Nupedia system agreed upon last November, or some other simpler system, presumably this sort of problem wouldn't exist...
--Larry