Consciousness Defined? Why It’s Still a Problem

And what we can learn from defining life

Recent astounding advances in AI have raised considerable concerns about the potential emergence of human-like consciousness in machines, which could lead to unforeseen consequences. It has undoubtedly sparked widespread and intense interest in studying consciousness across multiple disciplines, including philosophy, neuroscience, and psychology.

However, consciousness is still going through a crisis of definition. On the one hand, everyone appears to have an intuitive understanding of what consciousness is; on the other, there is no consensus on the available definitions. No wonder, after rounds of debates, people often find they have spoken past one another because the definition was unclear to begin with.

The same is true in the scientific arena. Over 40 theories of consciousness have been proposed in the past decade — and more are on the way — each focusing on a different aspect and hardly reconcilable with one another.

In a previous article, I reviewed the top theories of consciousness. In this discussion, we will delve into the current definitions of consciousness as presented by modern philosophers. We will then compare them with two examples (water and life) to examine the criteria of an ideal definition and the challenges we face in meeting them.

The Definition of Phenomenal Consciousness

In 1641, French philosopher René Descartes started to doubt everything and wanted to rethink from the beginning. As Descartes described in his book Discourse on the Method:

“I was then in Germany, where the wars… had called me; and as I was returning to the army from the coronation of the Emperor, the onset of winter detained me in quarters where, finding no company to distract me… I remained the whole day shut up alone in a stove-heated room, where I had complete leisure to meditate on my own thoughts.”

From those deep thoughts, he concluded with the famous statement, “I think, therefore I am (Cogito, ergo sum),” arguing that the act of thinking proves the existence of the mind and that the mind is a non-physical phenomenon separated from the body.

“But I have convinced myself that there is absolutely nothing in the world, no sky, no earth, no minds, no bodies. Does it now follow that I too do not exist? No: if I convinced myself of something, then I certainly existed… I am, I exist, is necessarily true whenever it is put forward by me or conceived in my mind.”

Today, we all recognize that Descartes’ mind-body dualism is incorrect. Our brain gives rise to our mind, and there is no separate “spectator” or “thinker” floating independently of the body. Yet, the workings of the mind, especially concerning consciousness, remain a mystery to philosophers.

In 1974, American philosopher Thomas Nagel published a seminal paper titled “What Is It Like to Be a Bat?” He believes the human experience can’t be objectively studied because it is confined to each person. For example, your experience of walking on a beach alone is only known to you. Nobody can have the same experience as you did. Similarly, humans can never know how it feels to be a bat.

In 1995, American philosopher Ned Block defined two types of consciousness.

• Access consciousness: “A representation is A[access]-conscious if it is poised for free use in reasoning and for direct ‘rational’ control of action and speech.”

• Phenomenal consciousness: “Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state.”

Access consciousness is straightforward and makes sense. Phenomenal consciousness, however, sounds vague and circular, where Block uses Nagel’s words “is like to be.”

Block emphasizes that “it is the raw experience, such as how it feels to see red or feel pain.” The question is, what is the definition of an experience being raw? For example, why is a thought or awareness of my speech not a raw experience?

Let’s look at another example of applying Block’s definition:

• Seeing the color red => Phenomenal Consciousness

• Saying “I see red” => Access Consciousness

Why are these two distinct? A more straightforward explanation could be that the saying adds a speaking action on top of seeing. It appears that phenomenal consciousness has been isolated to deny its functionality and accessibility. It exists for its own sake — because it feels like being.

The boundary between the two types is extremely fuzzy. How can we separate a thought from a feeling? How is our experience of seeing a natural wonder separable from seeing colors and feeling awe?

Furthermore, isn’t our feeling of our own action (e.g., speaking) part of the experience?

Around the same time, philosopher David Chalmers took it a step further by describing phenomenal consciousness as the “hard problem,” which can’t be explained by the computational neural mechanisms that neuroscientists currently use for other cognitive functions of the brain, such as learning, memory, and attention.

The easy problems of consciousness are those that seem directly susceptible to the standard methods of cognitive science, whereby a phenomenon is explained in terms of computational or neural mechanisms. The hard problems are those that seem to resist those methods of the brain.

He further explains why the experience is “hard” to explain:

How can we explain why there is something it is like to entertain a mental image or to experience an emotion? It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so 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. If any problem qualifies as the problem of consciousness, it is this one.

In the paper, he added “qualia”, the Latin word for experience, to the mix of phenomenal definitions. The Internet Encyclopedia of Philosophy defines qualia as “the subjective or qualitative properties of experiences” and “what it feels like experientially.”

We can now see the picture of this definition: it is entirely circular, with those words — phenomenal, experience, subjective experience, qualia, what it feels like — jumbled together. To define one of them, you can simply use the rest of the group, but nothing additional or more specific.

Note that with this “dual” definition, phenomenal consciousness has been stripped of all function and purpose. No wonder Chalmers questions why it exists at all.

The philosophers acknowledge the awkwardness of this circular definition. They argue that the reason is that experience cannot be reduced using the modern reductionist method. Moreover, Chalmers based his definition on a conceivable explanatory gap yet to be approved (i.e., it can’t be explained by information processing), adding another layer to the circular veil.

American philosopher Daniel Dennett denies the existence of qualia. He summarized the properties of a subject’s consciousness as:

• Ineffable

• Intrinsic

• Private

• Directly or immediately reprehensible in consciousness

Qualia does not possess any properties distinct from those mentioned above. Thus, Dennett concluded:

Qualia are not even “something about which nothing can be said”; “qualia” is a philosophers’ term which fosters nothing but confusion, and refers to the end to no properties or features at all.

In another article, “The Path Not Taken”, Dennett commented on Block’s separation of phenomenal (P) consciousness from access (A) consciousness:

There is an alternative, much more direct path that Block ignores, perhaps because it is deeply counterintuitive at first blush: the varieties of consciousness he thinks he sees falling under P-consciousness and A-consciousness can all be accommodated under the two brought quantitative headings of richness of content and degree of influence.

In other words, while we should recognize the experience as one of the phenomena of consciousness, it is not qualified as a stand-alone concept, separated from the rest of consciousness.

Ironically, the definition of phenomenal consciousness as a “hard problem” has also added a sense of mystery surrounding consciousness, almost like a modern version of Descartes’ dualism.

What is an Ideal Definition?

You may ask, what are the criteria for an ideal definition?

Generally speaking, it should be clear, precise (non-circular), and complete (specifying both necessary and sufficient conditions).

Let’s start with an everyday example: a student. The official definition is a person who is formally enrolled in an educational institution for the purpose of learning.

However, you might counter, what about someone studying every day using free online courses and videos on YouTube, yet not enrolled in any institution? Or someone who sits in on university classes with permission, takes notes, and asks questions, but isn’t officially enrolled? Or children who are homeschooled?

Further, is an LLM considered a student because it is in training?

These examples demonstrate that the definition of formal enrollment and learning intent only captures a central case. The actual concept of “student” in a language is much fuzzier and largely context-dependent.

Let’s examine another example of defining a natural object: water.

We all know what water is, and we can’t live without it. Ancient Greek philosophers defined it as one of the four fundamental elements, along with earth, fire, and air. The everyday definition includes its observable properties, such as colorless, odorless, wet, and quenching thirst.

Once chemistry kicks in, the definition of water becomes clear, precise, and final:

Water is a substance composed of H₂O molecules.

This definition is known as a stipulative one, which provides explicit technical meanings that are independent of ordinary language. In other words, only science (not philosophy) can define what it truly is.

Science enables the discovery of the underlying laws of Nature that can’t be directly observed. For consciousness, what it feels like is an observation, a phenomenon, with the property of continuity, privacy, and selectivity. It may be part of the mental process that drives speech, action, reasoning, and imagination. However, without understanding the actual inner workings of the brain, we should avoid vague circular definitions that could lead to more confusion and misunderstandings.

Another illuminating example we can learn from the history of science is the definition of life.

What Can We Learn from the Definition of Life?

Compared to the human mind and consciousness, we understand considerably more about what life is at every level, including biology, physiology, cellular mechanisms, molecular genetics, Darwin’s theory of evolution, and the origin of life.

Yet, scientists and philosophers still have not come up with a single definition that is universally accepted.

The main reason is that life is so complex with many facets that any one definition could lead to counterexamples to refute it. For example, we could define life as an organism possessing a metabolism, which involves the intake of energy to sustain itself. However, seeds can remain dormant for a long time without undergoing any metabolism. On the other hand, a fire consumes wood and oxygen and can grow while emanating heat, but we all agree fire is not life.

You might say that life can be defined by its capability of multiplying through self-reproduction. But scientists have observed that a crystal of sodium chlorate can grow by itself with its own seeds.

As of today, probably the best definition is what NASA has provided: life is a “self-sustaining chemical system capable of Darwinian evolution.” However, when considering searching for life beyond Earth (e.g., on Mars), the definition becomes both speculative and impractical because scientists can’t wait for generations to verify whether Darwinian evolution exists or not.

Nevertheless, the definition of life has gone through four historical stages that can be briefly summarized as:

1. Ancient Philosophy: Aristotle defined life through concepts such as the “soul” or “vitals,” focusing on observable traits like motion and growth.

2. Physiological, anatomical, and cellular mechanisms (17th- 19th Centuries): As chemistry and biology advanced, discoveries about cells, metabolism, and evolution led to breakthroughs in defining life.

3. Molecular and thermodynamics (20th Century): The discovery of DNA and RNA, which encode and express heritable information, revolutionized our understanding of life. Meanwhile, thermodynamics has provided scientists with a new perspective, extending down to the quantum level, on what life is in essence.

4. Modern Era: We are currently in an era characterized by synthetic biology, which aims to create “artificial” life, and an active search for extraterrestrial life beyond Earth. Both challenge the definition of life.

Looking back over the last 150 years, we have had a remarkable journey of human discovery that is deeply relatable to our understanding of ourselves. What have we learned from it?

First, the underlying natural laws can’t be obtained through deductive logic alone, as David Hume claimed two hundred years ago. Even though we feel our consciousness directly within each of our minds, it does not mean we can explain it or even define it using our own reasoning. The truth, yet to be discovered by scientific research, could be far from what we can think or imagine. Life is a great example — how could any philosopher fathom the genetic encoding of DNA?

Second, biological organisms are complex and exhibit diverse characteristics at various levels. For example, at the anatomical and cellular levels, life primarily manifests through its functions, such as growth, metabolism, and reproduction. At the molecular level, however, DNA and RNA operate within a completely different paradigm. A proper way to define life is to examine it vertically by leveraging expertise from various disciplines.

The same applies to the study of consciousness. Phenomenal consciousness has been arbitrarily demarcated from functional consciousness, and the hard problem is assumed to be something different from information processing. Both attempt to explain consciousness superficially before an in-depth understanding of the brain’s underpinnings is achieved.

Third, advances in modern technology can facilitate scientific discovery, provided that appropriate regulations are also applied simultaneously. For instance, biotechnology has enabled embryos to develop outside of a mother’s uterus, bringing happiness to many families and enhancing our understanding of life. Meanwhile, globally, a 14-day rule restricts the culturing of human embryos in vitro to no more than 14 days for ethical, safety, and scientific reasons.

Compared to the history of understanding life, the study of consciousness is still in its infancy; however, artificial intelligence (AI) has emerged relatively early compared to the synthesis of artificial life. While AI could act as a catalyst leading to faster progress in scientific research on consciousness, it may also pose a shorter timeframe for humans to evaluate and manage potential risks.

In conclusion, the fallacy of the current philosophical definition of consciousness has become clearer when viewed alongside the evolution of the definition of life. More importantly, the deemed “unexplainable” nature of consciousness could be counterproductive to modern science, whereas simply addressing consciousness as a “real problem,” as proposed by British neuroscientist Anil Seth (please refer to the previous article here), is more practical and thought-provoking for modern scientists.

Let me end this article with a quote from another contemporary philosopher, Patricia Churchland:

“Use of our current ignorance as a premise to determine what we can never discover is one common logical flaw. Use of ‘I-cannot-imagine’ arguments is a related flaw. When not much is known about a domain of phenomena, our inability to imagine a mechanism is a rather uninteresting psychological fact about us, not an interesting metaphysical fact about the world. Rather than worrying too much about the meta-problem of whether or not consciousness is uniquely hard, I propose we get on with the task of seeing how far we get when we address neurobiologically the problems of mental phenomena.”