Does physicalism enjoy the simplest ontology among all worldviews?

Are there alternative conceivable views of reality with a simpler ontology than physicalism's that can explain the same data? For example, what about idealistic worldviews, metaphysical solipsism, or some creative versions of brain in a vat scenarios where only one's mind exists accompanied by a deceiver that projects illusions on one's mind? Would something like that be simpler than positing an entire universe (or multiverse) with quarks, gluons, neutrinos, spacetime, laws of physics, other minds, etc.?

Can anything simpler than physicalism be conceived with equal or greater explanatory power?

  • 5
    Considering that "simpler" and "simplest" do not mean anything non-opinion-based, this question is off-topic for SE as is. You'll have to specify your version of "simplicity" at least. "Among all worldviews" is too broad to be meaningful. Parmenides's One "ungenerated and deathless, whole and uniform, still and perfect" and its Oriental equivalents, like Tao, answer to different concerns and are oranges to apples. Physicalism's apple-to-apple competitors, like property dualism, are few in number and compete on a range of criteria that make any "simplicity" rather moot.
    – Conifold
    Commented Mar 27 at 4:48
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    As I pointed out here the "physical" in physicalism is (at least on wikipedia) so loosely defined that physicalism, "a form of ontological monism", can't even be distinguished from traditional forms of ontological dualism.
    – g s
    Commented Mar 27 at 5:42
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    @Baby_philosopher in this context, it looks like simplicity is being used to describe explanatory models or objects as elements thereof, not objects in isolation: "this is the reason" vs "that is the reason". It does become impossible to say (without a very narrow definition excluding most of the common use) whether an explanation based on an object with much fewer elements is simpler than an explanation with many more elements. [...]
    – g s
    Commented Mar 27 at 16:06
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    [...]For instance, suppose I take a photograph of a tiny part of the night sky and the film negative shows one little black spot. I can explain the little black spot with a spontaneous atomic decay local to that tiny spot of the film involving only a few thousand atoms, or with a distant star involving 10^57 atoms. Neither gets to be "simpler" until "simpler" gets defined much more narrowly than common use, and depending on the definition, "simpler" may correspond with the much less likely answer (decay), or may indicate the much more likely answer (star) for a bad reason.
    – g s
    Commented Mar 27 at 16:12
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    Again, notions of anything can differ. Every single word has multiple definitions and every single concept in philosophy has differing views. But some notions are more obvious than others, such as an atom being simpler than the entire universe. Keep missing the point Commented Mar 27 at 16:54

7 Answers 7


There are several flawed assumptions behind this question, which could improve your thinking if corrected.

The first is that simplicity is not a good metric to use for the goodness of a worldview. This was discussed in the answers to a prior question: https://philosophy.stackexchange.com/a/110052/29339 What really matters, per Popper, is predictive power.

The second is that physicalism is not clearly an ontology. Physicalism was embraced as a stand-in for materialism, after Einstein refuted that matter is fundamental. But "what physics studies" isn't an ontology, and this has been an ongoing source of disquiet in the post-materialist era. There are two issues for physicalism as an ontology. One is that physics studied the fusion of two things -- stuff plus relationships. Relationships have no energy, or mass, but are key to what the "stuff" behaves like. Under Popper's 3 worlds ontology, physics is actually studying worlds 1 and 3, not just world 1. This makes physicalism a dualist ontology.

The other issue is that for physicalism to work as a worldview, it needs to be more than an ontology, but also an epistemology. Physicalism is most comfortable with two epistemological views: global reductionism, and scientism, but most thinkers on both subjects have concluded that neither are the case. There are three major problems with these assumptions.

The first is that physics as a science is intrinsically incomplete. All active work in physics is outside current "known physics", and we are unable to define what any boundaries for "future physics". This leads to a definitional problem called Hempel's Dilemma. Hempel's Dilemma holds that one cannot define physics to exclude the things physicalists want to reject -- Gods, ghosts, spirits, etc -- without asserting a definition we know to be wrong. The second problem is that physics is just a field of science, and science in general is not derived scientifically, but rather as a subset of the philosophical practice of empiricism. So science, and physics, are by definition not the only sources of knowledge. The third problem is a practical one, that science itself has realized that global reductionism is likely not true, and emergence needs to be accepted as a real phenomenon. This leads to science as a whole accepting that other sciences besides physics discover things that physics cannot. The implication of this admission, plus the inability of science to self justify is also that non-sciences are very reasonably valid sources of knowledge as well.

In addition to these theoretical issues for physicalism, there are practical test cases, in which physicalist explanations for consciousness have repeatedly been found to fail, as they predict we should not be conscious. This is the famous "hard problem of consciousness". Physicalism also, by leaving no place in its ontololgy for values, tends to lead to a futilitarian or nihilist worldview, which leads to a failure in the test case of "is this a useful philosophy to live my life by".

These problems for physicalism reveal a problem for the assumptions behind your resort to Occam's Razor. Physicalism does not explain everything we would like a complete philosophy to explain. It has contradicting test cases, and theoretical inabilities to self justify, or address all of our desired philosophical questions. Occam invoked his Razor to sort between competing explanations that can both explain the same problem set. But if the explanations don't explain the full problem set, then Occam isn't a valid metric at all, even in Popper's rewrite.

It is the nature of philosophical worldviews that they all have these sorts of problems and challenge areas that they struggle with. Idealisms, Popperian Triplism, Spiritual dualism, Russellian neutral monism, emergent naturalist pluralism -- NONE of these does not have similar issues of test cases they struggle with, or theoretical problems that limit their range of applicable scope, etc. None of them can explain the "full data set of the world".

The better way to sort between philosophic worldviews is to treat them as Research Programmes, in the theory Imre Lakatos developed to better explain how science operates. https://www.scientowiki.com/Imre_Lakatos

Under Lakatos' criteria, the question you are asking would be transformed to -- is there a more progressive philosophic research programme than physicalism? All worldview frameworks can be characterized for their progressivity and regressivity. Physicalism was, 3/4 of a century ago, an immensely progressive programme. The issues I have noted have been accumulating, unresolved, and have degraded this progressivity over the last 3/4 of a century.

The consequence of the increasing recognition that physicalism is not delivering on the promise it had in the mid 20th century, has been a revival of philosophers pursuing the various alternatives I listed. However, I do not believe that any of these alternatives is currently demonstrating greater progressivity. There is instead in the communities pursing alternatives, the hope that an alternate programme can overcome past challenges that made it difficult to address failed predictions, or made that programme difficult to make useful predictions with at all. There is more speculation and hope, rather than demonstrated accomplishments, behind the current increasing pursuit of alternatives to physicalism.


Its important to distinguish "explanatory" — which subdivides into "narrative" and "descriptive". And "predictive".

Clearly and trivially the more idealistic philosophies explain more parsimoniously. Apart from classic idealists like Berkeley, in our times Bernardo Karstrup in Materialism is Baloney and elsewhere makes a trenchant case for idealism

See also the spectrum from subject-oriented to object-oriented

Describe ←→ Narrate ←→ Predict ←→ Control

The problem is that we dont only want description. We also want narrative power.

[I am using the standard terms for literature where "descriptive" paints a scene and "narrative" tells a story ie. time is involved]

The limit of narration is prediction — story into the future. And ultimately control ie. technology. Here idealism fails utterly. If you go with your pathological reports to a doctor you dont just want explanations of what the numbers mean. You want predictions: if I let the problem be, X will happen; if I intervene — medicine, surgery etc — Y will happen. And so the expedient choice is Z.

Medicine is the most obvious example where we want "physical doctors" not idealists! But its really everywhere: We drive cars, live in buildings, use equipment — all these need to be designed ie. their creators need to display prediction and have and confer control. For this the idealistic side is utterly useless.

OTOH the impotence of idealism for prediction and control is mirrored by the uselessness of the physicalist outlook for addressing the most pressing and unanswerable life questions:

  • Why do I suffer? Or fear? Or rage?
  • What is the point of it all?
  • Who/what is God?
  • Where will I go when I die?

In short all of us are willy-nilly dualists. The only choice is one can consent to it with open eyes. Or else kicking and screaming.

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    "Why do I suffer? Or fear? Or rage?" - on a biological level, emotion is the result of brain processes and evolved since it provided a survival benefit to be drawn to or averse to certain situations. On a practical level, what happens to us and what we do affects our emotions. "What is the point of it all?" - "it all" doesn't have a point, but people certainly find their own meaning and purpose in life. "Who/what is God?" - an imagined entity. "Where will I go when I die?" - probably in the ground, maybe a furnace. Your consciousness will cease. There you go. The "unanswerable", answered.
    – NotThatGuy
    Commented Mar 27 at 7:07
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    @NotThatGuy What you call answers I call "physical corelates of self" When you go to a doctor with a tummy-ache, its not satisfactory if they say: Ah! From your reports I see your appendix is swollen. It will burst in a few hours. Then you will die. Though that may well be part of the answer. The full answer needs a completion of the form ... and so I suggest an immediate operation... inspite of these risks/downsides etc. And yes, "answer" is deeply inherently polysemic — it can range from the examples you give to profoundly life-changing «spiritual happenings» —various shades between
    – Rushi
    Commented Mar 27 at 7:13
  • @NotThatGuy Here is a simple experiment for you to try to see whether you actually agree with me that your rendering is possible but insufficient. Somewhere in your youth, perhaps between ages of 5 and 13, you had some questions like this. You asked this to Mum/Dad or whoever it was. The kind of answers you give (now), may well have been part of the answer-package you received then. Was it the full and final answer? For you? At that point?
    – Rushi
    Commented Mar 27 at 7:21
  • You are not a physical being with a spiritual soul; you are a spiritual being that happens to have a body right now I saw this somewhere, probably one of the new age gurus. While I dont push it as a truth, I do recommend it as something to play with
    – Rushi
    Commented Mar 27 at 7:25
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    If a computer generates the text "I am not performing computation", that would be self-contradictory / false, yet if you turn it off, the computation ceases. A computer would be quite correct to say "My computation will one day cease". Of course, that's a physicalist analogy. And I was way past childhood when I figured out what I currently consider to be the "right" answers to these questions, and I'm at least theoretically open to having my mind changed about those things... but that would require a compelling case to be made in favour of some other conclusion.
    – NotThatGuy
    Commented Mar 27 at 8:57

Physicalism is a form of naturalism:

Everything has a natural cause, miracles do not happen.

Because naturalism does not rely on gods, devils and other spirits its ontology is more parsimonous than a theistic ontology with its theological superstructure.

A naturalistic worldview has to pay a price: It has to let open several fundamental questions and leave them as a topic for later generations.

Combined with the critical rationalism of Karl Popper, naturalism relies on falsibilism. Hence naturalism is freed from the search for final explanations with absolute certainty.

  • would you say that in time e.g. the hard problem will be more soluble or more statable?
    – andrós
    Commented Mar 27 at 21:25

Imo the best way to gauge the simplicity of a model is to program a simulation of that model. Compare the size of the programs, the smaller one is simpler.

Now, that obviously gets unfeasible in certain contexts, especially contexts where no such program exists, and so one must try to speculate and surmise what such programs might look like.

That being said, it's generally taken that simulating the Christian God would take more lines of code than the code for simulating, say, quantum physics. Until someone can write a program that simulates the Christian god, we have to assume quantum physics is simpler, since quantum physics CAN be simulated (even if only at small scales, like at the scale of a super simple molecule).

Our failure to simulate the Christian god indicates one of two things, maybe both: the Christian god would be an incredibly complicated program to write, AND/OR the model of the Christian God is so poorly defined that it doesn't even make sense to try to simulate it.

If it's the second case, then it ceases to be a matter of comparing the simplicity of two models - you're comparing one real fully featured model to an idea that isn't well defined enough to call a "model" at all.

This post oversimplifies pieces of the debate, no doubt. However, here's more reading material on the idea:


Now, op said Physicalism and I've made my post about the Christian God in particular - I've done that just for illustrative purposes. You can apply the same kind of thought pattern here to any non physicalist view of the world. The fact is, we don't have any models of souls or spirits either - we have many models of physical things, but not a single model of how souls operate.

  • What about idealism, metaphysical solipsim, brain in a vat scenarios, etc.?
    – Mark
    Commented Mar 27 at 9:36
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    Brain in a vat explains every possible observation, which makes it a poor explanation for any specific observation. I think idealism and Physicalism are incorrectly placed at odds with each other, potentially.
    – TKoL
    Commented Mar 27 at 9:37
  • Metaphysical Solipsism is like brain in a vat - no matter what you experience, metaphysical Solipsism could explain it, which makes it a poor explanation
    – TKoL
    Commented Mar 27 at 9:38
  • Brain in a vat explains every possible observation, which makes it a poor explanation for any specific observation - How so? I don't follow the logic.
    – Mark
    Commented Mar 27 at 9:38
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    Those are epistemological considerations, not ontological considerations. And you still need to make dogmatic assumptions about your subjective experiences, your memories, the external world, etc., to get this off the ground. See en.wikipedia.org/wiki/M%C3%BCnchhausen_trilemma
    – Mark
    Commented Mar 27 at 10:08

Mark: Is physicalism the simplest worldview in terms of the complexity of its ontology?

Does physicalism enjoy the simplest ontology among all worldviews?

Are there alternative conceivable views of reality with a simpler ontology than physicalism's that can explain the same data?

Can anything simpler than physicalism be conceived with equal or greater explanatory power?

Alistair: I find physicalism simplicity and naturalism to be the best guiding lights.

However, currently, "physicalism" seems lacking in the "physical"... which raises questions...

Is there a "physical"? Who's/which "physical"? What is "physicalism"? Does "physical" help in figuring out reality? Why are we considering physicalism? How are we defining physicalism?

As far as I can tell (you can trust me, I have delved)... the current human "best guess" at "physicalism" is the Standard Model of Particle Physics"... which lacks in physicality, except as an emergent phenomenon.

One philosopher to another. In any of all existing physics theories...

And then add for review...

The challenge would be to find a single suggestion or single claim of any actual physical object that is non-divisible and has a volume greater than zero (0).

If you look at the Planck's constants what you find is they are a relationship. A ratio. Size (amplitude, wavelength), and time (frequency) with the result being in "Joule-Seconds" which is a quantification of the mysterious and fuzzy "energy".

Asked "What is E or energy?" ChatGPT returned this:

Energy (E) is a fundamental concept in physics that represents the capacity of a system to do work or produce heat. It comes in various forms, including kinetic energy (energy due to motion), potential energy (energy due to position or configuration), thermal energy (energy associated with temperature), and many others.

In different contexts, energy can manifest in different ways, but its fundamental nature remains the same: the ability to cause changes in a system.

Do you remember the old Star Trek episode with "energy beings"?

Provocative "forces and Energy"

The chosen images labelled fundamental forces and fundamental energy are purposefully a little provocative. They are to invite yourself to ask yourself... when you hear the terms:

  • Forces
  • Fields (the new forces)
  • Energy
  • Fluctuations
  • Spin
  • Charge

Can you envision anything that you would describe as "physical"?

Anything with volume and shape and size and physicality anywhere among any of the theories or candidate theories?

(Note: You can try, but fair warning, it is a rhetorical question)

So when we say "Is physicalism the simplest take on reality, or worldview?"

Given that the current Planck's Constant based Standard Model of Particle Physics is energy-based, I would say... is energyism is what we are calling "physicalism".


Physicalism is simpler than idealism because it contains physical laws that explain the orderliness of things happening in the world. In an idealistic world, there are no laws proposed, hence the orderliness that we see in the world becomes a complete and utter miracle.

  • How are you quantifying simplicity?
    – Mark
    Commented Mar 27 at 15:12

I apologize for making 2 answers, but I think this one is potentially distinct enough to warrant a second answer. Also, fair warning, wacky speculation ahead.

The natural interpretation of the question is, "What is the simplest view of the nature of our reality?", but in thinking about it more, I keep finding myself tempted to think bigger than "our reality".

What if the simplest program to explain this universe is a program that generates all other programs?

You wanted to compare physicalism to idealism - this is perhaps a type of "idealism", if you can call it that, that resonates with me. And then, this universe is physicalist, but it's physical because "physical universes" are one of the ideas generated by this type of idealism.

So physicalism would be true of this universe, but true on a bedrock of a type of idealism which says "all implementable ideas are implemented".

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