Tuesday, May 24, 2016

A review of Sean Carroll's The Big Picture: Part II

We are continuing our survey of physicist Sean Carroll's book The Big Picture (Part I here) by moving on to his second section of the book entitled Understanding.

This part of the book is where Carroll puts forward his epistemology, which he calls "poetic naturalism." He does a great job of articulating his case, and is very thorough and covers many topics while not sacrificing depth. In fact, there were many times where I thought to myself "but what about X?" and, sure enough, that would be the very next topic Carroll addressed. Also, Carroll's first chapter in this section is a great primer on Bayesian Reasoning for laymen -- he explains it beautifully with simple and common-sense examples.

Contrary to what many might think, I actually agreed with Carroll on many aspects of his epistemology -- he does make some correct predications. But obviously I do not agree with it all, since it is, after all, a form of naturalism.

That being said, let us dive into the material and see what Carroll has to say.

Bayesian reasoning
Bayesian reasoning, based on Bayes' Theorem, is foundational to abductive reasoning. It gives you, in principle, a very logical and matter-of- fact way of forming beliefs and updating them in light of new observations and information. It is a way of making inferences to the best explanation -- the very type of inferences science is interested in.

I have no qualms about Bayesian reasoning itself, only about when it can, and cannot, be applied. Bayesian reasoning is useful for (and really is) abductive reasoning, however, it is irrelevant to deductive reasoning. For if a deductive argument is sound, then the truth of the conclusion is guaranteed, whereas nothing guarantees an inference predicated on abductive reasoning. On the contrary, abductive reasoning deals with probabilities, and this should make sense since Bayes' Theorem is itself a theorem dealing in probability.

Why is it important to contrast Bayesian inference with deduction here? Well, because Carroll seems to pay little attention to deduction and focuses mainly on abduction (for reasons we'll survey below). This isn't a problem in itself, but it becomes one when one realizes that many arguments that attempt to demonstrate the falsity of naturalism are deductive in nature.

In any event, Carroll also claims the following:
Each of us comes equipped with a rich variety of beliefs, for or against all sorts of proportions. Bayes teaches us (1) never to assign perfect certainty to any such belief; (2) always be prepared to update our credences when new evidence comes along; and (3) how exactly such evidence alters the credences we assign. It's a road map for coming closer and closer to the truth. (p. 82-83)

On first glance this seems like a great point, and I would, in most cases agree. Bayesian reasoning is indeed a fantastic "road map for coming closer and closer to truth." However, contrary to Carroll's claims here, there are beliefs that are (to borrow a phrase from the presuppositionalist camp) preconditions of intelligibility. That is to say, there are beliefs and propositions that are necessary conditions for any sort of intelligible epistemology, and because of this it follows that such beliefs must be certain and cannot be "updated" or revised pending any new evidence (again, see below). One such proposition is the law of noncontradiction. This is a belief that we can be absolutely certain about, especially since any denial of it, even in principle, requires that it be true.

Poetic naturalism
I briefly expounded PN in the last post, yet there wasn't much space devoted to it. That's because the current section is where Carroll largely unpacks this epistemology.
[O]ur best approach to describing the universe is not a single, unified story but an interconnected series of models appropriate at different levels. Each model has a domain in which it is applicable, and the ideas that appear as essential parts of each story have every right to be thought of as "real." Our task is to assemble an interlocking set of descriptions, based on some fundamental ideas, that fit together to form a stable planet of belief. (p. 4) 
This brings us to the "poetic" part of poetic naturalism. While there is one world, there are many ways of talking about it. We refer to those ways as "models" or "theories" or "stories"; it doesn't matter. (p. 94) 
[S]omething is "real" if it plays an essential role in some particular story of reality that, as far as we can tell, provides an accurate description of the world within its domain of applicability. (p. 111)
 Again, on first glance there isn't much to quibble with here. It is true that certain models and theories regarding parts of reality, with their respective vocabularies, only need to be utilized in their respective domains of inquiry. Talking about free will and volition on the macroscopic scale of human experience utilizes a different model, and different vocabulary, than the models utilized when inquiring into the nature of atoms, electrons, and other subatomic particles.

However, the pertinent questions that need to be posed regarding this epistemology are the following: (1) Carroll places a lot of weight on models being "useful," and this utility being the litmus test for labeling something as "real," but what determines whether a specific model is useful, and why is utility important for our epistemology in the first place? Also, why should the fact that it is useful to describe reality using different models at different levels dictate what the actual nature of reality is, in principle?  (2) Are there other ways of talking about or modeling the world, besides PN?

Note that Carroll attempts to answer (almost) all of these questions. So, it's not as if he hasn't thought this through, and he probably wouldn't at all be fazed by any of them. However, that doesn't mean that his answers are convincing.

(1) is a question, or set of questions, that Carroll attempts to answer:
The question, however, is whether a particular way of talking about the world is useful. And usefulness is always relative to some purpose [...] "useful" means "providing an accurate model of some aspect of reality." (p. 143)
It is important that our models are accurate representations of some aspect of reality, however, this is not the traditional meaning of usefulness. Something is not useful if it accurately reflects a part of reality, rather something is useful if it can serve a practical purpose. Now, it is true that models that accurately reflect reality tend to be more useful than models that do not, but this doesn't mean that the latter is defined in terms of the former. This might seem like a minor quibble, but one problem with Carroll's PN is that throughout the section he constantly equivocates between both of these definitions. Sometimes "useful" is used as "serving a practical purpose" and other times it's used as "provides an accurate model of a part of reality."

What's the problem though (as if equivocation is not bad enough)? The problem is that the two definitions utilized by Carroll are sometimes mutually exclusive -- that is, there are times when a "model" or "story" can be useful even though it fails to accurately reflect reality. Carroll actually demonstrates such with his own example: he highlights the phenomena of transgender individuals -- people whose gender identity is different than the gender they were assigned at birth. Carroll says that if someone born male identifies as a female, then if this identification is "useful and meaningful" (p. 142) then why not identify them as a female? The problem here is that no matter how "useful" it is to identify someone as a female, this doesn't entail the fact that they are, in reality, a female.

Carroll doesn't see this as problem since he believes that classifications like male, female, and even human, are "human inventions." (p. 142) He claims these categorizations are not illusions because they are useful and meaningful in the contexts that we apply them. But again, something being useful does not necessitate that it accurately reflects an aspect of reality, and therefore it is possible that something be useful, yet be illusory.

And even worse for Carroll, the claim that a classification like "human" is a human invention is actually self-defeating. For to say that something is a cognitive construct of the human mind, one needs a nature of  "humanity" to objectively obtain. That is to say, for one to assert that something is a human invention necessitates that "human" be an objective referent, and not just a construct. So the proposition that the concept human is a human invention literally contradicts itself.

While Carroll doesn't comment on question (2) directly, he does make the following comment:
Poetic naturalism is at least consistent with its own standards: it tries to provide the most useful way of talking about the world we have. (p. 112)
Carroll is correct that PN is prima facie consistent with itself, but what about when we delve a bit deeper and consider the implications of question (2)? That is, is PN the only, or even the most useful, model, or story, of reality?  Well, surely it's not the only model of reality: there are a multitude of different ontologies. Ok. So then how do we determine which model is most useful? Well again, it depends on how Carroll is using the word useful.

If by "useful" Carroll means "serves a practical purpose," then it's not clear that PN is the most useful way of talking about the world. Moreover, how, on PN, do we even determine the most useful, or practical, way of talking about reality? It seems that we would need some idea regarding the fundamental nature of reality to be able to say model X is more useful than model Y. But then, is this "idea" about the fundamental nature of reality itself merely another "story" or "way of talking about the world" on some narrow domain? If so, then we're right back to the problem at hand wherein we need to determine how we know that this "model" or idea is "useful." What this means is that you can't have an ontology founded on nothing but "stories" and "ways of talking about the world." At some point you need a concrete ontology that describes how nature objectively operates, and this entails that you can't have an ontology that is purely "poetic", as Carroll uses the term here.

Moreover, if by "useful" Carroll instead means "providing an accurate model of some aspect of reality," then we run into the same problems. For, again, in order to know that a model is an accurate model of reality, we need to know something objective about the behavior and nature of reality that is not just another "way of talking about it" -- otherwise we go round and round in a circle again.

Carroll then promulgates an emergentist ontology to make sense of different models of the world at different levels:
One pivotal word enables [the] reconciliation between all the different stories: emergence [...] A property of a system is "emergent" if it is not part of a detailed "fundamental" description of the system, but it becomes useful or even inevitable when we look at the system more broadly. (p. 94)
I do agree with Carroll that there are "emergent" phenomena. There are many such examples one could give of such phenomena, and Carroll gives a good explication using his own examples. But how does emergentism help PN? Carroll explains:
[E]mergence is about different theories speaking different languages, but offering compatible descriptions of the same underlying phenomena in their respective domain of applicability. (p. 100)
So emergence is a way to continue talking about the world at different levels, wherein the higher levels usually "emerge" from the lower levels.  This is all well and good, and so far I have no bone to pick with Carroll here, in principle. Where I might begin to disagree is if Carroll, later on in the book, tries to explain away something like consciousness as merely a "model" or "way of talking about" human experience that only applies at higher levels. (I haven't read the whole book yet, so if he does argue this then we can cross that bridge when we get there. )

Rationalism vs. empiricism
Since Carroll's epistemology is heavy on science and Bayesian reasoning, it should come as no surprise that he advocates a form of empiricism. That is, he believes that we can only know things about reality by looking at it and observing it. He contrasts this with rationalism wherein it is believed that knowledge comes intuitively without any need for empirical observation.

Carroll surveys the case usually given in justification of rationalism wherein the proponents appeal to the domains of mathematics and logic. Carroll argues against such an appeal by claiming that in both math and logic we simply derive consequences from differing axioms. This is, in a sense, correct, at least for math. For example, Euclidean consequences follow from Euclidean axioms, and non-Euclidean consequences follow from non-Euclidean axioms. But we need to actually look at the world to be able to determine whether it can be described by Euclidean or non-Euclidean geometry. No problem there.

However, there are those, like myself, who claim that there are axioms and necessary truths that must hold in any possible world at all. One example of this, as was already mentioned above, is the law of noncontradiction. This is not an axiom that might only hold in certain worlds, but might possibly fail to hold in others -- as in the case of Euclidean geometry. Rather, it is a necessary feature of having any kind of a reality at all. There is no axiom of non-contradiction and axiom of non-noncontradiction; there is only the former.

There are other propositions that are also claimed to be axiomatic and necessary -- e.g. law of identity, PSR, principle of causality etc. -- but I need not defend them presently. The point is that there are indeed things that we can know a priori, that is, without having to actually look at the world to justify them.

Carroll considers this point (briefly), and claims the following:
If we were thinking deductively, like a mathematician or logician, we would say that no collection of particular facts suffices to derive a general principle, since the very next fact might contradict the principle. (p. 135)
This seems to be quite absurd. For according to Carroll's reasoning, for instance, we cannot say the law of identity is an immutable principle, because we might one day come across something which is not identical to itself. This seems silly, and it should, because we already know intuitively that identity is a precondition of intelligibility of any thing that will ever exist. And so it goes with all other necessary truths. Now, there may not be many necessary truths with which we can know a priori, but there are a few, and they are a very crucial aspect of one's metaphysic.

All of this is important because it goes against Carroll's PN, as well as his form of empiricism. For if there are propositions that are necessary truths, then these truths aren't merely "models", "stories", or "ways of talking about reality." Rather, they are immutable principles that hold throughout any domain and any level, and cannot be shoved aside by the thought that one day we could discover them false. This is like saying that one day we might find someone who is successfully married and a bachelor.

Part III

Saturday, May 14, 2016

A review of Sean Carroll's The Big Picture: Part I

Physicist Sean Carroll's new book The Big Picture: On the Origins of Life, Meaning, and the Universe Itself was released this past Tuesday (yay!). I, as well as many others, have been greatly anticipating the release of this book ever since Carroll announced it himself, and it's a pleasure to finally have it in my possession, and to be reviewing it.

I pretty much figured, before the book was released, that I would take up the task of writing a review. I felt this way because Carroll is an extremely articulate and modest philosophical naturalist and has been securing more of a secular following as of late--especially since he debated William Lane Craig, and, in my opinion, won--and I was very curious as to how he would make a cumulative case for a coherent naturalist metaphysic. And after beginning to read the book I do in fact feel that there are many things to comment on, as I had hoped. Though I obviously disagree with Carroll on many of his positions, Carroll's humble and unboastful attitude coupled with his articulate writing make this a great read.

So, on with the review, then. Carroll's book is split into six sections: Cosmos, Understanding, Essence, Complexity, Thinking, and Caring. I am, so far, planning to write a review on each section individually, though it might be the case that I don't have many comments to make on a particular section, and thus I might not review all of them. This Part I review will focus on the section labeled Cosmos.


 Carroll begins the book by asking some important questions about the fundamental nature of reality, and stressing the importance of thinking about ontology. It is among this discussion of ontology that he begins advocating for philosophical naturalism. But Carroll's naturalism does not merely claim that all that exists is the natural world exhibiting patterns. Rather, Carroll introduces what he calls poetic naturalism. The "poetic" aspect of poetic naturalism (PN) is constituted by how we talk about, model, and interpret reality. Carroll describes this view:
[O]ur best approach to describing the universe is not a single, unified story but an interconnected series of models appropriate at different levels. Each model has a domain in which it is applicable, and the ideas that appear as essential parts of each story have every right to be thought of as "real." Our task is to assemble an interlocking set of descriptions, based on some fundamental ideas, that fit together to form a stable planet of belief. (p. 4)
This explication of poetic naturalism is very similar to two theories I've surveyed in the past, namely Model-Dependent Realism, as promulgated by Hawking, and Embodied realism, as promulgated by Lakoff. The key aspects of this philosophy are that we, as humans, talk about and describe different aspects or "levels" of the world using different models and different vocabularies, and that, as long as these models are consistent and coherent, they can overlap and reconcile with one another.

Unfortunately, Carroll doesn't delve too deep into this philosophy in the first section. Rather, he spends more space expounding this perspective in his second section Understanding--which should make sense since the "poetic" aspect of this philosophy is mostly epistemic. Therefore, I will save my comments on poetic naturalism until the next installment of the review.

One way that Carroll attempts to demonstrate the "layered" models of reality we conceptualize, as predicated by PN, is with Aristotle's notions of natures and causes. For Aristotle famously promulgated the principle of causality, which stated that something can only be "moved" if it was caused to do so by something else in motion. (Of course, by "motion" Aristotle really meant change, and by change he really meant something which is being reduced from potency to act.) But Carroll claims that the conservation of momentum has relegated such notions to mere useful macroscopic descriptions and constructions:

[T]he whole structure of Aristotle's argument for an unmoved mover rests on his idea that motions require causes. Once we know about conservation of momentum, that idea loses its steam. [...] What matters is that the new physics of Galileo and his friends implied an entirely new ontology, a deep shift in how we thought about the nature of reality. "Causes" didn't have the central role that they once did. The universe doesn't need a push; it can just keep going. [...] Of course, even today, we talk about causes and effects all the time. But if you open the contemporary equivalent of Aristotle's Physics--a textbook on quantum field theory, for example--words like that are nowhere to be found. We, still, with good reason, talk about causes in everyday speech, but they're no longer part of our best fundamental ontology. (p. 28-29)
I have a couple comments at this point. First, the conservation of momentum--which is embedded in Newton's law of inertia--doesn't, at all, call Aristotle's idea of motion into question. For, again, Aristotle said that when something changed, this required something responsible for that change. But uniform inertial motion is seen, as explicated by physicists, as a state in itself, and not a change per se. That is, the state of motion of an object is its velocity, and thus an object with a uniform state of motion is an object that is moving at a constant velocity--as long as it is not being acted upon by an unbalanced force--and thus is not changing, according to physics. Therefore, the conservation of momentum does not at all run counter to Aristotle's metaphysical principle, in fact, it is completely irrelevant to the principle.

Second, it is simply not true that talk of causality, at least efficient causality, is absent from contemporary scientific textbooks. In fact, it's ironic that Carroll specifically mentions quantum field theory textbooks since in An Introduction to Quantum Field Theory the authors write the following: The necessity of having a multiparticle theory also arises in a less obvious way, from considerations of causality[...] In a relativistic theory, this conclusion would signal a violation of causality. (p. 14)

These points may seem peripheral, but I believe they are important for a couple of reasons. First, the unmoved mover argument of Aristotle, if valid, would defeat a naturalist ontology, which Carroll holds. Yet, Carroll quickly dismisses Aristotle's unmoved mover argument, in light of the supposed irrelevance of concepts of causality, yet he does so fallaciously. Again, this isn't that big a deal since Carroll's thesis is not predicated on discussing Aristotle's proofs for God. Nevertheless, his fallaciously swift dismissal of the efficacy of causality is still a strike against his case.

Second, Carroll is trying to score a point for poetic naturalism by claiming that the language of causality is only a folk theory constructed from interactions at the macroscopic level, and isn't part of our "fundamental ontology" and has no utility in the domain of physics. Yet the fact that this has been demonstrated to be false with the quote above (one of many) already begins to poke holes in Carroll's form of naturalism. That is, we see that a concept like causality is not simply a model that only applies in one limited domain. Rather, it in itself should be part of one's fundamental ontology.

Carroll also makes much of the fact that causality is nowhere to be found in the laws of physics, and claims that such concepts are "emergent":
We look at the world around us and describe it in terms of causes and effects, reasons why, purposes and goals. None of those concepts exists as part of the fundamental furniture of reality at its deepest. They emerge as we zoom out from the microscopic level to the level of the everyday. (p. 54)
This is not correct, though. While it is true that causality is not palpable in the mathematical equations of physics and quantum physics--though we shouldn't expect it to be, since causality is not quantitative--this does not mean that causality is not operative and efficacious as it pertains to "reality at its deepest." I maintain that causality is ubiquitous at every turn, in the microscopic and macroscopic levels of reality.

To see this, consider the famous experiment conducted by physicist Hendrick Casimir in 1948. Casimir placed two metal plates one ten-thousandth of a centimeter apart in a quantum vacuum. As one might logically theorize, these plates would stay put, since the space is empty and thus there are no forces to affect the plates. But they didn't stay put, rather they were driven towards each other! And the first question that should come to one's mind is "Well, what was the cause of this effect?" It turns out that the cause is that there is an imbalance between the quantum fluctuations in between and outside the plates, and this imbalance yields a pressure imbalance, which pushes the plates together.

The point here is that, contra Carroll, causality is no less efficacious in a quantum vacuum than in our familiar everyday lives, and causality does simply emerge as we "zoom out" from the microscopic to the macroscopic.

Reasons Why
Carroll also spends a good amount of the first section discussing our constant search for "reasons why" things happen or why facts obtain. He agrees that the search for explanations is extremely rational and makes sense in our everyday lives. Where Carroll draws the line is when one makes this search for explanation a metaphysical principle (e.g. the Principle of Sufficient Reason) that pronounces that everything must admit of explanation, or a "reason why." This is, no doubt, a very modest and logical position to take. Carroll is not committing one way or another to whether all things and facts admit of explanation. He humbly claims that they might or might not, and leaves the door open to the possibility of brute facts.

However, as one who does in fact believe that all things and facts must necessarily and logically admit of explanation, I do not agree with Carroll here. And I find that his arguments against the PSR to be rather weak. Carroll claims that "[o]ur standards for promoting a commonsensical observation to a 'metaphysical principle' should be very high indeed. "(p. 41) Now, I would agree here, but Carroll really doesn't survey any concrete arguments actually given (besides Leibniz's Principle of the Best) that would attempt to demonstrate why the PSR should be taken as a metaphysical principle. He merely says the following:
[F]or every fact we notice about the universe: as soon as we apprehend it, we think there must be a reason behind it. This isn't an argument that the Principle of Sufficient Reason is logically incontrovertible; it only implies that we often act as if something like it were true. If we're honest, it's an empirical, evidence-based argument, not an a priori one. (p. 42)
I agree with Carroll that this argument he has articulated is not a priori, and is not logically incontrovertible. The problem is that no (logical) person attempting to establish the PSR as a metaphysical principle would use this argument, especially since it's just an inductive argument which cannot form an immutable principle at all.

The type of arguments that are given in favor of the PSR (and that are a priori) consider the nature of epistemic chains of explanation themselves. And they argue that explanation forms an instrumental and transitive chain, so that if even one member of a chain is unexplained (i.e. is a brute fact) then the chain as a whole loses efficacy. (Indeed, I have argued that very thing here, though I don't expect Carroll to have read my own specific post.) The point is that Carroll has not done the appropriate philosophical leg-work to dismiss the PSR as casually as he has done. And again this is important because the PSR puts a wrench in the works of his poetic naturalism, and also calls into question many other pronouncements he makes in the book, as we'll see in subsequent reviews.

The arrow of time
More importantly, in Carroll's eyes, the denial of the immutability of causality and explanation, as well as the displacement  of their existence as a mere human convention of utility, is ultimately illuminated by the increase in entropy and the arrow of time:

"Memories" and "causes" aren't pieces of our fundamental ontology describing our world that we discover through careful research. They are concepts that we invent in order to provide useful descriptions of the macroscopic world. The arrow of time plays a crucial role in how those contexts relate to the underlying time-symmetric laws of physics. (p. 66)
Carroll's point is that we only utilize concepts like causality and explanation because events progress from past to future, due to the arrow of time. This is to say that such concepts are contingent upon the direction of time, which is itself a contingent fact of the universe and could have been otherwise. But the laws of physics, on the other hand, do not have an arrow of time imprinted into them, and thus, as Carroll claims, concepts like causality and explanation are not carving reality at its joints, but are only concepts that humans constructed in order to make sense of the world as we interpret it. For had the arrow of time been in the opposite direction, things would be very different, as would our concepts and models.

Now, while it is true that if the arrow of time were pointing in the reverse direction, from future to past, events in the world would unfold in a completely counterintuitive and foreign manner, this would still not remove the necessity for concepts like causality and explanation. For explanation and causality are always present wherever things exist and behave, and wherever events and processes occur. And even in a universe where the arrow of time were reversed, you would still have things which exist and events which transpire; and as long as you have that, you have causes and effects, as well as explanations.

So I maintain that Carroll has not demonstrated how humans "invent" these concepts, and again,  this is important, because Carroll's poetic naturalism in founded on the idea that these concepts are human constructs and models, invented through our interaction with the world on the macroscopic level due to utility. However, if these concepts are not cognitive constructs but are immutable principles embedded in the fabric of reality, then Carroll's form of naturalism loses ground.

Part II

Monday, May 2, 2016

Consciousness and emergence

Let me preface this post by articulating the fact that I don't view my following comments as a rigorous philosophical treatise on the topics of consciousness or emergentism. Rather, this post is more in the form of a random collection of my thoughts, which may or may not be right, on said topics.

Consciousness continues to present problems for any physicalist or materialist philosophy of mind. Theories like eliminative materialism, functionalism, and identity theory seem, by some, to fall short of accounting for the peculiarities of consciousness such as intentionality, qualia, and the "illusion" of free will. Some of these problems and difficulties have caused a preemptive adherence of materialists to another philosophy of mind: that of emergentism.

Emergentism, as a philosophy of mind, holds that properties, patterns, or realities of consciousness are novel qualities that emerge from the interaction and configuration of their constituents. These qualities are called "novel" because they do not exist--either in the same degree or even in the same kind--at the substrate level of their aggregate parts. An example of this emergence is given by the quality of solidity. That is, the table I'm currently typing at is solid and firm, yet this quality is not found, and least not at all in the same sense, in the particles and atoms that make up this table. In fact, it is said, the atoms are mostly empty space, and "solid" is one of the last adjectives we would use to describe them. Thus, the solidity of the table would seem to emerge upon the configuration of the constituents.

How does this help physicalism/materialism? Well materialists famously have trouble accounting for how compositions of particles, atoms, and neurons which are not intentional and conscious can produce qualities antithetical to those very parts. However, we see cases all around us, evident in the table example, of component parts generating emergent properties that the parts did not themselves possess. So, it is said, it might very well be the same with regards to the brain and consciousness. For if a set of aggregate parts X1 can produce an emergent quality Q in light of the fact that each element in X1 does not possess Q then it is at least in theory possible that consciousness and the qualities therein can emerge from mere particles and neurons.

Now while I admit the possibility of emergentism as a philosophy of mind, I don't at all find it to be persuasive, nor do I believe anyone has come close to demonstrating its validity. Let me articulate my reasons for the former. First, we've only discovered two reasons that a quality might emerge from certain constituents: 1) emergence from mere structure, or 2) proto-emergence. In 1) a quality is generated strictly from the arrangement or structural relation of its constituents. An example of structural emergence is a box that has the property of "containment". The pieces that makes up the box do not harbor this property, but when these pieces are arranged a certain way, we see the emergence of the ability to contain--and it is the structural relation that grounds this emergence. In 2) the qualities of the component parts produce the same quality, but to a higher degree, in the emergent property. An example of this proto-emergence is a magnetic field emerging from charged iron atoms. This is proto-emergence, and not structural emergence, since each iron atom is itself a little bit magnetic, and thus all of these magnetic iron atoms together generate a magnetic field.

So, why is the distinction above important? Well, it seems that if the qualities of consciousness are emergent then they would need to be either structurally emergent, or proto-emergent. But, and here's where the problem arises, we know that consciousness cannot be the result of proto-emergence, since particles, atoms, and neurons are not themselves conscious, or intentional, and do not exhibit qualia, and no amalgam of non-conscious constituents can generate a conscious property through proto-emergence. Thus, proto-emergence is not a possibility for the materialist. But what about structural emergence? This seems to be a dead end as well. For while there are many mysteries yet to be uncovered about the brain, it's structural physical arrangement and components are quite well known. Neurologists know all about the mechanics of neurons, axons, dendrites, synapses, and the like--the building blocks of the brain. And yet, there is nothing about the arrangement, structure, and pathways between these components that would yield the properties of consciousness.

Again, I don't want to stretch this too far as if what I've said is a knock-down argument against emergentism--it's not. But what we've surveyed so far does paint emergentism in an unfavorable light, and puts a burden on the one who wants to claim that the ontology of emergence can adequately account for the most pervasive human experience--consciousness. I'll end on a note from philosopher James Madden:
[T]here is absolutely nothing about the chemical processes occurring within neurons with which we are remotely acquainted that in any way explains the fact of consciousness. Of course ignorance of an explanation does not entail that there is no such explanation, but we should ask ourselves how likely such an explanation is given our general understanding of the world. The probability, as far as we can tell, seems to be exceedingly low.