Some time ago I discussed the question of whether the behavior of a whole should be predictable from the behavior of the parts, without fully resolving it. I promised at the time to revisit the question later, and this is the purpose of the present post.

In the discussion of Robin Hanson’s book Age of Em, we looked briefly at his account of the human mind. Let us look at a more extended portion of his argument about the mind:

There is nothing that we know of that isn’t described well by physics, and everything that physicists know of is well described as many simple parts interacting simply. Parts are localized in space, have interactions localized in time, and interactions effects don’t move in space faster than the speed of light. Simple parts have internal states that can be specified with just a few bits (or qubits), and each part only interacts directly with a few other parts close in space and time. Since each interaction is only between a few bits on a few sides, it must also be simple. Furthermore, all known interactions are mutual in the sense that the state on all sides is influenced by states of the other sides.

For example, ordinary field theories have a limited number of fields at each point in space-time, with each field having a limited number of degrees of freedom. Each field has a few simple interactions with other fields, and with its own space-time derivatives. With limited energy, this latter effect limits how fast a field changes in space and time.

As a second example, ordinary digital electronics is made mostly of simple logic units, each with only a few inputs, a few outputs, and a few bits of internal state. Typically: two inputs, one output, and zero or one bits of state. Interactions between logic units are via simple wires that force the voltage and current to be almost the same at matching ends.

As a third example, cellular automatons are often taken as a clear simple metaphor for typical physical systems. Each such automation has a discrete array of cells, each of which has a few possible states. At discrete time steps, the state of each cell is a simple standard function of the states of that cell and its neighbors at the last time step. The famous “game of life” uses a two dimensional array with one bit per cell.

This basic physics fact, that everything is made of simple parts interacting simply, implies that anything complex, able to represent many different possibilities, is made of many parts. And anything able to manage complex interaction relations is spread across time, constructed via many simple interactions built up over time. So if you look at a disk of a complex movie, you’ll find lots of tiny structures encoding bits. If you look at an organism that survives in a complex environment, you’ll find lots of tiny parts with many non-regular interactions.

Physicists have learned that we only we ever get empirical evidence about the state of things via their interactions with other things. When such interactions the state of one thing create correlations with the state of another, we can use that correlation, together with knowledge of one state, as evidence about the other state. If a feature or state doesn’t influence any interactions with familiar things, we could drop it from our model of the world and get all the same predictions. (Though we might include it anyway for simplicity, so that similar parts have similar features and states.)

Not only do we know that in general everything is made of simple parts interacting simply, for pretty much everything that happens here on Earth we know those parts and interactions in great precise detail. Yes there are still some areas of physics we don’t fully understand, but we also know that those uncertainties have almost nothing to say about ordinary events here on Earth. For humans and their immediate environments on Earth, we know exactly what are all the parts, what states they hold, and all of their simple interactions. Thermodynamics assures us that there can’t be a lot of hidden states around holding many bits that interact with familiar states.

Now it is true that when many simple parts are combined into complex arrangements, it can be very hard to calculate the detailed outcomes they produce. This isn’t because such outcomes aren’t implied by the math, but because it can be hard to calculate what math implies. When we can figure out quantities that are easier to calculate, as long as the parts and interactions we think are going on are in fact the only things going on, then we usually see those quantities just as calculated.

The point of Robin’s argument is to take a particular position in regard to the question we are revisiting in this post: everything that is done by wholes is predictable from the behavior of the parts. The argument is simply a more extended form of a point I made in the earlier post, namely that there is no known case where the behavior of a whole is known not to be predictable in such a way, and many known cases where it is certainly predictable in this way.

The title of the present post of course refers us to this earlier post. In that post I discussed the tendency to set first and second causes in opposition, and noted that the resulting false dichotomy leads to two opposite mistakes, namely the denial of a first cause on one hand, and to the assertion that the first cause does or should work without secondary causes on the other.

In the same way, I say it is a false dichotomy to set the work of form in opposition with the work of matter and disposition. Rather, they produce the same thing, both according to being and according to activity, but in different respects. If this is the case, it will be necessarily true from the nature of things that the behavior of a whole is predictable from the behavior of the parts, but this will happen in a particular way.

I mentioned an example of the same false dichotomy in the post on Robin’s book. Here again is his argument:

But consider a key question: Does this other feeling stuff interact with the familiar parts of our world strongly and reliably enough to usually be the actual cause of humans making statements of feeling like this?

If yes, this is a remarkably strong interaction, making it quite surprising that physicists have missed it so far. So surprising in fact as to be frankly unbelievable. If this type of interaction were remotely as simple as all the interactions we know, then it should be quite measurable with existing equipment. Any interaction not so measurable would have be vastly more complex and context dependent than any we’ve ever seen or considered. Thus I’d bet heavily and confidently that no one will measure such an interaction.

But if no, if this interaction isn’t strong enough to explain human claims of feeling, then we have a remarkable coincidence to explain. Somehow this extra feeling stuff exists, and humans also have a tendency to say that it exists, but these happen for entirely independent reasons. The fact that feeling stuff exists isn’t causing people to claim it exists, nor vice versa. Instead humans have some sort of weird psychological quirk that causes them to make such statements, and they would make such claims even if feeling stuff didn’t exist. But if we have a good alternate explanation for why people tend to make such statements, what need do we have of the hypothesis that feeling stuff actually exists? Such a coincidence seems too remarkable to be believed.

I am currently awake and conscious, hearing the sounds of my keyboard as I type and the music playing in the background. Robin’s argument is something like this: why did I type the previous sentence? Is it because I am in fact awake and conscious and actually heard these sounds? If in principle it is predictable that I would have typed that, based on the simple interactions of simple parts, that seems to be an entirely different explanation. So either one might be the case or the other, but not both.

We have seen this kind of argument before. C.S. Lewis made this kind of argument when he said that thought must have reasons only, and no causes. Similarly, there is the objection to the existence of God, “But it seems that everything we see in the world can be accounted for by other principles, supposing God did not exist.” Just as in those cases we have a false dichotomy between the first cause and secondary causes, and between the final cause and efficient causes, so here we have a false dichotomy between form and matter.

Let us consider this in a simpler case. We earlier discussed the squareness of a square. Suppose someone attempted to apply Robin’s argument to squares. The equivalent argument would say this: all conclusions about squares can be proved from premises about the four lines that make it up and their relationships. So what use is this extra squareness? We might as well assume it does not exist, since it cannot explain anything.

In order to understand this one should consider why we need several kinds of cause in the first place. To assign a cause is just to give the origin of a thing in a way that explains it, while explanation has various aspects. In the linked post, we divided causes into two, namely intrinsic and extrinsic, and then divided each of these into two. But consider what would happen if we did not make the second division. In this case, there would be two causes of a thing: matter subject to form, and agent intending an end. We can see from this how the false dichotomies arise: all the causality of the end must be included in some way in the agent, since the end causes by informing the agent, and all the causality of the form must be included in some way in the matter, since the form causes by informing the matter.

In the case of the square, even the linked post noted that there was an aspect of the square that could not be derived from its properties: namely, the fact that a square is one figure, rather than simply many lines. This is the precise effect of form in general: to make a thing be what it is.

Consider Alexander Pruss’s position on artifacts. He basically asserted that artifacts do not truly exist, on the grounds that they seem to be lacking a formal cause. In this way, he says, they are just a collection of parts, just as someone might suppose that a square is just a collection of lines, and that there is no such thing as squareness. My response there was the same as my response about the square: saying that this is just a collection cannot explain why a square is one figure, nor can the same account explain the fact that artifacts do have a unity of some kind. Just as the denial of squareness would mean the denial of the existence of a unified figure, so the denial of chairness would mean the denial of the existence of chairs. Unlike Sean Carroll, Pruss seems even to recognize that this denial follows from his position, even if he is ambivalent about it at times.

Hanson’s argument about the human mind is actually rather similar to Pruss’s argument about artifacts, and to Carroll’s argument about everything. The question of whether or not the fact that I am actually conscious influences whether I say that I am, is a reference to the idea of a philosophical zombie. Robin discusses this idea more directly in another post:

Carroll inspires me to try to make one point I think worth making, even if it is also ignored. My target is people who think philosophical zombies make sense. Zombies are supposedly just like real people in having the same physical brains, which arose the through the same causal history. The only difference is that while real people really “feel”, zombies do not. But since this state of “feeling” is presumed to have zero causal influence on behavior, zombies act exactly like real people, including being passionate and articulate about claiming they are not zombies. People who think they can conceive of such zombies see a “hard question” regarding which physical systems that claim to feel and otherwise act as if they feel actually do feel. (And which other systems feel as well.)

The one point I want to make is: if zombies are conceivable, then none of us will ever have any more relevant info than we do now about which systems actually feel. Which is pretty much zero info! You will never have any info about whether you ever really felt in the past, or will ever feel in the future. No one part of your brain ever gets any info from any other part of your brain about whether it really feels.

These claims all follow from our very standard and well-established info theory. We get info about things by interacting with them, so that our states become correlated with the states of those things. But by assumption this hypothesized extra “feeling” state never interacts with anything. The actual reason why you feel compelled to assert very confidently that you really do feel has no causal connection with whether you actually do really feel. You would have been just as likely to say it if it were not true. What could possibly be the point of hypothesizing and forming beliefs about states about which one can never get any info?

We noted the unresolved tension in Sean Carroll’s position. The eliminativists are metaphysically correct, he says, but they are mistaken to draw the conclusion that the things of our common experience do not exist. The problem is that given that he accepts the eliminativist metaphysics, he can have no justification for rejecting their conclusions. We can see the same tension in Robin Hanson’s account of consciousness and philosophical zombies. For example, why does he say that they do not “make sense,” rather than asking whether or not they can exist and why or why not?

Let us think about this in more detail. And to see more clearly the issues involved, let us consider a simpler case. Take the four chairs in Pruss’s office. Is it possible that one of them is a zombie?

What would this even mean? In the post on the relationship of form and reality, we noted that asking whether something has a form is very close to the question of whether something is real. I really have two hands, Pruss says, if my hands have forms. And likewise chairs are real chairs if they have the form of a chair, and if they do not, they are not real in the first place, as Pruss argues is the case.

The zombie question about the chair would then be this: is it possible that one of the apparent chairs, physically identical to a real chair, is yet not a real chair, while the three others are real?

We should be able to understand why someone would want to say that the question “does not make sense” here. What would it even be like for one of the chairs not to be a real chair, especially if it is posited to be identical to all of the others? In reality, though, the question does make sense, even if we answer that the thing cannot happen. In this case it might actually be more possible than in other cases, since artifacts are in part informed by human intentions. But possible or not, the question surely makes sense.

Let us consider the case of natural things. Consider the zombie oak tree: it is physically identical to an oak tree, but it is not truly alive. It appears to grow, but this is just the motion of particles. There are three positions someone could hold: no oak trees are zombie oaks, since all are truly alive and grow; all oak trees are zombies, since all are mere collections of particles; and some are alive and grow, while others are zombies, being mere collections of particles.

Note that the question does indeed make sense. It is hard to see why anyone would accept the third position, but if the first and second positions make sense, then the third does as well. It has an intelligible content, even if it is one that we have no good arguments for accepting. The argument that it does not make sense is basically the claim that the first and second positions are not distinct positions: they do not say different things, but the same thing. Thus the the third would “not make sense” insofar as it assumes that the first and second positions are distinct positions.

Why would someone suppose that the first and second positions are not distinct? This is basically Sean Carroll’s position, since he tries to say both that eliminativists are correct about what exists, but incorrect in denying the existence of common sense things like oak trees. It is useful to say, “oak trees are real,” he says, and therefore we will say it, but we do not mean to say something different about reality than the eliminativists who say that “oak trees are not real but mere collections of particles.”

But this is wrong. Carroll’s position is inconsistent in virtually the most direct possible way. Either oak trees are real or they are not; and if they are real, then they are not mere collections of particles. So both the first and second positions are meaningful, and consequently also the third.

The second and third positions are false, however, and the meaningfulness of this becomes especially clear when we speak of the human case. It obviously does make sense to ask whether other human beings are conscious, and this is simply to ask whether their apparent living activities, such as speaking and thinking, are real living activities, or merely apparent ones: perhaps the thing is making sounds, but it is not truly speaking or thinking.

Let us go back to the oak tree for a moment. The zombie oak would be one that is not truly living, but its activities, apparently full of life, are actually lifeless. In order to avoid this possibility, and out of a zeal for form which is not according to knowledge, some assert that the activities of an oak cannot be understood in terms of the activities of the parts. There is a hint of this, perhaps, in this remark by James Chastek:

Consciousness is just the latest field where we are protesting that something constitutes a specific difference from some larger genus, but if it goes the way the others have gone, in fifty years no one will even remember the controversy or bother to give the fig-leaf explanations of it being emergent or reductive. No one will remember that there is a difference to explain. Did anyone notice in tenth-grade biology that life was explained entirely in terms of non-living processes? No. There was nothing to explain since nothing was noticed.

Chastek does not assert that life cannot be “explained entirely in terms of non-living processes,” in the manner of tenth-grade biology, but he perhaps would prefer that it could not be so explained. And the reason for this would be the idea that if everything the living thing does can be explained in terms of the parts, then oak trees are zombies after all.

But this idea is mistaken. Look again at the square: the parts explain everything, except the fact that the figure is one figure, and a square. The form of a square is indeed needed, precisely in order that the thing will actually be a whole and a square.

Likewise with the oak. If an oak tree is made out of parts, then since activity follows being, it should be unsurprising that in some sense its activities themselves will be made out of parts, namely the activities of its parts. But the oak is real, and its activities are real. And just as oaks really exist, so they really live and grow; but just as the living oak has parts which are not alive in themselves, such as elements, so the activity of growth contains partial activities which are not living activities in themselves. What use is the form of an oak, then? It makes the tree really an oak and really alive; and it makes its activities living activities such as growth, rather than being merely a collection of non-living activities.

We can look at human beings in the same way, but I will leave the details of this for another post, since this one is long enough already.