In the 18th century, Abraham Trembley discovered that a microscopic, fresh-water animal called the hydra could be cut up to form as many hydras as one would like. This troubled the then current idea of the soul, which held that all animals had souls. If all animals had souls, then the hydra should as well. Does cutting up the hydra mean that one is cutting up the soul? If not, does God grant each of the pieces a soul? Or does the experiment imply — as many atheists of the time inferred — that there simply is no immaterial soul?
In our time, unknown to most people, there is a new challenge to the soul. In this new challenge, instead of cutting up hydra, neuroscientists cut up the human brain. It has been found that splitting the brain into two produces two independent personalities with distinct minds (the split-brain procedure is used out of medical necessity in the treatment of certain disorders). In fact, these two minds can have distinct religious beliefs. Here is neuroscientist VS Ramachandran explaining an experiment in which one patient was recorded as having both atheist and theist halves of his brain:
While this split-brain patient is probably the most damning implication of neuroscience for soul-beliefs, there are other difficulties as well. For example, the by-now trivial observation that physical manipulations of the brain cause changes in the mind, to the extent that the elimination of brain function eliminates mind function, is a part of our normal experience of the world. Most of the people in our society know that taking anti-depressents, drinking alcohol, inhaling paint fumes, having brain surgery, and so on, have severe effects on the brain. Are we to infer that the soul is just as susceptible to alcohol as the body? Or does it seem that a different conclusion is more likely — that there is no soul distinct from the physical system of the brain?
Do discoveries like these show that the soul is incompatible with contemporary science? That’s the topic I will address in this post.
To begin, consider the following sort of question: Can one accept neuroscience while still accepting the existence of the soul?
That question seems to have a variety of interpretations. On one reading of that question, one is simply asking whether or not humans are capable of believing in souls when they know about neuroscience. Humans are certainly capable of believing many things, but of course that doesn’t have anything to do with whether or not they should. For example, humans are capable of believing that crystals have magical powers while also believing in contemporary geology — but they shouldn’t. And believing in souls, while also believing in neuroscientific results, is certainly something that humans are capable of doing (there is no psychological block to doing so). Nonetheless, I think a much more interesting question concerns whether or not they should.
Another way to understand the question is to ask whether or not neuroscience and soul-doctrines logically contradict each other. There are some soul-doctrines which do contradict neuroscience — such as substance dualism — and others — such as Christian materialism — which do not. But I don’t find the question of logical contradiction to be very interesting either. There is no logical contradiction between the belief that weather patterns are actually caused by invisible, immaterial dragons that perfectly mimic natural forces and the belief that all of the scientific evidence about weather patterns is consistent with those patterns being caused by natural forces. Yet we would still say that natural forces are a better explanation for weather than invisible, immaterial dragons and that any consistent use of science would reject the dragons.
This brings us to what I think is a better way to ask the question. Does a consistent use of science yield the conclusion that there is a soul? And, of course, the answer is no. And if science is the best method that we have for arriving at explanations and simply infers to the best explanation, then these theological explanations can be nothing other than inferences to less than best explanations using less than the best methods. I call that an incompatibility between science and religion. When asked in this way, I say that soul-beliefs are not compatible with science.
The Christian might push back against this conclusion by claiming that there are “many ways of knowing”. But this cannot work as a rebuttal, since I did not claim that there were no other ways of knowing. What I claimed was that science constituted the best ways of knowing which we presently have, a claim that I would back by citing both the history of knowledge claims and by appeal to the no-miracles argument, and by noting that science involves inference to the best explanation, itself relatively non-controversial amongst philosophers of science. To fully respond to this accusation in a satisfactory way, what the Christian would need to demonstrate is not only does there exist another way of knowing but that this other way is at least as reliable and veridical as our scientific methods. I have never seen a demonstration of this sort provided for a religious epistemology.
Another unsatisfactory response the Christian may give would be to point out that there are plenty of non-scientific things which contain truth. Poetry isn’t scientific, yet it can provide us information about the world. If that’s true, then theology may contain truth as well. This response isn’t satisfactory for two reasons. First, because poetry isn’t veridical in any appropriate sense. Reading a poem does not inform us in some satisfactory way about the nature of the universe unless it either contains an argument, reference to scientific data, or is considered jointly with scientific information. In other words, poetry itself doesn’t do any of the epistemic work. Second, because it is unclear why the existence of one acceptable non-scientific epistemology should entail that theology is an acceptable non-scientific epistemology. If the existence of a single non-scientific epistemology implied that any other non-scientific epistemology was acceptable, then reading tea leaves and consulting horoscopes should be acceptable as well.