Michael Levin: A Farewell to Physicalism

There’s a pattern you notice in science writing. Whenever a scientist is positing something he thinks is really far-out or paradigm-shaking, there will come a place in his writing when he stops and clarifies that he is not, of course, trying to cross The Line. He is not (of course!) saying that anything exists outside the material world. 

That may be the biggest sacred cow in modern science: materialism, the idea that matter is all that exists. Or, to be more accurate, physicalism, the idea that the “physical world” is all that exists. (This newer term was coined after it had become glaringly obvious in physics that “matter” is not all that exists. Since “the physical world” has proven a wonderfully flexible concept, physicalism is easier to hold on to than materialism is.) 

It’s fine to believe in all sorts of wild and daring things. You can believe in the mind, you can believe in free will, you can believe in teleology and purposiveness, you can even talk about a “vital force” — but at the end of the day, you have to pay your materialist dues and clarify that you are not invoking anything… ahem… spooky.¹ You understand that the physical world is all there is, was or, ever will be.²

Michael Levin, however, is done with all that. 

Levin is a professor of biology with appointments at Tufts University (the former academic home of none other than atheist Daniel Dennett) and at Harvard, so one wouldn’t necessarily expect him to be in the vanguard of rebellion against materialism. But that’s where he has positioned himself, with a new article (“Ingressing Minds: Casual Patterns Beyond Genetics and Environment in Natural, Synthetic, and Hybrid Embodiments,” currently in preprint) that explicitly and vehemently rejects the materialist paradigm.  

Non-Mechanistic Phenomena in Biology

Levin begins his case by pointing to emerging evidence in biology that organisms do not, as is commonly thought, develop according to a mechanistic unfolding of the blueprint coded in their DNA. There is important information in the DNA, of course. But organisms seem to develop with a goal in mind, so to speak, and are able reach that goal in spite of shifting and inherently unpredictable circumstances. This is significant, because if the circumstances and the developmental pathways necessary to adapt to them are unpredictable, then those pathways cannot have been programmed into the organism in advance. They have to be invented on-the-fly.

Some examples: If you cut a salamander’s limb off, it regenerates an identical new limb — regardless of where you made the cut. Tadpoles’ heads can be “scrambled,” but they will rearrange themselves and develop into normal frogs. Developing embryos can adapt to significant changes in the very number of cells comprising them. (In some circumstance, when only one cell is available to form an embryonic structure, the cell will wrap around itself to form the desired structure! The entire mechanism of development is changed, in order to solve an engineering problem.) A developing organism can even work around genetic problems — which is pretty astounding if you think that genes alone are guiding the development. In fact, planarian flatworms can be manipulated to grow the heads of other species of flatworms — without any genetic changes. 

Levin writes:

This illustrates the ability to creatively use genetic affordances as needed, to implement a high-level anatomical specification. In other words, an incipient newt coming into the world not only cannot predict the vagaries of the external environment, but worse yet, even its own parts are unreliable. It can’t count on having the correct copy number of genes, or the correct number or size of its cells. It must get the job done using the tools at its disposal in novel circumstances. What can it count on? It can count on the relentless competency of its agential material, honed over eons of evolution, that builds problem-solving agents (not fixed solutions to environments), and the pole star that guides its activity — the attractor in morphospace to which it must find a path. [Citations removed, as throughout this article.] 

The Platonic Paradigm 

Instead of searching for a purely physical explanation, Levin argues that this evidence points to something else entirely.  He proposes a “radical Platonist view in which some of the causal input into mind and life originates outside the physical world.”

Platonism, as far as philosophies go, is about as far from materialism as you can get. It departs from the materialist paradigm at the very root, in maintaining that, not only is not everything physical, but not everything is even particular — universal “ideals” are just as real (and indeed, more foundational in reality) than are particular things in the world. For example: in a Platonist perspective, capital-B Blue exists, by itself, apart from any particular blue object that might be out there. 

Although this idea is not necessarily intuitive, the argument for why it must be so is easy to understand: in order for a particular “blue” thing to exist, “being blue” has to be an option in the first place.³

Levin points out that respected physicists have been Platonists (e.g. Werner Heisenberg, Max Tegmark, David Deutsch, George F. R. Ellis, Roger Penrose), as well as plenty of computer scientists and mathematicians. In other words, it’s not that quack-ish of an opinion at all. (Although Levin doesn’t mention it, a number of contemporary biologists have come out as Platonists as well: University of Zürich evolutionary biologist Andreas Wagner, Discovery Institute’s Richard Sternberg, the recently departed paleontologist Günter Bechly.)

It’s not the color blue that has seduced most of these scientists away from the firm dogma of materialism, however. The most common Platonic seductress seems to be mathematics: it’s hard to deny that the world operates according to mathematical principles, and it’s hard to explain how these principles can be physical. Levin argues out that once you invoke non-physical mathematical realities as explanations, you have already left the physicalist paradigm; and yet, it is impossible to explain much in biology without such invocations. Organisms develop into exquisite patterns and structures, and these patterns and structures do not come from the physical world at all — they are mathematical. 

Levin is very taken with the fact that these beautiful structures seem to exist on their own in the mathematical world, and much of his argument rests on the fact that unshakeable mathematical rules have explanatory value for physical patterns. It’s not just that a fractal pattern (for example) might be found in a living organism — it’s that you can’t explain why that organism developed the way it did in any meaningful way without getting into the mathematical nature of the fractal. And the nature of fractals is inherently non-physical. 

This point is important for Levin’s case, because many scientists do not care much for complex metaphysical arguments, and prefer a heuristic approach where whatever does the job is used, and whatever doesn’t is thrown out. As my first organic chemistry professor told us, “Science isn’t about what’s true. It’s about what works.” This mindset favors a materialist paradigm, since most of what science “works” for is manipulating the material world. (And if you start manipulating the immaterial world, you are classified as a mathematician or a philosopher, not a scientist.) But Levin makes a strong case that even on the basis of sheer pragmaticism, Platonic ideals have a lot going for them. Scientists use them all the time, even if they don’t think about it. And Levin contends that there are worlds of biological discoveries ahead if we stop treating the incursions of the metaphysical world as an embarrassment, and instead study the physical and the non-physical together in an integrated way.

Not Mere “Emergence”

Despite his emphasis on “what works,” Levin does care about “what’s true.” And he has metaphysical principles. Specifically, he is adamant that his Platonic forms cannot be reduced to mere “emergent phenomena” of the material world. 

First, he points out that invoking “emergence” can sometimes be a hand-wave to get off the hook of actually explaining a phenomenon; in his words, it is “a mysterian approach that limits progress.” This is a clever rhetorical move, since emergentists often deride non-physicalist explanations as “mystical.” Mysticism is in the eye of the beholder, I guess.

Beyond that, Levin contends that emergence falls short in biology. It describes some things, of course, but many complex features of life do not simply emerge naturally from their basic physical parts. 

Levin writes:  

A crucial aspect of biological patterns is that they are often not simply results of a process that rolls onward in a mechanical fashion. The parts may well be describable by various aspects of mechanics, but biological wholes have the ability to achieve specific patterns despite novel conditions, interventions, changes of environment and of their own parts, etc. In effect, these patterns serve as goals for intelligent (context-sensitive, creative, problem-solving) navigation in anatomical, transcriptional, physiological, metabolic, and other spaces in the same way that creatures navigate 3D space in traditional examples of adaptive behavior. This is distinct from the complexity/emergence paradigm, dominant today, which focuses on the ability of simple rules to drive complex outcomes. Such “emergence” certainly happens in biology, but by itself it is not sufficient to explain the most interesting aspects of morphogenesis.

According to Levin, the remarkable complex structures that exist in biology are not merely the inevitable result of natural selection. They are not even the inevitable results of physics. Instead, they are based on logical and mathematical realities that can only be described as non-physical: “All of these are specific facts about a world which do not depend on facts from physics — they can be linked to other aspects of mathematics but they form a set of findings that do not reduce to any facts of physics.” Even if you changed all the constants and initial conditions of the Big Bang, Levin points out, these Platonic structures would be untouched: “There is nothing in the physical world that can be used as a control knob to alter them.” 

An Immaterial Mind? 

If all this seems radical to anyone, Levin is only getting started. He argues that there is no a priori reason why Platonic space would only contain static abstract objects. Indeed, some Platonic realities (such as the ever-changing “this statement is false” paradox) seem to be constantly shifting, in their very natures. And if Platonic space can include objects that move and shift, why can’t it include… minds? 

“Why couldn’t Platonic space contain patterns that are intelligent and active to some degree…?”  Levin asks. “What if some of the Platonic patterns that matter for biology are, themselves, intelligent to a degree?”

This is an intriguing concept. Unfortunately, Levin does not explain how complexity or being able to move should allow something to experience subjective awareness. In this respect, his theory is no different from physicalist theories of the mind, which tend to make the same leap. 

But How Does It Work? 

At this point, after all this explanation, you may feel like a piece is missing. 

Okay, sure, biological life operates according to abstract principles. 

And okay, sure, maybe these principles really exist, and are really not reducible to the physical world. 

And, great, the laws of physics and chemistry and biology aren’t enough to explain why life reaches for these abstract goals.

But then why does life follow these principles? What causes organisms to grow and develop towards an immaterial “pole star”? 

To his credit, Levin is aware that he hasn’t answered this question. Also to his credit, he doesn’t pretend to be able to. 

“Is there a ‘force’, beyond the ‘if you build it, they will come’ model of physical objects pulling patterns from the space?” he asks. “Are the contents of the Platonic space under ‘positive pressure’, somehow encouraging their appearance in the world as intrusive thoughts, archetypes, works of art? Is there a symmetrical dynamic through which they push outward — inherently driven to ‘haunt’ matter as much as matter calls to the patterns that animate it, projecting outward through interfaces made to that space[?]”

Levin doesn’t know. But he thinks that scientists need to get serious about finding out. I can’t say I disagree. 

What to Make of This? 

Levin’s theory is certainly exciting, but I don’t want to get carried away. Personally (and not without doubts) I’m inclined to believe that Levin is overstating his case concerning the richness of the mathematical realm.

For instance, consider a basic mathematical truth, “2+2=4.” Humans clearly did not invent that truth, so you might say that it was “discovered,” that it is an unshakably real “structure” in Platonic reality. However, if you look at it a different way, you see that this structure is an artifact of language, a side-effect of our ways of talking about numbers: “two” really means “one and one,” and “plus” really means “and,” so “two plus two” really just means “one and one and one and one,” which happens to also be the definition of “four.” Thus, the apparent “Platonic structure” amounts to the fact that “one and one and one and one is one and one and one and one,” which is trivial. My suspicion is that all of the more complex mathematical structures that Levin is so taken by can also be broken down in this way. 

But that doesn’t negate Levin’s deeper point. Even if we deconstruct these Platonic structures and find that each amounts to something very simple, a Platonic structure is still there. In the above example, after all our attempts at deflation and explaining-away, we are still left with one (non-physical!) reality: “numerosity,” or the quality of “having a quantity.” That isn’t so easy to get rid of. Likewise, all the Platonic structures in geometry might be deflated into mere “spatiality,” and we would still be left with the reality of spatiality itself to contend with. 

In other words, if you want to say that the universe is just matter sitting around in a simple grid of empty Cartesian space, you still have to explain where the grid comes from. Before one lump of cold, dead matter can sit next to another lump of cold, dead matter, “next to” has to mean something.

And once you upon the door to one immaterial quality, you can no longer exclude other qualities on mere principle. You have to take them seriously. You have to take them one at a time, and decide if they exist Platonically, or if they amount to mere words. If Numericity and Spatiality can be real — and Levin is right, the heuristic value of these two qualities makes them very difficult to dismiss as unreal — then why not other intangible qualities? Why not, say, Awareness, the quality of something experiencing something else — in other words, Mind? For that matter, why not Pain? Why not Love?

The camel’s nose is under the tent. 

And that’s probably why most scientists in the 21st century are not comfortable taking the bold, small step that Levin has taken. “Spooky” things are… well, spooky. 

Notes

1. The term “spooky” tends to come up when naturalists are trying to explain exactly which category of entity is excluded by their philosophy. For example, the Stanford Encyclopedia of Philosophy defines ontological naturalism as the view “that reality has no place for ‘supernatural’ or other ‘spooky’ kinds of entity.” 
2. Except for the other worlds in the multiverse, of course. And the quantum structure that the multiverse presumably arises from. 
3. And if you argue that blue is just an emergent property of some other things, such as the wavelength of light, that just pushes back the question to those other things. If those prior things have qualities — and you can’t really talk about something without any qualities (though Aristotle tried) — then those qualities must first exist as possibilities or “settings” in the universe. What is it about the universe that makes things like light waves have “length”? What is “length”? That’s the fundamental argument of Platonism.