The Tricky Business of Measuring Consciousness
Quote:As an idea, IIT is audacious. It ignores the meaning of information to quantify the way systems use information. The theory proposes five axioms and postulates that are properties of consciousness, which physical systems must possess to support sentience. Briefly, the more distinct the information in a system and the more fused those bits, the higher the information integration in a system and the more phi or consciousness. Considering information integration as the key to consciousness makes intuitive sense. Remember a first kiss: the touch of her lips, the smell of her skin, the light in a room, the feel of your heart racing. You were supremely conscious at the moment, because there was a very high level of information integration.
The great strength of IIT is that it’s mostly consistent with common sense, in contrast to competing theories, which often propose deeply weird solutions (such as denying that we are conscious at all). IIT explains why an assault to the cerebellum, which encodes motor events, causes ataxia, slurred speech, or a stumbling walk but results in no diminishment of consciousness. That’s because the cerebellum, unlike the neocortex, doesn’t integrate internal states, even though it is home to 69 of the 86 billion nerve cells in the human body. IIT tells us that human beings in deep sleep or under general anesthesia aren’t conscious, because information integration has broken down. And IIT is consistent with how life feels: Consciousness is graded over a lifetime, blooming in an adult but withering with age, drugs, or alcohol, when our capacity to integrate information falters.
But the theory has its surprises too. Because IIT proposes that consciousness is a fundamental property of the universe and that any system that integrates information is to some degree sentient, it follows that things that we do not think of as conscious at all, such as a light diode or the clock in a computer, will possess non-zero phi values, like temperatures just above absolute zero. This seems wrong, but Tononi promises that an upcoming paper will show that computers that are feed-forward systems, even artificial intelligences that employ deep learning, would not be conscious. “The phi of a digital computer would be zero, even if it were talking like me,” Tononi says. To make a conscious AI, Christof Koch speculates, would require a different computer architecture with feedback mechanisms that promote information integration, such as a neuromorphic computer. Other things that have zero phi, according to Tononi, include collectives of sentient individuals, such as corporations or the United States.
Critics of IIT share similar objections. “It’s promising, but Tononi doesn’t know if his axioms and postulates are complete,” according to David Chalmers. Others object to the theory’s creeping pan-psychism, the ancient belief that everything material, however, small, has some consciousness, including the universe itself, the anima mundi. Scott Aaronson complains, “Tononi and his followers identify consciousness with information integration, or what a mathematician would call “graph expansion.” That doesn't work for the fundamental reason that you can have information integration without any hint of anything that anyone who wasn't already sold on IIT would want to call intelligence, let alone consciousness.”
Giulio Tononi is undeterred. He believes that IIT’s evasion of the hard problem, by beginning with the brute fact of consciousness, is the only way to explain sentience. “Most things are not conscious,” he says. “Some things are trivially conscious. Animals are conscious, somewhat. But the things that are certainly conscious are ourselves— not our component parts, not our bodies or neurons, but us as systems.” What’s next for IIT, according to Koch, is more work like Massimini’s, with more kinds of humans in many different conditions, as well as animals and machines: “Experiment, experiment, experiment.”
'Historically, we may regard materialism as a system of dogma set up to combat orthodox dogma...Accordingly we find that, as ancient orthodoxies disintegrate, materialism more and more gives way to scepticism.'
- Bertrand Russell
- Bertrand Russell