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.