Suppose that we create a perfect model of a hydrogen atom. After all, we know all the elements of the atom, a single proton paired with a single electron. Each of these elements is understood for all purposes of discussing the atom. The electron’s dynamics are perfectly understood: the energy levels, the probability distributions, the electron’s spin, the Lamb shift, it is all well defined. We can simulate this atom to any degree of detail we’d like, including representing it in a quantum computer that actualizes the quantum properties of the constituents.
But can that simulation ever bridge the gap to reality? Is the story about something ever the same as the thing? Can two perfectly represented hydrogen atoms be added to a real oxygen atom to make a real water molecule? No.
That is one argument for why machines cannot be made sentient: we can make a machine do all of the things we think sentience entails, but in the end it is just a simulation of intelligence, thinking and consciousness. It is a story, perhaps a very detailed story, but in the end just a story.
This reminds one of C. S. Lewis’ remark “If God is our Creator, then we would relate to God as Hamlet would relate to Shakespeare. Now, how would Hamlet ever gonna know anything about Shakespeare? Hamlet’s not gonna find him anywhere on stage.” And similarly, Shakespeare is never going to know the real Hamlet.
Sentience in a Dish In December of 2022, Bret Kagan and colleagues at Cortical Labs in Melbourne, Australia published an article in the journal Neuron, describing how brain organoids, small lab-grown networks of neurons, were able to learn to play the classic Pong video game. The authors claim that the organoids met the formal definition of sentience in the sense that they were “‘responsive to sensory impressions’ through adaptive internal processes”.
This may or may not be true, but it is certainly distinct from a simulated sentience that plays Pong. After all, this is not a description of cells that interact with a simulated or even real Pong game. These are real live cells, requiring nutrients in a Petri dish. Those that argue that consciousness can only come through embodiment would be happy with this definition of sentience.
But what is it that makes these cells sentient? Where in their soupy embodiment lies the sentience? If we tease apart the network, can we get down to the minimum viable network that plays Pong and meets our formal definition? After all, this is a brain organoid, grown in the lab. We could do this over again and stop when there are fewer cells and see if the same behavior is exhibited. If so, we can repeat the process and find that minimum network that still plays a good game of Pong.
Whatever that number is, 10 cells or 10,000 cells, we can study and very likely represent with a model that replicates the connections, spiking behavior, even the need for simulated nutrients, everything that is meaningful about the organoid. Would this simulation learn to play Pong? Given progress in machine learning in the past decade, we have every reason to believe the answer is yes. Would this create sentience in a machine? Or just tell a very detailed story about an organoid that is sentient? And if the latter, then where is the difference?
Is the simulation of the hydrogen atom qualitatively different from that of the organoid? The simulated hydrogen atom can’t be used to make water. But the simulated organoid, for all practical purposes, does exactly the same thing as the real thing. Both meet the same formal definition of sentience.
I don’t believe these thoughts get closer to understanding whether machines can be conscious or not. Reductionism might just fail for this problem, and others will argue that embodiment is a requirement. But I do think that we are not far from having that simulation, which in all meaningful ways, can be called sentient.
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