The Theological Dilemma of Medieval Neuroscience

To casual observers the history of science goes something like this: Greek philosophers introduced the world to rational, naturalistic ways of thinking which freed us from superstition and myth. Sadly, the Roman Empire crumbled, Christianity replaced paganism, religious dogma replaced rationalism, and progress stagnated until about the 16th century when the foundations of science began taking shape. Of course, the real story is more complicated (interested readers should see David Lindberg's The Beginnings of Western Science). At the risk of disorienting casual observers, I am going to explore one of those interesting complications: Medieval neuroscience.

The 12th and 13th centuries witnessed a flourishing of natural philosophy in Christian Europe. While creation, the cosmos, miracles and the nature of God were uppermost on the agenda, medieval natural philosophy also included the biological basis of the human mind. The major brain theory of the time was called the theory of the "inner (or interior) senses," the roots of which ran back to Aristotle (see Simon Kemp's book Cognitive Psychology in the Middle Ages, chapter 4). In his De Anima, Aristotle identified a number of intellectual functions including sensation, imagination and memory. Originally, Aristotle located these functions in the heart, but the renowned Roman physician Galen relocated them to the brain. Physicians after Galen (precisely who is unclear) put these function specifically in the ventricles of the brain given that the ventricles were highly interconnected via nerve fibers to sensory and motor systems throughout the body. Animal spirits flowing from the ventricles through the nerve fibers could then account for the direction of thought and action throughout the body.

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