Seems a bit self-serving. Surely the physicists could make a claim that all fields (including philosophy) are subfields of physics.
In fact, the soundness of the scientific method itself is a philosophical argument, as it cannot be scientifically demonstrable without assuming the conclusion.
That's conjecture. Some philosophies of mathematics in fact disagrees with this claim, which is exactly my point. This debate we're having cannot be settled by any sort of scientific or mathematical argument, it's a purely philosophical debate about the meaning of scientific and mathematical arguments and what should or should not qualify.
Philosophy is extremely broad, in most areas there hasn't been a dominant successful way to do it. In Natural Philosophy however, one way took over entirely, it's named Science, and Physics is just the name for the use of Science for a particular type of question in Natural Philosophy.
Philosophy in other areas didn't have this. For the question "Why do we die?" there are a bunch of approaches and none of them is especially satisfactory. Different philosophers each take their own approach. But for the questions in Natural Philosophy like "What is the Sun made of?" Science turned out to be very, very good at providing satisfactory answers and other methods largely fell away. Whilst good answers to "Why do we die?" feel nice, answers to questions like "How can I preserve this meat in order to eat it a week from now without getting sick?" had very practical consequences that were hard to argue with. Science took over the whole world.
But it's just a way to answer questions within one (important) corner of philosophy. Science doesn't have any answers for "Why do we die?" or "What is good?" which aren't questions of Natural Philosophy.
Historically, all branches of knowledge were branches of philosophy. There is a reason why PhD stands for "philosophiae doctor" ( aka "Doctor of Philosophy" ).
> Surely the physicists could make a claim that all fields (including philosophy) are subfields of physics.
Certainly not since physics deals with the empirical natural world. Physics doesn't delve into morality, virtue, essence, good, evil, etc. There is the physical world and the metaphysical one.
In modern times, the empirical branch of philosophy ( hard sciences ) have cut out their own special niche, but fundamentally, they are still a specialized branch of philosophy.
I gotta say, i agree with the grandparent. Metaphysics is philosophy. It is not physics. It is not cognitive science. At best the questions posed by metaphysics provide inspiration for physics and cogsci, but they are fundamentally not part of those fields.