22 July 2016

A Layered Approach to Reality. Part II.1


What I aim to do in the rest of this essay is make some observations and generalisations about the relations between levels of description. A "description" is way of talking about reality, though I have scientific theories at the forefront of my mind. The focus is on description rather than reality itself, though my view is that our descriptions are based on objective knowledge that we have inferred about a mind-independent, though entirely natural, reality through critical observation and comparing notes. What I call Collective Empirical Realism is similar in some ways to Object-Oriented Ontology. It seems that Realism is in the process of making a come back in academic philosophy (for what it is worth). In this sense, one could read this essay as an attempt at a naturalist ontology, though it is not compulsory. The levels of description seem to me to reflect the way that reality is organised into hierarchical levels of structure. I don't say this with any metaphysical certainty, but I think the picture is accurate.

This idea of a layered hierarchy of structure based on a fundamental substance seems to me to be far more productive than either reductionism or antireductionism considered on their own. The problem being that reductionism tries to ignore structure; while antireductionism tries to ignore substance. Acknowledging both allows for a much more interesting discussion.

While I think the ontological implications of this approach are natural and intuitive, we are on much safer ground discussing the epistemology and methodology of this layered hierarchical approach to the world. In two parts I will now outline some properties of hierarchical layers of description and draw out corollaries that I think are important for how we understand ourselves and our world.


~ Key Points About Levels of Description ~


Part 1.
  • Descriptions of the universe typically apply within a few orders of magnitude and break down as scale changes in either direction, requiring new descriptions.
  • This happens because structures are real.
  • Hence, descriptions of the universe are necessarily layered and there is a hierarchy of sciences.
  • Levels of description are mostly autonomous.
  • What applies to one layer does not necessarily apply to another.
  • Therefore, we cannot collapse levels of description, even in principle.
  • The higher the level of description a scientist is working at, the less interest they have in structure reductionism.
Part 2.
  • Lower level descriptions are more general and apply more widely to the universe as a whole; higher level descriptions more specific and apply more narrowly to subsets of the universe.
  • Lower level descriptions are more susceptible to be described in mathematics; higher lever descriptions require the use of narrative.
  • Lower level descriptions can only produce generalisations about higher levels of description, not complete descriptions.
  • The further apart levels are, the more general the generalisations produced.
  • If structure reductionism works at all, it becomes less plausible or applicable the further up the hierarchy one is working.
  • Higher level descriptions usually say nothing about lower levels.
  • A lower level description cannot specify or anticipate an autonomous higher level property. 
  • Properties, such as determinism, do not propagate upwards through layers of description.
  • Arguments about freewill, values, morality or other high level properties based on fundamental physics are incoherent because they use the language of a different level.
  • Our approach to "levels" is anthropocentric.
  • We are still stumped by how mind fits into this picture. Which means that any conclusion about the ontology of mind is premature

~ Commentary ~

  • Descriptions of the universe typically apply within a few orders of magnitude and break down as scale changes in either direction, requiring new descriptions.
Scale is vitally important in any account of the world, precisely because of the discontinuities that it causes in our descriptions. The observable universe covers about 60 orders of magnitude from the Planck length to the furthest galaxy. In energy, the range is over 100 orders of magnitude.

The incompleteness of a physical theory is almost always brought to light by extending the scales of reality that can be observed (i.e. scales of mass, length, and energy). The inventions of the telescope and the microscope, at roughly the same time in the early 17th Century, both produced revolutions in our understanding of the universe at scales beyond which our human senses work. Increasingly sophisticated versions of each have brought us to a number of watersheds that changed our view of the world we live in and our place in it. New discoveries about the mechanics of the universe are still being made at the extremes: distant galaxies and very high energy particle collisions.

The importance of scale is overlooked by many people searching for similarities between traditional Buddhist knowledge and science knowledge. The knowledge gained from doing Buddhist practices is psychological and thus high level. Importantly this means it is completely unrelated to the science of substance or any of the science of structure at the level of biology and below. For example, there is no connection, and can be no connection, between traditional Buddhism and quantum mechanics. Buddhist theories about living things are also unrelated to modern theories of biology. However, we may find correlations with higher-level scientific theories from the domains of psychology and sociology. Worse, many Buddhist doctrines are metaphysical speculations, i.e. things we believe to be true, but for which there is and can be no evidence. Like our supposed theory of causation, which I will deal with in a separate essay. There is no way to correlate speculative metaphysical doctrines from Medieval India with modern scientific knowledge. Myths that might have served a purpose in the Iron Age do not necessarily serve that purpose now. Times change.

  • This discontinuity happens because structures are real.
The substance of the universe is a relatively straightforward problem. The world is made of fields. But matter is also made into things. When matter is made into things, those things have properties that cannot necessarily be explained in terms of the lower level properties. In many cases, complex wholes (or systems) are greater than the sum of their parts. And importantly, many structures bestow an apparent causal potential on complex objects. So reducing everything down to the simplest level is not a way to explain the world, because important aspects of the world are left out of reductionist accounts. Particularly life and consciousness. 

Allowing for real structure alongside real substance makes for a much richer view of the world without some of the problems of substance antireduction (dualism, pluralism) or metaphysical reductionism. It also explains why we need levels of description and allows for descriptions to be autonomous: we can talk about chemistry in terms of atoms without having to reduce everything to quantum fields. Being sensitive to scale, we can treat atoms as real on the atomic scale, not as substance, but as complex objects with a real structure. 

The reality of structure is where I disagree with metaphysical reductionists and probably with most Buddhists. Buddhists labour under two misapprehensions:
  1. Existence = permanence. This axiom of Buddhist doctrine is demonstrably false and has confused Buddhists for centuries (see Buddhism and Existence); and 
  2. Metaphysical reductionism; the whole is only the sum of its parts. This is apparently required to eliminate any essence (ātman), but it eliminates any structure as well. 
The trouble seems to be the supernatural. If we eliminate the supernatural, we are left with the natural world in flux, but with persistent (though not permanent) real structures that in no way support the idea of a soul. Indeed, the Naturalist critique of the soul is far more powerful and comprehensive than the Buddhist critique.

I also disagree with Sean Carroll on this issue. Carroll's Poetic Naturalism has many attractive features and I largely agree with him. However he makes an awkward distinction between what he calls weak emergence and strong emergence. These labels more or less align with epistemic structure antireductionism and ontological structure antireductionism. Carroll is enthusiastic about epistemic structure antireductionism. The "poetic" part of Poetic Naturalism refers to the fact that our various descriptions are "stories" that we tell about the universe. Stories about the world apply to layers that are autonomous, with the caveat that they cannot break the laws of physics. 
"Something 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." (Carroll 2016: 111). 
That is to say that for Carroll a "story" is an epistemological statement related to what we know about the universe and how we express it. However, he also contrasts "real" with "fundamentally real", which shows that his ontological commitment is to reductionism.

In Carroll's discussion of what he calls "strong emergence", he suggests it is characterised by downward causation: the whole affecting the parts. But ontological structural antireductionism does not seem to require downward causation. It does requires two things: firstly, that the whole is greater than the sum of its parts, i.e. higher level properties are real in an ontic sense rather than an epistemic sense; and secondly that complex objects are causally potent on their own level. The molecule need not affect the behaviour of its own atoms, but it surely does affect the behaviour of other molecules. 

It is difficult to pin Carroll down on this point because he uses "ontology" synonymously with "story" or "description", but he defines it in epistemological terms as a form of knowledge. Ontology ought to be used more strictly to refer to what exists, not to stories about what exists, which is the domain of epistemology. His ontology is that quantum fields are fundamentally real. So although he cheerfully admits to the reality of atoms, for example, he clearly believes that they are not fundamentally real. In other words he does not accept the reality of fields, but he does accept the necessity of descriptions which contain atoms. This is fine as far as it goes, but I think we can go further. 

  • Hence, descriptions of the universe are necessarily layered and there is a hierarchy of sciences.
This approach to describing reality has inherent discontinuities related to scale, which seem to be related to discontinuities in reality caused by structuring. That is to say that because structures can have unique properties, we find that we are forced to develop level-specific descriptions. These descriptions are autonomous, in that they do not depend on lower levels, though they cannot contradict them or break the fundamental laws of physics.

So, for example, we use physics to describe the structure of the atom; but chemistry to describe the behaviour of the various atoms interacting; biology to describe matter organised into living cells; and psychology to describe the functioning of our minds. Even if we were to stipulate that it is possible to use lower level descriptions, it is almost never practical. Low level descriptions take on enormous unwieldy complexity when applied to higher levels. This renders them practically useless at best, but also useless in principle as well. Quantum field theory is utterly useless in the field of psychology. Atomic theory is useless in sociology.

For all that metaphysical reductionism dominates public discourse on science, our universities have departments of chemistry, biochemistry, geology, microbiology, zoology and so on. And this is unlikely to change. 

In other words, despite the rhetoric associated with metaphysical reductionism, in practice science is not reduced to physics. Science is mostly about higher level, non-fundamental patterns. The typical scientist is not a physicist and probably not a metaphysical reductionist. All the different sciences and many of the subdivisions produce descriptions of the world that are domain or scale specific and deal with real phenomena.

The argument over whether this epistemology accurately reflects an ontology (whether what we talk about as real is in fact real) is far from settled and may never find a consensus, though for the purposes of discussing the dynamics of levels of description it does not matter how the mapping of description onto reality works. Though of course we can say that it does work; often to a level of accuracy and precision that is set by the limits of our ability to measure things or the apparent limits of the physical universe. 

  • Levels of description are mostly autonomous.
We can use the description of a volume of hydrogen gas as an example. We can describe this using different levels of description. We might opt for a fine grained (lower level) description, by specifying the number of hydrogen molecules and the position, velocity of each. This would be a demanding computation, but would accurately describe the gas and it's behaviour. Or we might opt for a coarse grained (higher level) description and treat the gas as a fluid by specifying the density, temperature, and pressure of the gas. This can be in a few simple equations known as the gas laws

If we choose the coarse grained description we don't have to reference individual hydrogen molecules at all. All fluids behave the same way. If we do choose a coarse grained description, we do so without reference to a fine grained description. If we say that gas is characterised by density, temperature, and pressure, these are high level concepts that need not reference lower level descriptions such as the number of molecules or their individual velocities.

This is example of a volume of gas is one that Sean Carroll chooses in The Big Picture (2016). It has what turns out to be an unusual feature. One level maps directly onto another: the number of molecules in the volume of gas is the density; the average velocity of the molecules is the temperature. Carroll probably chose this example because the coarse-grained model is reducible to the fine-grained model. It allows him to demonstrate the value of higher level descriptions while still subscribing to a fundamental reality.

However, in most cases it is not possible to see how the descriptions at different levels are related. Levels do not typically map well onto each other so well (and it seems more likely to happen at lower levels than at higher levels). We can describe an organism, for example, from a (relatively coarse grained/higher level) biological perspective or a (relatively fine grained/lower level) chemistry perspective, but we cannot simply map one level onto the other in this case. There is no equivalent of the rule that says that the average velocity of molecules of gas equate to the temperature of a volume of gas considered as a whole. This is partly because complexity increases as we go up the levels, structure is built upon structure, and complexity of elements promotes complexity in relations between elements and between levels involving complex compounds.

A corollary of this is that no one theory of emergence is going to describe how emergent properties manifest across levels. Scale affects emergence as well.

  • What applies to one layer does not necessarily apply to another.
The lack of transitivity is most striking as we move from sub-atomic particles to bulk matter. Quantum mechanics very precisely tells us about properties/behaviour in the sub-atomic. And it does this in terms of the probability that a vibration in a field will have a particular value for a variety of parameters (position, momentum, spin, energy, and so on). Electrons for example, do not "orbit" a nucleus, but form a cloud of probable locations. If we "look" at any given time, i.e. if the electron interacts with another particle, we will "see" the electron at one location. And because of the Uncertainty Principle, the more precisely we specify the position, the less we know about its momentum (i.e. speed and direction of movement). The process of interaction involves the exchange of a virtual particle representing the expression of a force, and application of force (which includes any observation) changes the value of the electron's parameters. 

Objects visible to the human eye do not behave like subatomic particles. At all. A baseball being pitched towards a batter does not spread out, take all possible paths to the plate, and adopt a location only when the batter swings (that would make it a very different game indeed!). Nor does looking at the baseball change its speed, direction, or spin. The motion of a baseball is classical. We can precisely know both the position and momentum of the baseball at any time. Bulk matter does not obey quantum mechanics, and sub-atomic particles do not obey classical mechanics. To be sure there is a transition area. Scientists have forced a fairly large single molecule (a 60 carbon atom "bucky ball") to behave like a quantum wave; but this is at the limit and requires a great deal of tinkering with conditions. No object visible to the human eye will ever behave like a sub-atomic particle. In which case, describing a baseball in terms of quantum mechanics is pointless.

But something like this is true of all the transitions between levels. Molecules, on the whole do not behave like atoms. Organisms do not behave like molecules. Self-conscious organisms do not behave like non-sentient organisms. And so on. The fact that we require different descriptions is not something we arbitrarily impose on reality in order to make it more manageable. Levels necessarily emerge from the patterns of behaviour of the world on different scales and impose different descriptions on us.

A corollary of this is that any Grand Unified Theory of the universe will be practically useless. The first level of emergent structure will cause it to break.

  • Therefore, we cannot collapse levels of description, even in principle.
To be clear, I accept that we can always reduce substance from any level down to a more fundamental level. The world is made of fields. However, what we see when we look at the world depends on the scale we look at, at any given scale the organisation of those fields makes the world look different.

Minimally, epistemological antireductionism agrees that even if we can reduce everything in principle, that in practice the computations are so difficult as to be impractical for any computer less complex than the universe itself. Ontological antireductionism denies that reductionism works, even in principle; it would say that the organism, for example, is greater than the sum of its parts and must always be studied as an organism. 

As far as I can see, we have to accept that levels of description will always be necessary, even if we argue that our descriptions don't map onto reality. But in my view, the levels of description are imposed on us by reality and so reduction, even in principle, doesn't work for structure. 

  • The higher the level of description a scientist is working at, the less interest they have in structure reductionism.
The obsession with reductionism is very much a thing for physicists and neuroscientists. When Professor Brian Cox is talking on his BBC radio show, The Infinite Monkey Cage, he often says things like, "It's all just physics". One can hear the other scientists guests on the show wince at this.
Since physicists work in the lower regions of the hierarchy they tend not to see the really difficult cases of emergence that falsify metaphysical reductionists.

Biologists, by contrast, are seldom interested in reductionism because organisms reduced become very much less interesting. One cannot

The real surprise is that so many neuroscientists, working at the interface of biology and psychology, are hardcore metaphysical reductionists. A good number of them, for example, deny that there is any such thing as consciousness. They deny that we have subjective experiences, an inner life, or any kind of mental state. No hope, joy, fear or any of that. Understanding why this is so will prove the rule (in the old sense of testing it).

The difficult is three-fold. Firstly, few scientists distinguish structure from substance in a useful way. The reductive program in physics has been incredibly successful and it would be irrational to reject it. But without a proper distinction between substance and structure, they end up adopting reductionism across the board. It becomes a metaphysical stance. Even if this makes their attitude to structure irrational (which it does), the powerful logic of substance reductionism over-whelms any other concern. This is a good example of a powerful belief changing the salience of other information, particularly counter-factual information (as outlined in my theory of religious beliefs over a number of essays).

Secondly, consciousness is currently an intractable problem. When your career depends on saying "I know", admitting that "I don't know" is career suicide. No one ever gets published explaining that the problem is too difficult for them. Better to publish nonsense and survive, than to not publish and perish. So academia has produced a whole raft of nonsensical theories that eliminate consciousness. And it has produced a smaller number of nonsensical theories that embrace ontological dualism or pluralism. And a bunch of theories in the middle that seem quite interesting, but which struggle to reach the evidential barrier that would make them truly plausible. Long time readers will know that I favour the explanations being developed by representationalists such as Antonio Damasio and Thomas Metzinger. These seem to me to be the most interesting avenues for exploration. In a fascinating recent development Metzinger's research group is offering 10 scholarships for PhDs in neuroscience/philosophy combined with intensive training in mindfulness meditation over three years. The idea being that the candidates will combine third person and first person investigations of their experience (The Mental Autonomy Project - applications close 15 Sept 2016).

Thirdly, the field of neuroscience is bedevilled by legacy terminology. Consciousness, for example, turns out to be largely unconscious. We mostly still talk about mind as an entity rather than a process. And despite the fact that the mainstream long ago abandoned Cartesian Dualism, we still often read about, for instance, the difficulties of explaining mental causation versus physical causation. If we are not dualists, why are we still making this distinction? The point was made, quite forcibly, by John Searle in 1992, but we seem to be stuck using the terminology developed under dualism. So of course there is confusion.

The upshot is that neuroscientists are the exception to this rule because they lack the proper tools for thinking about the problem, and the problem itself seems insoluble in the terms that it is presented. However, generally speaking biologists and psychologists go through their whole career with no reference to quantum field theory. And why would they? Such lower level descriptions have little or no contribution to make at these higher level structures - quantum mechanics simply does not apply on the macro-scale. 


~ Conclusion of Part II.1. ~

In this part of the essay I've been making some broad generalisations about layers of description and about how the layers relate to each other. Part II.2, which follows, will start to draw out some finer details about the relationships that have important consequences for how we use science knowledge in philosophy (and in Buddhism). It should be finished by next week (29 July)

~~oOo~~


Searle, John R. (1992). The Rediscovery of the Mind. MIT Press.
Related Posts with Thumbnails