Sunday, August 25, 2013

Science, the Roots of Nature, and the Branches of Knowledge

I'm always going on and on about how great science is. I know I do it too much, and some of my friends are probably a little mystified (and a little irritated) by this behavior. I think I might be to blame for that, because I may not have adequately explained my point of view. Or...maybe I'm just being a pain. Anyway, in this post, I'd like to explain why science is such a big deal to me, why it strikes me as so beautiful and powerful, and why I think it's harmful when it's ignored or denied.

My outlook is heavily based on science, but it's not an outlook all scientists or science buffs share. In fact, I first started thinking hard about science when I got irritated by a bunch of scientists. I was in graduate school studying animal behavior. Some of my professors were psychologists and some were biologists. Most were brilliant people, but I couldn't believe how obsessed some of them were with their own little specialty, and how little regard they had for other disciplines. The biologists looked down on psychology, and the psychologists from different perspectives (behaviorists and cognitivists, for example) looked down on each other. It seemed to me the world was big enough for all these perspectives to be true, at least partially. In fact, it seemed like combining insights from many fields would be a great way to learn more about all of them. But many of them didn't see it that way.

Anyway, all this got me thinking about fragmentation in human ideas in general. People today have a million different worldviews, ideologies, and perspectives. Such diversity can be a good thing, but it can also lead to mutual misunderstanding and contempt, as well as confusion about what's really true. What I wondered was, is there any point of view that could be seen as universal? Is there any way to find unity in all that diversity?

Well, I thought, nature is one source of unity. Whatever our ideology or nationality, we all live on the same planet and belong to the same species. We all breath the same air and look up at the same moon. We're all related—we share a common evolutionary heritage, and somewhere back there, we all share a common ancestor. We're even made of the same parts--each of us is made of the same kinds of cells, which are made of molecules, which are made of atoms, and so one. In fact, if I leave out “same species”, all the commonalities I've mentioned above don't just apply to humans. They apply to every animal on earth. Many of them apply to every living thing on earth, and some of them, like “made of atoms” apply to things across the entire universe. We all live in the same natural world, and it existed long before all the ideologies we hold so dear. It's the ultimate source of common ground.

So there's that. But how do we know these things about nature? Some are obvious to anyone, but most of them were discovered by scientists. If nature is a source of unity, then science is too, because science is our best method for figuring out how nature works. That's how I see science. When I think of science, I don't think of laboratories, or computers, or space probes. Those are just tools. I see science primarily as a means of understanding nature—not just nature as in “what you see when you leave the city”, but nature in the sense of the entire universe; the grand cosmic order of things. For me, science is a way of understanding how the universe works, and how—at least in the physical, factual sense—we fit into it.

And one thing science has shown us repeatedly is that we are not what nature is about. Copernicus showed we aren't at the center of the universe, and Darwin showed we are related to all the other living things on earth. It's not that we're not special—we are in many ways—but we're still a young species among several million others on a tiny little fleck of a planet that is one of countless trillions in the universe. We shouldn't get too big for our britches.

But most people have never really taken those lessons to heart. To hear them talk, you would think the human world and the natural world were two separate spheres, with the human world by far the most important of the two, as in the image below. In this view, science is just one of many human pursuits, and it's seen as having as much to do with technology as nature. 

The reality is different, and more like the next image. We're actually just a small, odd subset of nature. We're not an exception to nature's basic laws, but an unusual elaboration on them. People talk about things being "unnatural", but we actually can't do anything truly unnatural, in the sense that it would violate fundamental natural laws and exist outside of nature. What we do might be stupid and destructive, but it can't be unnatural in the deepest sense. We aren't that powerful. Anyway, in this view, science is like a telescope looking outward from the human sphere to try to understand the wider world we are a part of, and the laws by which it operates. It's not just a way of making better gadgets.

So. We are a part of nature, and science is our best way of understanding nature. What does that tell us about the problem of intellectual fragmentation? How does this shed light on how different branches of science are related, or how other important branches of knowledge, like ethics or the arts, fit in to the landscape of ideas? 

I think the first step in understanding this is to take a bit of a detour, and think about how reality is like a layer cake, or a set of nested Russian dolls--it has many levels. The whole universe is a great hierarchy of parts and wholes. Particles combine into atoms, and atoms into molecules. All these things combine into stars, planets, and nebulae; which in turn combine to form galaxies. Even galaxies combine into clusters and superclusters. Here on Earth, there are even more layers. Atoms and molecules combine in intricate ways to form living cells, which combine to form living things, which can combine into larger social groups, like an anthill or IBM. 

As you move up and down this hierarchy, you find that each whole system has emergent properties that aren't present in any one of its parts. A brain can do things a single neuron can't, and even a water molecule can behave in ways that the oxygen atom inside it couldn't on its own. There's nothing magical about this, it's just whole systems have different structures than their parts, and that gives them different properties, which you can't see if you focus on the part alone. The image below illustrates this with simple geometric shapes.

The fact that wholes have these holistic properties is the reason each level of nature needs to be studied at its own level. If you want to understand biology, you have to know something about chemistry, because it describes the atoms living things are made of. But you also have to study processes at a higher level than atoms, such as cell division or the evolution of species. Those things are just as real as the chemical reactions they are ultimately based on.

When you look at this hierarchy of parts and wholes, there are some very interesting trends we see as we move up and down the scale of complexity.The first, obviously, is that most parts are simpler than wholes. A subatomic particle is simpler than an atom, an atom is simpler than a molecule, and a molecule is simpler than a cell. Another obvious fact is that parts are more numerous than wholes. There are more atoms than cells, and more particles than atoms. Parts also tend to be older than wholes--not necessarily the part itself, but the category it belongs to. Atoms have been around longer than molecules, which have been around longer than living cells, which have been around longer than multicellular organisms. Finally, parts tend to be more universal. Particles, atoms, and molecules can be found throughout the universe, and they obey laws that seem to hold throughout space and time. Cells, as far as we know, only exist on earth, and they follow the more complex and less universal laws of biology. Even more complex whole systems, such as human societies, follow even less universal laws.

None of these trends are absolute--you can find many exceptions--but they are clear trends. You can combine all of them and think of the hierarchy of structure in the world as a big pyramid, as in the image below.

But this image leaves out something important. Whole systems are far less numerous than parts, but they are (or have the potential to be) far more diverse.There are untold gazillions of subatomic particles in the universe, but they only come in a few types. Atoms are somewhat more diverse--there are just under 100 naturally-occurring elements. But there are millions of kinds of molecules. There are also millions of species of living things. It's like letters and sentences. There are only 26 letters in the English language, but each can be repeated over and over again. Letters aren't very diverse, but they're very numerous. If you surveyed everything ever written, you would obviously find more letters than sentences, but sentences are endlessly diverse. In other words, whole systems are fewer in number, but far greater in kind, than their parts. The pyramid above doesn't capture that. A better image would be a tree, where a few roots give way to many, may branches. Superimposing the tree image on the pyramid, we get the image below, which sums up the changes we see from the bottom to the top of nature's hierarchy.

Where did this hierarchy come from, and why the changes we see from bottom to top? The answer, I'm convinced, is that nature's hierarchies were built up gradually over time in the evolution of the universe. Scientists today are almost unanimous in thinking that everything in the entire visible universe began in one place and time, in the Big Bang. That's why there are common features across the whole universe--it all shares a common origin. At first there was just a seething sea of subatomic particles, interacting according to the most basic laws of physics. But some of those particles combined into wholes called atoms, and some of those combined into wholes called molecules. As the pyramid of complexity grew, nature got more diverse. Here on earth, nature got extremely diverse and complex, as the first living things evolved and diversified over the eons into the millions of organisms we see around us today. Whole new layers of complexity and diversity were added when humans appeared, grew big brains, and started developing complex cultures--giving rise to things like art, philosophy, technology, and politics.

And that brings us back to the issue of intellectual fragmentation. I think the idea of an evolving hierarchy of structure in the world can help us figure out how the different branches of knowledge fit together. Consider the image below.

When you think about different branches of knowledge in terms of the hierarchies of complexity in the world, this gives you a clear way of arranging many of them. Each one has its place, and can't be collapsed into another. It describes the world at a certain level, where there are emergent properties that don't exist at lower levels. You don't want to try to understand what an artist was trying to say in a painting by learning more about the chemistry of pigments. That's looking at things at the wrong level; collapsing everything into science and forgetting about emergent properties. On the other hand, you don't want to try to explain a scientific idea, like the origin of humanity, with mythology. Mythology has its place, but that's not it. The point is, there doesn't need to be any conflict between the humanities and the sciences. They simply describe the world at different levels. In fact, the humanities may not even be about describing the world at all, but about creating new ways of looking at it. Each point of view has its own strengths.

Still, as I said above, I do think the natural sciences are vital. They describe nature at its most fundamental, universal levels. Physics is the most fundamental science, because it's concerned with nature's most basic particles, forces, and laws--which exist throughout the universe. Chemistry is slightly less fundamental, because it focuses on how atoms interact to form different kinds of matter, and not everything in the universe is made of whole atoms. But chemistry and astronomy both concern processes that occur across the universe, so they are pretty universal. Biology is far less universal, because it is concerned with life, which as far as we know only exists on this little speck of a planet. But what biology lacks in universality, it makes up in complexity and diversity.

What I'm trying to say is that the natural sciences describe the roots of nature--it describes where all that diversity converges into the fundamental unity of the natural world. Science is how we understand that huge circle above labeled "Nature". It's not the only valid way of seeing the world, but it is an essential one, because the facts it uncovers about nature are the same no matter what our ideology. If the facts are well-established, and our ideology conflicts with them, then the ideology needs to be revised. That's why science could be a source of unity in human ideas. It tells us about the biggest branches in the tree of knowledge. It tells us how nature works, how we fit into it, and where we come from. EO Wilson once pointed out how economists and politicians like to talk about "the real world", but they forget that nature is "the real real world." The natural sciences allow us to understand the real real world.

But people don't often realize that; sometimes not even scientists. For one thing, science is often presented as being primarily about technology, or as a way of predicting or controlling the world, rather than simply understanding it. And science is taught piecemeal. Teachers don't talk enough about how the different sciences fit together--how biology is grounded in, but transcends, chemistry, and how chemistry is grounded, but transcends, physics. The idea of nature's hierarchy of emergent forms isn't common enough, which may be why people think things like art and physics are in competition, when in fact there's plenty of room for both.

I think a great way of explaining the basics of science, and many other branches of knowledge, and how they all fit together, is to tell the story of how the universe evolved. When you talk about the birth of the first particles and atoms in the Big Bang, you automatically talk about the basics of physics. Talking about how the most of the elements in the periodic table were forged inside exploding stars is a great way to make chemistry a little more exciting. When you talk about early living cells on earth, you automatically talk about many of the common features all living things share, such as DNA, cell membranes, and the basic types of organic molecules. Discussions of human evolution naturally lead into anthropology and archaeology, and those naturally lead into history, which touches all the other, more recent, branches of knowledge. Of course, human history, and even life on earth, have little effect on the history of the universe as a whole. What a history like I'm describing would really do is trace a particular set of branches on nature's tree of diversity--zooming inward from the universal limbs of physics and cosmology into the branches we inhabit here on earth, as in the image below, or the one at the top of the page.

Of course, writing a big cosmic history like that would be a pretty tall order. I know--I tried it once, and it quickly got bigger than I could handle (not to mention bigger than most people will read). But I still think it's a good idea. Maybe I'll try to write a shorter version someday, covering just the natural sciences. Maybe even a super-abbreviated one; one that could fit in one of my standard, overly-long blog posts. Maybe. But not today.


My attempts: (More successful)