Emergent Complexity Pluralism

The View from Oregon – 326: Friday 31 January 2025

My paper “Peer Complexity in Big History” has been published—finally—in the Journal of Big History. It has been a long journey for this paper to eventual publication. This paper is important to me, since I think it’s the most important piece I’ve written so far that has been published. The ideas in the paper first came to me when I was on a beach on Menorca (specifically, Cala Galdana) during the summer of 2018. Since these ideas occurred to me they have shaped everything that I’ve thought since that time, and while I’ve given some minor expositions of connected ideas since that time, this is my first published statement that presents the idea in a fuller context.

The idea that came to me I have come to call emergent complexity pluralism. The sequence of emergent complexities that appear on after the other are usually presented as a linear series, but I see them rather as one pathway through a branching bush (which is the metaphor S. J. Gould used for the large-scale structure of evolution, preferring this to the metaphor of a tree of life). At each node of a complex adaptive system, when emergent properties appear, I argue that other emergent properties either appear or could potentially appear, though the exact structure of emergent complexity is, I think, subtle and cannot be appreciated without getting into the details. It is entirely possible, for example, that some emergent thresholds are tightly constrained, and can produce only a single suite of emergent properties, whereas other emergent thresholds might issue in a riot of different forms of complexity, so when I said above that the structure of emergent complexity is like a branching bush, I’m not saying that any node of emergent complexity necessarily produces a large number of further complexities, but some thresholds clearly do issue in a diversity of forms of complexity.

Such a structure becomes very complex very rapidly. Because of our selective way of viewing the record of natural history, as a chain of events that lead up to us, seen in hindsight as a regular if not predictable sequence of growing complexity, we need to look back on this history and learn to see it as a variety of complexities, each of which in turn has produced its own subsequent forms of complexity (again, not necessarily; some forms of complexity may be dead ends). So here are some simple examples: when stars formed out of primordial matter, many different kinds of stars formed. The earliest universe had a selection bias for large and rapidly burning stars (population III stars), that rapidly went supernova, enriched the interstellar medium with the results of its nucleosynthesis, and the next generation of stars (population II and then I stars) incorporated these heavier elements and the kinds of stars themselves became more diverse. Different kinds of stars were collected into different kinds of galaxies. Just as all stars are stars, and by that identity have much in common, all galaxies are galaxies, and they also have much in common, but we also have to recognize a variety of kinds of galaxies. As far as we know, only dwarf galaxies (globular clusters) that surround larger spiral galaxies produce a kind of star known as blue stragglers; some galaxies are radio loud; some galaxies have active galactic nuclei.

This is about as much as we can know about other parts of the universe without visiting them ourselves, with important exceptions—exceptions that grow as our technologies and techniques of observation improve. Within our own solar system, we can see a variety of different planets. We are now starting to get a glimpse of planets and planetary systems elsewhere, and we’ve discovered a variety of planetary types that aren’t represented in our solar system, for example, hot Jupiters, mini-Neptunes, and superearths (as they are called, by which we can see that our own solar system is taken as the norm to which all others are compared, which is anthropocentrism extended to our cosmological context). The structures of these planetary systems also differ from our solar system in interesting ways. I suspect that the more we learn about the universe, the more surprised we will be in the variations on the basic themes that we know from our own solar system.

Stars, galaxies, planets, and planetary systems are all forms of emergent complexity, and at each threshold we find that many of each kind appear. The idea of there being many kinds of life is now very familiar, and the focus of many research programs seeking to produce related forms of life with, say, minor substitutions for the base pairs in DNA. But from the perspective of emergent complexity pluralism, we should push this back to earlier to in the sequence of emergents. What we know on the scale of the universe is that simple molecules appear throughout the universe as far as our telescopes can see. We also know that planets elsewhere in the universe can be made of different materials than the silicate planets known from our own solar system. We know this from what astronomers call polluted white dwarfs, which are the remnants of stars with bits of pieces of former planets breaking up and impacting on the surfaces of these remnants. By examining the puffs of smoke that result from the impacts, we can learn something about the composition of these former planets, and some of them are quite different from the planets of our solar system.

We need to think of different stars in different galaxies with different planets, all made from the same basic materials that we know to be present throughout the observable universe, though assembled in different ways and in different proportions. It’s not difficult to make this intuitive. When a big supernova goes off in a galaxy, it sets off a shock wave in the region and this sometimes results in star formation. The sun is one of many stars that got its start at about the same time because of a supernova billions of years ago that enriched the local interstellar medium and set up a shock wave that resulted in the formation of many stars. These stars and their planets, then, have a “family resemblance” in terms of the materials of which they are composed. Differences in the composition of a given star that explodes as a supernova will result in distinctive chemical compositions (often with distinctive isotope signatures also) of the stars and planets that form partially as a result of that supernova. If you were to travel to a part of the galaxy where the stars were formed from another supernova with different proportions of chemical abundances, you would find these different proportions of chemical abundances in the later stars and planets.

Given the possibility of emergent complexity pluralism, these different planets around different stars may assemble their basic molecules into macromolecules, minerals, and chemical compounds in different ways than they have assembled (or self-assembled) on Earth. Emergent complexities that represent the same number of thresholds of complexity from some original source of complexity I call “peers,” and this is where peer emergent complexity, in the title of my paper, comes from. There may be assemblies of basic molecules, present throughout the universe, into forms of emergent complexity that are our peers in this sense, but not the same emergent complexity as those familiar to us from Earth. So on some other planet, there may be something fully as complex as life, but not life—not even alien life, or life-as-we-do-not-know-it (as Peter Ward called it). And, just as many forms of complexity on Earth have arisen out of life—e.g., sensation, consciousness, social organization—we should think of many forms of alternative emergent complexity emerging from this peer complexity. Not just different forms of sensation, consciousness, and social organization, but distinctive and different emergent properties that represent peers to complexities like consciousness, but not being consciousness.

We are limited in our ability conceive anything so different from ourselves, and I believe this is one of the problems that we create when we project not only ourselves and our wishes and desires onto the universe, but moreover we project the kind of emergent complexity that we are onto the universe at large. In my presentations touching on emergent complexity pluralism I grasped at straws trying to find examples that would point to the radically different way we need to think about emergent complexity. We look for alien forms of life, instead of looking for alternative emergent complexity. SETI in particular jumps the shark, because its search is based on the idea of a parallel sequence of emergent complexities appearing elsewhere, down to the finest details of building radio transmitters and transmitting to us some kind of language encoded in EM modulation. It’s not that I don’t think that there are interesting things to find in the universe, but that the interesting things we will eventually find in the universe won’t be like us. Indeed, I believe that the universe is more weirdly wonderful than we can imagine at present, and this constitutes a limit for science, since science is human science created by human beings in our image. Our ability to conceptualize that which is fundamentally other is fundamentally constrained by what we are.

My first attempt to give a public account of emergent complexity pluralism was at Claudio Maccone’s big history event in Milan the next year after the idea came to me, in 2019. I got a reasonably good response, but the paper I wrote that was supposed to be included in a collection of papers from the conference fell through the cracks and didn’t get published at that time. I contacted the editors several times and nothing happened. But I continued to work on emergent complexity pluralism, sometimes at a furious pace. In the later part of the summer of 2019, after I had given my presentation in Milan, I filled three notebooks in rapid succession as I developed and filled out the possibilities of emergent complexity pluralism, and I used some of these ideas in my presentations in subsequent years, especially in a couple of my presentations to NoRCEL (Network of Researchers on the Chemical Emergence of Life) and to the Forming and Exploring Habitable Worlds conference. It was my presentation to NoRCEL at the University of St. Andrews in the summer of 2022, “How Many Branches on the Tree of Life?” that netted me the invitation to speak at Forming and Exploring Habitable Worlds in November of the same year. The ideas in these talks were all applications of emergent complexity pluralism, but nothing more came of this particular direction of my efforts.

Eventually a different paper, “A Complexity Ladder for Big History,” appeared in the Journal of Big History last year, in 2024, since that interested the editors more than my work on emergent complexity pluralism, and when I wrote an expansion of this paper that is to appear in an upcoming volume on complexity in big history, I included a lot more of emergent complexity pluralism in this, but it still wasn’t a fundamental exposition of the ideas, and this paper isn’t yet published (hopefully it will appear sometime this year). I kept pressing the case for my earlier paper that was passed over, and now it has finally appeared in print. The editors changed the title, which was originally “Peer Complexity during the Stelliferous Era,” but it was a small sacrifice to get it published, which is a kind of relief to me, since, as I said earlier, it is the framework within which my thought moves. Now I can work on other papers derivative of this and be able to refer others to this paper as the background for other arguments. For example, I have been working on a SETI paper that is based on emergent complexity pluralism, and now I have more incentive to finish this.

As with “A Complexity Ladder for Big History,” the papers collected with “Peer Complexity in Big History” in the most recent number of the Journal of Big History are to appear in an updated form in a volume (probably from Springer). So now I have an opportunity to expand and extend this argument, but I’m not yet sure how I will approach this. I can take the argument into greater detail, which is kind of what I did in my presentation on “How Many Branches on the Tree of Life?” or I can take the argument in the direction of greater generality. There is a sense in which the ultimate question I am addressing is what kind of universe we live in. While my view overlaps a lot with most contemporary scientific thought, the SETI (or Star Trek) extrapolation of this view is of a universe probably filled with simple life and with maybe a few civilizations more-or-less like ours sprinkled in across space and time. It’s this extrapolation that marks the point where I part company with most familiar conceptions of the universe.

If we ever get out there and really explore, in the way I discussed in last week’s newsletter, whether early or late, rapidly or slowly, I think we’re going to find a universe that is much stranger than we suppose, or, as Haldane famously put it, stranger than we can suppose. The conceptual framework of human beings is largely a consequence of our biology, and outside our biology we are really at sea when it comes to understanding what may be out there. But whatever may be, it will be assembled from the familiar elements, and even from familiar molecules like adenine, cytosine, guanine, and thymine that are assembled from familiar elements. Only, they will be assembled differently, and I think what this means is that the other forms of complexity that we eventually encounter are going to be nightmarish—neither animal nor vegetable nor mineral—like things that we know, but different enough to be disturbingly familiar and at the same time frighteningly alien. In short, I think we will find ourselves to be living in a Lovecraftian universe in which the other forms of complexity are incomprehensible abominations that will make some among us wish we had never sought knowledge of such things. I can imagine a scenario in which human civilization initially expands rapidly into the cosmos, but, in encountering things we cannot understand or explain, we choose to return to Earth and make of it Fortress Earth, walled off from an intimidatingly alien cosmos, and focusing on what is human, all-too-human.

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