Clemens Lode
September 30, 2023
Man standing on a hill looking towards the horizon (source: Shutterstock).

Theories of Consciousness

It is easy to believe that the mind and the brain are two separate things. After all, we perceive consciousness to be something immaterial (it is difficult to locate and impossible to touch) and non-causal (intuitively, we see ourselves as independent actors with free will). In fact, our subjective experience of the world seems far too rich and intense to ever be explained by a physical process in the brain. How can we be sure that this intuitive distinction is based in reality and does not simply stem from having separate brain parts to think about ideas (theory of mind) and things (object permanence)?

The challenge with the approach of seeing mind and brain as separate is that such an approach works fine in daily life only as long as we have a healthy brain. For example, we learned that Wernicke’s area is the part of the brain responsible for forming words and sentences. Damage to this brain area can also affect a person’s ability to find the right words or put them in correct order. Either the theory of having a separate mind and brain is wrong, or coming up with words and sentences is a function of the brain and not the mind. This could be repeated with any other brain impairment with fewer and fewer functions attributed to the mind. This apparent contradiction between the intuitive understanding and observable facts has been part of philosophical discourse for centuries.

History of Theories of Consciousness

Why did philosophers and scientists of the past struggle with the question of consciousness? What theories did they rely on to explain the material brain and the immaterial mind?

Plato (429–347 BC) studied and wrote about the perceived differences between the material world (our body, including our brain) and the immaterial world (our subjective experience of the world). He called his approach the “theory of forms.” Plato’s position was that concepts or ideas were the basic building blocks of reality and the material world was merely a shadow or imitation of this ideal world. As such, Plato saw consciousness as part of the ideal world. He thought that a person’s consciousness creates mental images of concepts and ideas that are only imperfect once an individual tries to manifest those mental images in the real world. For example, there is the concept of an apple, and there are actual (imperfect) apples. We can imagine the ideal concept of an apple, but when actually trying to draw it or grow it, our apple is merely an imperfect copy of the ideal apple. Likewise, there are ideal forms of “us” and there are our actual bodies—imperfect representations of “us.” This view that mind and brain are separate is called “mind-brain dualism” or also “mind-body dualism” (with “body” including our brain).

Mind-brain dualism   The philosophical view of mind-brain dualism (or also mind-body dualism with “body” including our brain) states that what we call the (immaterial) mind is separate from the material world (the body, including the brain).

Plato used the allegory of the cave to stress his point that we could exist in an allegorical cave, just watching shadows of the real world. Plato thought that the ideal form of humans existed both before our birth and after our death. This ideal form is connected with the real world only temporarily during our life on Earth. Plato’s disciple Aristotle (384–322 BC) disagreed with Plato’s approach of the primacy of consciousness (see Philosophy for Heroes: Knowledge) where ideas about an entity (Plato’s Forms) are more important than the entity itself. While Aristotle also believed in a distinction between the material brain (part of the body) and the immaterial mind, he did not place one above the other. In his view, the mind was a property of the brain and died with the brain.

For Aristotle, an apple had properties that made it an apple, while for Plato, there was a separate realm of an ideal apple of which the physical apple is just a representation. Still, Aristotle believed that conceptual thought was separate from the physical brain, as he could not see how something material as the brain could process concepts which in themselves are essentially limitless. In his view, there must be something special about the mind as we can think about any kind of material object.

Mind-brain dualism was not unique to Plato and Aristotle, although they were among the first who examined it systematically. Abrahamic religions like Judaism, Christianity, or Islam share a view regarding the relationship between mind and brain that lies somewhere between Aristotle and Plato. Judaism (with its origins around 600 BC) shares Plato’s basic ideas about an immaterial afterlife and a dualistic world, while Christianity (Jesus lived around 6 BC to 33 AD) and Islam (the Quran was written from 609 to 632 AD) share the belief in a bodily resurrection.

In Thomas Aquinas’ (1225–1274, an influential Catholic theologian) discussion of mind and brain (or soul and body), he does not see them as two separate entities interacting with each other, but instead as one. At the same time, he still argues for a separate, incorruptible soul. Thus, his philosophical position is somewhere between mind-brain dualism and the view that all we have is a material existence.

Later, Descartes (1596–1650) focused on the question of how the immaterial mind (or Plato’s ideal Form, or Aquinas’ soul) interacts with the brain. He proposed that there is a connection between the material and immaterial brain through a specific brain part. Given that it is located deep in the center of the brain, the primary candidate was the pineal gland, as it had been attributed with all sorts of mystical properties throughout history. In this theory, information would flow from the brain to the pineal gland, which communicates the information to the immaterial world where consciousness and free will supposedly sit. Having thought about the information, we (the immaterial mind) communicate back to the brain through the pineal gland, which results in an action.

To figure out where exactly to draw the line between the material brain and the immaterial mind, Descartes came up with the following thought experiment:

I shall think that the sky, the air, the earth, colors, shapes, sounds, and all external things are merely the delusions of dreams which [the evil demon] has devised to ensnare my judgment. I shall consider myself as not having hands or eyes, or flesh, or blood or senses, but as falsely believing that I have all these things. —Ren Descartes, Meditations, 1641
Evil demon   Descartes’ evil demon is a thought experiment to differentiate the immaterial mind from the brain. His “evil demon” is an entity that could make any changes to the material world without anyone being aware of such changes. Descartes’ assumption was that by examining the remaining things we could rely on, we would discover what the immaterial mind is.

The demon could feed you wrong information, but—at least in Descartes’ view—could not affect your ability to think about the information. So, maybe the colors, shapes, and sounds you are perceiving are not real, but at least the fact that you are making those perceptions is real. The reason for this rather odd approach is that Descartes wanted to examine such a question without bias. What would be left for the immaterial mind if nothing we see, hear, taste, feel, or touch could be counted on as being “real”?

Descartes argued that humans had a non-physical mind with consciousness (everything the demon could not affect directly, for example the subjective experience, the inner voice, the ability to perceive things, or the imagination), and a physical brain and sense organs (which could be influenced by the demon, directly or indirectly by the environment) that regulates bodily functions and provides intelligence (“What is 2+2?”) and perception (“What color is the box?”).

BiographyRen Descartes Ren Descartes was a French polymath (1596–1650) and is widely regarded as one of the founders of modern philosophy. He attempted to write about philosophy “as if no one had written on these matters before” (his words) and is best known for his statement “I think, therefore I am”—an attempt to explain the foundations of ontology (“what is?”) and epistemology (“how do we know?”). Besides his philosophical writings, he had significant influence in the field of analytical geometry (the Cartesian coordinate system is named after him).

The Origin of Consciousness

Which of our ancestors was the first to experience consciousness?

While Descartes’ distinction between the mind and brain at least provides usable definitions, it misses the explanation of how both of these entities would interact. But even more problematic is that it also misses the explanation of how the physical brain evolved to be able to access the non-physical mind. Mind-brain dualist philosophies generally skip this question, arguing that they must have had no consciousness at one point, and then suddenly had it at another. Religions like Christianity do not directly address this issue. It is believed that humans are different from all other creatures on Earth, having a soul which was either given to humans or with which they were originally created.

Since Descartes and Darwin, scientists were able to materialistically explain more and more functions of what Descartes called the non-physical mind. This diminished the need for an immaterial mind the physical brain could somehow access. Hence, more radical ideas that question existence itself became more popular. They proclaim that, after all, consciousness is primary, meaning that existence is created by consciousness and that your thoughts become physical reality. Therefore, the universe and all the matter it contained would be just the product of the underlying actual consciousness. Having a primacy of consciousness would address how the brain could have evolved: if consciousness is primary, then it would be the driver of evolution and, in a sense, it would mean that consciousness would have been always there, and it somehow built a brain and body around itself. It would also address how mind and brain could communicate (both mind and brain originate from the same consciousness).

While the primacy of consciousness seems to be the answer we are looking for, it comes with a lot of philosophical baggage. How exactly would consciousness direct evolution to create our brain? As we cannot easily resolve this issue, let us consider a more general idea. Let us assume that both the mind and brain originated from a single source and see if this helps explaining both the communication between mind and brain and the evolution of consciousness.


While we have established that in dualism, there needs to be some kind of communication that goes back and forth between mind and brain, this condition does not necessarily apply if mind and brain are the same, if they come from the same source and run in parallel, or if there is only our mind and no brain or body. This view is a variant of what is called monism (see Figure 6.3). Monist views of consciousness have existed for many centuries. They assume that reality ultimately consists of only one substance—an approach that makes the search for a connection between the material and immaterial world superfluous.

Figure 6.3: Comparison of different types of monism.

Monism   The philosophical view of Monism is that everything that exists (including what we call mind or consciousness) can be traced back to a single fabric of the universe. The consequence of this view is that the mind must be a result of a (mechanistic materialist) process and that mind and matter are not two separate things.

While there are many different variants of monism, the main categories are:

Materialism   In the materialist worldview, there is no separate “mind.” Instead, everything can be explained by a single substance (matter).
Neutral monism   In the neutral monist worldview, while both mind and matter exist, they both stem from a third, undefined substance.

According to Baruch de Spinoza (1632–1677), both mind and body (including the brain) are merely different “modi” of God, resulting in the same manifestation. When you move your arm, it is not your will that causes your arm to move. Instead, something else causes both the movement of the arm, as well as the experience that you are moving your arm. This is also called psychophysical parallelism. In this view, the mind and brain are separate, and they do not interact with each other. Instead, everything is parallel, so that it merely looks like they are interacting. This parallelism is either established by repeated Godly intervention, for example, when our body is hurt, God makes the mind feel pain (Nicolas Malebranche, 1638–1715), or by perfect starting conditions like two clocks showing the same time although they are not connected (Gottfried Leibniz, 1646–1716).

This parallelism is similar to what we discussed in Philosophy for Heroes: Continuum about the “spooky action at a distance” when it comes to quantum mechanics. Let us say I split a coin horizontally into two and give you one half without either of us looking at it and then I leave on a journey to the stars. While my part of the coin is then light-years away, it is still connected with your part of the coin (if I look at the coin, I immediately know which side of the coin you have) because both coin parts share an initial action.

Parallelism is basically materialism but with the added explanation of where our subjective experience comes from. If we can explain our subjective experience with materialism, we can safely ignore parallelism and just focus on materialism.

Subjective idealism   In the subjective idealist worldview, there is no such thing as “matter.” Instead, everything is but perception, mind, or “consciousness,” and nothing exists but human minds and gods.

Gottfried Leibniz (1646–1716) described a variant of subjective idealism (pluralistic idealism) which states that the world is the product of many individual minds that generate a virtual world, similar to an online multiplayer computer game.

Indian idealism (Vedanta)   In the Indian idealist worldview, there is but a single consciousness and our experience of the world as separate beings or consciousnesses is an illusion.

Technically, Buddhism and Objectivism are monist world views, too. We can use them as sources of inspiration as they already include something that resembles the concept of attention. Ignoring their special positions concerning focus and free will (we will pick up the topic of free will in the next book, Philosophy for Heroes: Persona ), Objectivism most closely resembles materialism, while Buddhism most closely resembles idealism, so we will focus on those instead.

Objectivism   Objectivism (founded by Ayn Rand, 1902–1982) is a monist philosophy that recognizes a distinction between the brain and a “prime mover” that has a power of whether to focus the brain or not.
Buddhism   Buddhists (Buddha lived 563–483 BC or 480–400 BC depending on the source) believe in a difference between brain and consciousness, with consciousness being compared to a light that shines on thoughts. The mind dies with the bodily death while “you” are reborn into a new being with no memories of your previous life.

With this discussion in mind, we can easily see how religions (and of course philosophies) are based on different interpretations of those basic philosophic questions—Monism versus Dualism, rebirth, and primacy of consciousness (see Figure 6.4):

Figure 6.4: Comparison of different religions and philosophies based on their position on questions of primacy of consciousness, mind-brain dualism, and afterlife.

Quantum Mind Hypothesis

Does human consciousness exist in the quantum world?

Instead of trying to see brain and mind, materialism and idealism, or ontology and epistemology as irreconcilable, it helps to see them as two sides of the same coin. An analogy would be the hardware and software of a computer. Is a computer a series of connected modules, or is it program code that gets executed? Arguing that computers are just program code sounds as silly as arguing that we are just consciousness. The same goes with arguing that computers are just hardware. Instead, it helps to see them as an integrated system: individual modules through which data flows. Hence, our approach will be to identify the role of the individual brain parts and connect them together to explain how information flows through them.

In recent years, a group of hypotheses that gained popularity proclaimed that consciousness cannot be explained with classical mechanics. Their authors are proposing the existence of a “quantum mind” which could bridge the gap between mind and brain through quantum mechanics. The quantum mind would reside in a separate quantum world and would have to determine the state of the brain at a quantum level (the quantum brain) to access the sense data from the sense organs. Moving in the other direction (quantum mind to brain to muscle), the quantum mind would have to affect the macroscopic (classical) brain, which in turn could cause the body to act based on the command given by the quantum mind (see Figure 6.5).

Quantum mind   The term quantum mind refers to a collection of theories that consider quantum mechanics as the basis of consciousness.
Figure 6.5: The proposed architecture of a quantum mind.

The idea of a quantum mind seems plausible as both consciousness as well as quantum mechanics are seen as equally difficult to understand. But the question remains that if consciousness is based on a quantum mind, how would it work? After all, the reason to move the mind into the physical world is to be able to explain how it works.

Looking at the actual research, we quickly discover that the answer depends on the specific interpretation of quantum mechanics that is being used. In the scientific community, some twenty different interpretations of “quantum mechanics” are recognized, all being mathematically correct according to quantum theory. They involve different philosophical assumptions about causality and the role of the observer (see Philosophy for Heroes: Continuum ). If you read something along the lines of “scientists prove that the world is created by thoughts,” that means only that the scientists have used a proven mathematical theory and built their (unproven) interpretation on top of it. Just because the interpretation is non-contradictory does not mean it is true.

One theory assumes that the universe splits into many different versions of itself with each decision you make. But this many-minds interpretation is not proven; it is merely an interpretation of what the results of the underlying (and mathematically sound) quantum theory could mean.

Many-minds interpretation   The many-minds interpretation of quantum mechanics is similar to the many-worlds interpretation, in which the universe splits into infinite universes. In the many-minds interpretation, the split of the universe happens with each thought for each individual brain, instead of with each measurement (as in the many-worlds interpretation). Consequently, one’s consciousness splits into many consciousnesses whenever a decision was made.

An ontologically less wasteful theory was the original interpretation of quantum mechanics, the Copenhagen interpretation (also see Philosophy for Heroes: Continuum for a detailed discussion).

Copenhagen interpretation   In the Copenhagen interpretation of quantum mechanics, an observer is required for the wave function to collapse. Without observation, the wave function never collapses and never becomes a particle. While the interpretation does not mention consciousness as such (measurements by a device are observations, too), it raises the question of who observes the observer, resulting in an infinite loop.

The von Neumann-Wigner interpretation of quantum mechanics also assumes that entities exist only when they are observed. But it breaks the infinite loop by arguing that the quantum mind is the final observer, and that the final observer (the quantum mind) does not need to be observed itself in order to exist (see Figure 6.6).

Von Neumann-Wigner interpretation   The von Neumann-Wigner interpretation of quantum mechanics tries to solve the loop of the Copenhagen interpretation by stating that consciousness is outside of the quantum world and is the final observer that collapses the wave function. For consciousness itself to exist, no observation of consciousness would be needed.
Figure 6.6: The von Neumann-Wigner interpretation addresses the Copenhagen interpretation’s observer problem by arguing for a final “quantum mind” observer.

While these interpretations of quantum mechanics involve consciousness to some degree, none of them gives us any deeper insight into what consciousness could be or how we can describe it. Biology and physics seem to be pointing at each other to solve problems relating to consciousness. Hence, we focus on the connection between the quantum world (physics) and the macro world (biology). If we can determine how both worlds communicate with each other, maybe we can answer the question about the nature of the quantum mind.

A Janitor’s Dream

How could something existing in the quantum world have an effect on the macro world?

In a way, the supposed influence of quantum fluctuations of a quantum mind on our thinking could be compared to the impact of genetic mutations on evolution. In Philosophy for Heroes: Continuum , we made the point that mutations are not the drivers of evolution, and they merely provide variety in the gene pool. The actual driver of evolution is the selection of the best adapted individuals for procreation of the next generation. For example, eyes did not develop through a series of mutations. Instead, minuscule differences in the eyes (or precursors of eyes) provided a small evolutionary advantage (like providing images with a higher resolution). Similarly, in the brain, signals pass through several layers of filtering (selection!) while noise (a mutation) is getting filtered out. This happens by focusing on patterns in the incoming sense data (for example, the visual system tries to detect contours in order to identify entities). For effects on the quantum level to have an effect on the macro level of nerve cells and ultimately muscle cells, they would have to pass through those layers, starting from the physics of atomic forces, and moving up to the macro-world level of biological molecules, cells, cell structures, neural networks, etc.

The neurobiologist William H. Calvin dismisses this idea of a quantum mind (or “quantum consciousness”)—the notion that our consciousness is somehow rooted in the physical phenomena of quantum mechanics—as a “janitor’s dream” with the janitor of a high-rise building working in the basement (the quantum world), having to influence indirectly what is happening in the penthouse (the macro-world of biology). [cf. Calvin, 1996, p. 181].

The janitor’s dream describes only one direction, namely how something like a quantum mind could affect the macro-world. For example, when we tell each other about our subjective experience of consciousness, information travels from our consciousness to our muscles, causing our hands to write and our vocal cords to move. We connect the information from our “mind’s eye” that experiences consciousness to our language output.

But how a quantum mind could perceive the macro-world is yet another mystery altogether. After all, information also travels from our senses to our consciousness. The brain gathers sense data (for example, the question “Do you hear the noise of the train in the distance?”), the information is processed by the brain, perceived consciously, an answer is consciously decided on, and then the answer is transformed into sound waves using one’s voice (“Not only do I now hear the train in the distance, I also know that I hear the train in the distance.”). When you look at an apple, your eyes process the image and create a signal that activates various parts of your brain. These activations cause changes in the quantum state of individual atoms. A quantum mind would have to (somehow) “read” changes to produce a “quantum-level concept” of the apple. If the quantum mind then decides (how?) to reach for that apple, it would have to encode that decision back into microscopic quantum fluctuations that in their entirety produce a macroscopic pattern in the brain to activate the right set of neurons to cause the action of grabbing the apple. In summary, a quantum mind would:

  1. First, “read” quantum level changes caused to neurons by the senses; then
  2. Decipher this raw data back into high-level concepts (for example, “apple”); then
  3. Make a decision on the quantum level about what to do with the apple; and finally
  4. Encode that decision back into quantum level fluctuations to produce a macroscopic pattern.

But that is not a viable model for a quantum mind because a quantum mind would itself need a separate brain-like structure to translate the signals between the two systems. We already have a way of synchronizing multiple microscopic elements to produce a concerted change on a macroscopic level: that is the macroscopic world (the brain!) and there is no need to interpret and re-interpret data on a quantum level. That is what the brain itself is already doing. The proposed architecture of a quantum mind (see Figure 6.5) could be simplified by drawing an arrow from the left neurons box to the right neurons box, skipping the quantum mind altogether. Neurons would then be communicating with each other directly instead of having to hop back and forth between the macroscopic world and the quantum world.

In other words, a quantum mind could use the very brain it is reading to calculate what high-level information the brain is currently processing. Like the aforementioned janitor could go through each level of the building, pick up pieces of trash like a detective, and ask each tenant questions. By that standard, we could also argue that a bicycle wheel works using quantum mechanics because the molecules that make up the metal and rubber interact with each other on a quantum level. Of course, this raises the question: Why do we even need to bring up anything related to quantum mechanics or an immaterial mind? Because if the quantum brain uses the material brain to create consciousness, we can simply skip the idea of quantum mind and focus on how the brain works—just like we would focus on the wheel and chain when trying to understand how a bicycle works.

While there are exceptions to this idea of the quantum world not affecting the macro world (for example, the photoelectric effect), in this case the brain is more like a bicycle. If we cannot explain how one can ride a bicycle with its wheels, frame, and chain, we surely cannot explain it by referring to its molecular structure. Or even simpler: to grab a cup of coffee, you do not have to translate the cup and your hand into their molecular structures and calculate how they would interact with each other on that level. Most likely, evolution has found a way to optimize fundamental chemical and electrical processes (like neurons firing nerve impulses) in the brain at the subatomic scale. That does not necessarily mean that the brain has a “quantum mind.” This is also in line with what we have learned about quantum computers in Philosophy for Heroes: Continuum : all they are doing is running controlled physical experiments, and then using the results to speed up certain calculations.

Just because the two concepts of quantum theory and consciousness have yet to be fully understood does not mean that they have anything to do with each other.

We can conclude that the value of the “janitor’s dream” is very limited. Placing consciousness into the quantum world (as part of a “quantum mind”) does not explain the observable macroscopic effects (muscle movements) of consciousness. We have learned, though, that the brain needs some kind of structure that is responsible for calculating what is going on at a macroscopic level—like a central information point at an airport gathers all the data about incoming and outgoing flights. The brain needs to know a summary of what it is thinking. We will address this issue again later.

Given that we do not have any evidence for a separate quantum mind or for any communication from our biological brain to that supposed quantum world brain, we should consider that consciousness is a system consisting of macroscopic building blocks of reality (for example, the neurons and axons of the brain or interconnected brain parts). With the quantum mind hypothesis out of the way, we can continue to focus on other monist theories of consciousness. To arrive at such theories, we will first discuss what elements of the brain could be part of a system that produces consciousness.

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September 30, 2023

About the Author

Clemens Lode

Hello! My name is Clemens and I am based in Düsseldorf, Germany. I’m an author of books on philosophy, science, and project management, and coach people to publish their books and improve their approach to leadership.

I like visiting the gym, learning to sing, observing animals, and creating videos on science and philosophy. I enjoy learning from nature and love the idea of optimizing systems.

In my youth, I was an active chess player reaching the national championship in Germany, and an active pen&paper player leading groups of adventurers on mental journeys. These activities align with my calm approach to moderating meetings, leading meetups, and focusing on details. My personality type in socionics is IEE/ENFp.

Clemens Lode

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