This next series of posts will be organized as follows: first, I will take a brief look into the views of consciousness held by prominent mind theorists and philosophers; I will next explore what it means to be artificially intelligent; then I’ll move onto what physics, neuroscience, and computer science have to tell us about the possibility of a conscious machine. I will conclude with the important question: is it possible?
So what is it like to be a bat? This question, asked by Thomas Nagel, helps frame our reference point. In his paper of the same name, Nagel rejects reductionism, arguing that we can’t reduce our descriptions of the mental experience to pure neurological terms. Mental states have a qualitative character, something it is like to be. He refers to this as the subjective character of experience. In terms of the bat, if we assume that the bat has conscious experiences, then we can put ourselves in the bat’s position and therefore assume what it must be like to be the bat. However, we cannot possibly know what the exact same situation is like for the bat itself. It may be completely different because, as Nagel argues, the central characteristic of the mind is consciousness, and we cannot possibly know exactly what any other conscious being is experiencing. In Nagel’s view, we cannot rationally reduce conscious experience to physical properties or neural substrates or pathways in the brain. Nagel’s description of qualitative consciousness is vague at best. To address this issue, Frank Jackson wrote the paper “Epiphenomenal Qualia.” Qualia, as defined by Jackson, are “certain features of the bodily sensations especially, but also of certain perceptual experiences, which no amount of purely physical information includes," that is, qualia cannot be described in a purely physical vocabulary. Examples of quale include sensations and perceptual experiences, things such as “the hurtfulness of pains, itchiness of itches … experience of smelling a rose." If qualia exist, then, in Jackson’s view, materialism does not. To put it bluntly, he states, “Nothing you could tell of a purely physical sort captures the smell of a rose, for instance. Therefore, physicalism is false." If Jackson is correct, this may present an important issue for consciousness in the machine. As we will see, most neuroscientists and computer scientists are physicalists.
But do qualia hold up under close examination? Daniel Dennett doesn’t think so, and he uses his paper, “Quining Qualia,” to do just what the title implies, resolutely deny qualia’s testability, and therefore fundamentally question the utility of qualia in any argument. The main issue Dennett takes with qualia is their nature: they are private, ineffable, incommunicable, irreducible. In principal, it is impossible to know exactly what another conscious being experiences, and therefore the question of whether a certain experience exists is senseless. The lack of verifiable criterion is important in understanding (or not understanding) qualia. It is what makes two individuals’ definitions of the same thing different, and therefore meaningless. In terms of neural activity, Dennett still holds the view that there is no evidence for, and will never be evidence, that can infallibly correlate a certain neural event or sequence of activity with a certain experience.
David Chalmers, former Director of the Center for Consciousness Studies at the University of Arizona and degree holder in mathematics and computer science, begs to differ with Dennett. He believes that the very ineffable qualitative experiences that Dennett rejects as fictions are of utmost importance in understanding consciousness. He says, “It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does." And yet it does. This is a ray of hope for AI scientists. Somehow, amidst the precisely controlled milieu of a computer system, consciousness, that indescribable and unpredictable property, may emerge.
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