Where nature and nurture intersect to create human behavior is as evasive a locality as where the physical brain and metaphysical consciousness intersect to create human thought, if such an intersection exists at all. The discussion of just such an intersection has occupied much of philosophy past, psychology past, and present, and anticipates the biopsychology of the future. Thus, implicit in the discussion of this intersection is an understanding of the realm of mind and consciousness, how each is related to the physical body, and the consideration of an independent consciousness that transcends the physical functions of the body.
If a tree falls in the forest and no one perceives it, did the tree really fall? For the ardent empiricist George Berkeley, the answer is a resounding “yes”. Berkeley believed that objective reality does not exist apart from our perception of that reality (Goodwin, 2005). This puts Berkeley at odds with the materialist tradition of his time, which asserted that all that exists is objective reality. For him, the act of perceiving was reality. The way he circumvented the aforementioned question, reminiscent of Einstein’s cosmological constant, is that God, the Permanent Perceiver, is omnipresent and can, therefore, perceive every event concurrently. According to Berkeley, the mind existed only as an extension of consciousness, rather than the other way around, a concept that has been labeled subjective idealism. In contrast, Gottfried Leibniz proposed that the physical and metaphysical work in concert, parallel in fact, held constant by the direct hand of God himself, a notion that Leibniz stated as psychophysical parallelism. To apply Leibniz to the above question, the tree did fall because an objective reality, apart from our perception of it, exists. He bridged the gap between mental and physical reality through the use of what he called monads. Leibniz hypothesized that through the energy forces of monads consciousness could exist in the physical mind. He went on to conclude that certain mental processes operated below the level of perception and called them petites perceptions. This further insight would lay the groundwork for the Freudian understanding of unconscious mental processes.
The Enlightenment brought with it the move in intellectual circles from a dependency on immaterial explanations of human consciousness to the belief that objective reality could be understood through scientific methodology. The last vestige of the Renaissance and the legacy of immaterialism was the vitalism of Johannes Muller. Muller proposed that in addition to the physical and chemical machinery of physiological systems a “vital force” underlay mechanical and mental action. Vitalism predicted that a special life force, which could create its own energy, could explain the link between the physical body and consciousness. However, one of Muller’s students, Hermann von Helmholtz, took up the mantle of materialism and put forth the law of conservation of energy to combat vitalism. The law of conservation of energy states that the total energy in any given system does not increase or decrease when “work” occurs but rather just changes form. Helmholtz argued that mechanical and mental action could be explained through purely chemical processes, thereby sidestepping the need for a vital force. Furthermore, the finite speed of nerve impulses promotes the idea that all action, whether mental or physical, can be explained in purely physical terms. Indeed, the Enlightenment carries with it freedom from mysticism and consequently slavery to scientific explanation.
Rene Descartes, utilizing his faculties of reason, put forth a dualistic theory of the physical body and the innate consciousness. Descartes believed that through the mechanism of reason we, as humans, can arrive at knowledge innately, that some ideas can be attained through reason rather than through experience. This opinion flies in the face of later empiricists who believed that we perceive the world through wholly experiential mechanisms. Descartes also claimed that the place where the mind influenced the body was the pineal gland. He did not claim that the mind resided in the pineal but only that this gland acted as the gateway between the mind and body. For Descartes, the mind operated in conjunction with the body rather than within the framework of the body. It is this subtle distinction which set him apart from the later influence of materialism.
In conclusion, a trend from immaterial explanations of the mind/body interaction can be seen from the one extreme of Descartes to the other outermost of Helmholtz. This shift in the philosophical understanding of how the body interrelates with the mind can be viewed within the context of the relentless push towards a more scientific understanding of the world within and without. It is this driving force which brought human understanding from vitalism to materialism, from monads to the law of conservation of energy, from innate ideas to the scientific acquisition of objective truth.
Goodwin, C. J. (2005). A history of modern psychology (2nd ed.). Hoboken, NJ: Wiley.
- Describe major developments in medicine and biological studies that contributed to the early field of psychology.
- Identify major historical steps toward the mapping of brain structures that are associated with behavioral processes.
- Examine the historical elements of the study of the physical body and brain in antiquity.