as has been said around here many times, science is a method. so i guess that any sort of topic of inquiry could be a science assuming that you go about it in a scientific manner.
Metaphysics Metaphysics represents everything which is possible, but can not be proven due to a lack of observable manifestation. Metaphysics is the art of providing contrast with what we do know, and what we want to know. It guides science to the doors we wish to open, but it never provides the key. The only thing that exist capable of forging a key is not science, nor is it metaphysics. It is imagination. It is no wonder that Einstein said that imagination is more important than knowledge.
spacemanspiff, how can metaphysics be taken in a scientific manner if it "can not be proven due to a lack of observable manifestation"?
For the sake of clarity ... Metaphysics is a branch of philosophy. It is notoriously difficult to define, but for purposes of briefly introducing it to nonphilosophers, it can be identified as the study of any of the most fundamental concepts and beliefs, on which many other concepts and beliefs rest--concepts such as being, existence, universal, property, relation, causation, space, time, event, and many others. [More...]
RE: metaphysics Metaphysics is a concept which presupposes an essential idea beyond the physical things. EG. we have tables of different forms and shapes but there exist (according to Plato) an (basic/essential) idea of tableness a concept on which all existing tables are based/derived from. The material world of things is only a shadow of the world of ideas. (cq. Some sort of reversed cinema: the world of material things is projected from a projector of ideas.) Metaphysics is not science. It is more a basic direction in philosophy, basis for idealism and romanticism as opposed with classicism, which is based on (testable) reason and material reality.