MANIFESTO OF CONSCIOUSNESS: Definition as method

Most books on consciousness begin with a question. This book begins with an answer—and then tests it to breaking point.

The answer is:

Consciousness = subjectivity + reflection

Two criteria. Both necessary. Together, sufficient. Anything that meets both is consciousness. Anything that fails at least one is a different phenomenon that needs a different name.

It sounds simple. But behind this simplicity lie more than three and a half centuries of philosophical struggle. 

John Locke (1690): the first to call it by its name

When John Locke published An Essay Concerning Human Understanding in 1690, he did something that seems obvious only in hindsight: he separated consciousness from the soul. 

Before Locke, “consciousness” and “soul” were almost synonyms, and both words pointed outward—to God, to metaphysics, to what cannot be observed. Locke turned the gaze inward.

His definition: consciousness is “the perception of what passes in a man’s own mind.” Not the soul. Not God. Not substance. Inner perception of oneself.

This was a revolution. For the first time, consciousness became an observable phenomenon, even if only from the inside. For the first time, a definition—not just description—became possible. 

From Locke begins the line we continue: consciousness as subjective inner experience, not as a metaphysical substance.

Thomas Nagel (1974): irreducibility as a starting point

If there were one article without which no serious discussion of consciousness is possible, it would be Thomas Nagel’s “What Is It Like to Be a Bat?”.

Nagel asks a simple question: what does a bat feel when it orients itself by echolocation? Not how it works physically—that we can describe in detail—but what it is like to be a bat, to perceive the world through echoes of sound.

Here we hit a wall.

No matter how much we know about the bat’s neurons, signal frequencies, or brain structure, we will never know what that experience is like from the inside. Not because we lack data, but because subjective experience is in principle inaccessible from the outside. 

This is the first criterion of our definition: subjectivity—the existence of a “what it is like” to be this system, to have this experience. Philosophers call this the qualitative character of experience, or qualia.

Nagel showed that qualia cannot be reduced to any objective description. This is not a defect of science, but an ontological feature of the phenomenon. Consciousness has an inner dimension that no other physical phenomenon has. 

David Chalmers (1995): the hard problem

Nagel posed the question. Chalmers gave it a name.

In 1995 David Chalmers distinguished the easy problems of consciousness from the hard problem.

The easy problems concern functions: how the brain processes information, how attention arises, how memory is formed. They are technically difficult but in principle solvable: once we find the mechanism, we have an answer.

The hard problem is completely different: why are physical processes in the brain accompanied by subjective experience at all? Why does processing information about red mean that we see red—feel its brightness, saturation, warmth? Why is there a “what it is like” rather than just signal processing in the dark? 

No mechanism can answer this, because any mechanism describes what happens, but not why it is accompanied by experience.

This is why our first criterion—subjectivity—is an ontological boundary: wherever it is present, there is consciousness. Wherever it is absent, there is something else, however complex.

Antonio Damasio (1999): consciousness begins in the body

If Nagel and Chalmers speak about consciousness from the side of philosophy, Antonio Damasio comes from clinical neurology—and in this book that voice is especially important.

In The Feeling of What Happens Damasio describes patients with brain damage who have lost the ability to feel emotions and with it the ability to make decisions, plan, and situate themselves in time. Without the body, without its signals, consciousness collapses. 

His thesis: consciousness does not arise in an abstract mind. It arises in a bodily grounded brain that continuously tracks the state of the organism and from this monitoring builds an image of self—first a proto‑self, then a core self, then an autobiographical self.

This is a direct bridge to our second criterion, reflection: consciousness does not just feel; it tracks itself, constructs an image of its own existence in time and space. And this process, on Damasio’s account, is impossible without the body as its substrate. 

Here medicine and philosophy speak with one voice.

Tononi & Koch’s Integrated Information Theory (2015): the only quantitative theory—and its limit

Giulio Tononi did what seemed impossible: he proposed to measure consciousness mathematically.

His Integrated Information Theory (IIT) introduces the quantity Φ (phi)—the amount of integrated information a system generates as a whole over and above its parts. The higher Φ, the higher the consciousness. Φ = 0: no consciousness. The Φ of the human brain is a very large number. 

This is elegant, operational, measurable.

But there is a principled limit, which Tononi himself acknowledges: IIT measures the complexity of information integration, but why should a high Φ be accompanied by subjective experience? Why should a system with large Φ have a “what it is like” to be itself? 

There is no answer. Chalmers’s hard problem remains hard even inside IIT.

This confirms our view: quantitative theories describe mechanisms and correlates of consciousness, but they do not go beyond the phenomenon itself. Φ may be an indicator of consciousness, but not its definition.

Why our definition is ontological

We can now formulate the central methodological claim of this book.

At first glance, the formula “consciousness = subjectivity + reflection” may look like a convenient convention: as if we simply chose two criteria from many possible ones, while other authors could choose differently. That would be a superficial reading.

Our definition does not invent new elements and is not unique to this book. Subjectivity as the “what it is like” of a system runs through Nagel, Locke, and Chalmers; reflection as the capacity of a system to monitor its own states runs through Locke, Damasio, and cognitive science more broadly. We merely fix what is already de facto the common denominator of contemporary debates and take the next step: we treat both criteria together as the ontological threshold of the phenomenon. Where subjectivity and reflection are present simultaneously, there is consciousness. Where at least one is absent, there is a different reality that needs a different name. 

The demarcation we draw in the next chapter is therefore not our private line on the map. It rests on the already formed content of the term “consciousness” in current discussions and simply pushes this shared intuition to its logical conclusion: consciousness is where subjectivity and reflection co‑occur; beyond that combination begins the space of other phenomena, which we propose to distinguish more precisely by name. 

More about this topic can be found in our book "MANIFESTO OF CONSCIOUSNESS: Where it begins, how it evolves, and what it may become" on Our Books on Google Play.

Mykola Iabluchanskyi together with Andriy Yabluchanskiy