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Mind & Self

Francis Crick’s Deliberately Provocative Reductionism

Paul Austin Murphy repudiates a blasé reduction of mind to matter by one of the discoverers of the structure of DNA.

In Francis Crick’s 1994 book, The Astonishing Hypothesis: The Scientific Search for the Soul, he wrote the following oft-quoted passage:

“‘You’, your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules.”

It’s easy to believe that here Crick was being willfully provocative and rhetorical. I want to consider to what degree he may also have been telling the truth, if at all.

In terms of the rhetoric and provocation, it’s true that Crick’s critical attitude towards religion was one motivation for his writing this. Crick certainly believed that religions are often wrong about scientific issues (as do many religious people). He also claimed that it is science’s job to rectify the false claims of these religions (or at least those claims which appear to have a scientific subject). He was also well aware that when he began studying consciousness he was tackling a subject which traditionally had been the property of religion and philosophy.

Another point about Crick’s rhetoric is that one of the simplest ways to get a point across is to be poetic and extreme. Nonetheless, the seeming extremity of a view doesn’t automatically mean that it’s false, at least not in every respect. And despite the opening quote, Crick does express the same idea in a slightly less provocative way when he later wrote:

“A person’s mental activities are entirely due to the behavior of nerve cells, glial cells, and the atoms, ions, and molecules that make them up and influence them.”

So, is that any better? In fact, I used the word ‘seeming’ (as in ‘seeming extremity’) because what Francis Crick says isn’t really extreme at all. It’s partly true; or at least, it becomes truer once the rhetoric is stripped away and the remaining position is analysed. In addition, the very fact that Francis Crick decided to study consciousness in the first place suggests that he couldn’t have been a reductionist in any strict sense. After all, in much psychology, neuroscience, or neurobiology, and sometimes even in philosophy, consciousness had been entirely reduced to the brain or behavior. Then again, most of The Astonishing Hypothesis is about neurobiology, and although the opening quotation is a philosophical position, the philosophical defence and implications of that position are rarely developed in the book.

Dependency Is Not Identity

Graphic © Amy Baker 2019. Please visit instagram.com/amy_louisebaker

Let’s put the position as formulated in the second quote in this very simple way. If it weren’t for our ‘nerve cells’ as Francis Crick puts it, then it’s indeed the case that we wouldn’t have “memories, ambitions, personal identity, free will, sorrows.” All these things do depend on the brain. But does it follow from this that joys, sorrows, memories, ambitions, personal identity, free will and so on are ‘no more than’, that is, identical to, a group of neurons, a part of the brain, or even the entire brain taken holistically? No.

Indeed, how can one thing actually be another thing? Let me cite Leibniz’s Law:

If x and y are identical, then everything true of x must also be true of y.

Applying this law, to take an example: Is the physical behavior of a group of neurons identical to your memory of a cat drowning in a river in 2010? In terms of Leibniz’s Law:

If your memory of a cat drowning in 2010 is identical to the physical behavior of neuron set x, then everything true of that memory is also true of the physical behavior of neuron set x.

Yet surely that can’t be the case. The memory itself is about a cat’s death in a river. Is the physical behavior of neuron set x also about a cat drowning in a river? The memory itself has some kind of relation to a past event which was evidently outside the brain. But the neuronal behavior is by definition inside the brain. The memory itself relates to something which occurred in 2010. Does the physical behavior of neuron set x also relate to an event in 2010 – at least in the same way as the memory does? It’s certainly possible that the memory of a cat drowning in 2010 might be somehow ‘encoded’ (let’s ignore the precise meaning of that word) in a part of the brain or even (somehow) in all of it. However, is the memory itself simply and purely a part of the brain? Brain part x is grey-pink, fleshy and three-dimensional. Is the memory of a dying cat also grey-pink, fleshy and three-dimensional? The active brain – which is sometimes called ‘the subvenience base’ of the memory – is material, being made out of neurons, glial cells, axons, dendrites, myelin, molecules, charged particles, electrical currents, and neurotransmitters. Surely the mental memory of a dying cat isn’t itself made out of any of these things. And so on.

So although the memory is indeed dependent on a part of the brain, it can’t be identical to it. To apply Leibniz’s law again, there are things true of the memory of a dying cat that aren’t true of the part of the brain which is its material subvenience base, so they’re not identical.

The original Crick quote is problematic in another important way, too. He seems to be referring exclusively to the brain, or to ‘nerves cells’. However, joys, sorrows, memories, ambitions, personal identity, etc have physiological aspects which go beyond the brain. Being sorrowful, for example, can make you physically lethargic, even ill. It’s true that these physiological effects are also related to the brain/nerve cells, and there are nerve cells (motor, sensory, and autonomic) throughout the body. So when you’re tired and your body becomes weaker, and you become sleepy, even these physiological events are related to nerve cells (nerve cells outside the brain are sometimes classed as ‘projections of neurons’). However, like memories, they aren’t identical to them.

None of this stuff extra to the brain or nervous system is necessarily non-natural, or in some vague way ‘spiritual’ in nature, by the way. This extra something can include mental states or events; other parts of the body as well as bodily physiology; the external environment; personal and communal history; language, culture, and many other things – all of which are indeed natural.

Where in the Brain is an Ambition?

In the case of certain examples cited by Francis Crick, it’s hard to even conceive of what he means. For instance, he mentions ‘ambitions’. The idea that a particular ambition is identical to a particular set of nerve cells, or the physical behavior in a particular part of the brain, seems very odd. What could it mean?

Let’s take the case of a particular ambition of a particular person at a particular time. Let’s use Mr T’s ambition to rule the universe as an example. Could that really be fully accounted for by his brain alone – that is, understood purely as the physical behavior of a set of neurons? If it could be, then a neuroscientist could look at that set of neurons and literally either see the ambition or get to know it in some other empirical way. And an ambition (as with any other psychological attitude) would then be brought about by electrochemical behavior in a particular part of the brain, which in principle can be fully and successfully observed and investigated by magnetic resonance imaging (MRI), electroencephalography (EEG), or by positron emission tomography (a PET scan). But even if he fully mapped the activity of Mr T’s brain, the neuroscientist still wouldn’t observe, or get to know the content of, Mr T’s ambition to rule the world. The only way he could know about the Mr T’s ambition would be to ask him, and hope he was telling the truth in his response. Even if a precise correlation existed between this ambition and the behavior of part of the brain, the neuroscientist would still need to question Mr T about it.

So Crick may well be confusing the fact that the brain physically causes memories, attitudes, etc, or even that such things can be strongly correlated (at least in principle) with particular parts of the brain, with the idea that they are identical to them. However, active brain parts or sets of nerve cells aren’t themselves memories or attitudes or whatever. The two things are very different. It’s a little like the difference between the cause of a fire and the fire itself. A struck match may have been a cause of a particular forest fire. However, the striking of the match and the forest fire are very different things. So although the brain’s parts are necessary for memories, sorrows, etc, they aren’t identical to them (or sufficient for them). That all means that Crick’s assertion that our mental features “are in fact no more than” nerve cell behavior is, strictly speaking, false.

Paul Austin Murphy is a writer on politics and philosophy. His philosophy blog is at paulaustinmurphypam.blogspot.co.uk.