[michael_dorfman]

PS: I suspect that most articles can be reached by every other article so you can take just about anything and say it's the "root" article for the rest of Wikipedia.

Most articles can be reached by every other article, but not if you are only following the first link. You can make a case that anything on the chain that leads from Philosophy back to Philosophy is the root, but anything outside of that is going to be tough to argue, in my opinion.

[Retric]

With that metric Philosophy is just one of a chain that ~99% of articles link to, looking at this graphs science or math is probably going to have a lower average chain length.