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#719 A Neuro-Chemical Disproof of God?

February 14, 2021

Dear Sir,

I am a neurologist dealing with patients suffering from movement disorders and particularly Parkinsons's disease. Some of these may receive medications such as dopamine receptor agonists. They activate dopamine recpetors the brain and the main scope is to improve patients movements. These medications may induce side effects what we call impulsion control disorders. Some of them concern sexuality and rarely patients may even change their sexual orientation becoming homosexual or have the need to dress life women and so on... When you withdraw the medication they become as they usually were, heterosexual. And more surprising, patients do not realize they do not have the insight of the modification of their sexuality.

An other option of treatment in Parkinson's disease is deep brain stimulation in the subthalamic nucleus. This nucleus has different functional parts among which the cognitive and limbic parts. Some of my patients change also their beahaviour and in particular also their sexual behaviour also by having difficulties with controling their sexual impulsions (as with the dopamine receptor agonists). When we modify the stimulation parameters, these symptoms disappear. Hence, we can change a part of a person's most intimate intentions and behaviours. We can make them sin (from christian point of vue which theoretically is the God's vue). It seems to me that God is "just" a very complex matter of neuroscience that we do not yet fully understand and that God's existence is "just" a matter of faith.

My question is the following one: as noted above, if we can modify the person's most intimate intentions by some medication and make them sin, how can God exist in all this? Is not God in our incredibly sophisticated neuron net that we call brain even for explaining such mental activites as intentionality and self-consciousness?

Best regards from Paris,


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Dr. craig’s response


My father died a slow death from the ravages of Parkinson’s disease, Vadim, so I thank you for your efforts to counteract this dread illness. As I read your question, I thought you were going in an entirely different direction until the unexpected twist at the end. I thought you were going to ask whether God would hold morally responsible those persons who were treated with the drugs you described and who then carried out actions which God proscribes. My answer was going to be that such persons under the influence of drugs or stimulants administered by a physician are not culpable for the proscribed actions. In such a case they do not sin, any more than someone pushed into another person is morally responsible for any harm suffered.

But your question was quite different! You want to know whether God can exist if neurologists can so affect a person’s brain activity with either drugs or stimulation so as to cause that person to do things he wouldn’t normally do. Well, it’s hard to see any problem here. God has given us incredibly complex bodies and brains operating according to natural laws, so we should expect that if we tinker with the brain’s chemistry or neural firings, that would naturally have effects that would otherwise not occur. Just as a person can’t get drunk without physical effects, so a person whose brain has been artificially altered will behave differently. There’s just nothing surprising here.

Nor is it any basis for the sweeping conclusion that “God is ‘just’ a very complex matter of neuroscience that we do not yet fully understand.” In fact, I’m not sure I even understand that hypothesis. You ask, “Is not God in our incredibly sophisticated neuron net that we call brain even for explaining such mental activities as intentionality and self-consciousness?” Even given atheism, such a suggestion is just bizarre. God is a net of neurons and synapses that sits in your cranium? Your brain is God? That would make you a polytheist, I guess, since there are then a plurality of gods coming into being and dying every day.

And why the brain? Why not say your digestive system is God? Maybe you think we need “God” to explain intentionality and self-consciousness, and the digestive system wouldn’t be up to the task. That makes me wonder if I’ve misinterpreted your question. Maybe you’re suggesting that God is an immaterial being that somehow indwells our brains to produce intentionality and self-consciousness. But theists don’t appeal to God to explain such phenomena. Rather one appeals to the mind or soul to explain intentionality and self-consciousness, which cannot be explained purely physically. The question is not about theism, but about mind-body dualism. I discuss that in my Defenders lectures on the Doctrine of Man.

In any case, I see no reason to think that “God's existence is ‘just’ a matter of faith.” As I try to show in my book Foi raisonnable: Vérité chrétienne et apologétique, trans. Christiane Pagot and Gérard Pech (Villefranche d’Albigeois:  Éditions la Lumière, 2012), there are good reasons to think that God—i.e., a transcendent Creator and Designer of the universe who is the paradigm of moral goodness—exists.

- William Lane Craig