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10.2 The Hard Problem of Consciousness

Anyone who has dabbled in the field of philosophy will have definitely come across “The Hard Problem of Consciousness”. It is a controversial topic. There are many people who don’t admit that there is a hard problem here at all. I beg to differ. The phrase ‘the hard problem’ comes from the philosopher David Chalmers. He distinguished the ‘easy problems’ (how the brain processes information, focuses attention, etc. - easy in the sense that they’re the normal business of neuroscience) from the hard problem: why does any of it feel like something from the inside?

Before we get into the hard problem, let’s first work out what Consciousness is. I have been using the term “mind” so far as I was just too lazy to type “consciousness”. From here on, let’s treat them as the same. What does a mind consist of?

Can a physicalist system explain all these phenomena in terms of physical processes?

Thinking

A physicalist could argue that thinking is just information processing, and that modern computers are doing something functionally similar, with developments in AI. There are still open questions about whether a machine is as capable as a human, when it comes to rational and even creative thinking. But the gap is reducing fast with AI.

Intentionality

This is the expression of will. As opposed to a rolling ball which feels to us like just going through its motion in a physical world, following the laws of physics, we feel a sense of intentionality within ourselves and the other humans and even many animals. It is one of the signs that we use to decide if a being is conscious. Someone walking down a hill feels very much an intentional choice by the person though we don’t think the ball rolling down a hill had a choice. Philosophers call this intentionality in a technical sense: mental states being about something - your thought about the hill, not just movement on it. Modern development in robotics means one can build a robot which looks as intentional as humans. So maybe this gap is reducing fast too?

Experience

This is where the most controversial and the hardest challenges for physicalism’s explanation for Mind comes from. “Experience” here means both experience of the external world, like colour, shape, smell, sound, touch and internal experiences like thoughts, joy, anger, a sense of self and so on. Explaining all these in a coherent way has to cross a lot of obstacles. We will go through them one by one.

Qualia

Philosophers often use the word qualia to describe our sensory experience. What is qualia? Look around you. You see objects, maybe some people, maybe a garden outside of your window and so on. You sense your environment in terms of shape, colour, sound, smell and even temperature and many more qualitative factors. This qualitative sensory experience is called qualia.

Is colour, for example, a property of matter in itself or a property of how we sense it? How does science explain colour? When light waves hit an object that is made up of atoms, the object absorbs a part of the light and reflects the remaining part (depending on the wavelength of the light). The light waves of different wavelengths which are reflected by the object reach our eyes which react to this light. The cones and the nerves in the eyes react differently to different colours. Thus, the eye translates the light signals of different wavelengths to different nervous signals which eventually reach the brain.

The nervous signals reach the brain and then, suddenly, you get a visual experience of the object along with its colours. According to physicalism, the colours you experience are just the work of your brain which presents these signals to you based on the nervous signals it received. This presentation which you experience is what philosophers call qualia. How do the signals that reach the brain get translated to this visual experience? The signals the brain receives are different for different wavelengths of light which hit our eyes. But how does that translate into different colours we perceive? All we can see with the help of medical devices are waves or signals travelling inside the brains, interacting with the neurons. We don’t see how this gets translated into the qualitative experience that we have.

Philosophers question this because none of the phenomena we observe directly in the world and are explained by science are like this. We see objects, molecules, atoms and sub-atomic particles moving. We see them exerting and experiencing different types of forces. But we never directly observed this phenomenon where physical matter along with some waves translate into a qualitative experience. The same applies to sound, touch, smell and all the sensory experience we have.

We experience the qualia ourselves. But we cannot experience other people’s qualia. You can see the light waves from a bulb reaching other people’s eyes and if you have the medical devices, you can see the signals reaching their brains, but you never get to actually see them experiencing the light. You don’t have direct access to how they experience the scene.

Qualia

This leads to the problem of inverted qualia. What if the blue colour you have been seeing throughout your life actually looks yellow to your friend? When you look at the bluebells, both of you call it blue. But within your friend’s mind, the colour of the bluebell looks exactly the same as how a yellow coloured flower looks to you. Because this has been the case ever since your friend was born, he calls it blue colour even though his sensory experience of the blue colour is same as the sensory experience of your yellow colour. You have no way to know if this is the case. Maybe, in the mind of your friend, a sunflower’s colour is same as how you see blue colour. Again, you have no way of knowing this because you do not have a way to experience the world exactly the way your friend does.

Within the hard problem of consciousness, I think this is the hardest problem. How does the physical state comprising of the brain cells and the signals turn into this beautiful experience we are having? Scientific experiments could give us a clue about which part of the brain has to be triggered in what pattern so that we could experience a specific colour. But how the brain state translates it to the qualitative experience of the colour is not solved yet. Same with sound, touch, smell and so on.

Physicalists claim that it will be solved eventually. Others argue that it cannot be solved for various reasons, the biggest one being the private nature of mind.

The Private Mind

The world would be simpler and more boring if we could all read each other’s minds. The mystery is what makes navigating the world difficult and at the same time interesting. Just take the case of a romantic relationship. Will asking someone out, first date, proposal, etc. be as exciting if you can just read their minds and see what they are going to do?

Some philosophers argue that the mind is not necessarily private as you can read someone’s mind through their actions most times. Your chatterbox friend is suddenly silent for a long time? You know they are worried about something. There is an element of truth to it. But one would be lying if they haven’t come across any person in their lives with a permanent poker face who is hard to understand. And then, there are cats. We could make judgments based on actions. But as things stand, it is impossible to get a meaningful understanding of other people’s minds unless they are willing to share it through words.

Getting back to the problem of physicalism, how does the private nature of mind affect physicalism? It throws a challenge to the scientific method itself, not just physicalism. Remember the rule that any law added to the system must make observable predictions and be falsifiable.

Can any law about how the mind works make observable predictions? If you are verifying the law of gravity by dropping a ball from a building, everyone can observe the results and agree that the law works. But what about a theory of mind that says if the brain cells in a region are in an L shape, you will see a zebra in your mind? Let’s say that we have managed to build an experimental set-up where someone is awake while we have drilled into their skull and are working with their brain cells. Horror movie material, I know. We then set the L shape in the region of the brain to produce the zebra vision. The test subject says that they see a Zebra. Is that a successful test?

What we have now is a report of what a person observed. It is not a direct observation of the result. This is where the controversy lies. Can you trust this as observational evidence? Does it still fit within the scientific requirement of observational evidence? Maybe you will see this as a valid experimental result if you are the test subject. But will you trust the results from the others? That’s the challenge here compared to a traditional scientific experiment.

The Sense of Self

We all have a sense of self - The I that feels indivisible and immutable. Our character and thinking changes but we constantly have a sense of self that seems to experience the world. This raises the question of whether the self itself is a part of the experience or is it the self that experiences the world. Is the self a part of the mind or is the mind the self? Either way, physicalism has a challenge explaining the sense of self because everything physical seems to be divisible and mutable. Even if we assume that the particles in the standard particle model are indivisible, physicalism explains our mind using the brain which has a lot more particles than just one.

Most physicalist theories of mind just admit that your brain changes a lot over your lifetime and hence a unique identity for yourself across time is indeed an illusion, which is a fair argument.

Unitary experience

The mental experience also feels like a single unitary experience. How did such a complex brain end up creating a single unitary experience? You have numerous sensory signals coming from your eyes, ears, nose, tongue and body and somehow the brain puts them all together and gives you a unitary experience. Can this be physically broken? Can the brain suddenly split into multiple conscious experiences at the same time? There are some obscure cases where claims have been made that it indeed happens. But nothing that categorically proves this is the case. This is another thing that science is yet to explain. This is called the Binding Problem.

When did consciousness develop?

We de facto assume that humans have consciousness. That was one of the two primary assumptions we made when we built the layman’s philosophical system. We also admit that many big animals like dogs, cats, lions, etc. have consciousness. But we don’t admit that bacteria have consciousness. Where in the evolutionary chain between the unicellular organisms and the humans did consciousness develop?

Some physicalists explain it by saying that consciousness is not binary and there are levels to it. What level an organism is in depends on the physical properties of the brain. Again, a fair explanation, but yet to be proven.

There are also questions around the evolutionary advantages of qualia. Take a humanoid that has a brain like us except for the parts which generate the qualia. It still has the ability to think and act intentionally just like a human. This is what philosophers call a philosophical zombie. It can still be as good at survival as humans. Why did evolution add qualia to living organisms if we can survive the same even without it?

Subjective vs Objective

Beauty lies in the eye of the beholder

Art is subjective

Your mileage may vary

We often use lines like these to say that many things in this world are subjective. An art that is beautiful for one person looks not so great to another. And yet, when it comes to qualia, our default intuition is that it is objective and things look the same to everyone. We treat qualia as if it were objective - my blue is your blue - but we treat our reaction to qualia (beauty, liking) as subjective - I may like this art but you may not. Why draw the line there? The same brain does both.

Explanations

We don’t have a single agreed answer to the explanation of mind in the physicalist framework. There are multiple theories.

They all agree that the brain and a bit of the nervous system is responsible for our mental experience. But there is no single agreed upon theory among them.

Eliminativism claims that mental experience is an illusion and it doesn’t exist at all. Though I promised not to take sides with any philosophy, this is a bit too much, even for me. Maybe the eliminativists don’t have a mental experience and are just philosophical zombies. But I do have it.

Each of the physicalist theories mentioned above has its own gaps and contradictions which critics question. But the biggest areas of criticism against physicalism is what we have seen in this chapter. The critics believe that the foundational issues in physicalism means that we will never explain the mind using physicalism. The usual physicalist answer is that we will find answers to these questions with time. It is up to you to decide if the weaknesses in the physicalist explanation of mind are insurmountable or not.

Further Reading

Note: Dennett is on the other side of this debate - he argues the hard problem is an illusion. I’ve included him so you hear the strongest counterargument.