There is a lot of confusion about dualism. Few people today hold to Cartesian substance dualism, but that is often the straw man that materialist opponents to dualism attack. Over at O’Leary’s Phineas Gage post Dr. Vincent Torley asks: “Why are we wasting our time debating a completely discredited theory (Cartesian dualism) which most Christians don’t accept and which the Christian Church has never accepted, anyway?”
He then goes on to explan:
The favored theory of the Catholic Church, for instance, is hylomorphism, originally developed by Aristotle and Christianized by St. Thomas Aquinas. A further discussion of hylomorphism may be found in this article by by Fr. John O’Callaghan. The author demonstrates that belief in a soul does not imply substance dualism – the belief that soul and body are two things. On the contrary, every human being is a unity. An organism’s soul is simply its underlying principle of unity. The human soul, with its ability to reason, does not distinguish us from animals; it distinguishes us as animals. The unity of a human being’s actions is actually deeper and stronger than that underlying the acts of a non-rational animal: rationality allows us to bring together our past, present and future acts, when we formulate plans. When Aquinas argues that the act of intellect is not the act of a bodily organ, he is not showing that there is a non-animal act engaged in by human beings. He is showing, rather, that not every act of an animal is a bodily act.
Hylomorphism claims that some acts that persons perform (acts of the intellect and free decisions) are non-bodily acts. But “personality” is much broader than these. Hence we should not be surprised at findings that personality is linked to the brain. In any case, an individual’s personality may change significantly during their lifetime, even without brain injury; yet we still say they are the same person. Indeed, personality can change as a result of a voluntary decision. My wife tells me that she was a very shy child until the age of ten – and then she suddenly decided to change her personality. Everyone remarked upon how different she was.
Speaking for myself, I would not be one whit perturbed if my personality does not survive my death – indeed, I rather hope it doesn’t!
Thus the following comments are attacking a straw man:
“If mind is independent of brain, one would not expect a brain injury to change personality (as opposed to simply reducing function, for example).”
“That suggests then that personality is formed and governed by somatic and environmental factors – and is not therefore not linked to an immutable soul … “
The above comments are problematic only for dualists who hold that all mental phenomena (thoughts, decisions, memories, mental images, emotions, feelings and sensations) reside exlusively in an immaterial soul.
A hylomorphist, by contrast, will happily grant that the following are all acts we perform with our brains and nervous systems: seeing, hearing, touching, smelling and tasting; feeling happy, sad, angry or afraid; imagining something; and remembering something.
What about the evidence that brain damage impairs intellectual function, as described in this article by Joanne McGee? (Thanks for the link, B. L. Harville.) We have to keep in mind that abstract thought is a very high-level operation, which cannot occur unless a whole host of lower-level activities are occurring. The brain is a magnificent information processor. Hence, damage to the information processor can mean that the intellect has nothing to process. It is not that the intellect has ceased to be; it is lower-level functions that are at fault here.
For those readers to whom the prospect of bodiless survival appears too dismal to contemplate, the Christian message is: well, it should! I suspect that a disembodied soul could not deliberate about anything without a massive degree of Divine assistance to make up for the loss of a brain. In any case, this artificial mode of post-moterm existence is but temporary. What a Christian looks forward to is resurrection: a permanent reunion of soul and body.
Finally, this article by Professor Alfred Freddoso is well worth reading for any Christians who may be tempted to jettison the doctrine of a dismebodied soul altogether: