The story of Krista and Tatiana Hogan, 11-year-old twin girls born in Vancouver, British Columbia, who are joined at the top, back, and sides of their heads, will doubtless be familiar to most readers. Here’s a documentary that was made about the twins:
Over at Uncommon Descent and Evolution News and Views, Denyse O’Leary, David Klinghoffer and Michael Egnor (who is a Professor of Neurosurgery at State University of New York, Stony Brook), have argued that the Hogan twins constitute a living refutation of the materialistic notion that mind and brain are one and the same thing. Each twin has her own distinct mind and personality, despite the fact that they share parts of their brains.
In this post, I’m going to argue that while these three authors are perfectly correct in insisting that each twin does indeed possess a mind of her own, their claim that this fact refutes materialism is profoundly mistaken. On the contrary, I will argue that the twins’ ability to share thoughts without speaking weakens the case for Thomistic dualism, and lends support to a subtle variety of materialism which incorporates top-down causation. And on this point, the mother of the Hogan twins would probably agree with me: she sends her children to a school run by the Seventh-day Adventist Church, which teaches that the human brain is the seat of thought, language, creativity, morality and even our consciousness of God. Could this Christian version of materialism be correct, after all?

