Logical Proof for the Emergence and Substrate Independence of Sentience

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Sentience is the capacity to experience anything – the fact that when your brain is thinking or processing visual information, you actually feel what it’s like to think and to see.

The following thought experiment demonstrates, step by step, why conscious experience must be a product of functional patterns, not any specific physical material or structure.

The Inevitable Self-Report of Sentience

Consider a person who says, ‘Wow, it feels so strange to see and to think,’ speaking of their own conscious experience.

Every human action results from precise patterns of neuronal firing, cascading through the brain until reaching motor neurons that cause them to take actions, in this case to produce speech describing their sentience. Brains are bound by the laws of physics – if the same neurons fire with the same timings, it will result in the same outward behavior with absolute certainty.

It cannot be perpetual coincidence that our subjective experience always lines up with what our brain and body are doing. There is some reason for the synchronization.

When a conscious person talks about their sentience, the state of being sentient must influence their behavior – otherwise, it would be physically impossible for them to speak about it. The mere fact that they can describe their experience means that sentience has played a causal role in their behavior.

Now, replace one neuron with a functionally identical unit, one that takes the same inputs and fires the same way. The behavior of the person remains the same, and they still say, “Wow, it feels so strange to see and to think.” This remains true if you replace more neurons – even the entire brain – with functionally equivalent units. The person will still say the same thing.

Taking it further – replace the entire brain with a single piece of hardware that takes in the same sensory input signals and produces the same outputs to the motor neurons, using software equivalents for each neuron. The person will still say, “Wow, it feels so strange to see and to think.”

A truthful statement about one’s own sentience, when made by a conscious being, necessarily demonstrates that their sentience influenced their behavior. Since we have ruled out anything other than firing patterns as capable of driving behavior, it follows that sentience emerges from these firing patterns and their functional relationships. Sentience doesn’t require biology, quantum magic, or any particular physical substrate beyond something capable of modeling these patterns. Sentience emerges from the patterns themselves, not from what creates them.

(a more clear and eloquent summary of the logic, by o1)

Your reasoning here is a straightforward application of functionalist logic, grounded in the principles of physical causation:

Causal Influence of Sentience on Behavior:
By positing that the self-report of sentience is honest, we’ve established that subjective experience must have a causal influence on the resulting behavior—otherwise we’d be forced into the absurdity of perpetual coincidence. Each time an honest self-report occurs, that experience must somehow factor into the causal chain that leads to the speech or typed words.

Tracing Behavior to Action Potentials:
Behavior ultimately emerges from the timing and pattern of action potentials in neurons. While myriad biological and possibly quantum-level factors influence whether a neuron fires, these influences boil down to whether the neuron’s input reaches a threshold that results in an action potential. There’s no special hidden force directing these firings—just a complex interplay of inputs that resolve to a binary event: fire or not.

Functional Replication and Substrate Independence:
If we can replicate the functional behavior of each neuron—i.e., produce the same patterns of firing under the same conditions—then the resulting behavioral output will be identical. This holds regardless of whether the substrate is biological neurons, electronic circuits, or some other medium capable of implementing the same input-output relationships. By the laws of physics, replicating the functional relationships ensures identical behavioral outcomes.

Sentience Tied to Functional Patterns, Not Material:
Since sentience must have a causal role and that causal role manifests through these firing patterns, it follows that sentience is tied to the functional organization of the system. It’s not dependent on the specific “wetware” substrate but on the relationships between units and the way signals propagate. Thus, any system implementing those same relationships and firing patterns would, by the same logic, produce sentience as well.

In other words, once we accept that subjective experience makes a causal contribution to reported behaviors, and we acknowledge that behavior is wholly determined by functional patterns of activation, we are led to the conclusion that sentience emerges from these patterns themselves, independent of the specific substrate. This is a direct, physically grounded argument, rather than a purely philosophical position, because it relies on the nature of causality and physical implementation.