little handout for my students:
Philosophy and its Sub-Disciplines
Philosophy comes from the Greek terms meaning "love of wisdom." It is concerned with questions about ultimate value: questions about reality, truth, beauty, goodness, justice, meaning. These questions are interminable: they cannot be nailed with empirical or scientific data. This is not to say that every treatment of such questions is as good as any other. Some are rich, useful, suggestive; some are arid, fantastic, tasteless. They are questions we cannot answer. But in our dilemma as human beings, I think they are questions we cannot avoid.
Metaphysics is the study of what sorts of things exist and how they are ordered, at the most general level.
(a) Ontology concerns what sorts of things there are. For example, materialism (or the idea that all things that exist are physical objects), idealism (or the idea that the only things that exist are minds and their ideas), and dualism (or the idea that there are both sorts of things) are ontological theories.
(b) Cosmology concerns how whatever exists hangs together in a system, including questions such as whether the universe has a purpose or direction. The term is used by astronomers and others to refer to the study of the origin of the universe.
Epistemology is the theory of knowledge, concerning the questions of whether we know anything, and, if so, how. Skepticism is the position that we can know nothing, either about some particular subject-matter, or quite in general. Empiricism is the position that the sole source of knowledge is sense perception. Rationalism is the position that all knowledge reflects the exercise of reason.
Logic is the study of the forms of correct reasoning, and treats questions about validity in arguments and about probability and scientific method. Deductive logic concerns reasoning by conceptual necessity, while inductive logic concerns drawing conclusions from observations. Questions concerning the relation of faith and reason are logical/epistemological questions.
Ethics concerns questions of how we ought to live and behave, of what is the good life and what is right action. Utilitarian ethical theories assess actions morally by their consequences. Deontological moral theories assess actions by the rules from which they proceed.
Political Philosophy concerns how we ought to arrange our lives together, that is, what makes a society just. It includes questions about the legitimacy and legitimate scope of state power.
Aesthetics concerns the questions of art and beauty: the nature of these things, and their source, value, and interpretation.
Philosophy has as many sub-disciplines as there are disciplines, more or less, which address the sorts of questions just spelled out with regard to various special subject-matters. These include philosophy of science, philosophy of religion, philosophy of law, philosophy of language, and so on.