Metaphysics is a sub-field of philosophy that examines the nature of reality including relationships between the mind and matter. It can also deal with cosmology.
In 2364, when the USS Enterprise-D crew were infected with polywater intoxication, the training division ordered officers to attend a lecture in metaphysics. (TNG: "The Naked Now")
Captain Phillipa Louvois felt that determining the nature of Data was a case of metaphysics. (TNG: "The Measure Of A Man")