Brains in Vats

Brain in a vat - Wikipedia

Could it be possible that you, as you are right now, sitting there reading this article, are nothing more than a brain floating in a vat, hooked up to a super computer which is generating electrical signals that perfectly simulate sensations received from sensory organs interacting with an external world, and capable of detecting and responding perfectly to your willed movements and behaviours? That’s the brain in a vat thought experiment in a nutshell, and our task in this article is to determine whether or not it’s possible. Begin challenge…

The Brain

There is a myth going around about the brain. Maybe you’ve heard it. Maybe you believed it. I used to. It says that the brain produces something. At the extreme end of the spectrum, the believers in this myth hold that the brain generates something which accompanies all elements of our cognition. This ‘something’ they call consciousness, or qualia, or first-person this or that, or ‘the feeling it is like to X.’ Of course, it doesn’t really matter what term they use because no one knows what any of them actually refers to. At the less extreme end, this fable says that the brain accepts afferent signals from the sense organs and then generates a mental representation, or an internal model, of the surrounding world. This is no Cartesian theatre, the faithful assure us. There is no single place in the brain where an image is assembled. That would be ridiculous. Instead, the whole process is decentralised. It’s modular in nature. I see. So, what we’ve done here is bring Descartes into the Digital Age. We’ve progressed from the Cartesian theatre to Cartesian data streaming, in which the whole is never present in one place at one time. Instead, our internal model of reality is being generated continuously by information taken from various modules. Whichever end of this spectrum we start from, there is one thing all believers in the myth agree on; in some way we don’t yet understand, the brain adds something non-physical to physical processes.

Henri Bergson

French philosopher Henri Bergson (1859-1941) had a radical position on the brain. He argued that the brain is just a physical object. This may not sound particularly radical, but in the modern intellectual climate, it is just about as radical as it gets. It is virtually universally accepted that the brain produces non-physical thoughts, sensations, and images. We cover our ignorance with words like ‘emergence’ as we try to uncover the secret to this transubstantiation trick of which the brain is capable – the generation of the non-physical from the physical – but no one doubts that the brain is where the magic happens, except for one largely forgotten French philosopher who dared to look behind the curtain. What he found there was… nothing; in other words, the brain doesn’t produce any unextended representations, sensations, or internal models of the external world. It doesn’t do this because it can’t. You just can’t get the non-physical from the physical – you might as well try to turn lead into gold. It is in this sense that I like to say Bergson outmaterialises the materialists (despite not even being one!), beating them at their own game, so to speak. Score one for HB.

What does the brain do, then? Bergson’s memorable analogy in Matter and Memory is to a central telephonic exchange. The brain accepts afferent signals (those coming in from the sense organs and limbs) and sends out efferent signals (those going out to the limbs) for action, but its principle function in this stimulus-response cycle is to delay the latter. (Why this delay takes place is well beyond the scope of this article, but, if you are interested, Bergson calls it the zone of indetermination, and what it does is give memory time to interject, thereby making our responses more than those of automatons mindlessly reacting to stimuli). That’s it. No magic. It doesn’t generate experience, consciousness doesn’t emerge from it, it doesn’t produce an internal representation of the world.

Your next question is, “If the brain doesn’t generate consciousness, or experience (or anything!), where does experience come from?” And to answer this, we’ll need a new section…

Conscious Experience

Disentangling the mess that has sprung up around the word ‘consciousness’ is not something we are going to do here (I made a first attempt at this in an earlier series of three articles, starting with The Qualia Delusion, which you are welcome to read if you’re interested). However, since the question driving this article is whether a genuine, lived experience in a real world with a real body can be convincingly simulated for a brain in a vat, we will need to have some idea of just what a lived experience is.

Let’s start with what experience isn’t. It isn’t some ephemeral quality produced by the brain (I don’t care how high it’s phi score is), nor is it something which belongs to an opaque soul-like entity inhabiting the body. In fact, the problem with understanding lived experience through these approaches and all others like them is that they all start from the inside. This then reifies the ‘internal’ as something; i.e. something separate from the outside, and it thinks that it is onto a winner with this because those internal feelings or sensations or phenomenal experiences (call them what you will) appear indubitably certain. If you’re experiencing red, that experience appears certain, whether or not there is actually something red before you at the moment. The problem with this approach is that it cleaves the world into two; your experience on the one side, and the thing on the other. Once you set the dichotomy up in this way, you can never bridge the gap. Whatever fancy label you come up with to denote this picture, it is, in truth, a direct descendent of Cartesian dualism. To really make a break from Descartes, we need to go the other way, start from the outside and work inwards.

We are going to do a metaphysical deep dive here, but we don’t have the time to walk through the steps that get us to the conclusions, so I am just going to jump straight to the conclusions themselves, and leave you with a promissory note to (try to) fill in the gaps in later articles. The first thing we have to be clear about is that, at the deepest level, the universe is not comprised of clumps of matter separate both from other clumps of matter and from the intervening spaces. Reality is continuous. This includes your body and your brain.

And yet we look around us and see objects which are clearly separate and distinct. How is this possible? Because reality is not only continuous, it is also a perpetual flux, continual change. Parts of this continuous whole change (evolve) in different ways in relation to other parts; all without ever separating themselves from that whole, of course; such a thing is impossible. Some of these parts have changed in particularly interesting ways, such that the parts of which they are comprised themselves function as a whole (a whole within a whole, if you will), and are able to detect and respond to other parts, as if they were genuinely separate from them, but, of course, at the deepest level of reality, they aren’t. By ‘detect’ and ‘respond,’ I mean sense organs and motor capabilities, and by ‘wholes’ (within a whole), I mean living organisms.

So we have living organisms, which are still intrinsically a part of the whole, that are nevertheless aware of other parts of the whole through a variety of sense organs they have used to carve this whole up into (apparently) separate and distinct objects. The main point here is that none of this requires the generation of a secondary, ‘phenomenal’ object in addition to the external one. Where are the objects, then? Why, out there in the world, right where they have always been, of course! Where else could they be? When one of these living organisms detects a stone in front of it through the sense organ we call an eye, a second, ‘internal’ stone does not come into existence in some magical ‘mind’s eye’ or as an unextended ‘mental representation.’ It might help to think of the organism as something like a mirror. When a mirror reflects an apple, does it generate a secondary, less-substantial one? Do we now have ‘two’ apples, one in the real world and one in the mirror? Of course not. The apple in the mirror is the apple in the real world.

 But this process is still mindless. Thus far, we have only described the perception of automata. How do we get ‘mind’ into the equation? For this, we need to return to my man Henri Bergson and his concept of duration. Duration is essentially time, but ‘real’ time, as opposed to the scientific conception of time, which is really a static series of already completed moments co-existing and projected onto an imaginary spatial (homogeneous) background. What is required for duration is a succession, and the capacity to prolong previous members of that succession and contract them into a single intuition.

We get the succession for free, as it were, from nature herself. At the most fundamental level, every part of the universe is vibrating or oscillating, pulsing with its own internal rhythm. In fact, this is a good way to think of reality, as a single whole rippling with waves of different kinds of motion, some of which we are sensitive to (e.g. the visible frequencies of light), most of which we aren’t. What is red? Some fixed quality inhering in the apple? Hardly. It’s electromagnetic radiation of a specific wavelength continuously entering our retinas at some unimaginable frequency. Pure dynamicity. Constant flux. What are electrons and quarks? Little discrete chunks of something? Nope. They are themselves vibrations. Modern physics nicely confirms Bergson’s intuition here when, in its latest formulation (as far as I am aware, anyway), it describes particles as vibrations of quantum fields which themselves ‘stretch’ throughout the entire universe. Can you think of a better expression of continuity? Score two for HB.

The second half of duration is prolongation and contraction, and this is effected through memory. This might sound a little like a ghost in the machine, the mystery of ‘Mind’ smuggled inside a less mysterious-seeming package, but it isn’t quite as bad as that because, in actual fact, memory is really a latent potentiality of succession; something like the way ice is a potentiality inherent in water. If you already have water, you don’t need to do so much to explain ice. What you do need to explain is how you move from the former to the latter. So, we already have succession, and the how, which will explain the way past events get prolonged and contracted, Bergson builds into the fundamental nature of the universe with his concept of the élan vital. The basic idea with the vital impulse is that the changes (evolution) that occur in the universe are aren’t random or mechanical, nor are they teleological, in the sense of being aimed towards a specific end. Instead, they reflect a tension in nature which naturally tends towards the prolonging and contracting of those successive events; i.e. which tends towards memory, towards the whole, as opposed to individual, separated parts. If we look at the highest point to which evolution (change) has progressed, at least that we know of, we find the psychic states of the animal known as Homo sapiens, and what are these if not an exact duplicate of the succession we see in nature, combined with memory; i.e. the capacity to prolong previous events into the present and contract the whole into one apprehensible intuition?

I know I have taken many shortcuts with this metaphysical foray, in particular dropping the élan vital on you out of the blue, but hopefully the broad outlines of what I am getting at are clear enough. The single point that I want to emphasise here is that in none of what I said did I invoke an experiencing subject, a conscious witness, or a spectator Mind enjoying qualia-laden mental representations and sensations. Instead, and this is how I have come to understand human experience, what we have here is one part of the universe ‘waking up’ to become aware of other parts of the universe. Now, in all likelihood, you will have heard this phrase before (I know I have), probably in a spiritual/mystical setting, but here the emphasis is not on the ‘waking up,’ which inevitably casts the spotlight on consciousness or subjectivity, in turn sending us on a merry goose-chase looking for some kind of internal, first-person experience or conscious witness; but rather, on ‘part of the universe’ because, in truth, there is no inner domain, and there is no inner subject. Perception places us out there in the world, literally in the things themselves (there’s nowhere else to be!), and memory places us literally in the past, although a past that is prolonged and contracted into the present.

Brains in Vats

Whew! What were we talking about again? Oh, that’s right, brains in vats. So, where does all of this leave us regarding that? Well, here is the argument: brains produce experience on the basis of afferent signals they receive from the environment. If we eliminate the environment but perfectly simulate the signals, the brain will continue to produce the same experience.

This is an air-tight argument, but for one flaw; it is quite evidently false. As I’ve argued above, brains don’t generate anything unextended, including experience. But if this were all I had to offer, I think BIV would still be on the table. “Fine,” the BIV adherent would say, “Brains don’t produce experience. Nevertheless, experience arises somehow out of the combination of afferent signals and brain activity. Whether the former come from a ‘real’ world or a supercomputer perfectly imitating a ‘real’ world is irrelevant.” But is it?

The argument is a classic example of reductionism and functionalism on steroids. It says an event is nothing more than its parts and their functions. It therefore believes that if we assemble similar parts in the same way, doing the same thing, then we will have perfectly recreated the original event. In everyday domains, those comprised of parts which have already been abstracted from the whole; i.e. those domains with which science deals, this formula is fine. However, when we start talking about wholes (like life, living organisms, and the universe) which are, in their essence, duration, reductionism and functionalism break down.

To return to the argument, we are being asked to believe that a simulated external reality will yield the same outcome as an actual external reality. Phrased as a question: Can electrical signals replace the real world? From the perspective of science, the answer is obvious. Of course they can. The brain is enclosed in a hollow space which is completely dark, and it lacks any form of contact with the outside world. Somehow, in the pitch black, silent cave it spends a whole lifetime within it is able to see colours and hear sounds. This is only possible because of the electrical signals that flow to it from the sense organs. The source is irrelevant.

And yet, thanks to our metaphysical meanderings above, we can see that this impeccably argued position is false. Perceived objects are literally out there in the real world. If we replace these objects with electrical signals, we have lost something essential; namely, the objects themselves! Electrical signals aren’t objects. If the brain doesn’t take the afferent signals it receives from the external world and generate an internal picture from them (which it doesn’t), and if perceived objects are the external objects themselves (which they are), then substituting these objects for electrical signals will have the underwhelming effect of eliciting electro-chemical and neuronal activity that we can look at and measure from the outside, but that won’t be experiencing anything… because there’s literally nothing to experience!

We can say exactly the same thing for our psychic states, which don’t appear in some magical, internal, subjective realm that is buzzing with phenomenal activity. Instead, our psychic states are that succession of events we found make up nature, prolonged and contracted by memory. Once more, if you get rid of nature; i.e. a real world, you lose the succession that memory, and therefore our psychic states, is grounded in. Using electrical signals as a substitute for the real world yields a simulation of that world in the same way that electrical signals and pixels can produce a simulation of a glass of juice; that is to say, a glass of juice that won’t quench your thirst in the slightest.

An Objection

One objection that comes to mind is to claim that I have assumed that we are not already brains in vats. Who’s to say that my metaphysical account of reality isn’t already being artificially generated by a supercomputer and relayed to my brain which is gently bobbing up and down in a vat? This is a true, but wholly unproductive, objection, and one that leads nowhere. If we assume, against what is the reasonable position (after all, even if we are brains in vats, we know there must be a real world somewhere – it can’t be brains in vats all the way up! BIV, on the other hand, is pure speculation), that we are already brains in vats, then what? Perhaps start formulating, what will have to be wildly speculative and ungrounded, beliefs about the nature of the entities running the supercomputer? Maybe try to convince other people that your beliefs are true? Possibly write a book about them? Perhaps theorise about ways to transcend the simulation? Congratulations – you’ve just started a cult. I’m reminded of the Christian claim that the evidence for evolution is real, but only because God planted it there for us to find, to test our faith. The Christian would argue that you only think evolution is true because you’re assuming God doesn’t exist and didn’t plant fossils in the ground for us to unearth. A ridiculous claim, to be sure. Just as ridiculous as objecting that I have assumed all of my thinking on the subject hasn’t already been conditioned by the aliens controlling the supercomputer feeding signals into my brain which is resting comfortably in a vat of some nutrient-rich liquid.


We have seen that the notion that we might just be brains in vats relies on the assumption that brains produce experience. This is purely and simply the Cartesian theatre dressed in modern garb; Cartesian data streaming. If we look carefully at human experience, we will see that the whole notion of an inner realm filled with exotic, phenomenal fauna like qualia, existing over and above an outer realm full of clumps of matter is, not just implausible, but incoherent. Perception, memory, psychic states; these are all out there in a world that is essentially a continuity characterised by movement and change; a world that is, in other words, Henri Bergson’s duration. Our bodies are a part of this continuity, but parts which have windows that open onto other parts. If you take away those other parts that are not me, and replace them with bits and bytes, or even qubits and qubytes, you take away the very thing at the core of experience. Is it possible that we are brains in vats plugged into a supercomputer? Absolutely not.


(On a personal note, this conclusion is particularly interesting to me because when I was planning this article, I thought I was going to conclude the exact opposite. I wrote three pages before getting hit by the realisation that the metaphysics wasn’t panning out. After three to four days of agonising over it (and wavering on my answer to the question more times than I care to remember), I finally landed on the position you have just read. Now, it seems so obvious, I can’t believe it took me so long to figure out!)

2 thoughts on “Brains in Vats

  1. There is an interesting psuedo-trade off here. Doing away with the cartesian split makes me feel like something special has been robbed from me! Yet, now the ‘outer’ world and my ‘inner’ experience are intiminately connected in a way that can’t be imitated. Certainly something wholesome about that… more over, nothing is really lost in this explaination save for assumptions/metaphysics that can’t really be supported in either case…

    Something is left wanting in me though.. perhaps it’s because I can’t quite place the utility of this view (or most explainations of consciousness). This is not say there isn’t utility, but rather to ask if you find any functional advantage in this explaination. I know, pragmatics are boring, but still I’m curious.

    Re-reading, I guess I’ve answered my own question on utility with the wholesome comment, and I bet you could do away with not a few phenomenological/hermetic theories of experience with this explaination.

    Well, still, interested if you have anything in mind (ha! Get it ?).

    Let me know if I’ve misunderstood anything.


    • Hi Warren,

      Thanks for taking the time to comment. I always appreciate hearing from folks interested in this stuff.

      That’s exactly the way I see it. The only real loss are the Cartesian metaphysical assumptions, but how much of a loss is it to cast off beliefs that haven’t done much more than generate endless confusion, anyway?

      Regarding utility: I think you’re right that there isn’t any here. That is just the nature of metaphysics, as I see it. If you want practical, real-world usefulness, you go with science; but what makes science useful (quantifiability, precision, etc.) is precisely what makes it unsuitable for describing reality. There is an unavoidable trade-off in that, and I think it’s the principle reason the humanities are struggling these days – we just no longer value things that don’t yield practical benefits.


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