A thoughtful historical review but the author's conclusion is murky. It seems as though his head answers "No!" but his upbringing and feelings answer "Wouldn't it be nice?"
Do We Have Souls?
Plato taught that the soul is a simple immaterial thing that relates to the human body (brain included) as a captain to a ship. The person is a soul, the bearer of all psychological capacities and the fount of purposive action. It has a body as a vehicle for acting upon this world, until death severs its ties and it continues on forever, as something that is naturally indestructible and so immortal. Recent evidence suggests that Plato wasn’t spinning out an entirely novel idea. People, it seems, are ‘natural-born dualists,’ natively disposed to think of themselves as entirely separable from their bodies. But others have thought differently about the soul. Plato’s own, more empirically-minded student Aristotle held that the human soul is the distinctive ‘form’ of the human body, different in kind from the souls of other living things in conferring capacities such as rationality. However, at death, the organization of the body breaks down and so with it the soul, the living body’s form, ceases to be.
Zoom ahead from ancient Athens to 17th century Europe. Many took the success of the new mechanistic and reductionistic approach to physics to leave one with two stark options regarding the soul. The first, argued by Descartes, is a softened variant of Plato’s mind-body dualism. The material world ultimately consists in material particles wholly governed by mechanical laws of motion. The human soul is an immaterial substance, but (departing from Plato) its existence and proper functioning intimately depends, causally, on the healthy functioning of the brain. It is not naturally immortal; if it survives death, it must be a consequence of God’s sustaining it apart from the body. We still have a sharp dualism: bodies large and small generally operate according to principles distinct in kind from those according to which souls/minds do. Their convergence in the human brain has to be taken as a brute given, a contingent connection perhaps established by the power of God. The other option, one that grew in popularity over time, was de la Mettrie’s reductive image of ‘man a machine.’ It is essentially Descartes’ picture of reality minus souls. According to it, human persons, no less than inanimate chunks of the physical world, can be entirely understood (in principle) in terms of the interactions of the body’s basic parts. Psychological states that Descartes assigned to the soul are here taken either to be epiphenomenal—having no influence on other psychological states or bodily behavior—or as (somehow) consisting in complex states of the brain.
Many contemporary thinkers follow de la Mettrie in dismissing philosophical and religious talk of “the soul” as having no place within our ever-growing scientific knowledge concerning the embodied natures of human persons. But insofar as there is more than one notion of the soul, it may be no less misleading to state simply that there “is no such thing as the soul” than it would be to affirm its existence without qualification—one may be taken to deny not only unwanted associations but also others that one embraces or (as I will suggest) should embrace. Let us take a different, rehabilitative tack and use the word “soul” as a placeholder for whatever underlies the constellation of capacities of thought, emotion, and agency that we observe in mature, fully functioning human beings. Then our question shifts from the categorical Do we have souls? to the open-ended What is the nature of ‘the’ soul (or ‘ensoulment’) and its current and future limits? This way of posing our question invites us to consider answers lying between the extremes offered by Descartes and de la Mettrie.
With many, I take mind-body dualism of Descartes’ sort to be implausible. We have had an explosion of relevant information from evolutionary and developmental biology and cognitive neuroscience. This information, while still incomplete and only imperfectly understood, sheds light on the deep natural history of humans and present-day animals; the processes by which individual organisms of any species develop from inception to maturity; some of the function-specific neural structures and processes that sustain and help regulate the unfolding first-person perspective of conscious agents; and finally, observed correlations between increasing complexity of neural structures and increased psychological complexity (in organismic development and across sentient species). This information does not comport well with the two-substance or dualist metaphysical account of human persons. The fundamental problem is that our sciences point to highly continuous processes of increasing complexity, but the two-substance account requires the supposition of abrupt discontinuity. The coming to be at a particular point in time of a new substance with a suite of novel psychological capacities (awaiting only physical maturation in the body in order to become activated) would be a highly discontinuous development, both in large-scale bio-geological time and within the development of individual organisms.
However, de la Mettrie’s reductionist vision is even less plausible than mind-body dualism: conscious states of experience, thought, emotion, and purposive agency are our most immediately accessible empirical phenomena, and consequently they lie at the root of all our understanding of the world around us. We are not simply given the world to our understanding; we are given most immediately our experiences of it. To deny this givenness is to cut off the branch on which scientific understanding sits. And, while not self-defeating, the claim that all such experiential and belief states and purposive intendings just are enormously complex neural states or processes is also deeply implausible. We have direct, first-personal acquaintance with properties of these states that are manifestly different in kind from the hierarchically-structured physico-chemical properties of the brain states that are the most plausible candidates for such an identification. Just consider the feeling of a sharp pain or of coming to understand a complex scientific idea; how a red rose looks to you in bright sunlight and then later at dusk; the confident, considered belief that Beijing is the capital city of China; the thought that it is doubtful that there is life on Mars; and your conscious decision to pick up some milk on the way home. Each of these conscious states have distinctive intrinsic features, immediately apprehended by their subject, that in no way resemble the sorts of features science attributes to complex neural states
If neither dualism nor reductionism is plausible, what might a middle way alternative look like? Start by noting that the reductionist ‘atoms in the void’ conception of nature came under fierce scientific challenge in the twentieth century, and is growing ever stronger. (For a sampling of evidence from diverse contemporary sciences, see the Feb 2012 themed issue of Interface Focus: A Journal of the Royal Society entitled ‘Top-down Causation: An Integrating Theme Within and Across the Sciences?,’ co-edited by cosmologist George F.R. Ellis, systems biologist Denis Noble, and myself.)
Despite such evidence, De la Mettrie’s reductionist vision has had a tenacious hold not just on the beliefs, but also on the imagination, of many scientists and philosophers. They have lost sight of the ‘Aristotelian’ alternative. Aristotle’s specific philosophical account of objects as form-matter compounds is no more appealing to many of us than are his antiquated physics and biology. But his broader nonreductionist, nondualistic vision is very much worth developing in contemporary terms. A number of scientists and philosophers attracted to this vision have latched onto the term “emergentism,” and I will follow them here. But we should be careful to note that this term has meant different things to different thinkers. Here I mean a view on which human persons, other sentient animals, and possibly a wider array of complex systems are wholly materially composed while having irreducible and efficacious system-level features. These features are originated and sustained by organizational properties of the systems (in animals, by properly functioning brain and nervous systems) while also having in turn causal influence on components of the system in its evolution over time. That is, emergent systems involve an interplay of ‘bottom-up’ and ‘top-down’ causal factors. While they are not fundamental building blocks of the world in the way that fundamental particles or Descartes’s souls would be, they nonetheless are natural unities, causally basic entities.
The difference between reductionism and emergentism is empirical. The reductionist posits the bold and sweeping thesis that all organized phenomena in our world are wholly fixed or determined by comprehensive micro-physical patterns constrained only by global features such as the topology of spacetime. The emergentist recognizes that such fundamental-level physical laws apply everywhere, but holds that they are incomplete: corresponding to some kinds of organized complexity there are additional laws, interfacing with the fundamental laws, that are no less basic, though they have application only in limited contexts. These laws identify holistic properties of specified system kinds and describe both the preconditions and causal impact of their occurrence. This is nothing objectionably strange or ‘magical’ in such a layered picture of physical reality as against the ‘flat’ picture of the reductionist: both are pictures of the world as law-governed and causally unified, open to scientific exploration and description. Hence, deciding whether our world manifests emergence should be a matter of empirical evidence, not a priori presumption or bias in favor of the tidiness of reductionism. For many of us, the evidence, particularly when it comes to human psychological phenomena, points strongly in favor of emergentism.
And now I return to my question: What is the nature of the human soul? What we know from our own subjectivity and agency, evolutionary biology, and the emerging sciences of brain and behavior point in the direction of human beings as wholly materially composed individuals—yet composed individuals of a very special, emergent kind. We are living bodies, dynamically changing parts as all bodies do, but bodies with psychological and moral (and perhaps spiritual) capacities that do not reduce to the outworkings of a vast network of impersonal physical particle interactions within the human brain. To have a human soul, on this account, is to be an embodied creature having (in some measure) such personal capacities or the biological potential to develop such capacities.
Is this account congruent with religious understandings of the nature and destiny of human souls? In remarking briefly on this question, I will restrict myself to the understanding common to my own Christian belief and those of the other Abrahamic religions. Reflective theological speculation concerning the soul down through the centuries has not been so nearly uniform as popular thought, with many theologians emphasizing on scriptural no less than philosophical-empirical grounds the deeply embodied nature of human persons. (It is not for nothing that the ancient Christian creeds, e.g., look forward to the bodily resurrection of the dead.) However, we might wonder whether a psychological, fully embodied account of the soul is consistent with the belief that all persons are deemed of ‘equal worth in the sight of God,’ given that some human persons exhibit these psychological capacities to a far lesser degree than others. By way of reply, I turn to the foundational Genesis text that states that all humans are divine ikons, image-bearers of God. Plausibly, this is not only describes our present distinctive capacities for rationality, for self- and God-awareness, for moral freedom, and for self-emptying love, it promises a future gift: the offer of friendship with God and an eventual, fuller realization of our human potential. From this point of view, we are all in the process of becoming fully human: beyond a descriptive biological-psychological notion of human nature lies a teleological one—a telos not of nature but of God's loving purposes for us. Despite our unequally born deficits—physical, cognitive, emotional, and moral/spiritual—we are all destined for a fuller, supernatural realization of our common nature.
Of course, this promised destiny is predicated on the assumption that we will individually survive death. But how can this be, on an embodied view of the soul, given what death entails for the body? Note that in the Abrahamic religions, human persons are not naturally immortal. (Indeed, all of created reality is sustained in existence by God.) Survival of death would be a supernatural gift. Alas, we don’t (yet) get to see the miracle in action of God’s transporting us into another form of life and we have not been vouchsafed an account of how it goes. Thus, all we can do is speculate. Philosophers have done plenty of that, but there’s no space here to survey some of their ingenious ideas. But, to get you started, note that no particular bits of matter are essential to any living thing—biological life is continual change. And on the emergentist account of embodied persons, what survival would require is sufficient psychological continuity embodied in a minimally materially continuous but changing process. And with that, I offer a teaser: if God could endow the particles of my body (or some crucial subset of them) with the ability to fission into separated spaces, and arrange for this to occur just at the moment of my demise, then maybe…
Questions for Discussion:
What do the non-Abrahamic faiths suggest about the nature of the soul?
Is religious faith necessary in order to accept the idea of a soul?
How do recent scientific developments inform the understanding of what makes us human?