This paper surveys the philosophical and psychological history of the mind–body relationship in Western thought, beginning with Pythagoras' dualism and its influence on Plato and Aristotle, then examining how Thomas Aquinas fused Greek rationalism with Christian theology to devastating effect on the treatment of mental illness. It proceeds through the Renaissance contributions of Descartes and Spinoza, whose rejection of moralizing mysticism paved the way for empirical inquiry, and concludes with the emergence of psychology as a formal discipline in the eighteenth and nineteenth centuries. An appended literature abstract reviews R. E. Kendell's article on the historical distinction between mental and physical illness.
Throughout human history, philosophers, doctors, and — most recently — psychologists have attempted to understand the relationship between the mind and body and how it shapes human awareness and perception of reality. At least since the golden age of Greek philosophy, thinkers have been aware of an ostensible distinction between the mind and body, a distinction that nonetheless allows for some intermingling, such that physical ailments affect the mental state just as mental disturbances may produce physical symptoms. To truly understand how contemporary Western psychologists and philosophers conceive of consciousness through the interaction between mind and body, one must trace the history of these concepts beginning with the Greek philosophers, moving through the Middle Ages and the Renaissance, and continuing into the eighteenth and nineteenth centuries, when psychology first began to develop as a formal discipline. Doing so reveals how the conceptualization of the relationship between body and mind has been shaped by cultural and contextual necessities that, while fitting particular theories within accepted ideological frameworks, nonetheless managed to illuminate important truths regarding the functioning of the human psyche and its relation to the material world.
Perhaps the first major Greek thinker to postulate a theory of the mind and body was the philosopher and mathematician Pythagoras, who suggested "a dualistic universe: one part abstract, permanent, and intellectually knowable […] and the other empirical, changing, and known through the senses" (Hergenhahn, 2009, p. 35). Human beings were seen to be equally split, with the mind containing those "reasoning powers that allow us to attain an understanding of the abstract world" in addition "to the flesh of the body," such that "Pythagoras' philosophy provides one of the first clear-cut mind-body dualisms in the history of Western thought" (p. 35).
The importance of Pythagoras' idea cannot be overstated. This confident division between mind and body has remained one of the most commonly assumed formulations of human consciousness, to the point that Bunge (2010) notes in "The Mind-Body Problem" that "the most popular view about the nature of the mind is that it is immaterial, hence separable from the body," and "moreover, it is still widely believed that we are alive ('animated') as long as we have souls (animae), and that we die when these leave us" (p. 143). Pythagoras' theory went on to inform nearly all subsequent Greek thought, such that Plato's theory of idealized forms and Aristotle's notion of reason can be readily traced to Pythagoras' distinction between the empirical world and a "higher," more valuable plane of abstract thought (Hergenhahn, 2009, pp. 46, 62).
Before moving on to the Middle Ages, it is worth considering some of the ramifications of Pythagoras' ideas, because his theories influenced subsequent thought greatly and set humanity on a course of insufficient treatment for mental and physical ailments. Because Pythagoras' theory suggested that only the mind could provide "true" knowledge or fulfillment, the body itself was considered secondary — indeed, "such [sensory] experience interferes with the attainment of knowledge and should be avoided" (Hergenhahn, 2009, p. 35). Pythagoras and his followers therefore imposed strict behavioral taboos upon themselves, setting the stage for the unhealthy and hypocritical repression of bodily impulse and desire that would fully blossom when Greek philosophy merged with the moralism of Christianity during the Middle Ages.
It is important to note that the distinction between mind and body is not inherently the problem. Rather, the problem lies in the assumption that the mind, or the abstract, is de facto more valuable than sensory experience or the body. Pythagoras moves from the reasonable observation that there appears to be some distinction between the collection of sensory information and its subsequent processing to the unwarranted conclusion that the latter is somehow more valuable and constitutes the only means of accessing an eternal, pure, abstract world. This gap in reasoning is ultimately responsible for much of the inhumane treatment of the mentally ill throughout history: by elevating the mind above the body, Pythagorean ideology implies that failures or illnesses of the mind connote a corresponding moral failure — a notion that would be seized upon by a far more powerful ideology over the subsequent millennia.
The Middle Ages saw Greek philosophy assimilated into the rapidly expanding institution of the Church, such that "the emerging Judeo-Christian personalistic emphasis resulted in a novel mystical and symbolic view of man," blending Greek ideas regarding reason and the mind with Church-approved notions of the soul, "culminating in the great theological syntheses of the thirteenth century," the most important of which were produced by Thomas Aquinas (Mora, 1978, p. 344). Aquinas focused principally on Aristotle, because "Aristotle had said several things that, with minor shifts and embellishments, could be construed as supporting church doctrine" (Hergenhahn, 2009, p. 90). Perhaps the most consequential of these adjustments was Aquinas' conflation of Aristotle's reason with faith, which simultaneously granted blind, a priori assumptions about the nature of the universe the same critical weight as ideas arrived at through logical thought, and provided the elevation of the mind over the body with the imprimatur of divine authority.
Although "several philosophers following Aquinas argued that faith and reason could be studied separately and that reason could be studied without considering its philosophical implications," Aquinas' work effectively conflated the mind with the spiritual, such that mental illnesses could be — and were — assumed to be the work of demons or the result of spiritual failure (Hergenhahn, 2009, p. 91). The mentally ill were thus regarded not as ill, but as evil: "Thomas Aquinas attributed hallucinations and insanity to demons and other supernatural influences" (Kendell, 2001, p. 490). This conception of the mind–body division would persist for hundreds of years, until more courageous thinkers were willing to challenge the assumptions of the Church and its defenders.
"Descartes and Spinoza shift mind–body inquiry toward science"
"Psychology emerges as formal discipline; Freud presents hysteria theories"
"Review of Kendell's history of the mental illness concept"
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