In this post, I seek to clarify what I consider to be some common confusions about consciousness and “physics” stemming from a failure to distinguish clearly between ontological and epistemological senses of “physics”.

Clarifying Terms

Two senses of the word “physics” are worth distinguishing. There is physics in an ontological sense: roughly speaking, the spatio-temporal(-seeming) world that in many ways conforms well to our best physical theories. And then there is physics in an epistemological sense: a certain class of models we have of this world, the science of physics.

“Physics” in this latter, epistemological sense can be further divided into 1) the physical models we have in our minds, versus 2) the models we have external to our minds, such as in our physics textbooks and computer simulations. Yet it is worth noting that, to the extent we ourselves have any knowledge of the models in our books and simulations, we only have this knowledge by representing it in our minds. Thus, ultimately, all the knowledge of physical models we have, as subjects, is knowledge of the first kind: as appearances in our minds.*

In light of these very different senses of the term “physics”, it is clear that the claim that “physics is also qualia” can be understood in two very different ways: 1) in the sense that the physical world, in the ontological sense, is qualia, or “phenomenal”, and 2) that our models of physics are qualia, i.e. that our models of physics are certain patterns of consciousness. The first of these two claims is surely the most controversial one, and I shall not defend it here; I explore it here and here.

Instead, I shall here focus on the latter claim. My aim is not really to defend it, as I already briefly did that above: all the knowledge of physics we have, as subjects, ultimately appears as experiential patterns in our minds. (Although talk of the phenomenology of, say, operations in Hilbert spaces admittedly is rare.) I take this to be obvious, and hit an impasse with anyone who disagrees. My aim here is rather to clarify some confusions that arise due to a lack of clarity about this, and due to conflations of the two senses of “physics” described above.

The Problem of Reduction: Epistemological or Ontological?

I find it worth quoting the following excerpt from a Big Think interview with Sam Harris. Not because there is anything atypical about what Harris says, but rather because I think he here clearly illustrates the prevailing lack of clarity about the distinction between epistemology and ontology in relation to “the physical”.

If there’s an experiential internal qualitative dimension to any physical system then that is consciousness. And we can’t reduce the experiential side to talk of information processing and neurotransmitters and states of the brain […]. Someone like Francis Crick said famously you’re nothing but a pack of neurons. And that misses the fact that half of the reality we’re talking about is the qualitative experiential side. So when you’re trying to study human consciousness, for instance, by looking at states of the brain, all you can do is correlate experiential changes with changes in brain states. But no matter how tight these correlations become that never gives you license to throw out the first person experiential side. That would be analogous to saying that if you just flipped a coin long enough you would realize it had only one side. And now it’s true you can be committed to talking about just one side. You can say that heads being up is just a case of tails being down. But that doesn’t actually reduce one side of reality to the other.

Especially worth resting on here is the statement “half of the reality we’re talking about is the qualitative experiential side.” Yet is this “half of reality” an “ontological half” or an “epistemological half”? That is, is there a half of reality out there that is part phenomenal, and part “non-phenomenal” — perhaps “inertly physical”? Or are we rather talking about two different phenomenal descriptions of the same thing, respectively 1) physico-mathematical models of the mind-brain (and these models, again, are also qualia, i.e. patterns of consciousness), and 2) all other phenomenal descriptions, i.e. those drawing on the countless other experiential modalities we can currently conceive of — emotions, sounds, colors, etc. — as well as those we can’t? I suggest we are really talking about two different descriptions of the same thing.

A similar question can be raised in relation to Harris’ claim that we cannot “reduce one side of reality to the other.” Is the reduction in question, or rather failure of reduction, an ontological or an epistemological one? If it is ontological, then it is unclear what this means. Is it that one side of reality cannot “be” the other? This does not appear to be Harris’ view, even if he does tacitly buy into ontologically distinct sides (as opposed to descriptions) of reality in the first place.

Yet if the failure of reduction is epistemological, then there is in fact little unusual about it, as failures of epistemological reduction, or reductions from one model to another, are found everywhere in science. In the abstract sciences, for example, one axiomatic system does not necessarily reduce to another; indeed, we can readily create different axiomatic systems that not only fail to reduce to each other yet which actively contradict each other. And hence we cannot derive all of mathematics, broadly construed, from a single axiomatic system.

Similarly, in the empirical sciences, economics does not “reduce to” quantum physics. One may object that economics does reduce to quantum physics in principle, yet it should then be noted that 1) the term “in principle” does an enormous amount of work here, arguably about as much as it would have to do in the claim that “quantum physics can explain consciousness in principle” — after all, physics and economics invoke very different models and experiential modalities (economic theories are often qualitative in nature, and some prominent economists have even argued they are primarily so). And 2) a serious case can be made against the claim that even all the basic laws found in chemistry, the closest neighbor of physics, can be derived from fundamental physical theories, even in principle (see e.g. Berofsky, 2012, chap. 8). This case does not rest on there being something mysterious going on between our transition from theories of physics to theories of chemistry, nor that new fundamental forces are implicated, but merely that our models in these respective fields contain elements not reducible, even in principle, to our models in other areas.

Thus, at the level of our minds, we can clearly construct many different mental models which we cannot reduce to each other, even in principle. Yet this merely says something about our models and epistemology. It hardly comprises a deep metaphysical mystery.

Denying the Reality of Consciousness

The fact that the world conforms, at least roughly, to description in “physical” terms seems to have led some people to deny that consciousness in general exists. Yet this, I submit, is a fallacy: the fact that we can model the world in one set of terms which describe certain of its properties does not imply that we cannot describe it in another set of terms that describe other properties truly there as well, even if we cannot derive one from the other.

By analogy, consider again physics and economics: we can take the exact same object of study — say, a human society — and describe aspects of it in physical terms (with models of thermodynamics, classical mechanics, electrodynamics, etc.), yet we cannot from any such description or set of descriptions meaningfully derive a description of the economics of this society. It would clearly be a fallacy to suggest that this implies facts of economics cannot exist.

Again, I think the confusion derives from conflating epistemology with ontology: “physics”, in the epistemological sense of “descriptions of the world in physico-mathematical terms”, appears to encompass “everything out there”, and hence, the reasoning goes, nothing else can exist out there. Of course, in one sense, this is true: if a description in physico-mathematical terms exhaustively describes everything out there, then there is indeed nothing more to be said about it — in physico-mathematical terms. Yet this says nothing about the properties of what is out there in other terms, as illustrated by the economics example above. (Another reason some people seem to deny the reality of consciousness, distinct from conflation of the epistemological and the ontological, is “denial due to fuzziness”, which I have addressed here.)

This relates, I think, to the fundamental Kantian insight on epistemology: we never experience the world “out there” directly, only our own models of it. And the fact that our physical model of the world — including, say, a physical model of the mind-brain of one’s best friend — does not entail other phenomenal modalities, such as emotions, by no means implies that the real, ontological object out there which our physical model reflects, such as our friend’s actual mind-brain, does not instantiate these things. That would be to confuse the map with the territory. (Our emotional model of our best friend does, of course, entail emotions, and it would be just as much of a fallacy to say that, since such emotional models say nothing about brains in physical terms, descriptions of the latter kind have no validity.)

Denials of this sort can have serious ethical consequences, not least since the most relevant aspects of consciousness, including suffering, fall outside descriptions of the world in purely physical terms. Thus, if we insist that only such physico-mathematical descriptions truly describe the world, we seem forced to conclude that suffering, along with everything else that plausibly has moral significance, does not truly exist. Which, in turn, can keep us from working toward a sophisticated understanding of these things, and from creating a better world accordingly.

* And for this reason, the answer to the question “how do you know you are conscious?” will ultimately be the same as the answer to the question “how do you know physics (i.e. physical models) exist?” — we experience these facts directly.