"We think that grass is green, that stones are hard, and that snow is cold. But physics assures us that the greenness of grass, the hardness of stones, and the coldness of snow, are not the greenness, hardness, and coldness that we know in our own experience, but something very different. The observer, when he seems to himself to be observing a stone, is really, if physics is to be believed, observing the effects of the stone upon himself."
-Bertrand Russell

Reductionism and Emergence: What Kinds Of Things Are There, Really?

If you accept the hardness of the Hard Problem, you believe that it would be impossible, even in principle, to build and program a computer to be fully, qualitatively conscious the way we are. As we have seen, this reasoning extends to our own brains. Whether our substrate is zeros and ones in the form of electrical impulses in silicon, or wet gray brain matter, you just can't get there from here, as the old joke goes. If we take the Hard Problem seriously, we have to bite the bullet of claiming that we are missing something big and fundamental in our conception of how the world is put together. No mere implementation detail will solve the problem of qualia. No one in a lab coat will discover some hitherto unknown neurotransmitter that will explain consciousness, nor will any systemic analysis of the brain reveal some higher-level organizational schematic that will show how the redness of red came to be.

No, to crack this nut, we have to go deep, and do a little philosophizing about the nature of our universe and the ways we have of thinking and talking about it. Science is great, physics is wonderful, but they specify particular results in particular situations, and there are more and less conservative ways of interpreting the claims of science. Moreover, there are methods of thought in science that can become, over time, philosophical commitments in their own right. Chief among them is the doctrine of reductionism.

Reductionism

Galileo concluded that large objects must fall at the same rate that small ones do by using an ingenious thought experiment. First he imagined two rocks, roughly the same size, dropped from some height, falling at whatever rate rocks of their size fall. Then he imagined that the experiment were repeated, this time with the rocks tied together with a piece of string. Are we really to imagine, he wondered, that Nature would regard the two rocks tied together as one large object, and make it/them fall at a different rate just because they were now connected with a string? He reasoned that Nature would not. When does Nature treat things as actual, individual things, and when does Nature treat them as heaps, or aggregates of other things, like Galileo's rocks tied together? And perhaps more importantly, in what sorts of situations would the answer make any difference?

For an honest hard-nosed reductionist, the universe is really a sea of quantum soup. There are no true inherent things, just one continuous mesh of cause and effect. Minds, and only minds, draw boxes and lines upon reality based on perceived regularities, chunking reality into mid-level murmurations, like "rocks" and "cars". This chunking is an abstraction we impose, and is not there in the quarks, electrons, and photons. We could, in principle, see a certain number of molecules as a "rock", or we could just see it as a bunch of molecules with no loss of accuracy or predictive power. Everything worth knowing about the rock is straightforwardly derived from the properties and interactions of the bits that make it up. It is something of a joke among philosophers that they sometimes argue over whether something is a table or just a bunch of molecules arranged in a tablewise manner. It's not that tables and chairs don't exist, just that the universe does not respect these "high level" entities or any properties of them, as such, as it decides what to do moment to moment. All the universe needs to function properly is the very lowest level entities and laws and everything else pretty much takes care of itself.

"Reductionism" is a loaded term, and one that tends to get thrown around pejoratively. Daniel Dennett has said that at this point, "reductionist" means nothing more than "I don't like that idea." When I use the term, I will attempt not to make a straw man of it. Reductionism, very roughly, is the divide-and-conquer approach to understanding reality. It is the position that anything just is the sum of its parts. Sometimes philosophers like to say a thing is grounded in its parts, or supervenes on its parts. Once you have nailed down the behavior of the pieces, there are no more degrees of freedom left to the wholes that are made of them.

Reductionism combined with deterministic physicalism results in the claim that if you knew the exact initial conditions of the universe, and knew the true laws of physics, you could, in principle, predict everything that would ever happen during the lifetime of the universe, including the fall of the Roman empire and the Gettysburg Address. There are no big, large-scale things that can not be understood (in principle!) in terms of their simpler, small-scale underlying constituents and their mechanisms.

Now, sometimes reductionism means methodological reductionism, which is simply the practice of analyzing things in terms of their components. Methodological reductionism, as an approach to scientific inquiry, has been spectacularly successful over many centuries. When I speak of reductionism, however, I mean it in a stronger, ontological sense. I mean the presuppositions that:

  1. everything in the universe is made of simple building blocks
  2. anything we choose to study may, in principle if not in practice, be defined and described completely in terms of the simpler building blocks of which it is made
  3. there is a finite (and small at that) number of types of these basic building blocks
  4. each instance of a particular building block is interchangeable with any other instance of that same building block (one electron is absolutely identical to another electron)
  5. these building blocks are entirely characterized by their functional dispositions (i.e. they have no qualitative essence, just behavior, such as that described by the lowest-level equations of physics)

There are a great many isms in philosophy of mind, many of them downright deceptive, in that their literal meaning does not suggest a doctrine held by most people to whom the label is applied (I'm looking at you, "dualism"). So in theory, whether you are a physicalist, a dualist, a monist, a dual aspect theorist, a qualophile, an eliminativist, an illusionist, a mod, or a rocker, I think this question cleaves the community nicely: do you believe that everything in the universe can be exhaustively characterized in terms of a small number of types of tiny things, all interacting via causal dynamics, which are described by a small number of mathematical laws? You can answer "no" and still make a case that you are a monist, and in fact, a reductive physicalist, but only by squeaking in on a technicality. Most good reductive physicalists, as the term is generally understood, answer with an emphatic "yes".

My point is that this philosophical reductionism does not necessarily commit one to a particular scientific view. You can hold onto reductionism and admit that we still don't have all the physical laws nailed down yet (strings? Unifying general relativity and quantum mechanics?). If we suddenly discovered that Harry Potter magic is real, we could still be good reductionists: how does it work? Take it apart, see what particles, fields, and/or forces make it up, and derive a small number of mathematical rules that describe their behavior, and viola!

So the difference is not which final theory you settle on, and exactly which primitives you admit into your lowest level, as long as they are few in number, are well behaved, and don't have any "essences" lurking beneath that behavior. Indeed, it is really more of a spectrum of views than a sharp division. How many primitives can there be, how big can they get, and how unlawlike and complex can their behavior be before you just aren't a reductionist anymore?

Many prevailing theories of mind incorporate some form of strong ontological reductionism, even ones that make a point of claiming to reject strict reductionism. I think, however, we have reason to doubt that reductionism in this sense gives us a true or complete picture of the world. The problem is that it works too well. If everything can be explained or characterized in terms of the lowest level building blocks, there is no reason to consider higher level things as having any objective existence at all, or at least, any explanatorily useful existence. As the saying goes, once the reductionist has broken down the universe, he has trouble building it back up again.

How can we have things in a reductionist universe? By things, I mean just what it sounds like: cars, dogs, planets, paper clips. Is a pile of sand a thing, or is it a lot of little things? Does a car count as a thing? It depends on how you look at it, and why you want to know. What things can there be whose existence (as individual things) is not just a matter of perspective in this way? And do we have any reason to believe that there are any higher-level things in the world that just are the high-level things they are, whether you look at them in the right way or not?

If we are reductive materialists, then speaking absolutely objectively, there is either only one (extremely high-level) thing in the entire universe (the universe itself), or there are as many (extremely low-level) things as there are subatomic particles. There is no absolute reality to any intermediate level things as such. Their existence and all of their properties are may-be-seen-as, and derivative.

It does not buy you anything (in terms of imparting thinghood) to declare certain systems as unitary wholes on the basis that they are isolated from their surroundings, because everything interacts with everything else all the time. This is not New Age mysticism, but simple fact. The force of gravitation between any two objects is proportional to the product of their masses and inversely proportional to the square of the distance between them. This number is never zero for any two objects, no matter how small the masses or how great the distances involved.

I once read somewhere that the gravitational effect of an electron on the trajectory of a molecule of gas a universe away is such that after being amplified by about 50 collisions with other gas molecules, this tiny gravitational nudge is enough to cause the gas molecule's position to be off by the width of a entire molecule. This, in turn, determines whether or not the molecule collides with the next molecule at all or misses it entirely, a difference which quickly changes the dynamics of the entire volume of gas. Whether the correct number of collisions before this happens is really 50 or 50 million, there is some finite number of which this must be true. All particles in the universe interact causally with all others all the time (the contents of black holes possibly excepted).

But still, one might argue, there are some things which act more or less together as one, and are separable from their environment. Consider a toy truck. It seems thing-like if anything does. But just as the computer program does not "know" anything but the current machine code instruction, the truck is just made of atoms, each of which does not know or care anything about "truck" as opposed to all the other atoms that are "non-truck". Each atom only "knows" about the forces that act upon it, and each reacts accordingly. Each atom would still behave the way it does under the influence of any equivalent immediate environment (local to just that atom, that is) whether that environment was the result of that atom's participation in what we might be inclined to call a "truck", or some other, completely different system, as long as it presented the exact same interface to the atom. The atom does not act the way it does because of some high-level organization of the system of which it is a part. A complete knowledge of the forces acting immediately upon each atom in the truck is all that is necessary to have complete and perfect knowledge of the patch of reality that we call "the truck". It gives us complete predictive power over all of the atoms involved, at any level of detail you like. In a completely objective reductionist universe, there is nothing to know about the truck above and beyond all these atoms.

Once we have a complete causal picture of a bunch of atoms, we are certainly free to posit mid-level things as a cognitive convenience, but they better not, as such, have any causal powers. Otherwise, we wind up with what the philosophers call an overdetermined world, and William of Occam warned us about those. We use his razor to cut out any multiplied explanations. One is enough, thank you very much.

Downward Causation

Sometimes people speak of "downward causation", which is not merely causation in the physical direction of down, like rain or snow, but causation from the "high levels" to the "low levels". That is, in a system made of interacting parts, the system as a whole has causal effects on its own parts (in a top-down fashion) beyond what we can account for in a purely bottom-up analysis of the parts themselves and their individual causal powers. In real life, this makes no sense.

We, as human engineers, may model a device in our minds, then design a system and implement that design in our workshop using a bunch of parts. While it is easy to think of the parts as actively participating in the "whole system", and doing what they do because of their participation in the "whole system", the parts are still blind, stupid, and amnesiac. They do what they do under the same influences as they would if they weren't part of a system. The individual parts do not know or care anything about any larger system. Of all the forces impinging upon a given part, these forces could be the cumulative effect of some complex system, or they could be purely local. The part does what it does as a result of the influence of these forces either way. Almost no one, when push comes to shove, actually makes a contrary claim. In a universe of big things made of little things, the little things call the shots. Physics and stamp collecting, as Rutherford put it.

I should emphasize that the ability, for example, to reduce chemistry to physics is an in principle reduction only. No discoveries in the field of physics will ever render chemistry (or biology, or sociology, etc.) obsolete as fields of legitimate inquiry. Even in a universe in which reductionism is absolutely true, the physical world is hugely complex, and its complexities explode out of control very quickly in a chaotic fashion without any hope of being modeled at the low levels by beings with our limitations. It will always be astronomically easier to deal in terms of higher-level chunks of reality than in subatomic terms for almost all purposes (meteorologists, your jobs are safe for the foreseeable future). Nevertheless, in principle, if you could model reality at the low level in a reductionist's universe, that would be all you would need to derive any measurable fact about that universe. Any higher level chunking of reality is a cognitive convenience. Put differently, the universe has no need of any "high level" things or concepts as it clanks along one moment to the next. All of the causal heavy lifting is done at the lowest level.

Teleology

Talk of downward causation is closely related, if not identical, to teleology. Aristotle wrote about causation, and he divided it into categories, the only ones of which anyone remembers are his first, efficient causation and his last, final causation. Efficient causation is the kind we deal with when we speak of billiard balls colliding. A causes B because A came first, and straightforwardly exerted a causal influence (pushing from behind, as it were) and brought about B. Final causation, in contrast, has to do with goals and purposes. Telos is the Greek word for such future states of affairs and the effect they have, drawing things forward, pulling from ahead. The telos of an acorn is to become an oak tree.

There is a subtlety here, however. Aristotle was talking about causation as it manifested itself in events, spaced out in time: A causes B. Here, we are talking about things, as they exist in a snapshot, more constitutive causation than sequential causation. The point, however, is the same. The steady march of scientific progress for centuries has been characterized as the banishment of teleology from serious discourse. Anyone who invokes final causes is speaking poetically or magically (the giraffe has a long neck so it can reach the leaves). A ton of molecules, some of them DNA, banging around for eons, subjected to constant Darwinian winnowing, have the effect of seeming like teleology, that's all. Survivable, adaptable systems survive and adapt, and the ones that don't, don't. For the most part, we know we are exercising a bit of literary license when we speak as if the acorn wants to become an oak tree. By the same token, we should feel funny if we say that a particle behaves differently because it is part of a larger system. I'm not saying that we should never speak in teleological terms. As a panpsychist, I am comfortable getting a little freaky, but we should know that we are saying something freaky when we speak of these kinds of powers.

Emergence

It is sometimes said that higher level properties and thus higher level things emerge from the lower levels in a way that is not determined or even suggested by the lower levels. The flock emerges from the motions of the individual birds, liquidity emerges from the actions of trillions of H2O molecules. The claim that there is genuine emergence in the world is often contrasted with reductionism.

There are several flavors of emergentism (and the closely related theories of so-called nonreductive physicalism), but most of them do not dig their way out from under reductionism as they claim to do. This is because emergence usually reflects nothing more than a cognitive limitation on our part. We are just not smart enough to infer the liquidity directly from a complete knowledge of the H2O molecules. There is no objective, measurable property of a bucket of water (including facts about the liquidity of the water) that one could not, in principle, infer given:

  1. a complete and perfect description of each atom of hydrogen and oxygen in the bucket (i.e. a complete set of initial conditions)
  2. a complete and perfect set of physical laws that described the behavior of hydrogen and oxygen atoms through time as they interacted
  3. the vast cognitive power it would require to model all those atoms and calculate their interactions

In general, we are stupid - it is easier by far to frame our understanding of the world in high-level terms, to understand "water" as "sloshing" in certain ways, and even to come up with precise laws about the ways in which water sloshes. But this is just a shorthand way of describing what is actually the aggregate motion of trillions of molecules. This shorthand description does not tell us anything that could not, in principle at least, be derived from the trillions of molecules themselves - its advantage is that it is so much easier to deal with. As David Chalmers has pointed out, emergence is a psychological concept: it is a measure of our surprise at the consequences of low-level natural laws, not a fundamental truth of Nature in its own right. Emergence is a reflection of our faulty intuitions, perceptions, and/or cognitive powers. There are no high-level facts or properties that "emerge" only at the high level. A bumper sticker slogan sometimes invoked by emergentists is "more is different", but actually more only seems different.

It is, perhaps, a tacit recognition of fact that emergence is somewhat weak tea when it comes to explaining the universe around us, that in recent years it has been rechristened "weak emergence". This also distinguishes what I'm talking about here from so-called "strong emergence", which is a whole different kettle of fish.

More to the point, emergence (invoked in this way) strikes me as an attempt to dodge the Hard Problem by paying lip service to the idea of qualitative (or qualitative-adjacent) essences (like the liquidity of water, and "higher-level" properties in general) but placing the problem out there in the world, when it is really in here, in our minds. There is no liquidity in the world, except that which is directly inferable from the actions of the H2O molecules (in which case the "emergence" of liquidity melts away as a concept capable of explaining anything), but there is a wetness quale in our minds.

The problem that emergence tries to solve (or at least articulate) is the Hard Problem that dare not speak its name. Proponents of most forms of emergentism and nonreductive physicalism are trying to straddle the fence. On one hand, they have some inkling that strict reductive physicalism is inadequate to account for the universe as presented to us, but on the other hand, they are unable or unwilling to make the freaky metaphysical commitments (to bite the bullets, as it were) that are necessary to address these inadequacies. They don't want to have to build any magic into the ground floor of their universe, so they try to slipstream it in somewhere in the middle. The sad truth, however, is that we need real magic here, and all mid-level things in a reductionist universe are only may-be-seen-as kinds of things. The only magic you can slipstream into the mid levels, then, is may-be-seen-as magic.

Scene from the movie The Matrix In a purely reductionist universe, with no absolute thinghood above the subatomic level, no natural mid-level principles of individuation, and everything just more or less dense patches in the quantum soup, I imagine that the mind of God is like that of Neo at the end of the movie The Matrix. If you have not seen it, I urge you to do so - it is great fun and very well done, and touches on some themes that are relevant to discussions (to quote David Chalmers again, don't bother with the sequels).

Much of the action in the movie takes place in an extremely realistic computer simulated reality ("the matrix" of the title). While the characters are really comatose in reclining chairs with data feeds plugged into the bases of their skulls sometime in the distant future, they perceive themselves to be walking, driving, fighting, etc. in late 20th century America. At the end of the movie, the hero, Neo, has an awakening while in the matrix as he confronts the sinister Agents who want to kill him (virtually dying while in the matrix results in actual physical death). The final confrontation had a great special effect in that it captured the essence of an inherently non-visual idea and did so simply and clearly. Neo sees the outlines of the floor, the walls, the ceiling, and the three Agents, but all of their surfaces from his point of view are a wash of iridescent green computer characters, the same ones that were on the screens in the matrix's monitoring center back in physical reality. Neo sees through the matrix, stops accepting it on its terms, and sees straight down to the level of the data of which it is made. And of course, this essentially makes him God within the matrix.

In a reductionist universe, God (if there were God in a reductionist universe) sees everything this way. His mind tracks every last neutrino with perfect accuracy, and He does not have to use our shortcuts of chunking patches of reality into "whale", "bridge", "apple". It is only a consequence of our own perceptual and cognitive limitations that we find it necessary to chunk the universe into "flocks" or even individual "birds". In real life, there are no higher levels. The universe, to a reductionist, models or computes itself at the lowest of all possible levels. Once all the hydrogen and oxygen atoms follow their basic laws, there is neither any need nor room for any further laws about "liquidity", "transparency", or any other high-level properties of water in order for the universe to "know" how water should behave instant to instant. The universe crunches along, doing what it must, not because of any patterns or any way in which such patterns are organized, or because of their purported complexity but because the particular particles with their particular positions and momenta must do what they must do. "Patterns" are a way of categorizing reality for us, a way of setting up a taxonomy of classifications of what are ultimately physical systems. You can't possibly get any magical new properties to "emerge" out of a collection of stuff because it is "complex", above and beyond what you would have gotten out of that same collection of stuff anyway. Anything that is really, really there at the high level must have been really, really there at the low level.

If, that is, we are committed reductionists.

How Naive Is Our Naive Realism About Our Mid-Level Chunks?

There is nothing wrong (in the sense of being incorrect) about our mid-level chunking of reality so we can avoid being eaten by tigers, forage for grubs, etc. any more than there is anything wrong with seeing an apple as red.

Philosophical realism is the claim that the world out there is pretty much as it seems to be. In particular, realism about X is the claim that if X seems a certain way, it's because X is actually that way. If that sounds vague, there is a reason for it - realism can be taken in a variety of different ways. Realism, often modified with "naive", is a position of taking things at face value, and not overthinking them. Naive realism about experience means that if I see something that looks like a red apple, that conscious event corresponds to an actual red apple in the real world. The apple appears red to me because it really is red, period. The apple reflects photons of red light, and they get absorbed by my retinas, and my brain faithfully registers the information that there is a red apple in front of me. Naive realism takes the mind to be merely reflecting the reality out there.

Naive realism in this example is not true, however, because of course there are no red photons. That is, while things seem red to us, all that really strikes the retinas in the backs of our eyes are photons of certain wavelengths. These wavelengths are just numbers representing a particular periodicity that the photons display. There is nothing in those numbers that suggests redness as we experience it. The association between wavelengths of light in a certain range and redness is one our minds make up out of whole cloth. Color is just the mind's way of representing different wavelengths of light, but we could have evolved to use some completely different representation with no loss of information about the real world.

Consider the inverted spectrum argument. If someone were born with their optic nerves cross-wired in such a way that when they were shown red it looked green to them and vice versa; so that in effect their perceived color wheel were rotated by 180 degrees, they might never know it. They would receive the same information about the world, and they would learn the color names as a small child, and they would agree that a sunset is a deep orange, but it would not really look orange to them the way it does to you. It would look teal, but they would call it "orange".

The inverted spectrum argument is usually made to convince people of the distinction between cognitive information and ineffable qualia: my inverted spectrum twin has the same information about the world that I do, but entirely different qualia. I am using the scenario to make a different point, however. It should be clear that, given me and my inverted spectrum twin, there is no fact of the matter of which of us is seeing the "right" view of the world. There are photons, there are perceived hues in the mind, and there is a correspondence between the two. The question of what is the "correct" correspondence between the two just doesn't make sense, since in both cases the actual mapping is arbitrary.

Color as perceived - that is, full-blown qualitative, experiential color - serves as a very good carrier of information that comes into our bodies by way of photons striking the retina, but one could speculate on other ways. Perhaps some alien species could consciously discriminate between all the wavelengths of color that we do, but perceive them through some sort of tactile radar-sense, or some other sense modality we can not even imagine. Similarly, while the sensation of redness conveys certain information to us in our visual field, that same sensation could conceivably convey different information. Perhaps our sense of smell could be wired into some perceptual field of color, for example.

If there are no red photons, and color exists only in our minds, what about sounds? By a similar argument, there is no middle C "out there" as it sounds to us in our mind's ear. There are just periodic pulses of fluid pressure. Hot and cold are just the aggregate motion of huge numbers of molecules and similarly could conceivably be represented in our minds with completely different qualia. The same could be said of pressure against skin, smell, and taste. Our qualia are only in our minds, and they are created there.

So at this low level of the qualitative sensory aspects of our world, naive realism is false. Assuming that we can claim to know something about the real world, that the world as we experience it internally is in some way like the world out there, at what level of abstraction does realism start to become true?

I would like to suggest that realism is false at a higher level of abstraction than we generally assume. That is, more of the things we think we perceive about the world are created in our minds than we acknowledge. The real world (almost certainly) exists, and its reality constrains what we perceive, but does not determine it. Most of the structures, patterns, and dynamics of the world are "really" out there and exhibit a lot of the regularities we think they do in the same sense that photons of certain wavelengths are really out there. But as with the redness of those photons, the ways in which we experience them are not really out there. Things are abstractions. We create all things, we infer unity and mid-level individuation in the world.

Seen in this light, consciousness has a much bigger job than just painting the apple red. It must create reality much more broadly, including the apple itself. Just as there are no red photons, there are no rocks, cars, dogs, or numbers. Nature presents us with a wash of particles, a continuous flux of quantum stuff, and we overlay this flux with stories about cars and rocks. Moreover, this story, and the way we create it, is not "merely" cognitive, not just one of Chalmers's "easy problems". There is as much a what it is like to think of an apple, as such, as there is to taste it. If we end up deciding, as I have (stay tuned for the next chapter), that there are inherent, mid-level things in our phenomenal consciousness (and not just qualities like redness, saltiness, and itchiness) and these mid-level things are just as irreducible to parts as the redness, then we have a big ontological bullet to bite indeed.