It's a fun Wikipedia phenomenon. If you click on the first non italicized, non parenthesis link of ANY page in the online encyclopedia, you will eventually end up in the page for Philosophy. Guess what? There's also a Wikipedia entry about that!
The article shows that 94.5% of all articles in the English Wikipedia eventually lead to Philosophy. The rest get stuck in loops or go to links that don't exist. The article's theory is that because Wikipedia tends to move up on a classification chain that becomes broader and broader, which results in the change to Philosophy.