Several friends who are generally sympathetic to the view that the mind is immaterial (the Thomistic dualist view) have expressed reservations about my assertion that reproductive cloning of humans is impossible, because of the immateriality of the human intellect and will. They fear that success in human reproductive cloning would discredit the dualist view.

Indeed it would—our theories should be testable and should be subject to disproof according to evidence. While Thomistic dualism is a metaphysical theory, it has empirical consequences that can be tested scientifically. Both materialist and immaterialist theories of the mind should be subject to empirical testing—neither should be exempt.

I believe that human reproductive cloning will never work because the human intellect and will are immaterial and cannot be cloned. I will recap my argument here, and comment on some theological issues that have been raised.

There are three lines of reasoning here—biological, metaphysical, and theological—and I think they all point to the same conclusion in a fairly straightforward way:

1. Biological: Reproductive cloning of non-human animals has become relatively routine and it works quite well. Reproductive cloning of human beings has been an abject failure, despite what are undoubtedly herculean efforts by some (probably many) labs. From a biological standpoint, there appears to be something radically different about cloning non-human animals and cloning humans.

2.Metaphysical: In the Aristotelian/Thomist view to which I subscribe, the animal soul has only material powers—i.e., the powers arise from and are caused by matter. The human soul has the material powers of the animal soul but also has immaterial powers of intellect and will. These powers do not arise from nor are they caused by matter. Thus, from a metaphysical perspective, it should not be possible to copy (i.e. manufacture) a human soul by cloning, which is a wholly material process.

3.Theological: In the Catholic tradition (and I think most Christian traditions), the human soul is spiritual, in God’s image, and is created directly by God at conception. As cloning alone does not entail divine creation, cloning could not create a spiritual human soul. The argument that God might choose to cooperate with the scientists and create a spiritual soul at just the same moment that a human clone is made is theological nonsense. Cloning a human being is an attempt to create a being that is made in God’s image, and it is manifest evil. There is no Christian theology I know of that proposes that God would participate in manifest evil.

I think my argument is fairly tight, given the complexities of the issue. If, in fact, a human being were reproductively cloned, and that human being grew to have the capacity for abstract thought, then either 1) the mind is wholly material, or 2) God will cooperate with manifest evil.
I believe that neither 1 nor 2 is true.

To summarize, I don’t think human beings can be reproductively cloned, because the spiritual soul can’t be cloned, and God will not cooperate with evil.

I believe it is a strong and coherent argument, consistent with Thomistic dualism, with neuroscience and with the science of cloning.

The scientific test will continue as long as scientists try to clone humans. So far, the immaterial view is the one supported by the science.

Also by Michael Egnor on human cloning:

Show me the human clones: If man is matter, and nothing more, man can be copied. If not, he can’t. If man can be copied by a wholly material process, I need to rethink things. If he cannot be, materialists need to rethink things.

and

Human cloning has thus far been a scientific dead end. The ability to clone a rational man is a straightforward prediction of the materialist view of man, and the inability to clone a rational man is a straightforward prediction of the immaterialist view.