3.2: Mind, Disembodied

In the seventh century, nearly the entire Hellenistic world had been conquered by Islam. The Greek texts of philosophers such as Plato and Aristotle had already been translated into Syriac; the new conquerors translated these texts into Arabic (Kuhn, 1957). Within two centuries, these texts were widely available in educational institutions that ranged from Baghdad to Cordoba and Toledo. By the tenth century, Latin translations of these Arabic texts had made their way to Europe. Islamic civilization “preserved and proliferated records of ancient Greek science for later European scholars” (Kuhn, 1957, p. 102).

The availability of the ancient Greek texts gave rise to scholasticism in Europe during the middle ages. Scholasticism was central to the European universities that arose in the twelfth century, and worked to integrate key ideas of Greek philosophy into the theology of the Church. During the thirteenth century, scholasticism achieved its zenith with the analysis of Aristotle’s philosophy by Albertus Magnus and Thomas Aquinas.

Scholasticism, as a system of education, taught its students the wisdom of the ancients. The scientific revolution that took flight in the sixteenth and seventeenth centuries arose in reaction to this pedagogical tradition. The discoveries of such luminaries as Newton and Leibniz were only possible when the ancient wisdom was directly questioned and challenged.

The seventeenth-century philosophy of René Descartes (1996, 2006) provided another example of fundamental insights that arose from a reaction against scholasticism. Descartes’ goal was to establish a set of incontestable truths from which a rigorous philosophy could be constructed, much as mathematicians used methods of deduction to derive complete geometries from a set of foundational axioms. “The only order which I could follow was that normally employed by geometers, namely to set out all the premises on which a desired proposition depends, before drawing any conclusions about it” (Descartes, 1996, p. 9).

Descartes began his search for truth by applying his own, new method of inquiry. This method employed extreme skepticism: any idea that could possibly be doubted was excluded, including the teachings of the ancients as endorsed by scholasticism. Descartes, more radically, also questioned ideas supplied by the senses because “from time to time I have found that the senses deceive, and it is prudent never to trust completely those who have deceived us even once” (Descartes, 1996, p. 12). Clearly this approach brought a vast number of concepts into question, and removed them as possible foundations of knowledge.

What ideas were removed? All notions of the external world could be false, because knowledge of them is provided by unreliable senses. Also brought into question is the existence of one’s physical body, for the same reason. “I shall consider myself as not having hands or eyes, or flesh, or blood or senses, but as falsely believing that I have all these things” (Descartes, 1996, p. 15).

Descartes initially thought that basic, self-evident truths from mathematics could be spared, facts such as 2 + 3 = 5. But he then realized that these facts too could be reasonably doubted.

How do I know that God has not brought it about that I too go wrong every time I add two and three or count the sides of a square, or in some even simpler matter, if that is imaginable? (Descartes, 1996, p. 14)

With the exclusion of the external world, the body, and formal claims from mathematics, what was left for Descartes to believe in? He realized that in order to doubt, or even to be deceived by a malicious god, he must exist as a thinking thing. “I must finally conclude that this proposition, I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind” (Descartes, 1996, p. 17). And what is a thinking thing? “A thing that doubts, understands, affirms, denies, is willing, is unwilling, and also imagines and has sensory perceptions” (p. 19).

After establishing his own existence as incontestably true, Descartes used this fact to prove the existence of a perfect God who would not deceive. He then established the existence of an external world that was imperfectly sensed.

However, a fundamental consequence of Descartes’ analysis was a profound division between mind and body. First, Descartes reasoned that mind and body must be composed of different “stuff.” This had to be the case, because one could imagine that the body was divisible (e.g., through losing a limb) but that the mind was impossible to divide.

Indeed the idea I have of the human mind, in so far as it is a thinking thing, which is not extended in length, breadth or height and has no other bodily characteristics, is much more distinct than the idea of any corporeal thing. (Descartes, 1996, p. 37)

Further to this, the mind was literally disembodied—the existence of the mind did not depend upon the existence of the body.

Accordingly this ‘I,’ that is to say, the Soul by which I am what I am, is entirely distinct from the body and is even easier to know than the body; and would not stop being everything it is, even if the body were not to exist. (Descartes, 2006, p. 29)

Though Descartes’ notion of mind was disembodied, he acknowledged that mind and body had to be linked in some way. The interaction between mind and brain was famously housed in the pineal gland: “The mind is not immediately affected by all parts of the body, but only by the brain, or perhaps just by one small part of the brain, namely the part which is said to contain the ‘common’ sense” (Descartes, 1996, p. 59). What was the purpose of this type of interaction? Descartes noted that the powers of the mind could be used to make decisions beneficial to the body, to which the mind is linked: “For the proper purpose of the sensory perceptions given me by nature is simply to inform the mind of what is beneficial or harmful for the composite of which the mind is a part” (p. 57).

For Descartes the mind, as a thinking thing, could apply various rational operations to the information provided by the imperfect senses: sensory information could be doubted, understood, affirmed, or denied; it could also be elaborated via imagination. In short, these operations could not only inform the mind of what would benefit or harm the mind-body composite, but could also be used to plan a course of action to obtain the benefits or avoid the harm. Furthermore, the mind— via its capacity for willing—could cause the body to perform the desired actions to bring this plan into fruition. In Cartesian philosophy, the disembodied mind was responsible for the “thinking” in a sense-think-act cycle that involved the external world and the body to which the mind was linked.

Descartes’ disembodiment of the mind—his claim that the mind is composed of different “stuff ” than is the body or the physical world—is a philosophical position called dualism. Dualism has largely been abandoned by modern science, including cognitive science. The vast majority of cognitive scientists adopt a very different philosophical position called materialism. According to materialism, the mind is caused by the brain. In spite of the fact that it has abandoned Cartesian dualism, most of the core ideas of classical cognitive science are rooted in the ideas that Descartes wrote about in the seventeenth century. Indeed, classical cognitive science can be thought of as a synthesis between Cartesian philosophy and materialism. In classical cognitive science, this synthesis is best expressed as follows: cognition is the product of a physical symbol system (Newell, 1980). The physical symbol system hypothesis is made plausible by the existence of working examples of such devices: modern digital computers.