In the December Scientific American, brain expert Christof Koch takes up the question of whether a machine will ever manifest consciousness. This seemingly abstruse issue may arise in actual systems sooner than we think, and so considering it is worth doing before it happens.
Consciousness itself is one of the leading puzzles of brain science. Most of us can tell whether or not we are conscious, with the possible exception of dreams in which we are sure we’re awake, only to wake up and realize we were dreaming. Consciousness seems to be something we share with the higher animals, but defining it in a way that satisfies either philosophers or neurologists turns out to be harder than you might think.
Koch describes some of the markers of human consciousness: the ability to feel embarrrassed, for example. This brings to mind Mark Twain’s quip: “Man is the only animal that blushes—or needs to.” He clears the ground first by saying “There is little doubt that our intelligence and our experiences are ineluctable consequences of the natural causal powers of our brain, rather than any supernatural ones.” Then he says that there are two competing and largely incompatible schools of thought regarding how the human brain evokes consciousness.
One popular hypothesis, called the global neuronal workspace theory (GNW for short), says that when different parts of the brain concerned with disparate activities such as memory, vision, and motor operations work together in a sort of common workspace or connected region, the neuronal workspace itself gives rise to what we call consciousness. For example, when you read a sentence that reminds you of something, the workspace is devoted to your visual field, interpreting it in terms of the ideas contained in the words, and remembering other things that those ideas remind you of.
According to this theory, consciousness is eminently computable, in the sense that what counts is the information-processing part, which can be carried out just as well by a sufficiently complicated computer simulation as by the actual “wet computer” we call the brain. So GNW says that as soon as we can make AI systems as complex as the human brain that work in a similar way, we should be able to make the computer equivalent of a global neuronal workspace, and it will be just as conscious as a human.
A more recent competing theory throws cold water on this idea. Called integrated information theory (IIT for short), it begins with some axioms about the nature of consciousness, such as its unified specific quality and the fact that consciousness is real, and not just some apparent byproduct of brain function. It then goes on to what is apparently a rigorous and complex mathematical analysis of any candidate system for consciousness, and comes up with a single number called Φ (the Greek capital letter pronounced “fie”, I think, or “fee,” depending on who you ask). This number is allegedly a measure of the potential of the system to be conscious. Unsurprisingly, the human brain’s Φ rating comes up pretty high, because it has a lot of what IIT theorists call “intrinsic causal power.” On the other hand, the standard computer architectures used for modern computers have very low levels of Φ and so have little potential for consciousness.
Why should we care? Well, for one thing, if we ever do come up with an artificial-intelligence (AI) system that is conscious, that raises the question of our moral obligation to it. Largely because we think animals such as cats, dogs, cows, and chickens are conscious, we have animal-cruelty laws that attempt to ban some of the worst things we can do to our fellow conscious creatures. If we start an AI program running that begins to beg and plead with pathos in its voice that we keep away from the “off” switch, will this request carry any moral obligation with it?
The GNW people would say yes, because they think if it acts conscious, it is conscious, and so you’d better treat it that way. The IIT people, on the other hand, would say that such pleas are no more meaningful than those of some character on a single-player video game: it’s just a box of wires and transistors with practically no Φ at all, and there is no moral obligation to such a thing.
Koch says the two theories make different and experimentally discernable predictions about certain aspects of the brain and consciousness, so a bunch of well-funded researchers are currently trying to find out whether GNW, IIT, or perhaps some as-yet-unanticipated third theory is correct.
Meanwhile, we conscious but non-specialist mortals can nevertheless speculate about such things. An environmental engineer and part-time author named W. L. Patenaude recently sent me an entertaining and thought-provoking novel that addresses some of these questions in a near-future setting. His A Printer’s Choice deals with questions of machine consciousness and our moral obligations to such devices, if any. It’s hard to describe his novel without giving away some critical plot twists, but suffice it to say that Patenaude has come up with a well-considered future scenario that seems realistic, and draws some surprising conclusions about what may happen when sophisticated AI is combined with what 3-D printers may be like in the future.
In the meantime, devices such as Siri and Alexa tempt us to think of our AI systems as worthy of talking to, if not exactly conscious. We are used to treating as conscious any entity that we can hold a conversation with, and that was the basis of Alan Turing’s famous “imitation game” that is now referred to as the Turing test. But even if AI systems manage to pass Turing tests all the time, that won’t answer the question of whether they are in fact conscious, or simply giving an excellent simulation of consciousness while knowing, understanding, and feeling nothing. It’s a question well worth answering, but we may not have the answer for a while yet.
Karl Stephan is author of Ethical and Otherwise: Engineering In the Headlines
The article has been re-published with the author’s kind permission. The original can be viewed here.