Physics Describes Everything Matter Does. Not What It Is

Pick up any object near you, a cup, a phone, a pen. Ask a physicist what it is made of and you'll get a good answer: atoms, then electrons and quarks, then quantum fields.

Now ask what an electron is. You'll be told its mass, its charge and its spin, and how it behaves when it meets other particles. Every one of those answers describes what the electron does. None of them says what it is.

That gap is not a failure of current physics. It is built into how physics works. Physics describes structure and behavior with mathematics, and mathematics captures relationships, not whatever it is that stands in those relationships.

In the last few decades, two old philosophical ideas have returned to fill that gap, and both make the same surprising move. Both say the missing ingredient is something like experience.

Why does physics leave the gap open? What do panpsychism and idealism each claim, and what is the strongest problem facing each one? I suspect the line between them is thinner than either side admits.

I have gone back and forth on this for a long time. My first instinct, written down in a hurry, was that it didn't have to be a contest:

"Funny how panpsychism and idealism can both be true if we think of the fact that consciousness cannot be captured due to self reference problems regarding the fundamental substrate, meaning the whole must be fully present fractally at each constituent part while still being the totality at the very top"

What Physics Leaves Out

In 1927 Bertrand Russell pointed out, in The Analysis of Matter, that physics tells us about the mathematical structure of the world but is silent on its intrinsic nature. Eddington made a similar point a year later and drew a bold conclusion from it.

The argument runs like this. There is exactly one place where we know the intrinsic nature of some physical stuff from the inside: our own brains, where it shows up as experience. So perhaps experience is the intrinsic nature of matter in general, and physics describes its outward behavior.

Philosophers call this family of views Russellian monism. It is the starting point for both positions.

Panpsychism: Mind All the Way Down

Panpsychism says that consciousness, in some extremely simple form, is a fundamental feature of physical reality. On most versions, a single electron might have an unimaginably faint flicker of experience.

It doesn't mean your coffee cup has thoughts. Most panpsychists say a cup is just an arrangement of particles, with no unified experience of its own. Brains are special because they organize experience into one integrated point of view.

Modern defenders include the philosopher Galen Strawson, whose 2006 paper "Realistic Monism" argued that if physicalism is true, experience must already be present in physical stuff, and Philip Goff, whose 2019 book Galileo's Error brought the view to a wider audience.

The Combination Problem

Panpsychism's hardest problem was spotted in 1890 by William James, in The Principles of Psychology:

"Take a sentence of a dozen words, and take twelve men and tell to each one word. Then stand the men in a row or jam them in a bunch, and let each think of his word as intently as he will; nowhere will there be a consciousness of the whole sentence."

— William James, The Principles of Psychology (1890)

If each particle has its own tiny experience, how do billions of them combine into your single, unified awareness? Nobody has a widely accepted answer. Panpsychists call it the combination problem.

One scientific theory is often grouped with panpsychism here. Integrated Information Theory, developed by the neuroscientist Giulio Tononi from 2004 onward, proposes that consciousness corresponds to how much a system integrates information as a whole, and that some degree of it may exist in very simple systems. It is also controversial. In 2023 more than a hundred researchers signed an open letter calling it pseudoscience, which prompted an equally sharp response from its supporters. The argument shows how hard it is to test any theory of where experience begins.

Idealism: Mind First

Idealism goes in the opposite direction. Instead of building one big mind out of many small ones, it starts with a single universal consciousness and treats individual minds as divisions within it.

The philosopher Bernardo Kastrup, one of its best-known current defenders, compares individual minds to dissociated parts of one larger mind, using dissociative identity disorder, in which one person develops several separate identities, as a model.

Idealism avoids the combination problem. My own reason for leaning toward it was this:

"Doesn't the fact that science hasn't found matter place idealism above panpsychism?"

Its weakness is the reverse problem. If everything is one mind, why does the world seem to be made of separate, stable objects that behave the same way for everyone? Explaining how one mind divides is as hard as explaining how many combine.

Closer Than They Look

At one point I realized the two positions might be converging:

"But panpsychism poses problematic matter. I guess you could say matter simply IS structure itself but then isn't that just structured idealism?"

If panpsychism admits that physics only describes structure, and that the only intrinsic nature we know is experience, then its "matter" is experience arranged in a certain way. If idealism admits that universal mind divides into stable, rule-following structures, then its "mind" behaves exactly the way physics says matter does.

Both agree on the main point. Experience is not something that appears late in the history of the universe from stuff that has none. It is there from the start. They disagree about whether it starts as many points or as one whole.

That may be a smaller disagreement than it first appears. Whichever is right, the question of what matter is has become a question about mind, and physics alone cannot settle it.