By Hedda Hassel Mørch

Originally published at Nautilus on April 6, 2017.

The enigma of consciousness stands out as a particularly challenging scientific dilemma. Neuroscientists struggle to explain how consciousness emerges from the brain's physical states, and there's skepticism about whether a satisfactory answer will ever be found. While fields like astronomy and geology tackle their own profound questions—such as the nature of dark matter and the origins of life—there's at least a general framework for investigating these issues. In contrast, our subjective experiences defy conventional scientific inquiry. Philosopher David Chalmers has termed this the "hard problem of consciousness."

However, it may be misleading to think of consciousness as uniquely problematic. Philosophers such as Gottfried Leibniz and Immanuel Kant have long grappled with another challenging question: What is the essence of physical matter beyond its mathematical descriptions in physics? This question also appears to elude the traditional scientific approach, as we only observe what matter does, not what it is at its core—the "software" of the universe without its foundational "hardware." These two issues may seem distinct, but they might share a deeper connection.

Consciousness, as a complex phenomenon, presents subjective experience as its most perplexing component. Our brains do more than process information or engage in biochemical reactions; they generate vivid feelings and experiences, from perceiving colors to grappling with philosophical concepts. Each individual experiences a unique consciousness that no one else can access in the same way.

Our consciousness encompasses a diverse range of sensations, emotions, desires, and thoughts. Nevertheless, conscious experiences can also be straightforward. For instance, an animal reacting instinctively to pain or hunger is conscious, even without reflective thought. Typically, our consciousness is directed toward something—awareness of external objects, abstract concepts, or self-reflection. Yet, even during incoherent dreams or vivid hallucinations, one still possesses a form of consciousness, albeit without specific focus.

Philosophers and neuroscientists often liken consciousness to software, with the brain as the hardware.

So, where does consciousness arise from? Current scientific understanding suggests that consciousness is anchored in the brain's physical and chemical processes rather than in any abstract or transcendent essence. To create a conscious system, one requires only physical matter, arranged appropriately—as in the brain—leading to the emergence of consciousness. The pressing question, however, remains: How does consciousness materialize from the intricate arrangements of non-conscious matter?

This dilemma is particularly challenging because its solution cannot be reached solely through experimental observation. Advances in neuroscience and neuroimaging provide us with increasingly detailed maps of the brain's conscious states. These studies may reveal commonalities among these states, such as high levels of integrated information, message broadcasting in the brain, or oscillations at specific frequencies. Yet, the fundamental question persists: How and why does a system that integrates information or broadcasts signals experience pain or pleasure? The emergence of consciousness from mere complexity remains an enigma, regardless of the specifics of that complexity.

Discovering the underlying biochemical and physical mechanisms of consciousness won't necessarily resolve this mystery. Even if we can detail the processes behind recognizing a tomato, we can still ask: Why does this recognition involve the subjective experience of redness? Could there exist a purely physical process without any conscious experience?

While other natural phenomena, like dark matter or the origins of life, present significant challenges, they do not seem insurmountable. Gaining a deeper understanding typically involves gathering more empirical data—improving observational tools or uncovering new laws. If we were to know every detail of the universe, we would expect these issues to resolve, similar to how understanding DNA clarified heritability. Yet the hard problem of consciousness appears to persist, regardless of our knowledge of physical details.

Consequently, the profound nature of consciousness seems to lie beyond the reach of science. Conversely, we generally assume that physics can, in theory, elucidate the essence of physical matter. Physics informs us that matter comprises particles and fields with characteristics like mass, charge, and spin. Although physics has yet to uncover every fundamental property of matter, it is progressing toward that goal.

Nevertheless, there are grounds to believe that matter possesses intrinsic qualities beyond what physics reveals. Broadly, physics describes how fundamental particles behave or interact but offers little insight into their intrinsic nature, independent of their relations.

For instance, charge defines how particles interact based on their attributes. Similarly, mass delineates how particles respond to forces and gravitational attraction, describing relationships rather than intrinsic properties.

Conscious experiences could represent the very structure of physical reality.

In general, the fundamental properties of physics can be articulated mathematically. Galileo famously stated that nature's great book is written in mathematics. However, this language has inherent limitations; it can only represent abstract structures and their relationships. For example, our knowledge of numbers is confined to their interactions with one another. Similarly, a purely mathematical physics can only inform us about the relations among physical entities or the rules governing their behaviors.

One might ponder how physical particles exist independently of their actions or relationships. What is the intrinsic nature of physical entities? Some argue that particles are solely defined by their relations, but intuition often resists this notion. To establish a relationship, there must be two entities to connect; otherwise, the relation lacks substance—like a performance without actors or a structure without material.

Thus, physical structures must be realized by a substance that is not purely structural. Otherwise, the distinction between physical and mere mathematical constructs blurs, as does the line between the tangible universe and abstraction. This dilemma mirrors Kant’s classic inquiry into our knowledge of things-in-themselves, and philosopher Galen Strawson has termed it the "hard problem of matter."

Ironically, we generally view physics as delineating the universe's hardware—the tangible substance. Yet, the aspects of physical matter revealed through physics resemble software: a logical and mathematical framework. The hard problem of matter posits that this software necessitates some form of hardware for its implementation. While physicists have adeptly reverse-engineered the universe's algorithms, they have overlooked the concrete realization of these principles.

The hard problem of matter differs from other interpretive challenges in physics. Current physics poses questions, such as the dual nature of matter as both particle-like and wave-like or the phenomenon of quantum wavefunction collapse. However, these inquiries focus on the conceptualization of reality's structure. The hard problem of matter would persist even if we could satisfactorily address all structural questions. Regardless of the structure—be it unusual or intuitive—there remains the question of its non-structural realization.

Indeed, this problem arises even within Newtonian physics, which intuitively describes matter as solid particles interacting through direct contact or gravitational attraction. Yet, what is the intrinsic nature of the substance that behaves in this straightforward manner? What serves as the hardware for Newton's equations? One might assume the answer is simple: solid particles. However, solidity merely describes the behavior of resisting intrusion—another relation to surrounding particles and space. The hard problem of matter emerges from any structural depiction of reality, regardless of its clarity.

Like the hard problem of consciousness, the hard problem of matter cannot be resolved through experiments or observations or by amassing further physical details. Such efforts will only reveal additional structure, at least as long as physics remains committed to capturing reality mathematically.

Could the hard problems of consciousness and matter be interconnected? There exists a historical precedent for linking physical dilemmas with consciousness, particularly in the realm of quantum consciousness theories. These theories are sometimes dismissed as fallaciously suggesting that because both quantum physics and consciousness are enigmatic, their interplay will somehow clarify both. However, a closer examination reveals that the two dilemmas may be intricately linked. Leibniz first noted this connection in the late 17th century, with Bertrand Russell later refining the concept. Contemporary philosophers, including Chalmers and Strawson, have revisited this idea.

The hard problem of matter necessitates non-structural properties, and consciousness may be the only phenomenon capable of fulfilling this requirement. Consciousness is replete with qualitative attributes, encompassing everything from the experience of redness to the sensation of hunger. While such experiences may possess internal structure, they transcend mere structural considerations. We have some understanding of what conscious experiences are like in their essence, not just in terms of their functions or relations.

For instance, consider someone who has never encountered red objects or been informed of the existence of the color red. This person lacks knowledge of how redness relates to brain states, physical objects, or light wavelengths. One day, however, they might spontaneously hallucinate a large red patch. It seems that, in doing so, they would learn what it is like to experience redness, despite not knowing its connections to other concepts. This knowledge would be non-relational—understanding redness in its essence.

This notion suggests that consciousness, in some fundamental form, serves as the hardware that the software described by physics operates upon. We can envision the physical world as a structure composed of conscious experiences. Our rich array of experiences realizes the physical interactions constituting our brains, while simpler experiences might correspond to the relations characterizing fundamental particles. For example, an electron’s behavior—its attraction, repulsion, and interactions—could be thought of as a manifestation of a stream of minute electron experiences. In this framework, particles may be conceptualized as mental entities with physical capabilities, representing flows of experience interconnected with other streams of experience.

Though this idea may seem peculiar or mystical, it emerges from a thoughtful exploration of science's boundaries. Both Leibniz and Russell were committed scientific rationalists, evidenced by their significant contributions to physics, logic, and mathematics, yet they held a deep appreciation for the uniqueness of consciousness. They concluded that a fundamental shift in thinking is necessary to reconcile these phenomena.

This shift is indeed radical. Typically, philosophers and neuroscientists equate consciousness with software and the brain with hardware. This perspective reverses that notion: examining what physics reveals about the brain leads us to discover software—purely relational constructs. In contrast, consciousness embodies more hardware-like qualities due to its distinct qualitative and non-structural properties. Hence, conscious experiences align with the very structure physical entities could embody.

With this insight into the hard problem of matter, the hard problem of consciousness may effectively dissipate. The question of how consciousness arises from non-conscious matter becomes irrelevant, as all matter is inherently conscious. The relationship between consciousness and matter shifts; consciousness is the foundation upon which matter relies—just as relations depend on entities, structure relies on its realization, and software relies on hardware.

One might argue that this perspective is mere anthropomorphism, an unwarranted projection of human characteristics onto nature. Why assume that physical structure necessitates an intrinsic realization? Is it not because our brains possess intrinsic, conscious qualities, leading us to view nature through a familiar lens? However, this objection falters. The notion that intrinsic properties distinguish tangible reality from mere abstract constructs is independent of consciousness. Furthermore, the critique of anthropomorphism can be countered by the notion of human exceptionalism. If the brain is entirely material, why should it differ from other matter concerning intrinsic properties?

This perspective—that consciousness constitutes the intrinsic essence of physical reality—has various labels, one of the most descriptive being "dual-aspect monism." Monism contrasts with dualism, which posits that consciousness and matter are fundamentally different kinds of substances. Dualism is often considered scientifically implausible, as there is no evidence of non-physical forces influencing the brain.

Monism asserts that reality consists entirely of the same fundamental substance. It comes in several forms, with physicalism (or materialism) being the most prevalent. Physicalism posits that everything comprises physical matter, revealing only one aspect—what physics uncovers. This view dominates philosophical and scientific discourse today. However, according to the hard problem of consciousness, a purely physical description of conscious systems like the brain appears to omit something crucial: the subjective experience remains unrepresented.

To address both phenomena adequately, a fundamental shift in perspective is essential.

Russell’s dual-aspect monism seeks to fill this gap. It acknowledges that the brain functions as a material system governed by physical laws while introducing an intrinsic aspect of matter that remains elusive from the external, third-person viewpoint of physics. This intrinsic facet, though escaping our physical theories, does not evade our subjective observations. Our consciousness serves as the intrinsic aspect of the brain, guiding us toward understanding the intrinsic nature of other physical entities. To paraphrase Arthur Schopenhauer's response to Kant: We can comprehend the thing-in-itself because we embody it.

Dual-aspect monism exists in both moderate and radical forms. Moderate versions suggest the intrinsic nature of matter comprises "neutral" properties, which are distinct from consciousness but remain unknown to science. The essence of such neither-mental-nor-physical properties remains enigmatic. Similar to quantum theories of consciousness, moderate dual-aspect monism risks merely compounding one mystery atop another.

The most radical interpretation posits that the intrinsic nature of reality consists of consciousness itself. This stance is not synonymous with subjective idealism, which posits that the physical realm exists solely within human consciousness, rendering the external world illusory. Dual-aspect monism maintains that the external world exists independently of human consciousness, yet it would not exist without any form of consciousness, as all physical entities are inherently associated with some variant of consciousness as their intrinsic realization.

As a proposed solution to the hard problem of consciousness, dual-aspect monism faces its own critiques. The most notable objection is that it leads to panpsychism—the belief that all entities possess some form of consciousness. Critics argue that it is implausible for fundamental particles to be conscious. This notion indeed challenges our intuitions. Yet, one must consider the alternatives. Dualism appears scientifically untenable, while physicalism suggests the objective aspects of reality constitute the sole existence, potentially rendering the subjective experience an illusion. Should we not trust our consciousness more than the notion that fundamental particles lack consciousness?

Another significant concern is the combination problem: how does the intricate, unified consciousness of our brains arise from the amalgamation of particles with simpler consciousness? This inquiry parallels the original hard problem. However, proponents of panpsychism argue that the combination problem is not as formidable as the initial hard problem. In certain respects, it seems more straightforward to derive one type of conscious matter (such as a conscious brain) from another (like a collection of conscious particles) than to explain how conscious matter emerges from non-conscious matter. Yet, many find this argument unconvincing. Perhaps, though, time will bring new insights. The initial hard problem has preoccupied philosophers for centuries, while the combination problem has garnered less attention, suggesting potential for a future resolution.

The idea that consciousness represents the fundamental substance of reality—serving as the core hardware for the software of our physical theories—is radical and profoundly alters our conventional understanding. However, it may simultaneously resolve two of the most significant dilemmas in science and philosophy.

Hedda Hassel Mørch is a Norwegian philosopher and postdoctoral researcher hosted by the Center for Mind, Brain, and Consciousness at NYU. Her research focuses on the combination problem and other topics related to dual-aspect monism and panpsychism.