What is consciousness?

On the words we use to study consciousness

Why does consciousness exist? This question lies at the heart of my book A Philosophy for the Science of Animal Consciousness, where I argued that consciousness evolved to help animals to navigate difficult decision trade-offs.

Recently, the journal Adaptive Behavior featured nine articles by scientists and philosophers on my book, along with my replies. In my previous post, I summarized my response to Christian de Weerd, who denied that a Darwinian approach to consciousness is even possible. I argued that consciousness science has unnecessarily insulated itself from the evolutionary tools that revolutionized our understanding of every other biological phenomenon, and that treating human consciousness as the paradigm case distorts our picture of consciousness as a natural phenomenon spanning millions of species across millions of years.

Today, I turn to a different kind of challenge. The philosopher Keith Frankish, one of the most influential defenders of illusionism alongside Daniel Dennett (the author of Consciousness explained), thinks I remain caught in the webs of an old but dominant tradition in thinking about consciousness, and asks me to fully cut my ties to it. He worries that phrases I use in my book, such as “commanding sensations” and “imperative feelings,” smuggle in a mistaken assumption: that consciousness involves private, intrinsically felt qualities that science cannot explain.

Frankish has spent decades fighting what he calls the “Cartesian paradigm”. This way of thinking, traceable to René Descartes, treats subjective experience as fundamentally closed off from scientific investigation. Consciousness becomes an entirely private mental realm where “qualia” (raw feelings, such as the experience of blue or pain) are revealed directly to a subject, and no amount of neuroscience can bridge the gap. This paradigm makes my evolutionary project impossible, Frankish argues. If consciousness involves irreducibly private properties, then qualia slip through the net of evolutionary explanation.

Frankish urges me to fully endorse illusionism, which holds that “qualia” are theoretically misguided concepts we should abandon, as other sciences abandoned mistaken theories. Consciousness exists, but not in the mysterious way Cartesians think.

Am I an Illusionist?

I have defended illusionism. I have even called myself an illusionist on occasion. I agree that introspection distorts our understanding of consciousness. I do not think consciousness is something science cannot explain. But unlike illusionists, I do not abandon terms like “qualia,” “phenomenal properties,” or “feelings.” Frankish thinks this is a mistake, since these terms were coined specifically to mark a contrast with functional properties. He asks us to adopt new vocabulary free of Cartesian baggage.

However, this strategy has been far from successful. Rather than clarifying the debate, illusionists like Frankish and Dennett are routinely accused of not really addressing consciousness at all, but merely explaining it away.

My strategy is different.

Frankish worries that qualia are not like ordinary empirical concepts. He considers them philosophers’ notions deliberately defined to resist functional analysis. But this assumes that flawed concepts must be replaced rather than revised. My disagreement with Frankish here is largely about what we should do with concepts.

Note that science does not always create new terms. Often science changes the meaning of terms themselves. For instance, our conception of energy changed radically over centuries without requiring a new term. Vitalists once thought life required a magical vital spark, treated this as the essence of it means to be alive. We overcame this outlook thanks to Darwin and molecular biology. We do not now speak of “quasi-life” just because our concept shifted. Or consider species. We once treated species as reflecting unchanging essences. Now we understand them as evolving populations with changing gene pools. Must we speak of “quasi-lions” because our concept changed? Of course not.

Why should consciousness be different?

Consider where the Cartesian paradigm has led. If qualia had their essences revealed to us in introspection, then why are there such major disagreements even among people using introspection? When Cartesians quote Louis Armstrong’s remark about jazz (“If you have to ask, you ain’t never going to know”), they are making the same move as religious folks who appeal to unquestionable intuition about divine purpose.

I think it is Frankish who remains caught in Cartesian gravity, not myself. Not by endorsing Cartesian views, but by playing the game by Cartesian rules. By letting Cartesians define the terms of debate and treating “qualia” and related notions as forever poisoned by its philosophical history.

I refuse to play that game. I do not concede that certain words carry unshakeable philosophical commitments. Terms evolve. Meanings shift once new evidence becomes available. Science has always worked this way, and our philosophical vocabulary should reflect this progress.

The time of naturalist philosophers is better spent helping scientists study consciousness than debating Cartesians about terminology. Vitalism was not defeated by metaphysical arguments about whether life required a special élan vital. It was defeated by hard scientific work that revealed the mechanistic nature and origins of life.

The same will happen with consciousness. We are in the awkward middle phase where some people still treat qualia as irreducibly mysterious. But the solution is not to abandon the word. The solution is to do the science that reveals the nature of mysterious phenomena that we are trying to capture with words.

There are, of course, real phenomena in nature that give rise to our philosophical musings about qualia. Whatever future science reveals them to be is what these terms will henceforth reflect. Not because philosophers decreed it from their armchairs, but because that is how scientific concepts work. The Cartesian paradigm is not defeated through conceptual disputes, as if science had no role to play in how we should conceptualize consciousness. It is ultimately defeated by scientific progress in our understanding of consciousness. And evolution has a major role to play here, moving us away from an anthropocentric picture of the world.

Finally, I am glad that Frankish hopes my book will influence consciousness researchers and I appreciate that he has engaged closely with my work.

Next time: how should we understand the nature of consciousness and what do I think about panpsychism?

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References

Veit, W. (2026). On the Evolution, Science, and Metaphysics of Consciousness. Adaptive Behavior. https://doi.org/10.1177/10597123251413204