Freewill – Brain Tumours all the Way Down

This is an argument for determinism I first heard made by Sam Harris. In a conversation he had with Dan Dennett, he discussed the mass shooting in 1966 by Charles Whitman where he murdered 17 people, including his mother and wife, and wounded 31 others. Whitman wrote a suicide note in which he claimed not to understand exactly why he had just murdered his mother and wife and that he had recently been the “victim of many unusual and irrational thoughts.” He also requested that an autopsy be performed on his body and wanted his life insurance policy to go to a mental health foundation to “prevent further tragedies of this type.” The autopsy revealed that Whitman had a brain tumour in the hypothalamus region of his brain.

Harris’ point is not just that Whitman was in fact a victim of his brain tumour and is less morally responsible for his actions as a result, but also that everybody is similarly a victim of their brains. In Whitman’s case, his brain tumour caused him to act the way he did, but this only drives home the point that we are all at the mercy of our brain wiring, development, and functioning. It’s, as Harris quips, “brain tumours all the way down.”

Harris is making two separate claims here. The first is that someone in the same situation as Whitman, i.e. someone with a brain tumour, is less morally culpable for their actions. The second is that our intuitions in this case can be expanded to include not just brain tumours but brains themselves, meaning that no one is responsible for what they do and freewill is an illusion.

Let’s look at the first claim. Do we think that someone with a brain tumour has less moral culpability? Imagine a man is on trial for assaulting a number of strangers without provocation. He seems distracted, angry, arrogant and unsociable but his friends and family say he never used to be like this. An investigation reveals that he has a brain tumour which is putting pressure on a certain part of his brain responsible for higher cognitive functions. The tumour is removed and his personality changes noticeably. He is friendly, polite, remorseful, and can’t understand what motivated him to attack all those people. In addition, his friends and family confirm that this is the man they knew and loved.

If we could be certain that his actions were a direct result of the tumour and that he would normally never have done anything like that (which we can be because it’s my thought experiment), is he fully morally culpable and deserving of the punishment he was to receive? In this case, I think it is reasonable to clear him of blame. He is a good man who, in a very real sense, wasn’t fully in control of his actions when he committed his crime; in short, he was a victim.


Once securing this, Harris then smoothly rolls into the second claim; that “a neurological disorder appears to be just a special case of physical events giving rise to thoughts and actions. Understanding the neurophysiology of the brain, therefore, would seem to be as exculpatory as finding a tumor in it.”[1] So, Harris is saying that if a tumour putting pressure on a certain part of the brain can cause thoughts and actions in a person, then the brain itself is where the buck stops as far as creating thoughts and actions goes. In other words, no one is really responsible for their thoughts and actions because everyone’s brains are causing their thoughts and actions, not them.

There are two problems with this, a minor and a major one. Let me tackle the minor one first. The reasoning is flawed. Consider another example. Imagine I have a device you wear on your head. While you are wearing it, I can send an electric current through it in such a way that it causes you to think of a dog every single time I activate it. We have here a pretty simple case of “physical events giving rise to thoughts”.  But has this demonstrated that under normal circumstances, i.e. when you aren’t wearing my device, you somehow don’t think thoughts and perform actions and that your brain is running the show? Not in the slightest.

In exactly the same way, it is illegitimate for Harris to infer from the fact that a tumour pushing on a part of the brain and inducing thoughts and actions tells us anything at all about what happens under normal circumstances, i.e. when you don’t have a tumour. Of course, he may be right, but noting that thoughts and actions can be induced by a foreign body doesn’t get him there.

Harris might say that there is still a suspicious parallel here. A tumour is just a growth, after all; not unlike all parts of the brain. Of course, but a tumour crucially isn’t a part of a normal, healthy brain and, just as crucially, it’s not involved in any thinking itself. It’s an inert, foreign body (similar to the electric current my device produces) affecting those other parts of the brain that do have a hand in producing thoughts and actions. While we may not understand exactly what the brain is at the moment, we do know that it certainly isn’t “tumours all the way down”.

Note that I’m not trying to prove that the brain doesn’t call the shots here. All I’m doing is showing that the tumour case doesn’t tell us anything at all about ‘who’ or ‘what’ normally does. All it tells us is that manipulating brains in certain ways can produce certain effects in the form of thoughts and actions – exactly how thoughts arise and actions get performed when a brain is free from external manipulation hasn’t been addressed at all.

So, to sum up so far; what does the brain tumour case do? Does it, at least in the worst theoretical case, exculpate the sufferer from moral responsibility? Yes. Does it reveal that everyone’s brains are actually masses of tumours and we’re all victims, completely at the mercy of physical events we have no control over? Of course not.


But we haven’t finished yet. What is the major problem I referred to earlier? Remember Harris’ claim is that no one is really responsible for their thoughts or actions because these all just flow from physical events in the brain (whether caused by a tumour or not). You are no more responsible for your thoughts or actions than Charles Whitman was for his. You think you’re free but this is an illusion. This intuition appears all the more obvious in the case of a tumour because a tumour can completely change a person’s attitude, thoughts, intelligence, and even personality; all against that person’s will, or at least, in such a way that they can’t control how they change. If you’re not free to choose something as deeply intimate as your thoughts and personality, how can anyone even pretend to claim that we have freewill?

The problem is that everything in the above is still mired in a kind of Cartesian dualist frame of mind. You aren’t responsible for your thoughts or actions. You aren’t in complete control over your thoughts and personality. Who is the you in these sentences? It can only be referring to a mythical Cartesian Mind or homunculus. If we agree that talk of these ideas is misguided (as I do), then these determinist analyses of what is going on in consciousness or the brain are all meaningless. If you want to transcend Cartesian ways of thinking, you can’t smuggle a Cartesian Mind in through the back door.

So how should we go about analysing this brain tumour problem? What does it actually tell us? It tells us that changes in the brain can change things like personality, intelligence, and a hundred other aspects of a person… and that’s all. Admittedly, this sounds like a major deal, until we realise that we change many of these things every time we drink more alcohol than we should; prolonged and excessive drinking can even change these things permanently. Events can change people. A spouse cheating, the death of a loved one, and a million other things can change many of these aspects of a person. But in none of these cases are we tempted to conclude that freewill is an illusion. And neither should we, because they don’t tell us anything about freewill.

It’s at this point that the determinists throw in their objection. If you can’t freely choose these things, then you can’t be free. And now we’ve fallen back into the Cartesian rabbit hole with a Cartesian Mind lurking somewhere in the back; if you can’t choose your personality, you can’t be free.

If we manage to avoid this trap, we realise something really interesting; we can still have freewill even if we don’t freely get to choose our personalities, our characters, our intelligence, etc., and even if those aspects can change without our consciously willing it precisely because we aren’t a separate metaphysical substance from the traits that describe us; we aren’t a thing that has them; we are those traits.[2] There is no you separate from your personality, your intelligence, even from your body and especially from your brain, and being free or determined has nothing to do with any of them.


So, we have seen that while the brain tumour case can legitimately cause us to rethink and even reverse our moral intuitions in specific circumstances, it doesn’t give us any reason to question our moral intuitions regarding a normal, healthy brain. But even more importantly, we have also seen through the Cartesian wool that determinists so often get tangled up in and realised that a brain tumour can alter many things about us, but even this doesn’t tell us anything interesting about freewill.


Note: Since I have only been concerned here with refuting the idea that the brain tumour case makes any kind of argument against freewill, arguing for freewill is outside the scope of this essay. If, however, you are interested in what a positive case might look like, I invite you to take a look at one such example here.


[1] Harris, S. (2012). Freewill. New York, NY: Free Press.

[2] We are those traits but only inasmuch as we are consciousness of them; hence not totally coincident with them. This line of enquiry takes us a little far afield from the narrow concerns here and into a subject I have discussed in more detail elsewhere.

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