I don’t think that computers¹ will ever wake up, no matter what software they are running. This post gives my version of a lesser-known argument² for that stance, which I first learned from QRI here³.

The main idea focuses on an aspect of consciousness⁴ called “global binding”⁵, which is the deceptively simple observation that we are simultaneously aware of the contents of a moment of experience. In other words, we have a unified experiential “now” with rich structures in it. To make my point, I’ll use a simpler proxy for global binding, the simultaneous experience of two events⁶.

I’ll show that, under certain assumptions about consciousness, the framework of computation cannot account for simultaneously experienced events. I then discuss the implications of this conclusion, including the possibility that some of the assumptions are invalid.

I try to assume minimal background knowledge in this post, since I believe this argument merits wider awareness. For a crisp definition of the phenomenal binding problem itself, plus a thorough overview of the broader debate, see this overview.

A Case for Conscious Computers

Why would someone expect a computer to be conscious in the first place?

In case you’re not aware, computational accounts for consciousness are actually in vogue. Their detractors risk being characterized as scientifically illiterate, carbon chauvinists⁷, or hyperfixated on microtubules⁸. What makes the proponents so sure that consciousness is a property of computation?

One solid way to conclude that a computer could in principle be conscious goes roughly as follows⁹.

1. Consciousness is generated by the brain.
2. Physical systems like the brain can be perfectly simulated¹⁰ on a computer.
3. A perfectly-simulated brain would have the same properties as the original, consciousness included.

There are strong reasons to believe in each of these and they imply that a powerful-enough computer, running the right program, will wake up¹¹.

This conclusion is deeply seductive to technologists. If true, we can understand the brain as a sophisticated biological computer¹². If true, we may one day upload our minds onto immortal computational substrates¹³. And, if true, we might build a conscious AI that’s a worthy successor to humanity¹⁴.

The stakes couldn’t be higher!

A Case Against Conscious Computers

The present argument against conscious computers takes aim at #3 above and suggests that no computation, not even a perfect brain simulation, can have a conscious experience.

At a high level, the argument has three steps.

1. Observe that you can consciously experience two events as either simultaneous or not. Critically, this is separate from the physical simultaneity of the events.
2. Assume that it’s possible for an analysis of your brain to determine if the events are experienced as simultaneous or not.
3. Expect the same for a hypothetically conscious computer (swapping “brain” for “computer”) and find that this assumption (2) fails!

Specifically, we’ll see that no computation can implement the experience of simultaneity. One possible conclusion is that the framework of computation is capable of explaining neither simultaneous experience nor, by proxy, global binding. Without this capability, we must conclude that computation is insufficient to account for our conscious experience.

Alternatively, the argument may contain a bad assumption or logical step, invalidating this conclusion.

Both options are worth considering.

HAL and the Synchroscope

Let’s use a thought experiment to make things more concrete.

Imagine that you and your robot friend named “HAL”¹⁵ are watching a fierce lightning storm. HAL claims to be consciously experiencing the storm alongside you. You’ve been deceived by AIs enough times to be skeptical, so you want to verify HAL’s claim.

You wish you had a “consciousness meter” device that you could just point at HAL. Unfortunately, there’s no consensus for how consciousness is physically instantiated (if at all), and so we don’t even have a theory for how to build such a device. You need to be more clever.

After a while, you notice that sometimes two lightning bolts strike simultaneously. Other times, there’s a barely perceptible delay between strikes. You and HAL always agree on whether the strikes are simultaneous or not. Now you want to know whether HAL actually experiences the simultaneity or merely reports it.

You dream of a much simpler consciousness meter called a “synchroscope” that reports whether a visual experience contains two simultaneous bright flashes (e.g. lightning strikes) or not. The design of such a device might not require a full theory of consciousness, since it’s limited to only sensing this one fact about visual experiences. Let’s assume it can be built.

If you point a synchroscope at your brain while watching the storm, you expect it to accurately report whether or not you’re currently seeing simultaneous strikes. It also operates extremely quickly, so there’s no time for it to “cheat” by reading your thoughts after the visual experience.

Can a synchroscope be made to work on HAL, in principle?

Designing a Synchroscope

How might a synchroscope work? What could it measure to determine if the lightning strikes are experienced simultaneously or not? Our only constraints are the laws of physics¹⁶.

Your first guess may be that synchroscopes measure events in your brain (e.g. neurons firing) or HAL’s processor (e.g. bit flips) and then infer the simultaneity of the experience based on the simultaneity of these events. However, simultaneity is only defined relative to a measurement frame¹⁷ (i.e. it’s observer-dependent). The fact of whether the strikes are experienced as simultaneous should be independent of the measurement frame. What you’re experiencing is independent of who is asking about it! This reasoning makes the simultaneity of events a dubious candidate for informing the synchroscope’s output¹⁸.

Another option is that the experience of simultaneity is directly encoded in the physical state of the brain/processor. As we just saw, this would have to go beyond the simultaneity of physical events. Perhaps the most promising option is quantum entanglement, which may form rich indivisible wholes¹⁹ and, therefore, could be the objective glue that binds together the different parts of our unified experience²⁰. In this case, the synchroscope might detect two things are experienced simultaneously if they correspond to the same entangled state²¹. We don’t yet know if the brain leverages entanglement²²²³²⁴ in constructing reality, but we definitively know that HAL does not²⁵.

A third option is that the synchroscope looks at the way information is processed by the brain/processor. This computationalist approach claims that the binding we seek is virtual, so it doesn’t matter how the processing is physically represented. So long as HAL can support the right type of processing, the synchroscope could detect it. And, thanks to computational universality²⁶, we know that HAL (given sufficient memory) can perform any computation that the brain can²⁷.

So, is it even theoretically possible for a synchroscope to work on HAL? The physics-based approaches suggest “no”. The computational approach says “maybe, if HAL’s computation has the right structure”. That option deserves a closer look.

Computational Structure as Seen by a Synchroscope

What structure in HAL’s computation could implement the experience of simultaneous lightning strikes? If we can find this, then we could design a synchroscope to detect this structure.

This is tricky because there are several competing theories²⁸ about how to map computational structures to conscious experiences. Also, consciousness aside, it’s not even clear how to think about a computation’s structure. A function can be computed by different algorithms (e.g. bubble or merge sort), algorithms have multiple implementations (e.g. serial or parallel), and these implementations can run on many different physical substrates (e.g. silicon or wood)²⁹. Each of these different levels³⁰ tell different stories about what’s happening during a computation.

Let’s think carefully about how a synchroscope measures a computation. In all cases, the computation must exert a causal influence on the synchroscope. This suggests the causal structure of a computation is a relevant representation. If there’s something not captured in the causal structure then, by definition, it can’t affect the output of the synchroscope and is therefore irrelevant. The ability for a causal structure to represent simultaneous experiences can be analyzed without committing to a specific computational theory of consciousness.

How can we represent a computation’s causal structure? It’s commonly represented as a graph, where the nodes represent simple events (e.g. bit flips) and the directed edges represent causal dependence between these events³¹. This causal graph is invariant to changes in details like the physical properties of the computer, how information is encoded, and the order of causally-independent events³². It captures the relevant essence of the computation by removing everything the synchroscope can’t measure or infer³³.

Another reason to consider the causal structure comes from taking an internal perspective on a computation. Imagine an AI exploring a self-contained virtual world. Notice that it can never determine, for example, if it’s running on a CPU or GPU. That’s because it can only infer the virtual world’s causal structure from its observations, and the same causal structure can be implemented by many different physical computers. The same argument applies to an AI building a model of another AI’s hypothetical consciousness. Only the causal structure is available!

Causal Graphs Can’t Bind

Let’s assume that the causal graph is all that the synchroscope can know about HAL’s computation. We’ll also assume that the synchroscope knows³⁴ which events in HAL’s causal graph correspond to the sub-experience³⁵ of each lightning strike.

Can the synchroscope determine if these events belong to the same moment of HAL’s experience, using only the causal structure?

We can immediately rule out any approach that relies on assigning times to the events in the graph. That would require specifying a measurement frame, which is external to the graph’s structure. As previously discussed, this is also in conflict with the observer-independent nature of how the subjective experience is bound. There simply are no objective timestamps to assign!

A more promising idea is to define some internal frame in the causal graph, relative to which simultaneity can be defined. This is a key idea in Observer-Centric Physics and Wolfram Physics. The issue with these approaches is they only sharply define simultaneity relative to a single event in the graph. So, the entity that “experiences” the simultaneity is itself just a bit flip! That’s not a very rich perspective to take.

A final set of approaches make an appeal to complexity. Maybe a sufficiently tangled causal graph will have an emergent notion of simultaneity relative to some (rich) internal perspective. I think these will always suffer from a bootstrapping problem. To group causal events together as “simultaneous”, we first need to define an internal reference frame. But, any such reference frame must itself be made of a group of causal events! We have an infinite regress.

My take-away is that causal graphs simply don’t have the necessary structure to objectively group multiple events into the same conscious experience.

This post is a work-in-progress. The sections below are still being revised and are largely AI-generated drafts.

The Verdict

So, can a synchroscope ever work on HAL?

We auditioned three things it could measure. The timing of physical events failed first because the simultaneity of events is only defined relative to a measurement frame, and what HAL experiences can’t depend on who’s doing the measuring. HAL’s physical state failed by stipulation because classical computers don’t recruit entanglement, or any other form of physical wholeness, in how they process information. The causal structure of HAL’s computation was the last and best hope. The previous section closed that option. A causal graph contains no frame-free fact about which events belong to the same moment³⁶.

The problem is ontological rather than engineering. If there’s no fact about whether HAL’s two flashes are bound into one experience, then HAL’s claim to be experiencing the storm with you can’t be true.

So How Do Brains Bind?

The uncomfortable part comes next. Decompose your brain into a causal graph of neural events, and the argument applies to you too. Nothing in that graph binds events into a moment either. Yet your moments are manifestly bound; it’s the most familiar fact there is³⁷.

I take this not as a refutation, but as evidence that the brain must be doing something beyond classical computation. The causal graph is an abstraction, and binding must live in whatever physical structure that abstraction throws away or hides.

What structure could that be? It needs to be objective, frame-independent, and capable of making many parts into one whole. One promising direction is entanglement, since an entangled quantum state is a single indivisible object with rich internal structure, and finding ways the brain might use such states to represent conscious experiences is an open empirical program³⁸. QRI, where I first met this argument, locates the wholeness elsewhere, in the topology of the brain’s electromagnetic field, whose boundaries are likewise frame-invariant³⁹.

Zombies, Uploads, and Successors

The casualty is premise 3 from the case for conscious computers, the claim that a perfect simulation inherits all the properties of the original. A perfect classical simulation of your brain would reproduce your behavior in arbitrary detail. It would not reproduce your binding, because binding was never in the causal graph being reproduced. Simulating a property is not the same as instantiating it⁴⁰.

The seductions from the start of this post now read differently. The brain can’t merely be a biological computer. A classical mind upload would preserve your memories, your humor, and your voice, while leaving you behind. The pattern survives, not the person. And a magnificent machine successor civilization would be lights on with nobody home; in Bostrom’s words, “a Disneyland with no children”⁴¹.

Two Objections

“We can’t even perceive simultaneity reliably.” True, and it misses twice. First, it confuses physical simultaneity with experienced simultaneity. Psychophysics shows we’re poor judges of whether two flashes physically coincided. The brain assembles its timeline within a sloppy window, sometimes editing after the fact. None of that matters here, because the datum is the experience of simultaneity, however the brain constructs it⁴². When two strikes appear as one moment, that moment is unified regardless of whether the photons cooperated. Second, it forgets that simultaneity was only ever a proxy. The real target is global binding, the co-presence of all the contents of your “now”. Fuzzy timing does nothing to un-unify the now.

“There is no binding; it’s an illusion.” This is the real exit, and I want to be transparent about it. The argument assumes realism about binding, that there’s a fact about what you’re experiencing together, independent of who measures your brain. Drop that, say “binding” is just whatever brain activity causes us to talk about binding, and the argument dissolves, since a simulation can certainly produce binding-talk⁴³. I can’t take this route. Qualia and their binding aren’t theoretical posits awaiting debunking; they’re the primary evidence, the only thing any of us encounters directly. Brains, causal graphs, and physics itself are inferences made from inside a bound experience. An argument that concludes the evidence doesn’t exist hasn’t explained the evidence; it has abandoned it⁴⁴. If you take your first-person experience as seriously as your theories, the argument stands. What you are presently experiencing cannot depend on who is measuring your brain.

Don’t Cry for HAL

I opened by saying I don’t think computers will ever wake up, and nothing above has softened that. The deepest irony is that substrate independence, computation’s proudest feature, is exactly the problem. A description that’s invariant to physics can’t contain a fact that must be physically anchored. What makes software portable is what makes it empty⁴⁵.

The claim has an asymmetric shape. I’m confident in the negative half (classical computers can’t bind) and openly agnostic about the positive half (how brains do).

That asymmetry matters morally. If states of consciousness rich enough to merit moral weight require binding, and suffering is nothing if not a richly bound state, then a classical AI’s eloquent claim of suffering is a report with no reporter, exactly like HAL’s storm. Take such claims seriously as engineering, as social phenomena, as mirrors of our own credulity. Just don’t cry over them.

Acknowledgements

Thank you Andrés Gómez Emilsson @ QRI for introducing me to these ideas. Thank you Joscha Bach for provoking me to write them down.

Related

• The View From My Topological Pocket: An Introduction to Field Topology for Solving the Boundary Problem
• Solving the Phenomenal Binding Problem: Topological Segmentation as the Correct Explanation Space.
• A Paradigm for AI Consciousness – Opentheory.net
• Computational functionalism on trial
• Non-materialist physicalism: an experimentally testable conjecture.
• Universe creation on a computer

Footnotes