Our efforts to solve the hard problem of consciousness will require significant scientific progress and a paradigm shift in what we consider an acceptable answer to this philosophical puzzle. 

In his book The Conscious Mind, consciousness researcher David Chalmers  distinguishes between what he calls the “easy problems” of consciousness and the “hard problems.”

The easy problems are those that can be satisfactorily solved by providing a mechanistic explanation based on the methods of scientific disciplines such as computer science, neuroscience, biology, and cognitive psychology. The easy problems include those of offering explanations of our ability to discriminate, categorize, attend to, and report on environmental stimuli; how information is integrated from different sensory modalities; and how internal body maps are used to guide our movements when we perform actions. Even if a complete explanation of these problems is not currently available, there is little doubt that one can be provided by employing scientific methodology. While solving these problems is an important step toward a complete account of consciousness, this doesn’t give us the whole picture. This is where the hard problems of consciousness enter the picture. These problems concern the phenomenal aspect of experience, or what it is like to have an experience, say, what it is like to experience bright pink, have a headache, or imagine your boss as a centaur.

There are several hard problems of consciousness - or aspects of the hard problem, if you wish. One is that of explaining why we have subjective and qualitatively rich experiences when our brain processes information from the environment, which we use to solve problems and act on the world. This problem is hard because it is highly plausible that we could do everything we do without any corresponding conscious awareness. For example, there are people who get out of their bed and complete complicated actions while still asleep. We call it “sleepwalking.” But walk is not all “sleepwalkers” do.

Scientific explanations of consciousness don’t offer any insight into the subjective and qualitative aspects of experience.

Rob Wood, a former chef, cooked spaghetti Bolognese, omelets, and fish and chips during his sleep. Computer expert Ian Armstrong was observed by his wife mowing the lawn naked at 2 a.m. while asleep, and some have even commit murder. In the early morning of May 1987, Kenneth Parks, a 23 year-old father and husband from Toronto,  got out of bed and drove 23 kilometers from Pickering to the house of his wife’s parents, where he proceeded to bludgeon them to death with a tire iron. After careful examination of the case, the experts could find no explanation of the crime other than sleepwalking. He was later acquitted of the double homicide in court. It has been scientifically demonstrated that people who sleepwalk (or sleep-cook or sleep-kill) are in a phase of deep sleep and have no conscious awareness of their surroundings.

Yet cooking spaghetti Bolognese, mowing the lawn or driving while navigating traffic lights and stop signs requires that the brain processes complex information and uses that information to guide the body. Such cases show that we are capable of processing and responding to information from our environment without any corresponding conscious awareness. Something similar is arguably going on when we perform routine actions while our attention is elsewhere, for example driving home, on auto-pilot, as it were, and not remembering how we got there.

If consciousness is not needed for us to respond to the environment, then why do we have it? It seems that consciousness must have played some causal role in evolution in order for it to have evolved. But if our ancestors could have succeeded in the survival game of evolution without any conscious awareness, which is highly plausible, then how could consciousness have been advantageous to our ancestors. One possibility is that rather than being a direct product of adaptive selection, it is an evolutionary byproduct - or what is also called a “spandrel.” Linguist Noam Chomsky, for example, has argued that our “language faculty,” that is, our innate ability to produce linguistic phrases with the same underlying grammatical structure, may have evolved as a spandrel. Similarly, one can imagine that consciousness evolved as a spandrel as animal brains reached a certain level of neurological complexity.

One problem with this explanation of how consciousness evolved is that it seems to presuppose that once consciousness evolved as a spandrel, it then took on a function that provided selective advantage. It is easy to see how language may have been advantageous to humans, even if it evolved as a spandrel. Not so with consciousness. So, the spandrel explanation doesn’t help explain the selective advantage of consciousness.

A more plausible suggestion is that consciousness is a causal product of its neurological realizer, which is to say that given our laws of nature, consciousness is inseparable from its underlying realizer. Thus understood, consciousness is an emergent property. Emergence, in this sense, is a familiar scientific phenomenon. Being liquid, for example, is a property that emerges when H₂O molecules are structured in a particular way.

While plausible, a complete account of consciousness goes beyond a conventional scientific account of how conscious experiences and brain states are causally connected. There are two interconnected reasons for this. One is that conscious states and their realizers have conceptually distinct properties. As Chalmers has argued, we could have had the same  physical and functional constitution while lacking the capacity for consciousness. Our unconscious counterparts, in this sense, are eternal sleepwalkers of sorts, or what Chalmers calls “philosophical zombies.” Of course, if we had been philosophical zombies, the laws of nature would have had to be very different. Perhaps they would have been such that no matter how H₂O molecules bind to each other, they will never be in a liquid form. We don’t really know.

If consciousness is not needed for us to respond to the environment, then why do we have it?

If, however, conscious states and their realizers have different properties, as this line of argument suggests, then conscious states are not identical to their realizers. So, regardless of how many truths we uncover about how the brain gives rise to consciousness, this is never going to give us a complete account of consciousness.

The other reason that using conventional scientific methods to account for the causal connection between conscious experiences and brain states does not provide us with a complete account of consciousness is that scientific explanations of consciousness don’t offer any insight into the subjective and qualitative aspects of experience.

This is the lesson of philosopher Frank Jackson’s (1982) Mary argument. Mary is an excellent neuroscientist confined to a black-and-white room with black-and-white computer screens hooked up to external cameras. After years of studying in her room she eventually knows everything about colors discoverable through the use of conventional scientific methods. Yet when she finally leaves the black-and-white room and sees a bright pink tulip for the first time, she learns something new: what it is like to see bright pink. As she knew everything about colors discoverable through the conventional sciences prior to her release but nonetheless learned something new after her release - namely, what it was like to see bright pink - no scientific explanation of her experience of bright pink can be regarded as complete.

In “What It’s Like to Be a Bat” philosopher Thomas Nagel (1974) offers a different version of this argument. Nagel argued that we humans will never understand what it’s like to be a bat, in part, because we are unable to understand what it’s like to use echolocation to identify objects and navigate our environment.

Echolocation, or what is also known as “bio sonar,” requires producing a sound, detecting the echo the sound makes when it is reflected from nearby objects, and then using this information to identify objects and navigate the world. The reason we humans are unable to understand what it’s like to be a bat is analogous to the reason Mary was unable to understand what it was like to see in colors prior to her release from her black and white room, but where Mary fails to understand what it’s like to see in colors because of her unusual environment, we fail to understand echolocation because we lack of the sensory capacity for echolocation.

There are numerous examples of these kinds of limitations in terms of our abilities to understand what it’s like to do something or what it’s like to be someone else. Most of us don’t fully understand what it’s like to have wings and use them to fly, and if you have never used a  parachute, you don’t really know what it’s like to go parachuting.

Although simulations of experiences do not currently count as explanations, it is possible that the progress in virtual reality technologies will prompt us to change our conception of what can count as explanation.

Laurie Paul has argued that our lack understanding of what it will be like for us to do something we have not already done presents a serious limitation to our ability to make an informed decision about whether or not to do it in the future. One of her best known examples is that of what it’s like to be a parent, which she argues that we cannot really know prior to becoming parents, which prevents us from making an informed decision about whether we want to have children. We can, of course, do our best to imagine what such potential futures will be like, but our imaginary capacities are highly limited and will never give us full or even close to full insight into what the possible future would be like.

So, what are the prospects for solving the hard problems of consciousness? In our view, solving the hard problems requires both significant scientific progress and a paradigm shift regarding what can count as an acceptable explanation.

It is plausible that we can account for the makeup of consciousness in terms of the science of the future. If, for example, consciousness is composed of certain fundamental particles or fundamental forces we have not yet discovered (e.g. a “menton”), then that would explain why we cannot equate conscious states and their realizers (Brogaard, 2018). The answer may simply be that consciousness and its realizer are not composed of the same basic constituents. In that case, the relationship between conscious states and their realizers would be analogous to that between the magic mushrooms (psilocybin) you are about to illegally consume and the informational changes that result from the information processing in the brain, ultimately resulting in hallucinations and synesthetic experiences (Brogaard & Gatzia, 2016). The mushrooms are made of molecules, which in turn are composed of atoms, and so on. The informational change is an abstract semantic entity. Both the mushrooms and informational change can be accounted for scientifically, for example by using the scientific methods of chemistry and computer science. But they are made up of different constituents.

As for the problem of explaining the phenomenal aspect of consciousness, we can achieve some level of understanding of the subjective and qualitative aspects of the conscious experiences we have had ourselves. When Mary is released from her prison, she will gain insight into what it’s like to have color experience. If you jump out of an airplane, you will gain insight into what it’s like to do so. And if you become a parent, you will have some insight into what parenting is like.

But how can we come to understand what it’s like to have experiences we haven't had ourselves? One way we might be able to approximate this type of understanding is through realistic simulations of the experiences. As virtual reality becomes increasingly sophisticated, we may become much better at simulating exotic experiences that we currently cannot grasp, such as echolocation. As technology advances, it may even be possible for us to use simulation to gain insight into exotic (low-level) properties such as the many shades of red, green, or blue experienced by creatures that have more than the three cone types that are available to most humans. Although simulations of experiences do not currently count as explanations, it is possible that the progress in virtual reality technologies will prompt us to change our conception of what can count as explanation. If simulations can serve as explanations in terms of helping us gain insight into “alien” experiences, then perhaps the solution to this aspect of the hard problem is right around the corner.

References

Brogaard, B. (2018). "In Search of Mentons: Panpsychism, Physicalism and the Missing Link", in Panpsychism, Godehard Brüntrup and Ludwig Jaskolla (eds), Oxford University Press, 2018.

Brogaard, B. Marlow, K. (2015). The Superhuman Mind, New York: Penguin.

Brogaard, B., Gatzia, D. E. (2016) “Psilocybin, Lysergic Acid Diethylamide, Mescaline, and Drug-Induced Synesthesia” (Chapter 83). In Victor R. Preedy (Ed.) Neuropathology of Drug Addictions and Substance Misuse, Volume 2: Stimulants, Club and Dissociative Drugs, Hallucinogens, Steroids, Inhalants and International Aspects (pp. 890-905)

Chalmers, D. J. (1995) Facing Up to the Problem of Consciousness. Journal of Consciousness Studies, 2(3): 200-19.

Chalmers, D. J. (1996) The Conscious Mind. New York: Oxford University Press.

Chen, P-J., Awata, H., Matsushita, A., Yang, E-C., and Arikawa, K. (2016) “Extreme Spectral Richness in the Eye of the Common Bluebottle Butterfly,” Graphium sarpedon. Front. Ecol. Evol., 4:18. doi: 10.3389/fevo.2016.00018

Jackson, F. (1982) “Epiphenomenal Qualia,” The Philosophical Quarterly, 32(127): 127-136.

Nagel, T. (1974) “What Is It Like to Be a Bat?” The Philosophical Review 83 (4): 435-450.

Paul, LA (2014) Transformative Experience, Oxford University Press.