The mind is the term most commonly used to describe the higher functions of the human brain, particularly those of which humans are subjectively conscious, such as personality, thought, reason, memory, intelligence and emotion. Although other species of animals share some of these mental capacities, the term is usually used only in relation to humans. It is also used in relation to postulated supernatural beings to which human-like qualities are ascribed, as in the expression "the mind of God."
Theories of the mind
There are many theories of what the mind is and how it works, dating back to Plato, Aristotle and other Ancient Greek philosophers. Pre-scientific theories, which were rooted in theology, concentrated on the relationship between the mind and the soul, the supposed supernatural or divine essence of the human person. Modern theories, based on a scientific understanding of the brain, see the mind as a phenomenon of psychology, and the term is often used more or less synonymously with consciousness.
The question of which human attributes make up the mind is also much debated. Some argue that only the "higher" intellectual functions constitute mind: particularly reason and memory. In this view the emotions - love, hate, fear, joy - are more "primitive" or subjective in nature and should be seen as different in nature or origin to the mind. Others argue that the rational and the emotional sides of the human person cannot be separated, that they are of the same nature and origin, and that they should all be considered as part of the individual mind.
In popular usage mind is frequently synonymous with thought: it is that private conversation with ourselves that we carry on "inside our heads" during every waking moment of our lives. Thus we "make up our minds," "change our minds" or are "of two minds" about something. One of the key attributes of the mind in this sense is that is a private sphere. No-one else can read our thoughts or "know our mind."
Nature of the mind
Both philosophers and psychologists remain divided about the nature of the mind. Some take what is known as the substantial view, and argue that the mind is a single entity, perhaps having its base in the brain but distinct from it and having an autonomous existence. This view ultimately derives from Plato, and was absorbed from him into Christian thought. In its most extreme form, the substantial view merges with the theological view that the mind is an entity wholly separate from the body, in fact a manifestation of the soul, which will survive the body's death and return to God, its creator.
Others take what is known as the functional view, ultimately derived from Aristotle, which holds that the mind is a term of convenience for a variety of mental functions which have little in common except that humans are conscious of their existence. Functionalists tend to argue that the attributes which we collectively call the mind are closely related to the functions of the brain and can have no autonomous existence beyond the brain - nor can they survive its death. In this view mind is a subjective manifestation of consciousness: the human brain's ability to be aware of its own existence. The concept of the mind is therefore a means by which the conscious brain understands its own operations.
History of the philosophy of the mind
A leading exponent of the substantial view was George Berkeley, an 18th century Anglican bishop and philosopher. Berkeley argued that there is no such thing as matter and what humans see as the material world is nothing but an idea in God's mind, and that therefore the human mind is purely a manifestation of the soul. Few philosophers take an extreme view today, but the view that the human mind is of a nature or essence somehow different from, and higher than, the mere operations of the brain, continues to be widely held.
Berkeley's views were attacked, and in the eyes of many demolished, by T.H. Huxley, a 19th century biologist and disciple of Charles Darwin, who agreed that the phenomena of the mind were of a unique order, but argued that they can only be explained in reference to events in the brain. Huxley drew on a tradition of materialist thought in British philosophy dating to Thomas Hobbes, who argued in the 17th century that mental events were ultimately physical in nature, although with the biological knowledge of his day he could not say what their physical basis was. Huxley blended Hobbes with Darwin to produce the modern materialist or functional view.
Huxley's view was reinforced by the steady expansion of knowledge about the functions of the human brain. In the 19th century it was not possible to say with certainty how the brain carried out such functions as memory, emotion, perception and reason. This left the field open for substantialists to argue for an autonomous mind, or for a metaphysical theory of the mind. But each advance in the study of the brain during the 20th century made this harder, since it became more and more apparent that all the components of the mind have their origins in the functioning of the brain.
Huxley's rationalism, however, was disturbed in the early 20th century by the ideas of Sigmund Freud, who developed a theory of the unconscious mind, and argued that those mental processes of which humans are subjectively aware are only a small part of their total mental activity. Freudianism was in a sense a revival of the substantial view of the mind in a secular guise. Although Freud did not deny that the mind was a function of the brain, he held the mind has, as it were, a mind of its own, of which we are not conscious, which we cannot control, and which can be accessed only though psychoanalysis (particularly the interpretation of dreams). Freud's theory of the unconscious, although impossible to prove empirically, has been widely accepted and has greatly influenced the popular understanding of the mind.
The debate about the nature of the mind is relevant to the development of artificial intelligence. If the mind is indeed a thing separate from or higher than the functioning of the brain, then presumably it will not be possible for any machine, no matter how sophisticated, to duplicate it. If on the other hand the mind is no more than the aggregated functions of the brain, then it will be possible, at least in theory, to create a machine with a mind.
The Mind/Brain/Behavior Interfaculty Initiative (MBB) at Harvard University aims to elucidate the structure, function, evolution, development, and pathology of the nervous system in relation to human behavior and mental life. It draws on the departments of psychology, neurobiology, neurology, molecular and cellular biology, radiology, psychiatry, organismic and evolutionary biology, history of science, and linguistics.