I would like to know what anybody thinks of the following argument against brute physical facts, such as the idea that the material universe as a whole is a brute fact.

A physical fact is taken to mean a true statement about something that is concrete, or actually instantiated, in the physical world. Given a physical fact F, then F is contingent if it obtaining is not a logical necessity, and necessary if it obtaining is a logical necessity. A brute fact is one which admits no explanation for why it's true, even in principle.

Assumption (Weak PSR): All contingent physical facts admit a further explanation as to why they're true, even if just in principle.

Note: An "in principle" explanation can be thought of as an explanans which, even if it does not obtain in actuality, is one which admits no logical contradictions.


  1. All brute physical facts must be contingent, or else appealing to their necessity would be explanation for why they're true.

  2. Therefore, since all brute physical facts are contingent physical facts, they admit a further explanation as to why they're true, even if just in principle. (by Weak PSR)

  3. Because brute physical facts do not admit a further explanation as to why they're true, even just in principle, we conclude that there are no brute physical facts.

Is this argument consistent with standard usage and strong in the informally logical sense?

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Philip Klöcking
    Feb 6, 2022 at 14:22
  • @DoubleKnot Yes, Leibniz and may philosophers since have gone a step further and tried to use the PSR to provide a positive "cosmological argument" for the existence of a necessary being (God). I am not trying to make such a strong claim. I only want to show that under rather weak philosophical commitments, brute physical facts seem implausible.
    – Mark
    Feb 6, 2022 at 14:22

5 Answers 5

  1. All brute physical facts must be contingent, or else appealing to their necessity would be explanation for why it's true.
  2. Therefore, by assumption, all brute physical facts admit a further explanation as to why it's true, even if just in principle.
  3. Because brute physical facts do not admit a further explanation as to why they're true, even just in principle, we conclude that there are no brute physical facts.

Step 2 does not follow from step 1. What is the "further explanation" you refer to in step 2?

I suspect that you are making an unstated assumption that contingent facts have a further explanation, i.e. that they are "contingent upon" something else. This is not part of the definition of contingent facts that you stated. Your stated definition of a contingent fact is that it's simply a fact for which obtaining it is not a logical necessity. There's nothing in that definition about a contingent fact being "contingent on" or "dependent on" something else.

  • 2 follows 1 given my Assumption, which is a weak version of the PSR. Right?
    – Mark
    Feb 5, 2022 at 18:47
  • @Mark Fair enough, but you're just assuming what you're trying to prove.
    – causative
    Feb 5, 2022 at 19:16
  • How so? That brute facts are contingent is not trivial, and then we show that all that one needs to commit to is the "Weak PSR" as stated in order to reject brute physical facts. It's not a complex argument, but I'm not sure it needs to be.
    – Mark
    Feb 5, 2022 at 19:20
  • @Mark Your "weak PSR" is just a rephrasing of your rejection of brute physical facts. It's not easier to accept or more obvious than a rejection of brute physical facts.
    – causative
    Feb 5, 2022 at 19:28
  • I think it is. Simply accepting the weak PSR does not allow you to reject a brute physical fact until you establish that brute facts are contingent.
    – Mark
    Feb 5, 2022 at 19:43

A brute [physical] fact is one which admits no explanation for why it's true, even in principle.

So are you excluding randomness??? Quantum physics typically provides explanations for the probabilities of observing different outcomes among a set of possible outcomes, but it absolutely never provides explanations for why one particular outcome is observed rather than another. It doesn't even permit any such explanation. So I think those would be examples of what you're calling brute physical facts.

There are various non-mainstream deterministic alternatives, usually one or another kind of hidden variable theory, or sometimes many world interpretations, or occasionally other deterministic arguments. So which one of those are you advocating? I think you necessarily must be advocating one or another such deterministic theory if you're trying to assert that observed experimental outcomes are examples of contingent facts. Or do you have some other way to reconcile "contingent" and "random"?

  • Thanks for your comment! This is an interesting point indeed. What if I said the following: An outcome being chosen due to a quantum/probabilistic process would indeed be a further explanation, hence excluding such things as being considered brute. Learning that this outcome was chosen by a probabilistic process certainly provides you with very interesting (and new) information. Furthermore, if it turns out that our universe was the result of such a process, it leads one to wonder what the the rules governing the random generating process lying behind physical reality actually are.
    – Mark
    Feb 6, 2022 at 14:15
  • @Mark Re An outcome chosen due to a quantum/probabilistic process; that isn't what happens (not according to the standard/Copenhagen interpretation, anyway). Outcomes aren't "chosen" whatsoever, they just "occur"...poof. You can predict the probability of an outcome's occurrence over repeated measurements of identically-prepared systems, but you can't predict which outcome will occur as a result of any one particular measurement, nor "explain" why that eventually-observed outcome did occur. As for rules governing the random process, sure. But the outcome of the process is still random.
    – eigengrau
    Feb 6, 2022 at 14:47
  • @Mark: Your comment is on the right track. Too many people wrongly believe that QM requires a non-deterministic universe. That belief is completely bogus. There is not a single bit of evidence that there is true randomization in the real world. Look at how chaos can arise from purely deterministic processes, to see that it's a total fallacy to believe that what appears random is indeed random.
    – user21820
    Feb 6, 2022 at 17:09

Brute facts were theorised by Poincare, Duhem and Anscombe. Poincare and Duhem were concerned about scientific descriptions underpinned by brute facts. Whereas Ancscombe also wrote about social and institutional brute facts.

Physical brute facts were introduced by Searle to distinguish them from social and institutuonal facts which have their truth grounded in human consensus.

However, informally the notion goes back to Liebniz who founded his logic on two principles: non-contradiction and the principle of sufficient reason. He also distinguished between necessary and contingent truths - this is more or less what you have with necessary and contingent facts as logic is used to assert there necessity and contingency. This principle states every truth has a reason. Hence, in your language there are no brute physical facts.

Now, if the principle of sufficient reason is a truth then it must, by its own reasoning, have a reason. The argument you supplied is such a rationale.


Short Response

Having thought things out more fully, I'll just provide a short answer. You claim:

Therefore, since all brute physical facts are contingent physical facts, they admit a further explanation as to why they're true, even if just in principle. (by Weak PSR)

This is not a true statement regarding physical facts. Explanations of physical facts in science are determined by criteria that need to be met. Inadequate explanations are no explanations at all. Therefore the importance of the distinction between the possibility of a scientific explanation, and an actual adequate scientific explanation (the existence of which itself is subject to debate regarding theory-ladenness in the instrumentalist-realist debate) is important.

This claim of your flies in the face of fallibilism on several accounts including mistaking modality for actuality, not recognizing the limits of non-monotonic logic, and failing to assert empirical criteria in the selection of adequate explanation of physical facts. Simply put, just because you can create a sentence and call it explanans doesn't mean it is actually a scientifically acceptable explanans.

Science may push the boundaries of brute fact by building bigger and better theories to encompass more and more, particularly through reduction, but there will always be a new hypothesis, and old theories may fall apart moving scientific facts back to the state of brute facts. Simply inventing an explanation and declaring a brute fact dissolved is not scientific.

This sentence can be made true by withdrawing the modifier 'physical', but then, at least from an empiricist standpoint the sentence becomes speculative metaphysics and relatively meaningless.

  • Thank you for commenting. You summarize by saying: "Simply put, just because you can create a sentence and call it explanans doesn't mean it is actually a scientifically acceptable explanans." I've framed my PSR in this way as a direct refutation of the commonly held definition of a brute fact: Not only is there no explanation that we have yet to discover, there is no possible explanation. My formulation then encompasses a challenge to this: Whenever somebody encounters a physical fact, it is not reasonable for them to believe it has no further explanation.
    – Mark
    Feb 6, 2022 at 20:38
  • Right, which is why I directly attacked PSR by saying that the contingency of physical facts having an explanation is insufficient; and if you were to amend the sentence to "adequate explanation", it follows that the definition of adequacy for explanation is itself not amenable to saving your argument. We're both fallibilists, but we are disagreeing over whether or not brute facts, which within the Agrippan Trilemma are foundationalist claims, can be eliminated. The argument purports to show they are, and in an extended sense, the structure of knowledge can indeed push back on brute facts...
    – J D
    Feb 7, 2022 at 14:43
  • But at any instant in time, there will always be brute facts because knowledge is neither perfect (any purported explanation might succumb to the scandal of induction) nor infinite (any constructed theory must start somewhere, even temporarily). Look, for perspective, I think it's important to note you're trying to reduce the Trilemma to a Dilemma (no brute facts eliminates the foundationalist leg), and contextually, we can look at the thousands of years of history and conjecture that if a strong argument existed for making the Trilemma a Dilemma, it likely would have surfaced already...
    – J D
    Feb 7, 2022 at 14:46
  • Prima facie, the "possibility of an explanation" seems to encompass a bona fide explanation that dissolves the brute fact, but the key philosophical challenge of mathematics and science has been to show that math and science always can provide an adequate explanation for a explanandum, say through the Deductive-Nomological model, and the chief takeaway from the logical positivists is that some theoretical possibility does not equate to a guaranteed actuality. If I were to concede the Weak PSR, I think it's a defensible, but not invulnerable thesis, bc the function of the WPSR in the argument..
    – J D
    Feb 7, 2022 at 14:51
  • is to patch over the glaring problem with finding explanations, which is THE challenge to eliminating foundationalist thinking, but it's a huge whole, and even your assumption doesn't fully solve the problem. Anyway, take my feedback for what it's worth, which is about $0.02. If you're hell bent on eliminating foundationalism as a valid leg of the Trilemma, you'll find a way to keep yourself convinced. But eliminating brute facts only leaves circularity and infinite regress, so your argument really boils down to your views on potential vs. actual infinity...
    – J D
    Feb 7, 2022 at 14:54


I have formulated a Short Response and posted it as a second answer for those who see this response as TLDR.

Short Answer

This argument is not strong because it betrays typical usage for 'brute fact'.

A brute fact is one which admits no explanation for why it's true, even in principle.

While a brute fact is a fact without explanation, it is very possible to adduce, say, a scientific explanation to make a brute fact a scientific fact. A claim can be both a brute fact and a scientific fact at the same time. Language is highly contextual.

...we conclude that there are no brute physical facts.

You've reasoned your way past common sense. It's simply a brute fact that there are brute facts. Let's look closer.

Long Answer

There are two primary flaws as I see it in your informal argument, one among the premises, and the conclusion itself, so let's see if we can explain why the argument you provide isn't strong or cogent.

First, if we consider the premise that a brute fact can't have an explanation, we can undermine an important foundational element in your rhetoric. Let's simply admit that a brute fact and a scientific fact aren't mutually exclusive. That's easy to do knowing that the function of the sciences as an empirically epistemological tool is to take brute facts and transform them into justified, true beliefs of a sort. Thus, that 'Snow is white' is a rather atomic, brute fact known to 2 year-olds everywhere, a brute fact can be bolstered in an epistemological sense by citing scientific theory to explain it. That explanation the science of optics, which includes facts and theories about light and perception, now provides. Thus a brute fact can also be a scientific fact. What started out as an intuitional claim thus has been vetted by the global and historical community of science. Thus, we have a brute fact with an explanation.

Brute facts generally have explanations, even if we're not aware of them when we make a claim that is a brute fact. What makes a claim a brute fact is whether it comes from a thinker's intuition or not. Thus, "Snow is white" is both a brute fact and a scientific fact depending not on the utterance or proposition, but it's place in the worldview of the claimant.

Second, you seem to think past what a brute fact is. A brute fact is simply a self-evident truth. 'Gravity pulls things down.' Brute fact. 'Things in motion come to a stop.' Brute fact. 'The sky is usually blue.' Brute fact. The traditional use of the term brute fact means that on the threshold between what we perceive and what we can claim, certain claims seem to be made universally by people everywhere, and therefore brute facts are a universal human experience and undeniably exist. In a naive sense, a brute fact is simply a nearly universally consensual agreement about the state of affairs. It might help to think of brute facts as natural foundational claims in the sense of the Agrippan Trilemma. What is a brute fact is subject to fuzzy logic and categorization, of course, and near-universal is necessary to qualify since a color-blind person wouldn't consider claims about colors brute facts.

But brute facts are a brute fact because human beings when they reason are capable of making simple, obvious claims about the physical world of which they are apart. That naturalism has led to various scientific methods that substantiates the brute facts as scientific facts based on empirical evidence isn't a forgone conclusion, and many cultures today simply don't have anything nearly as sophisticated as the sciences, and rely heavily on brute facts. The Yahgan people are good example of a culture where this is true. This is because brute facts are a product of our naive capacities, such as naive physics and folk psychology which are a resultant of our philosophical intuitions. In fact, sometimes brute facts turn out to be wrong.

Consider the claim the brute fact that 'Things in motion come to a stop.' This is a famous brute fact that was elevated through philosophical argument as a certain fact in Aristotelian physics. Not until Newton was the 'truth' of this claim undone. Now, we have a scientific fact which contradicts the brute fact. 'The existence of an object's inertia is nothing more than a claim a thing in motion tends to stay in motion until stopped by a countervailing force.' Does that mean that 'Things in motion come to a stop.' isn't a brute fact anymore? Of course not. Any child when asked after this principle is likely to make the former and not the latter claim. Why? Because human reason is defeasible and built on experience which begins as highly intuitional and never fully escapes intuition. Utterances and symbols derive their meaning from intuitions, ultimately.

So, not to mince words, your argument appears to have all of the hallmarks of a valid deductive argument, but in reality this is a masquerade of sorts since it is a weak argument based on premises that both contradict common-sense observations about what a brute fact is defined and which arrives as a self-evidently contradictory conclusion regarding the universal prevalence of brute facts as an aspect of human experience.

ADDENDUM 2022-02-06 - The Importance of the Duhem-Quine Thesis

I've received the criticism and respond.

First, the definition of brute fact can indeed be constrained to a narrow interpretation depending on how one views epistemic modality. I do not believe that Searle, Quine, Duhem, or others use it in the way you do. Let's clarify the narrow view you seem to advocating:

A brute fact is one which admits no explanation (no matter how contrary to physical experience and reason) for why it's true, even in principle (in no possible world perhaps even considering non-modal realism).

Whereas my experience seems more inline with what WP's article claims about Duhem's view:

A brute fact is one which admits no explanation for why it's true, even in principle (although the provision of one or more scientifically feasible explanans might dissolve the brute fact, though there is no non-defeasible measure of which explanans is best given the theory-ladeness of scientific theory).

Thus, we have two disparate worldviews at play, with the instrumentalism-realism debate rearing its head again. I simply assert that your views on naturalism are inconsistent with contemporary views on the nature of the defeasibility of reason and Duhem-Quine thesis.

Let's adduce a further passage from the article:

To reject the existence of brute facts is to think that everything can be explained.

This, of course, is your objective in your argument, to reject the existence of brute facts, and I think we're moving towards the same ends, but your argument again has an obvious deficiency. Must because linguistic facility allows us to explain anything doesn't mean that an explanation is adequate, and there is the rub where we split hairs. You seem to think that ANY explanation, no matter how absurd, inconsistent, or constructed willy-nilly disqualifies a fact from being brute, and on the face such a linguistic category 'explanation' certainly includes these members, but there's a wholesale effort to be blind to the obvious truth that there are grades of membership involved in explanation!

'It is raining.' is a brute fact, but should I accept the explanans that it's because 'Angels are crying.' satisfies the criterion of ADEQUATE explanation? Of course not. It's an absurdity. A fiction. A story told to fill in the gaps of knowledge of children in the Judeo-christian tradition usually rationalized with admonishments about the importance of faith. No. This simply won't do to disqualify a brute fact. An explanation must adhere to the best practices of the sciences (read epistemic methodologies used to reduce uncertainty) and we can use simple philosophical razors to dismiss bad and complicated explanations rendering them effectively non-explanatory.

Let's provide a more insightful example. Through complicated appeals to empirical evidence and an extensive exercise in computation, we might arrive at a brute fact. 'Subatomic particles are the ultimate constituents of matter.' This brute fact goes back to the ancient Greeks, and even under the current standard model, seems to be a fundamental truth, one of two which is contradictory under QM. Now, the question remains. Is there or is there not an ADEQUATE explanation for this fact, and I would posit simply no. It's a reasonable assumption about space-time and has been for thousands of years, but no ADEQUATE explanation exists, at least for me. I'm a conventional naturalist who rejects alternative physical realities such as the multiverse, Heaven, Brain in the Vat, the Simulated Universe and the Realm of Forms. (They're all lack any empirical validation.) For me, the universe simply is divisible into subatomic particles and it is a brute fact.

So again, your definition only works if you exclude the relative nature of what constitutes a fact. I do not believe post-Quine, that this is how the contemporary usage of brute fact applies, at least through my superficial readings with Searle, and I do not believe that the class of explanadum should consider any linguistic construct which is grammatical and barely sensible. This is not how science is done, nor how contemporary logic works except in the toy problems of logicians who generally insist that the traditional laws of thought must apply. It violates intuitionism, constructionism, and ignores the import of the discriminatory capacity of the thinker to decide what qualifies as an acceptable explanation.

Now, that being said, let's drill down one last time. You say:

Since all brute physical facts are contingent physical facts, they admit a further explanation as to why they're true, even if just in principle.

No empiricist in his right mind would accept this claim, because while all brute physical facts are contingent since they are constructed by thinkers, a theoretical criteria for the existence of an explanation does not satisfy the primary criterion of empiricists since Hume, that is the satisfaction of truth by empirical evidence. What. Because a scientist can think that the the universe is a simulation, the fundamental nature of subatomic particles as bits in a metaphysical computer means 'subatomic particles as fundamental' is no longer a brute fact? I would say to such a claim, dream on. This is exactly the angels-on-a-pin-head metaphysical debate that, while an interesting exercise in logic, has no bearing on the more certain world provided by the sciences. So, because a butterfly can dream us into existence there aren't inexplicable facts?!? Come on. You don't actually believe that to be true, do you?

No, an empiricist and by virtue scientist has to put her boots on the ground and draw a line between physical and fanciful, and that's exactly what science purports to do. To reject the existence of brute facts is to reject the efficacy of science, and to lack any criteria for differentiating between the natural and the supernatural, and I suspect few members of the NAS would subscribe to such a philosophy.

  • I very much thank you for engaging with the argument and providing insightful feedback. Allow me to offer my reply: I would contend that all of the examples that you provide as examples of brute facts are in fact not brute facts. The very link you provided for "brute fact" states the definition I have in mind: "a brute fact is a fact that cannot be explained in terms of a deeper, more "fundamental" fact."". Yet you write: "Brute facts generally have explanations." So right from the start I suspect we are using different definitions here.
    – Mark
    Feb 5, 2022 at 16:06
  • The fact that "snow is white" can indeed by explained by deeper, more fundamental facts, such as the physics of the color spectrum and the human perception of it, etc. When somebody says that the "instantiation of the physical universe as a whole" is a brute fact, I understand this to mean that there is no explanation for this instantiation. I grant that this could allow for a different scientific description of this state of affairs not yet considered, but I also take this to mean the claim that there are no "external" explanations which necessitate it.
    – Mark
    Feb 5, 2022 at 16:09
  • Which is why I opened with "This argument is not strong because it betrays typical usage for 'brute fact'" and provided a link to a conventional definition on WP. You've done nothing more than crafted an idiosyncratic definition to arrive at a conclusion creating the appearance of a philosophical problem where none exists. Feel free to define words in contradiction of convention, but never lose fact that language is a public activity, and that doing so seems to carry with it an agenda of obscurantism.
    – J D
    Feb 5, 2022 at 16:11
  • 1
    @jd -- but as Mark noted, your link to a "conventional" definition of brute fact, IS Mark's definition!!!!!! "In contemporary philosophy, a brute fact is a fact that cannot be explained in terms of a deeper, more "fundamental" fact.[1]". Neither Snow White the Disney character, nor things stopping their movement, would be "brute facts" per your linked definition, both are explainable with more fundamental physics!!!
    – Dcleve
    Feb 5, 2022 at 16:42
  • The scientific method SEEKS for explanations, but may not be able to find them. Currently in our science, the existence and propeprties of elementary particles have to be taken as brute facts. And with the failure of the reductionism/unity-of-science project, the existence of tiers of knowledge that are not reducible to physics (chemistry, biology, psychology, sociology, anthropology, geology, etc), and also non-science knowledge (math, philosophy, art, history) also has to be taken as a brute fact. And the Trilemma tells us that ultimately, we will have to settle for brute facts.
    – Dcleve
    Feb 5, 2022 at 16:50

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