Ontology of mind

The occurrence of thought raises difficult issues in applied ontology. The mind–body problem challenges our understanding of how thought relates to the established existence subdomains of physical and abstract entities.

What is a thought and what is the mind? If the mind and its contents are simply physical entities, if thoughts are simply physical events in the brain and nervous system of a living organism, then the ontic status of the mind can be classified without further ado as a special type of physical entity among others in the universe. The distinction between internal thought and the external world in that case is an illusion that collapses entirely into the world of objective facts about exclusively physical phenomena. If, on the other hand, thoughts are ineliminable and ontologically irreducible to physical events, then we must find a way to expand the existence domain to accommodate the mind and psychological events as something altogether different from physical and abstract entities.

Physicalism or materialism in the philosophy of mind proposes to explain mental phenomena reductively as physical occurrences, primarily in the brain and neurophysiological network. The elimination or reduction of mental to physical events is sometimes said to be mediated by environmentally conditioned behaviour or behavioural dispositions in a variation of physicalism known as behaviourism. Functionalism is a third type of eliminative or reductive physicalist theory, according to which psychological events can be discounted in favour of the mechanical information-processing subroutines performed by the brain as a living machine, a purely physical entity, functioning according to abstract rules much like the number-crunching algorithms of a computer program.