The pythagorean theorem could easily be tested empirically. In fact it was probably discovered through empirical observation as many ancient mathematical facts were.
Even if the idea came through empirical means, the theory itself isn't empirical.
That's why it's math and not science.
My original point was that calling a philosophical problem unscientific is like saying this ice cream is nonelectronic. It wasn't meant to be, it doesn't mean it's not good. Or in the case of mathematical theorems or philosophical problems, insightful.