You Are Multiply Realizable
Why neuroscience is overrated
Things that are more than the sums of their parts are multiply realizable. A thing is multiply realizable when configurations of the same parts can potentially create multiple different instantiations of that thing with unique properties. A multiply realizable thing’s properties emerge from the specific configuration of its parts. These emergent properties are created by relationships among the parts of the thing.
I separate 100 people into different rooms and give them each an identical 75-piece Lego set. The Lego set includes multiple sets of different wheels and pieces of various shapes and sizes. I ask each of them to create a Lego car using all 75 pieces. All 100 people produce a Lego car, but there is configurational variability across the 100 models. The different models have different sets of strengths and weaknesses. Some move faster but turn slower, some are slower but sturdier, and so on.
In one sense, the people individually produced one identical thing called “Lego car.” However, in another sense, all the people individually produced multiple different things. There’s “Marshall’s Lego car,” “Alyona’s Lego car,” “Ruthie’s Lego car,” and so on. Collectively, the configurations constitute a group of multiple unique things.
Is the Lego car one thing or many things? Here’s where the concept of multiple realizability is useful. The Lego car is a multiply realizable thing. It can potentially manifest different emergent properties depending on its unique system of part-whole relationships. It can be conceptualized as one thing with multiple potential configurations.
Where does the Lego car exist? I can point my finger at specific configurations of the Lego car. These are material objects locatable in the world. However, I cannot point to the multiply realizable and singular sense of the Lego car because it is a concept. Similarly, you can’t point your finger at potentialities because that which could potentially exist doesn’t materially exist — at least not yet.
Living things are multiply realizable. A specific tree grows leaves and then loses them. If you put a shelter over one side of it, it reaches toward the sun. It is constantly changing, yet it remains the same thing in your imagination.
Like the tree, you are multiply realizable. You are always changing. Your system changes as it metabolizes different foods, sheds and grows skin cells, learns and forgets ideas, and so on. Like the Lego car, you can have multiple different configurations. You can become potential configurations that don’t exist (yet). For example, you could potentially get ripped and learn new things even if you are fat and dumb right now.
Your multiple realizability goes deep. When you think the thought “that dog right there is good” while looking at a specific dog, you instantiate a particular bodily configuration. Many people think thoughts are produced by the brain, but this is myopic. If you didn’t have a beating heart, working lungs, eyes to see the dog, the actual dog right there, and a host of other non-brain things, you couldn’t embody the thought’s bodily pattern. All of these parts work together to produce the thought. In other words, your thought emerges from the body’s unique configuration.
How can people with different bodies, and therefore different brains, embody the same thought? After you verbalize the thought that the dog right there is good, I say that I agree with you. That dog there is good. How can this happen? How we possibly share a thought if our bodily configurations of that thought are different?
The key is language. Linguistically communicable thoughts like “the dog right there is good” are multiply realizable from many different bodily configurations. Like the Lego car and the tree, linguistically communicable thoughts are simultaneously one and many. Language is more than the sum of its parts, it is multiply realizable.
It’s trendy to attempt to explain thoughts in neurological terms. The idea is that if the brain does X, then Y thought emerges. People invoke neuro-mechanical analogies like “rewiring the brain” to discuss psychological changes in perspective. Underpinning all this is the assumption that thoughts supervene on brain states. In other words, it is animated by the notion that it is theoretically possible to map distinct thoughts to particular neurological patterns.
The multiple realizability of linguistic thought dooms this reductionist approach. Neuroscience is extremely useful in certain contexts, but it is theoretically impossible to ever map brain states to thought states because thought states are mediated by language and therefore culture. The multiple realizability of linguistic thought precludes neuroscientific reductionism because it means (1) bodies/brains in different configurations can produce the same linguistic thought and (2) linguistic creativity makes new potential thoughts and therefore new body/brain configurations possible.
For a neuroscientist to map a thinker’s brain states to a linguistic thought, she must ask the thinker what thought he is thinking. She must do this because a linguistic thought is multiply realizable by different brain/body states. If this were not the case, the neuroscientist would already be able to point her finger at patterns in the thinker’s neurological data (configurations) and identify them as distinct thoughts (multiply realizable things). Everyone’s thoughts would manifest in the same bodily/neurological patterns. The whole project would be redundant if that were so! Since she cannot already point out the thought in the data, she must ask the thinker. The thinker’s answer is necessarily mediated by language. Only after he verbally articulates his thought can the neuroscientist attempt to find a correspondence between patterns in neurological data (such as fMRI data) and the thought. She may then be able to identify when he is thinking that thought by looking at a live data feed, but only because she started her investigation by appealing to language. Since language shapes the body/brain into thoughts, neuroscientists are forever bound by culture.
Language is not only culturally colored and constantly evolving, it can also be creatively manipulated by specific individuals. Poetry, linguistic creativity, limits the scope of neuroscience with its multiply realizable potential. Every new poem is a new linguistic thought and therefore a new potential body/brain state. Neuroscientists can’t ever predict when thinkers are thinking poetic thoughts. No amount of data they collect can identify or predict poetic/creative linguistic thought because their data is constrained by language from the past. They would have to already know all potential poems to do that, which is theoretically impossible. Plus, most neuroscientists aren’t the poetic type.
Neuroscience has become mainstream and trendy because of the perennial human desire to find simple explanations for the complexity of human existence. If thoughts could be reduced to neurology, life seems more understandable and controllable. We would only need to look at people’s brain scans to know their perspective. We could “cure bad thoughts” with neurological interventions like pharmaceuticals. You see this false hope in the film Spider-Man: No Way Home. Spider-Man “cures” immorality with science because he knows so much about the human body/brain. He “heals evil thoughts” with medicine. This is not only impossible for the reasons discussed above, but it also turns doctors into gods. History has repeatedly demonstrated how the belief that morality is a matter of medicine ends in atrocity. Spider-Man is a modern medical eugenicist in this horrible movie, but his vile character is celebrated because the audience likes the outcomes. Just wait until Spider-Man comes to “cure” you for thinking “bad thoughts” and your doctor prescribes you medication to “heal” you of your political ideology or life philosophy.
I’ll leave you with this complication. You are always interacting with the environment. I mentioned that there must be an actual dog right there for you to think “that dog right there is good.” Environmental parts intermingle with body parts to produce linguistic thoughts. I said linguistic thoughts are multiply realizable from many different body/brain configurations, but it is more true to say that they are multiply realizable from many different body/brain-environment configurations. If you never come across a pangolin, you can never have the thought “the pangolin right there is good.” There isn’t a pangolin right there, so you can’t think that specific thought.
If you want to change your thoughts and experience new body/brain states, go new places, see new things, and learn the names of these new places and things. You expand your multiply realizable potential by realizing new potentialities.