Mind–body dualism in the context of "Mind–body problem"

Ontology is the philosophical study of being. It is traditionally understood as the subdiscipline of metaphysics focused on the most general features of reality. As one of the most fundamental concepts, being encompasses all of reality and every entity within it. To articulate the basic structure of being, ontology examines the commonalities among all things and investigates their classification into basic types, such as the categories of particulars and universals. Particulars are unique, non-repeatable entities, such as the person Socrates, whereas universals are general, repeatable entities, like the color green. Another distinction exists between concrete objects existing in space and time, such as a tree, and abstract objects existing outside space and time, like the number 7. Systems of categories aim to provide a comprehensive inventory of reality by employing categories such as substance, property, relation, state of affairs, and event.

Ontologists disagree regarding which entities exist at the most basic level. Platonic realism asserts that universals have objective existence, while conceptualism maintains that universals exist only in the mind, and nominalism denies their existence altogether. Similar disputes pertain to mathematical objects, unobservable objects assumed by scientific theories, and moral facts. Materialism posits that fundamentally only matter exists, whereas dualism asserts that mind and matter are independent principles. According to some ontologists, objective answers to ontological questions do not exist, with perspectives shaped by differing linguistic practices.

Pluralism is a term used in philosophy, referring to a worldview of multiplicity, often used in opposition to monism (the view that all is one) or dualism (the view that all is two). The term has different meanings in metaphysics, ontology, epistemology and logic. In metaphysics, it is the view that there are in fact many different substances in nature that constitute reality. In ontology, pluralism refers to different ways, kinds, or modes of being. For example, a topic in ontological pluralism is the comparison of the modes of existence of things like 'humans' and 'cars' with things like 'numbers' and some other concepts as they are used in science.

In epistemology, pluralism is the position that there is not one consistent means of approaching truths about the world, but rather many. Often this is associated with pragmatism, or conceptual, contextual, or cultural relativism. In the philosophy of science it may refer to the acceptance of co-existing scientific paradigms which though accurately describing their relevant domains are nonetheless incommensurable. In logic, pluralism is the relatively novel view that there is no one correct logic, or alternatively, that there is more than one correct logic. Such as using classical logic in most cases, but using paraconsistent logic to deal with certain paradoxes.

Jain philosophy or Jaina philosophy refers to the ancient Indian philosophical system of the Jain religion. It comprises all the philosophical investigations and systems of inquiry that developed among the early branches of Jainism in ancient India following the nirvana of Mahāvīra (c. 6th or 5th century BCE). One of the main features of Jain philosophy is its dualistic metaphysics, which holds that there are two distinct categories of existence: the living, conscious, or sentient entities (jīva) and the non-living or material entities (ajīva).

Jain texts discuss numerous philosophical topics such as cosmology, epistemology, ethics, metaphysics, ontology, the philosophy of time, and soteriology. Jain thought is primarily concerned with understanding the nature of living beings, how these beings are bound by the processes of karma (which are seen as fine material particles) and how living beings may be liberated (moksha) from the cycle of death and rebirth (saṃsāra). A peculiarity of Jainism is to essentially associate several renunciatory liberating practices with the imperative of non-violence (ahiṃsā). Jainism and its philosophical system are also notable for the belief in a beginning-less and cyclical universe, which posits a non-theistic understanding of the world and the complete rejection of a hypothetical creator deity. Jain philosophy is also noted for its "realist epistemology" of anekāntavāda ("many-sidedness"), a rejection of all simplistic and one-sided views of truth and reality.

The soul is the purported immaterial aspect or essence of a living being. It is typically believed to be immortal and to exist apart from the material world. The three main theories that describe the relationship between the soul and the body are interactionism, parallelism, and epiphenomenalism. Anthropologists and psychologists have found that most humans are naturally inclined to believe in the existence of the soul and that they have interculturally distinguished between souls and bodies.

The soul has been the central area of interest in philosophy since ancient times. Socrates envisioned the soul to possess a rational faculty, its practice being man's most godlike activity. Plato believed the soul to be the person's real self, an immaterial and immortal dweller of our lives that continues and thinks even after death. Aristotle sketched out the soul as the "first actuality" of a naturally organized body—form and matter arrangement allowing natural beings to aspire to full actualization.

In philosophy (metaphysics), physicalism or physical logicism is the view that "everything is physical", that there is "nothing over and above" the physical, or that everything supervenes on the physical. It is opposed to idealism, according to which the world arises from the mind. Physicalism is a form of ontological monism—a "one substance" view of the nature of reality, unlike "two-substance" (mind–body dualism) or "many-substance" (pluralism) views. Both the definition of "physical" and the meaning of physicalism have been debated. Physicalism is often treated as equivalent to naturalism but there are important distinctions between them.

Physicalism is closely related to materialism, and has evolved from materialism with advancements in the physical sciences in explaining observed phenomena. The terms "physicalism" and "materialism" are often used interchangeably, but can be distinguished on the basis that physics describes more than just matter. Physicalism encompasses matter, but also energy, physical laws, space, time, spacetime, exotic matter, structure, physical processes, information, state, and forces, among other things, as described by physics and other sciences, all within a monistic framework.