If you look at early philosophy, you may be surprised it covers a lot of topics that we wouldn't even remotely associate with it, like biology. The ever-famous Aristotle for example wrote about stuff from ethics to politics to dreams to animals. It's because in the original context, philosophy was really just learning about shit. ("Philosophy" means "love of wisdom" in Greek.) Before science broke off and became its own thing, philosophers would talk about the nature of friendship along with how whales reproduce. And why the hell not? It's not like there were clinical trials back then. It was a bunch of dudes sitting together and debating.

That was way back in the day, and I think philosophy has suffered a crisis over the past century because so much of it can be answered with, "Well, we'll just test that in a lab." For example, no one is going to talk about the soul anymore because there's no way we could prove anything either way. Plato for example divided it into three parts and actually identified those parts to specific parts of the body. Today if you try to submit something like that to an academic journal, people would just laugh at you.

That's not to say that there aren't topics left, but it's become even more narrow as even the humanities section of philosophy have formed their own departments, like political science. It's still moving forward, but I have difficulty reading modern works (well, okay, I'll admit I was never really a fan to start with) because now the topics are stuff like the linguistic definition of "the" in a mathematical proof. Exciting that is not for me. Although I guess it's probably better than people trying to calculate how large of a sphere the heavens are above us and being terribly, horribly wrong.