Controversy: the mind-body divide

Authored by Henry Strick van Linschoten

Whether mind and body are separate or not is an ancient philosophical question that is addressed within the discipline of philosophy more commonly and appropriately than within neuroscience. In the context of neurobiology the problem is often seen as equivalent to the question of “mind and brain” or of “consciousness and brain”, although the recent trend is away from that: the body is more than the brain, and the whole body plays a role in perceiving and interacting with its environment.

Most biologists in the 21st century are “physicalist” or “materialist” monists, believing that mind and matter, or mind, the consciousness and the brain are all made of the same substance. There are different ways in which this can be construed in detail, which are outlined in the philosophical footnote, but which do not matter as much as the key conviction that everything to do with the mind, the mental and consciousness must ultimately be physical. Interestingly, the same biologists also tend to agree that in practice many mental processes and events cannot be reduced or related to physical events and see this as a subject for future clarification. Neurobiologists, evolutionary psychologists, and French structuralists also tend to be materialists.

It may seem an esoteric philosophical question, but there are many issues where the position one holds makes a material difference, especially in this era of increasing interdisciplinary overlap where people of all persuasions agree that events, activities or experiences are influenced by both mental and physical factors and that it is practically impossible to distinguish between the two, even if it might be theoretically possible. A source of this discussion can be found in Damasio (1994).

The Introduction to DSM-IV-TR (American Psychiatric Association, 2000) addressed the mind-body problem thus:

“… the term mental disorder unfortunately implies a distinction between ‘mental’ and ‘physical’ disorders that is a reductionistic anachronism of mind/body dualism. A compelling literature documents that there is much ‘physical’ in ‘mental’ disorders and much ‘mental’ in ‘physical’ disorders.”

Philosophical note on the mind-body “problem”

The solutions to this problem can be divided between dualism, believing that mind and matter are different, and monism, believing that mind and matter are the same or different aspects or ways of viewing the same thing. Dualism goes back to Plato and Descartes. As it is defended by few 20th century philosophers of mind and even fewer neurobiologists, it will not be discussed further here.

The concept of monism can be found in the works of the Greek philosophers Parmenides, Aristotle and, later, the 17th century Dutch philosopher Spinoza. Idealism and many religious forms of monism propose that the only real substance is spirit or spiritual. Some proponents of non-idealist monism believe that the issue can be more or less avoided by considering that mental and physical are different ways of describing the same things, which are themselves neither mental nor physical (“neutral monism”, identified with Ernst Mach, William James and Bertrand Russell). There are other views that avoid taking a specific position inside monism, such as the functionalists, who claim that neurobiologists, scientists and practitioners only need to concern themselves with the functioning of the brain, and that it is immaterial to know or to speculate on further levels of complexity (e.g., H. Putnam, J. Fodor, David Lewis, D. Dennett).

Amongst physicalist or materialist biologists there is variation in their stance depending on whether they say that (a) mental things do exist, but are a special kind of physical thing (reductive) or (b) mental things simply do not exist (eliminative – B.F. Skinner, the Churchlands and to some extent D. Dennett).

An influential view in biology is biological naturalism, proposed by John Searle. It suggests that mental phenomena are all caused by “lower-level” neurobiological processes but are “higher-level” expressions of those processes. Searle and others holding this view take care to add that they do not know whether only human (or animal?) brains can be conscious. In addition they agree with many others that the idea of reducing the mind to neurobiological factors is only a position or a theoretical conviction, but that nobody as yet knows how to make this reduction or can display it.

References

Bennett, M. R. & Hacker, P. M. S. (2003). Philosophical Foundations of Neuroscience. Wiley-Blackwell

Damasio, A. (1994). Descartes’ Error: Emotion, Reason, and the Human Brain. New York: Penguin.