What Can We Know About The World Without Looking At It?

One last thought on all this God/cosmology stuff before moving on.

The crucial moment of our panel discussion occurred when John Haught said that he couldn’t imagine a universe without God. (Without God, the universe couldn’t exist.) It would have been more crucial if I had followed up a bit more, but I didn’t because I suck (and because time was precious).

Believing that something must be true about the world because you can’t imagine otherwise is, five hundred years into the Age of Science, not a recommended strategy for acquiring reliable knowledge. It goes back to the classic conflict of rationalism vs. empiricism. “Rationalism” sounds good — who doesn’t want to be rational? But the idea behind it is that we can reach true conclusions about the world by reason alone. We don’t ever have to leave the comfort of our living room; we can just sit around, sharing some single-malt Scotch and fine cigars, thinking really hard about the universe, and thereby achieve some real understanding. Empiricism, on the other hand, says that we should try to imagine all possible ways the world could be, and then actually go out and look at it to decide which way it really is. Rationalism is traditionally associated with Descartes, Leibniz, and Spinoza, while empiricism is associated with Locke, Berkeley, and Hume — but of course these categories never quite fit perfectly well.

The lure of rationalism is powerful, and it shows up all over the place. Leibniz proclaimed various ways the world must work, such as the Principle of Sufficient Reason. Lee Smolin uses Leibnizian arguments against string theory. Many people, such as Oxford philosopher Richard Swinburne, feel strongly that the world cannot simply be; there must be a reason for its existence. Paul Davies believes that the laws of physics cannot simply be, and require an explanation. William Lane Craig believes that infinity cannot be realized in Nature. Einstein felt that God did not play dice with the universe. At a less lofty level, people see bad things happen and feel the urge to blame someone.

But the intellectual history of the past five centuries has spoken loud and clear: the dream of rationalism is a false one. The right way to attain knowledge about the universe is ultimately empirical: we formulate all the hypotheses we can, and test them against data. (Making decisions about which hypotheses best explain the data is of course a knotty problem, but that’s for another time.) Broad a priori principles are certainly useful; they can help guide us in the task of formulating and testing hypotheses. But that’s all they do — if we get lazy and start thinking that they grant us true knowledge of the world, we’ve gone off the rails.

A common manifestation of the rationalist temptation is an insistence that a certain state of affairs cannot merely exist; it must be explained, we must find a reason for it. The truth is that, if things are a certain way, there might be a reason for it, but there might not be. Both are hypotheses that should be examined. I personally have a strong feeling that the low entropy of the early universe is an unusual situation that probably has a deeper explanation — it’s a clue pointing towards something we don’t understand about the universe. But I’m careful to distinguish that I don’t know this to be true. It’s perfectly conceivable that the universe simply is that way, and there is no deeper explanation. Ultimately the decision will be made by constructing comprehensive theories and comparing them to data, not by scientists stamping their feet and insisting that a better explanation must be found.

An inquisitive five-year-old might bombard you with an endless series of “Why?” questions. Sometimes you encounter an older version of this five-year-old; someone who, when you say “I have finally formulated a successful unification of all the laws of physics!” will insist on asking “But why is it that way?” If you say “it just is,” they will say “that’s not good enough.” That’s the point at which you are allowed to turn the tables. Just start asking, “Well why isn’t it good enough? Why do I need a deeper level of explanation for how the world is?” Not that it will actually change their attitude, but it can be personally satisfying.

Favorite targets for people insisting on deeper explanations include the existence of the universe itself (as Haught was indicating) and the particular laws of physics we observe (as Davies argues). The proper scientific attitude is to say: well, there may be a deeper explanation, or there may not. Before we go out and actually look at, the universe could very well be many things. It could be a single point. It could be a line or a plane. It could be non-existent. The universe could be a fiber bundle over a Riemannian manifold, an n-dimensional cellular automaton, a trajectory in Hilbert space obeying Schrödinger’s equation, a holographic projection of a conformal field theory, the dream of a disturbed demon, a layered collection of natural and supernatural dimensions, someone’s elaborate computer simulation, or any of a million other things. It could be unique or multiple, meaningful or intrinsically purposeless. It could be brought into existence by something outside itself, or it could be sustained by a distinct being, or it could simply be. If you personally find some of these alternatives unsatisfying, that is a matter for you and your therapist to work out; reality doesn’t care. The way we will find out the truth is not to insist that it must be one way or another; it’s to understand the likely consequences of each possibility, and line them up with what we actually observe.

You can see why a rationalist line of reasoning would be attractive to the theistically inclined. If you have God intervening in the world, you can judge it by science and it’s not a very good theory. If on the other hand God is completely separate from the universe, what’s the point? But if God is a necessary being, certainly existing but not necessarily poking into the operation of the world, you can have your theological cake without it being stolen by scientific party-crashers, if I may mix a metaphor. The problem is, there are no necessary beings. There is only what exists, and we should be open to all the possibilities.

None of this is to say that there is no room for logic or reason in understanding how the world could possibly work. “2+2=4” is a true statement in any possible world, once we specify the definitions of “2” and “+” and “=” and “4.” But that doesn’t mean it’s a true statement about anything that actually happens in the world. The universe might very well have been something where there weren’t two collections of two things to add together, nor sufficient computing power to perform the arithmetical operation. Once we accept some hypotheses about the world (through comparing their predictions to reality), we are allowed to use reason to draw inferences from those hypotheses. (That’s kind of what I do for a living.) But step one in that process is to be open to which sets of hypotheses are actually relevant to the real world.

The temptation of rationalism can be a hard one to resist. We human beings are not blank slates; not only do we come equipped with informal heuristics for making sense of the world we see, but we have strong desires about how the world should operate. Intellectual honesty demands that we put those desires aside, and accept the world for what it actually is, whatever that may turn out to be.

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103 Responses to What Can We Know About The World Without Looking At It?

  1. Gene says:

    @Stuart # 17, I see we were on the same track, minus the endorsement of Popper.

    @Lee #16, How is the principle of the identity of the indescernible even a valid heuristic principle?
    Is it not in blatant contradiction with all we understand about particle physics? It seems to me that we can find tremendous duplication in nature, and I don’t see why this couldn’t extend to universes themselves.

  2. Will says:

    “The man who is ready to prove that metaphysical knowledge is wholly impossible … is a brother metaphysician with a rival theory of first principles.” – Bradley

  3. Craig says:

    Sadly the philosophical meaning of the word Rationalism is not the same as the popular meaning. http://oxforddictionaries.com/definition/rationalism?view=uk

  4. Samuel Prime says:

    Didn’t Einstein arrive at his two theories of relativity by an approach similar to rationalism? He hardly had much experimental basis for making the postulates he made in these theories. (The tests came some years later.) I think beauty and simplicity were among the driving forces in his rationalism. Of course, you could argue that none of it would have been of much value had later experiments disproven his work. But nevertheless, a rationalism approach to nature seems to have worked for Einstein (at least twice). (I think also for Dirac when he derived his relativistic equation for the electron by his heuristic guess at taking the square root of the Klein Gordon equation.) That is why I don’t chuck rationalism out the window completely, though I agree that one ought to be careful with it (just as we are careful with experiment).

    We want to be as careful with experiment just as well, since they can be misleading (and their interpretation not too clear). The example comes to mind of Murray Gell-Mann who said that seven experiments supposedly proving his theory wrong were themselves shown to be wrong!

    As a mathematician, I think many/most things do have explanations or causes. But when
    it comes to most of mathematics, I have to stop at the fundamental axioms of set theory (Zermelo-Fraenkel, along with the Axiom of Choice and the Continuum Hypothesis). It would lead me into too much speculation to inquire as to the reason for them or a cause for them. I have no scientific or logical proof for why we settled on those axioms – they just seemed a natural choice reached by us humans (and on which physics and the sciences depend).

  5. AJKamper says:


    Why do you need a “being” that transcends space and time? Why not something else that transcends space and time?

    I honestly think this is a sort of argument from ignorance–or a weird form of anthropomorphism (or theomorphism?). That is, since we can’t really imagine what it takes to transcend space and time so that we have physical rules, we assume that it requires a being, because (like Haught) nothing else makes sense. In other words, because we are ignorant, the answer must be God.

    That doesn’t make sense to me. I can hypothesize, in response, a physical analogue to Anselm’s ontological argument: a set of laws so perfect that they must exist. It sounds crazy, but it’s no crazier than assuming some sort of being that somehow did it, and perhaps less so, since there are fewer attributes to explain.

  6. Low Math, Meekly Interacting says:

    Though I think Feyerabend’s anarchism was more than a tad extreme, every individual has their own way of thinking about things, and muddles about in their own way when not beset by arguments against their hypotheses. I think we all kind of converge on a fairly orthodox “method” of science, but getting to that point can involve as many tricks as there are people. Philosophizing in some way may be one of them.

    But, nature being the final arbiter and all, when all is said and done, we need the utmost discipline. No observation, no science. No controls, no science. No reproducibility, no science. It’s inescapable.

  7. Phil says:


    “Why do you need a “being” that transcends space and time? Why not something else that transcends space and time?”

    OK, whatever. You need something that transcends space and time. But it seems to me that if you create something (a universe) from nothing, it would have to involve intention. Also, this universe that is created is governed by laws of physics with certain values of constants that seem “just right” for life. So, these considerations make me think that this something that transcends space and time is some kind of supernatural “intelligence” that transcends space and time and that this being had intention when it created the universe from nothing.

    ” I can hypothesize, in response, a physical analogue to Anselm’s ontological argument: a set of laws so perfect that they must exist. It sounds crazy, but it’s no crazier than assuming some sort of being that somehow did it, and perhaps less so, since there are fewer attributes to explain.”

    Tell that to the string theorists. 😉

    Anyway, you cannot get anything from nothing and if science somehow is consistent with the idea that our universe was born from nothing, then there must be something transcending space and time that created our universe. That is, if your fundamental theory does not allow for the existence of other universes and if your fundamental theory doesn’t allow for an initial state of our universe that had always existed “before” the (classical) Big Bang singularity, then how do you explain the origin of the universe?

    So, since we know nothing about what the fundamental theory of physics is (the theory that will, presumably, allow us to progress through the issue of the origin of our universe as much as science can allow us), it is misleading and incorrect for Hawking to say that the known laws of physics render a creator unnecessary.

    How do you know quantum mechanics (or whatever) can exist without a universe there? What does “quantum mechanics” govern? General Relativity governs the curvature of spacetime and how objects move through spacetime? What does GR govern without a universe? What does quantum mechanics govern without a universe? The equations and principles of GR do not transcend spacetime because it is a theory of spacetime. Likewise, quantum mechanics does not transcend space and time because QM governs the behavior of subatomic particles, which can only reside in space and time.

  8. Cosmonut says:


    Thanks for raising a point which scientists keep hand-waving away – it is logically impossible to explain the origin of the universe using the laws of nature. Because, if there is no universe, there are no laws of nature either. End of story.

    Cosmologists keep trying to sneak in a means to have the laws of nature “always exist” in some sense, because otherwise there’s no hook to hang their theoretical coats.

    So, for instance, in the early days, Fred Hoyle’s Steady State theory was very popular because it implied that the universe always existed.

    The discovery of cosmic background radiation put an end to that.

    Then everyone started rooting for the so-called oscillating universe, where a previous version of the universe collapses and all the collapsing particles somehow shoot past each other and explode out in a new big bang and so on forever.

    Stephen Hawking’s singularity theorems stuck a nail in that as well.

    So, now the big hope is that quantizing gravity will somehow sort things out and allow the precious laws of nature to survive.

    It’ll be interesting to see what happens if we succeed in quantizing gravity and the new theory also predicts a breakdown of the laws at the beginning of the universe. 🙂

  9. Phil says:

    @ Cosmonut,

    Well, I think it will take some time for such a theory to be finalized. The LHC is only capable of probing physics at energies of 14 TeV. The Planck scale is at 10^19 GeV (or something like that). That’s a huge range over which we will have to study particle physics in order for us to know what the fundamental theory is because, it seems, the consensus is that one cannot quantize pure GR and forget about other particles/interactions. We need to be really clever to be able to reliably probe the Planck scale. Until then, we won’t be able to definitively say anything about what must have been going on at the Big Bang singularity or what had caused it.

  10. Cosmonut says:


    Yes, the unified theory is nowhere in sight, despite Hawking’s confident prediction that we’d have it in the “next 20 years”. This prediction was made in 1980 ! (Honestly, I wonder why anybody takes SWH seriously any more.)

    My speculation is that if we do find a theory, by 2050 say, and it predicts a singularity at the origin of the universe, scientists will just insist that the theory can’t be complete and a “scientific explanation” of the universe’s origin is waiting in the wings.

  11. Phil says:

    Well, I have heard that string theory has the potential to resolve classical singularities, so who knows. I don’t know much about string theory but many well-respected people say it’s very promising. But we still don’t know what string theory is, nor what M-theory is supposed to be or whether it is “the fundamental theory”. But whatever the fundamental theory is, it does not have the ability to make a universe (and physics tells us that universes are made up of spacetime and particles which interact with each other and with spacetime) out of nothing.

    Anyway, it will be interesting when we are finally able to conduct experiments at the Planck scale (if we ever learn how to do it) and see if we see any kind of evidence of having made new universes. I’m not sure what the experimental signatures of that will be (How do we obtain casual contact with other universes after we make them?). But if the theory you have allows you to predict what happens at the Planck scale and whatever energies you have the technology to reach beyond that scale, and allows you to derive all the physics that has ever been done before that at all lower energy scales, AND you can somehow show that your theory is mathematically unique and that, in your experiments, you should have made new universes, then that gives clear evidence that a multiverse exists and that our universe was made in the same way (with or without the participation of alien life forms 🙂 ).

    But like I said, we just don’t know.

  12. Cosmonut says:

    But whatever the fundamental theory is, it does not have the ability to make a universe (and physics tells us that universes are made up of spacetime and particles which interact with each other and with spacetime) out of nothing.

    Totally agree.

    From the literature I get the sense that scientists are hoping that M-theory or whatever will describe some kind of meta-universe which always existed. So, then *our* universe will have arisen from some Planck scale phenomenon in that metaverse.

    But yes, we are nowhere near that kind of a theory yet, so Hawking’s claims are vacuous.

  13. Cosmonut says:

    Sometimes you encounter an older version of this five-year-old; someone who, when you say “I have finally formulated a successful unification of all the laws of physics!” will insist on asking “But why is it that way?” If you say “it just is,” they will say “that’s not good enough.” That’s the point at which you are allowed to turn the tables. Just start asking, “Well why isn’t it good enough? Why do I need a deeper level of explanation for how the world is?” Not that it will actually change their attitude, but it can be personally satisfying.

    That’s a particularly idiotic argument.

    I can imagine a 17th century Sean “turning the tables” with:
    “What do you mean why do apples fall ? That’s just the way things are. Get over it.”

    Fortunately, we had Newton instead.

    The history of science is replete with examples of “brute facts” that turned out to have deeper explanations (conservation of energy comes to mind.)

    The honest answer to “Why that unified theory ?” is not “That’s a stupid question” or “It must be God”.
    Its simply – “That’s a deep mystery. Nobody knows.”

  14. God says:

    Sean, this is God.

    I just read your blog post, and it’s made me angry. You wouldn’t like me when I’m angry! Just look at what I did to everyone in Sodom and Gomorrah, as well as everyone on Earth other than Noah and his family during the great flood. And don’t forget all of the other trillions of people I’ve had to smite throughout your species’ millions of years of evolut-erm, I mean the several thousands of years since your creation (by me… God). So as I was saying… the fact that you choose not to believe in me and thank me personally every day makes me angry. Nevermind the fact that I didn’t embed even the slightest bit of reliable evidence of my existence into the structure of your universe, and that the only way I expected you to learn about me was through the constantly rewritten and handed-down, self-contradictory, factually erroneous, multi-thousand year old mythology of ancient civilizations. That should have been enough for you! Also, you are expected to overlook the fact that there are several other such mythological teachings coming from other ancient civilizations. Those other teachings are wrong! If you pick one of them by mistake or happen to be born into a religion where they are prevalent you are going to be punished for eternity by burning endlessly in agonizing infernos of torture. After all, I am a God of Love.

  15. Jimbo says:

    RightOn, Sean: Empiricism rules over Rationalism. Just this year:

    1. SUSY excluded out to a Tev, & probably dead – LHC.
    2. Large extra dims & micro-black holes excluded up to 7 Tev – LHC.
    3. Lorentz invariance violation pushed out to 10^ – 49 m – INTEGRAL
    4. Dark matter WIMPS excluded by the most sensitive test – XENON100
    5. Multiverse evidenced via Bubble collision excluded – WMAP7

    Repeatedly we find our most cherished cutting edge ideas cannot stand up to empirical tests,
    & altho not rigorously falsified, wither & fade in the vacuum of observation. We can only hold our breath & hope Higgsy does not meet the same fate.

  16. Tom S says:

    When John Haught said that he couldn’t imagine a universe without God, he may not have meant that he was lacking in imagination, or that he could not mentally wrap his head around some universe that did not include God.
    An equally likely meaning to the statement might be “I do not WANT to imagine a universe without God”. The idea of a universe without God would be repugnant, meaningless and somehow almost banal to him.
    If he did mean this, then his position is even less supportable than your kinder interpretation.

  17. Philip says:

    I think what you’ve writen about the “Why?” question is excellent. Oftentimes when I hear an appologist, like William Lane Craig speak, they start of by saying things like, “Why is there something rather than nothing?”, claiming that it’s one of life’s great questions. It’s obvious that they really don’t care about the question, because as you said, you can say that about every single explanation of the question. I think it’s importaint to point out that saying “god created the universe” is open to the same line of enquiry; “Why does god exist, rather than not?”. The dodge here is to say perhaps that god is eternal and so she doesn’t need an explanation, or she’s a nessesary being. I think neither of these are actually very satisfying.

  18. Lee Smolin says:


    By the Fermi exclusion principle every fermion is in a unique quantum state. That is compatible with the principle of the identity of the indiscernible (PII). Bosons are another story, of course. So for sure QED has lots of states that are not compatible with PII.

    But QED is not the final theory, so maybe the PII can offer a heuristic guide to making it better. Here is one way it might. As Steve Weinstein points out in a recent preprint, QED has to be supplemented by a boundary condition to eliminate spurious states and solutions that don’t occur in nature. The boundary condition is that there be no free incoming states of radiation in the universe. All photons we observe seem to reliably come from sources. Otherwise we could not trust our vision or our telescopes to give us information about how matter is distributed in the universe.

    Why should this boundary condition be imposed? It is highly time asymmetric, which is weird in a universe governed by almost perfectly time symmetric laws.

    So also inspired by the PII, we can ask another question about bosonic fields, which is the following: define the sky of an event to be the two sphere of directions from there. and call the pattern of radiation incoming from its past light cone, on that sky, the view of that event. Two events will be the same if it is impossible to distinguish their views. In a relational world (ie one compatible with the PSR) you have no label for events but what is measured there, so the view of every distinct event must be distinct.

    The next question is, do we live in a universe in which it happens to be the case that any two events can be distinguished by the patterns of radiation arriving to that event? I think there is a good case to be made that we do. This is because rather than living in a universe filled with a free gas in thermal equilibrium, we live in a universe that is highly structured on a wide range of length scales. This is due to a combination of the special initial conditions, the finely tuned laws, and the fact that gravitationally bound systems do not evolve to unique, featureless equilibria.

    Thinking about the universe in a way that makes its inhomogeneities and asymmetries essential for the description leads to some interesting places. This is for me an example of how the PSR serves as a heuristic guide to the questions we ask.

  19. Richard O’Connell says:


    Because we are crass
    utilitarians all
    we accept & cherish
    Crusoe’s daybook of accounts

    But what of Friday’s
    dark cry
    at the core of creation
    the fury & speech
    of unknowable forms
    like those lachrymose rock
    faces on Easter Island
    staring at Alpha Centuri

    We fish plant & write
    in our palm thatched hut
    hoping the universe
    is what we construct

  20. Phil Osopher says:

    What Sean just did is extremely useful to clarify his worldview to blog readers, in the sense that scientists view the world and its “ultimate” truths mostly accoding to their own (conscious or unconscious) philosophy of mathematics (platonism, constructivism, intuitionism, empiricism,…). So, Sean has just admitted being a “mathematical empiricist”. This is of course a very respectable position, but its main problem is that mathematics is unavoidably, at some point, about infinities: that’s what Hilbert called “Cantor’s paradise”, from which no empiricist will ever expel any mathematician. So, how does the rich and fruitful mathematics of the infinite develop under an empiricist account?

  21. psmith says:

    Oh dear, Sean, have you forgotten your post about free will?

    There you quite happily invoked causal compatibilism to explain away the disconnect between causal determinism and free will.

    Now, what if anything, is causal compatibilism but rationalism, pure and simple? Some philosophers snidely dismiss it as word jugglery. I certainly can’t see any empirical basis for that argument.

    You want to defend free will from the implications of causal determinism so you invoke rationalism.
    You want to defend atheism from the metaphysical implications of the laws of nature so you invoke empiricism.

    You can’t be a rationalist when it suits you and then an empiricist when the arguments get tricky. This is either a careless inconsistency or intellectual dishonesty.

  22. Jim Cross says:

    I’m with Mike and others about this being a false dichotomy.

    Strict empiricism isn’t possible because we, the observers, are a part of what we are observing. And strict rationalism isn’t possible either because the brain/mind it uses has evolved as part of the world and doesn’t exist independent of it.

    It shouldn’t be a surprise that mathematics models the world so well since mathematics is product of the brain/mind that the world created.

    Science in practice actually seems to swing between the two poles. It makes conjectures and looks for evidence. It finds evidence and makes conjectures.

  23. Arun says:

    Why this article? If there was something interesting going on in the author’s area of physics, then there would be little time to devote to this article.

  24. Pingback: The Temptation of Rationalism | Tangled Up in Blue Guy

  25. Arun says:

    Leave aside the mention of “Creator” in the sentence below. Even so, it is a sentence that cannot be arrived at by the observation of nature.

    “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.”

    If it were left to scientists, the millionth metasurvey of the billion double blind tests of whether men are created equal would be going on. Scientists would find no Rights in nature. Happiness is so vague as not to be a scientific concept – it gets replaced by “endorphin rush in the brain” or something. Liberty would be equally elusive. Life as in survival would be found by science, but whether it is the life of the rioter in London or of a celebrated artist in New York, science would only be able to say things like the hormones related to stress in populations of the two are different with some statistical significance.

    Despite brave declarations like The UN Declaration of Universal Human Rights, the concept of Rights is far from universal. Rights do not exist in nature, nor in every human culture. The mechanism of Rights seems to be effective as a principle in the organization of human society, that is the best that can be said objectively. That it might work is an act of faith, not really based on what can be called scientific evidence.