(post may be refined for clarity based on feedback)
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.