Consciousness’s abode: Subjugate the substrate

Philosophy of mind has some interesting implications for artificial intelligence, summed up by the question: can a machine ever be “conscious”? I’ve written about this in earlier posts, but recently I’ve come across an argument of which I hadn’t considered very deeply: that substrate matters. There are lots of ways to approach this issue, but if the mind and consciousness is a product of the brain, then surely the  neuroscience perspective is a good place to start.

Investigations show that the activity of different brain regions occurs predictably during different cognitive and perceptual activities. Also there are predictable deficits that occur in people when these parts of the brain are damaged. This suggests that a mind and consciousness are a product of the matter and energy that makes up the brain. If you can tell me how classical Cartesian dualism can account for that evidence, I’m all ears. 🙂

I will proceed under the assumption that there isn’t an immaterial soul that is the source of our consciousness and directs our actions. But if we’re working under the main premise of physicalism, we still have at least one interesting phenomena to explain–“qualia“. How does something abstract and seemingly immaterial as our meaningful conscious experiences arise from our physical brain? That question isn’t going to get answered in this post (but an attempt is going to emerge in this blog).

In terms of conscious machines, we’re still confronted with the question of whether a machine is capable of a similar sort of conscious experience that we biological organisms are. Does the hardware matter? I read and commented on a blog post on Rationally Speaking, after reading a description of the belief that the “substrate” is crucial for consciousness. The substrate argument goes that even though a simulation of a neuron might behave the same as a biological neuron, since it is just a simulation, it doesn’t interact with the physical world to produce the same effect. Ergo no consciousness. Tell me if I’ve set up a straw-man here.

The author didn’t like me suggesting that we should consider the possibility of the simulation being hooked up to a machine that allowed it to perform the same physical interactions as the biological neuron (or perform photosynthesis in the original example). We’re not allowed to “sneak in” the substrate I’m told. 🙂 I disagree, I think it is perfectly legitimate to have this interaction in our thought experiment. And isn’t that what computers already do when they play sound or show images or accept keyboard input? Computers simulate sound and emission of light and interact with the physical world. It’s restricted I admit, but as technology improves there is no reason to think that simulations couldn’t be connected to machines that allow them to interact with the world as their physical equivalent would.

Other comments by readers of that Rationally Speaking post mentioned interesting points: the China brain (or nation) thought experiment, and what David Chalmers calls the “principle of organisational invariance“. The question raised by the China brain and discussed by Chalmers is: if we create the same functional organisation of people as neurons in a human brain (i.e., people communicating as though they were the neurons with the same connections) would that system be conscious? If we accept that the system behaved in the exact same way as the brain, that neurons spiking is a sufficient level of detail to capture consciousness, and the the principle of organisational invariance, the China brain should probably be considered conscious. Most people probably find that unintuitive.

If we accept that the Chinese people simulating a human brain also create a consciousness, we have a difficult question to answer; some might even call it a “hard problem“. 🙂 If consciousness is not dependent on substrate, it seems that consciousness might really be something that is abstract and immaterial. Therefore, we might be forced to choose between considering consciousness an illusion, or letting abstract things exist under our definition physicalism. [Or look for alternative explanations and holes in the argument above. :)]


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