In the paper I attempt to show that the Mathematical Subject is irremovable from the Philosophy of Mathematics. In doing so I want to argue, first, that Church's Thesis should be seen as a statement about the Mathematical Subject. Second, I want to show that philosophical relations between some problems such as Koenig's lemma vs Fan theorem, or Goedel's theorem on incompleteness vs Halting problem, could be better grasped
within the framework of the Mathematical Subject.