The Reality of the Soul in an Age of Neuroscience

Introduction

Does it never give thee pause, … that men then had a soul—not by hearsay alone, and as a figure of speech; but as a truth that they knew, and practically went upon! Verily it was another world then. … But yet it is pity we had lost tidings of our souls—actually we shall have to go in quest of them again, or worse in all ways will befall!¹

Such were the thoughts of Thomas Carlyle in 1843 as he pondered the ruins of the ancient monastery of St. Edmundsbury. He marvels that the monks had not just known about the soul, but acted on that knowledge. Theirs was indeed "another world," he muses, one that, unlike his own, could still hear the "tidings of the soul." What of our world? Is it still possible to affirm the reality of the soul in this age of neuro-science? To explore that question, we will first have to discover something about the soul. We can then consider the problems and questions that neuroscience poses for the soul and look at some possible approaches and answers, especially in the thought of Aristotle and Thomas Aquinas.

Ancient Greek philosophers understood the soul as the source of movement in living things. Democritus believed it was composed of spherical fire atoms, while Anaximenes said it was air.² Plato emphasized the difference between soul and body, while Aristotle and his disciples, including Aquinas, began with the unity of the human person and saw the soul as the source of that unity. When Descartes rebooted philosophy in the seventeenth century, he tended to speak of "mind" rather than "soul." The mind was a thinking thing (res cogitans), while the body was an extended thing (res extensa). English-speaking philosophy has largely followed his example, using the word "mind" rather than "soul."³ So current neuroscience ponders the mind–brain relation.

The methodology of neuroscience leaves no place for the soul, as cognitive scientist William Uttal notes: "Two fundamental assumptions are likely to remain constant as the enterprise [of neuroscience] goes forward. The first is the basic idea of materialism. … The second is that all mental processes … are functions of that material reality. … Without at least an implicit acceptance of these assumptions, it would be meaningless to pursue work in the field of cognitive neuroscience; we would have to accept the existence of a set of supernatural and uncontrolled variables that would make any experimental results meaningless."⁴

Established firmly on such methodological assumptions, neuroscience has flourished. Beyond its home base in biology, where it studies the brain and nervous system, it now partners with fields such as physics, chemistry, mathematics, medicine, computer science, and psychology. Its discoveries are described in mind-boggling numbers: "The brain consists of some 1010 neurons with their many branching dendrites and axons all interconnected by networks of unfathomable complexity, in which one neuron may be connected with tens or hundreds of thousands … of other neurons. In each cubic mm of cortex there are one billion synapses!"⁵ The brain is both complex and plastic, developing new structures and connections in response to personal experience.⁶ Conscious activities have been mapped to specific brain areas, allowing for the discovery of previously unknown brain regions.⁷ The discoveries of neuroscience have been used to treat numerous neural pathologies, from the effects of stroke to obsessive compulsive disorder.⁸

The Dilemmas of Neuroscience

Despite these achievements, some basic questions still baffle neuroscientists. One is to explain how the observable activities of the brain result in consciousness. As Michael O'Shea observes: "We have no idea how consciousness arises from a physical machine and in trying to understand how the brain does that, we may well be up against the most awkward of scientific challenges."⁹ Uttal sees this as "an intractable problem that neither new measuring devices nor computational engines can ever begin to unravel."¹⁰ One source of the dilemma may be neuroscience's own materialistic, methodological assumptions. As David Chalmers explains: "Any account given in purely physical terms...