Metaphysics is concerned with explaining the way things “are” in the physical world. It is concerned primarily with ‘being as being’ i.e. with anything in so far as it has act of existence. However, metaphysics is not concerned with examining the physical properties of things that exist, but is, instead, the study of the underlying principles that give rise to the unified natural world. As such, the statement that “Evil does not exist” is metaphysical because it is a statement that deals with the object ‘evil’ as opposed to ‘good’ which is a metaphysical subject, whereas the statement that “all things are composed of atoms, which are in turn composed of electrons, protons, and neutrons” is definitely not metaphysics, utmost a concern of physical sciences.
Metaphysics is a branch of philosophy, and part of the answer to the question “What is Metaphysics” requires us to define the difference between science and philosophy. ‘Science’ is taken here as empirical sciences or non-empirical sciences. In physical science, it’s important for new explanations to make predictions that can be tested by experiments. But this is not a requirement of philosophy, specifically that of metaphysics. Instead, we reduce any philosophical statement to its ultimate concept or propositions. The ultimate concept of metaphysics is being while that of propositions is the principle of contradiction. In the case of the above statement that all things are made up of smaller things and so on to infinity, this explanation is clearly untestable because we’ll never have an instrument capable of detecting anything that is infinitely small. But then, metaphysically, one can be sure that it is impossible to have an infinite regression of materiality but must arrive at the ultimate or smallest particle of matter. But then, the philosopher can further ask : What is the ultimate composition of matter?” this time the answer cannot be anymore ‘the smallest particle of matter’ since the smallest particle of matter is matter also. Thus, Thales’ question: ‘What is the ultimate stuff?’ is a metaphysical question not an empirical one. His question separated physical science from philosophy. Aristotle offered an answer: his hylomorphic doctrine which states that any material reality is ultimately composed of prime matter (not the matter as we know it) and substantial form.