Why I’m a reductionist

The SEP article on scientific reductionism notes that the etymology of the word “reduction” is “to bring back” something to something else. So in a methodological sense, reduction is bringing one theory or ontology back to a simpler or more fundamental theory or ontology. The Wikipedia entry on reductionism identifies different kinds: ontological, methodological, and theory reductionism. I think the ontological one is the most interesting here, the proposition that all of reality consists of a small number of building blocks.

Most reductions aren’t particularly controversial, at least not in science. There aren’t many arguments that chemistry doesn’t reduce to physics, or geology to both those sciences. Today it’s not controversial that biology reduces to them as well, although this is a relatively recent development.

As late at the early 1900s there were people arguing that life was somehow different, that it was distinguished by a vital force, an ancient idea. Few talk about vital forces today. Biologists learned about evolution through natural selection, genetic inheritance, proteins, DNA, RNA, and overall organic chemistry. Life is now seen as largely a molecular chemical enterprise, albeit a hideously complex one.

This raises an important point. Most reductions are conservative, retaining the reduced concept, but not all. Sometimes it’s eliminative, as in the case of a vital force, or other things like phlogiston or a luminiferous ether. It seems to depend on whether the reduced concept remains useful.

Today there remain at least two areas where people tend to resist reductionist accounts: consciousness and quantum measurement.

The consciousness one goes back to Rene Descartes’ famous distinction between mental and physical substances. Descartes saw no issue with a mechanistic understanding of reality, except for the mind, which he could not conceive of being reducible to mechanisms. He was far from alone. Gottfried Leibniz presented his mill thought experiment, that if the mind were a mill which we entered, we wouldn’t find anything there that explained perception. The mind, he agreed with Descartes, had to be a different kind of thing entirely.

Although a lot of what these guys saw as irreducible has been reduced. Today, psychological concepts like memory and cognition are understood to be neural processes, albeit with still many unanswered questions. But contemporary philosophy of mind often draws a new line at perceived characteristics, typically called qualities or qualia. Because these characteristics are introspectively opaque, they seem irreducible. And studying some of them has proven hard, therefore many assume they’re fundamentally inaccessible to anyone but the subject.

The question is whether the notion of fundamental qualia really explains anything. Does it convey meaningful information? Certainly qualities understood as just perceived characteristics seem useful enough. But regarding them as fundamental seems to obscure rather than convey information.

As a reductionist, I think of qualities as categorizing conclusions. (If that seems radical, consider that the etymology of the Latin root phrase “qualis” is “of what kind.”) Our nervous system qualifies a stimulus for a category when a particular range of neural firing patterns trigger a galaxy of associations, some innate, but many learned, which collectively add to the richness of the experience of that perceived characteristic (redness, sweetness, pain, etc).

Am I completely confident this is the answer? No, but as an explanation, it seems like a more fruitful place to explore. I suspect future scientific studies will validate some aspects of it, but not others. But even if it’s completely wrong, these kinds of theories seem to spur more experimental work than simply assuming qualities are fundamental and inaccessible.

In the case of quantum mechanics, it’s observation that’s often taken to be fundamental. In its strongest forms, this ends up pairing with the idea of consciousness being fundamental. Although the more cautious variants see just measurement as fundamental (or interaction). This can be the idea that quantum states don’t really exist, that measurement itself creates reality, or that quantum states do exist but physically collapse in a measurement, a fundamental change in reality.

In the early years of quantum theory, something like these views seemed inescapable, and most of the physics community closed ranks around them. But there were holdouts, including Albert Einstein and Erwin Schrὅdinger, who kept digging, discovering the phenomenon of entanglement, which would later be used by David Bohm and Hugh Everett to posit mechanistic explanations for the disappearance of quantum effects. But it was the work of H. Dieter Zeh and Wojciech H. Zurek in the 1970s and 80s that really fleshed out the detailed explanation we now call decoherence.

Today, few question whether entanglement and decoherence happen, although many do continue to argue that they’re only useful mathematical tools. Even if they are real physical processes, whether they serve as a full explanation of what’s happening in measurement depends on your preferred interpretation of quantum mechanics. But the key thing is it’s an explanation that wasn’t found by those who were satisfied with measurement being fundamental.

Which gets to why I’m a reductionist. I can’t prove that ontological reductionism is true. Maybe there are unique aspects of reality that aren’t built on a few common building blocks. But there seems to be a lot of history showing that assuming it’s true is far more fruitful than assuming complex concepts are fundamental. From Thales positing that water was the fundamental substance to later Greeks assuming there were four fundamental elements, the history of assuming anything is fundamental seems cautionary at best.

Which is why when I hear “X is fundamental,” I’m reflexively skeptical. We can’t even confidently say that about “elemental” particles, quantum fields, space, or time. We only seem able to talk in terms of something being more fundamental or less fundamental. Scientific theories are always provisional, subject to change on new data. Absolute fundamentality seems like an assumption we can never justify. Calling something fundamental seems to say, “There’s nothing left to explain here. Stop digging.” A lot of progress seems to happen from the people who ignore these prescriptions.

What do I mean by “progress”? None of this is to argue that higher level concepts aren’t useful; thermodynamics, for instance, didn’t cease being a useful concept once it was reduced to particle physics. Or that holistic takes on phenomena can’t be beneficial. Or that in art or daily life, we can’t appreciate things without reducing them.

But reduction aids in acquiring more structurally or causally complete explanations, while assuming something is fundamental often seems to paper over structural or causal gaps. Closing these gaps, when achievable, provides more reliable knowledge, knowledge which gives us new abilities, abilities such as medical scanners, drugs, computers, and many other things. Yes, that does include nuclear weapons and other ills. It doesn’t seem like we can have the good without the bad, although usually the bad can be managed with more reliable knowledge.

At least that’s my view today.

What do you think? Are there benefits to non-reductive approaches I’m overlooking? Or drawbacks to reductionism I’m missing? If you think an alternative approach is better, what are the benefits of that alternative?