Preaching to the Unconverted

And now for something somewhat different. After I posted my article on “Does the Universe Need God?“, there were a few responses at the Intelligent Design blog Uncommon Descent, including a list of questions by Vincent Torley. Vincent then went the extra mile by inviting me to write a guest post for UD. Not my usual stomping grounds, but I ultimately agreed, precisely for that reason.

Here’s the post, which I’m cross-posting below. This might be controversial, as a lot of people on my side of things will say that there’s little point in engaging with people on the other side. And admittedly, this is a subject where feelings can be pretty entrenched. But you never know — not everyone has their mind made up on every issue, and it’s good to try to explain yourself to unsympathetic audiences on occasion. That’s all I tried to do here — to explain how I think about these things, not necessarily to pick a fight or even persuade any skeptics. I tried pretty hard to be as clear and unpretentious as I can be. (Success is for you to decide.) In a world of shouting and diatribe, I remain optimistic that real communication can occasionally occur! We’ll see how it goes.


I wanted to thank Vincent Torley and Denyse O’Leary for the opportunity to write a guest blog post, and apologize for how long it’s taken me to do so. I’ve written an article for the forthcoming Blackwell Companion to Science and Christianity, entitled Does the Universe Need God?, in which I argued that the answer is “no.” Vincent posed a list of questions in response. After thinking about it, I decided that my answers would be more clear if I simply wrote a coherent argument, rather than addressing the questions individually.

My goal is to try to explain my own thinking to an audience that is not predisposed to agree. We can roughly break people up into two groups: naturalists such as myself, who think that the best explanation we have for the universe involves physical quantities obeying laws of Nature and nothing else; and those who believe that a better explanation can be found by invoking a powerful being/designer/creator/God. (For the sake of simplicity I’m going to use “God” to refer to this notion, but feel free to substitute the more accurate description of your choice.) Obviously there are many nuances that are being passed over by this simple distinction, but hopefully it will suffice for this moment.

The dispute between these two camps isn’t one where people often change their minds at the drop of an argument. Minds do change, in either direction — but typically after extended periods of reflection, not suddenly in response to a single killer blog post. So persuasion is not my goal here; only explanation. I’ve succeeded if an open-minded person who disagrees with me reads the post and still disagrees, but at least understands why I hold my positions. (After giving an earlier talk, one of the theologians in the audience told me that I had persuaded him — not that God didn’t exist, but that the argument from design wasn’t the way to get to Him. That sort of real-time response is more than one can generally hope for.)

What I want to do is to elaborate on some crucial aspects of how science is done that bear directly on the issues raised by my article and some of the responses to it that I’ve seen. In particular, I want to talk about simplicity, laws, openness, explanation, and clarity. This isn’t supposed to be a comprehensive treatise on the philosophy of science, nor is it especially rigorous, or anything really new — just some thoughts on issues relevant to this conversation.

I will be taking one thing for granted: that what we’re interested in doing here is science. There are many kinds of consideration that may lead people to theism or atheism that have nothing whatsoever to do with science; likewise, one may believe that there are ways of understanding the natural world that go beyond the methods of science. I have nothing to say about that right now; that’s a higher-level discussion. I’m just going to presume that we all agree that we’re trying to be the best scientists we can possibly be, and ask what that means.

With all that throat-clearing out of the way, here’s what I have to say about these five issues.


Science tries to capture the world in the simplest possible description. We are fortunate that such an endeavor is sensible, in that the world we observe exhibits various regularities. If the contents and behavior of the world were completely different from point to point and moment to moment, science would be impossible. But the regularities of the world offer a tremendous simplification of description, making science possible. We don’t need to talk separately about the charge of this electron, and the charge of that electron; all electrons have the same charge.

Simplicity can be quantified by the concept of Kolmogorov complexity — roughly, the length of the shortest possible complete description of a system. It takes longer to specify some particular list of 1,000 random numbers than it does to specify “the integers from 1 to one million,” even though the latter contains more elements. The list of integers therefore has a lower Kolmogorov complexity, and we say that it’s simpler. Scientists are trying to come up with the simplest description of nature that accounts for all the data.

Note that a theory that invokes God (or any other extra-physical categories) is, all else being equal, less simple than a theory that does not. “God + the natural world” is less simple than “the natural world.” This doesn’t mean that the idea of God is automatically wrong; only that it starts out at a disadvantage as far as simplicity is concerned. A conscientious scientist could nevertheless be led to the conclusion that God plays a role in the best possible scientific description of the world. For example, it could (in some hypothetical world) turn out to be impossible to fit the data without invoking God. As Einstein put it: “It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience.” Alternatively, you could imagine deriving all of the physical laws from the simpler assumption that God exists. While these strategies are conceivable, in practice I don’t think they work, as should become clear.


A “law of nature” is simply a regularity we observe in the universe. All electrons have the same charge; energy and momentum are conserved in particle interactions. A law doesn’t necessarily have to be absolute or deterministic; the Born rule of quantum mechanics states that the probability of obtaining a certain observational result is the square of the amplitude of the corresponding branch of the wave function. A law is simply a pattern we observe in nature.

As far as science is concerned, it makes no difference whether we refer to these regularities as “laws” or “patterns” or anything else. It also doesn’t matter whether we think of them as “fundamental and irreducible features of the cosmos.” They simply are; science looks for them, and finds them. Vincent asks “How can rules exist in the absence of a mind?” That is simply not a question that science is concerned with. Science wants to know how we can boil the behavior of nature down to the simplest possible rules. You might want more than that; but then you’re not doing science. He also asks why we should believe that the rules should continue to hold tomorrow, simply because they have held in the past. Again, that’s what science does. Imagining that the same basic laws will continue to hold provides a simpler fit to the data we have than imagining (for no good reason) that they will change. If you are personally unsatisfied with that attitude, that’s fine; but your dissatisfaction is not a scientific matter.


This is probably the most important point I have to make, and follows directly on the issue of “laws” just addressed. There is a way of trying to understand the world that might roughly be called “scholastic,” which sits down and tries to reason about how the world should be. The great success of science over the last five hundred years has been made possible by throwing out that kind of thinking in favor of a different model. Namely: we think of every possible way the world could be, and then we go out and look at the world to see which is the simplest description that fits the data. Science insists that we be open to all possibilities, and let the data decide which is true.

Suppose that you are convinced that laws of nature could not exist without a guiding intelligence that formulated them and sustains them. That’s fine for you, but it’s a deeply unscientific attitude. The scientific attitude is: “We observe that there are regularities in nature. We might imagine that they are formulated and sustained by a guiding intelligence, or that they simply exist on their own. Let’s go collect data to determine which idea is a more parsimonious fit to reality.”

The primary sin a scientist can commit is to decide ahead of time that the universe must behave in certain ways. We can certainly have intuitions about what kind of behavior “makes sense” to us as scientists — theorists are guided by their intuition all the time. But the use of that intuition is to help us develop hypotheses, not to decide which hypothesis is correct. Only confrontation with data can do that.


Science has a complicated relationship with “Why?” questions. Sometimes it provides direct answers: Why do all electrons have the same charge? Because they are all excitations of a single underlying quantum field. But sometimes it does not: Why is there a quantum field with the properties of electrons? Well, that’s just the way it is. Which questions have sensible answers is dependent on context, and can even change as we learn new things about the universe. To Kepler, understanding why exactly five planets orbit the Sun was a question of paramount importance. These days we think of the number of planets (eight, according to the International Astronomical Union) as something of an accident.

The point, once again, is that we can’t decide ahead of time what kinds of explanations science is going to provide for us. Science looks for the simplest possible description of the world. It might be that we will eventually understand the inner workings of nature so well that we will be able to answer every conceivable “Why?” question — we will ultimately see that things simply could not have been any other way. But it is also perfectly possible that the best possible description of the world involves some number of brute facts that have no deeper explanation. This is an issue that will ultimately be decided by the conventional progress of science, not by a priori demands that the universe must explain itself to anyone’s individual satisfaction.


The final point I wanted to make involves the clarity of scientific hypotheses. Perhaps “unambiguity” would have been a more precise word, but it is so ugly I couldn’t bring myself to use it.

The point is that a respectable scientific theory should be formulated in terms that are so unambiguously clear that any two people, both of whom understand the theory and have the technical competence to elucidate its consequences, will always come to the same conclusion about what the theory says. This is why the best theories we have are very often cast in the form of mathematics; the rules for manipulating equations are absolutely free of ambiguity. You tell me the initial conditions of some classical mechanical system, as well as the Hamiltonian, and I will come up with the same predictions for its future evolution as absolutely anyone else wit the same information.

Earlier I mentioned that the God hypothesis could actually be simpler than a purely naturalistic theory, if one could use the idea of God to derive the observed laws of nature (or at least some other features of the universe). This isn’t idle speculation, of course; many people have taken this road. The fundamental problem, however, is that the idea of God is utterly unclear and ambiguous, as far as conventional scientific thinking is concerned.

One might object: God is simply the most perfect being conceivable, and what could be more unambiguous than that? (One possible response, not the only one.) That sounds like a clear statement, but it’s not in any sense a clear scientific theory. For that, there would have to be a set of unambiguous rules that let you go from “the most perfect being” to the laws of nature that we see around us. As I argued in my paper, this is very far from what we actually have. It is sometimes argued, for example, that God explains the small value of the vacuum energy (cosmological constant), because without that fine-tuning life would be impossible. But why does God choose this particular value? Actually it could be quite a bit larger and life would still be very possible. Why are there 100 billion galaxies in addition to the one we live in? Why are there three generations of elementary particles, when life is only constructed from the first one? Why was the entropy of the early universe enormously smaller than it needed to be to support life?

Obviously these are perfectly good questions for naturalistic theories as well as for God. The problem is that we can imagine coming up with naturalistic theories that do provide clear answers, while it’s very hard to see how God could ever do that. The problem is simple: God isn’t expressed in the form of equations. There is no clear and unambiguous map from God to a particular set of laws of physics, or a particular configuration of the universe. If there were, we would be using that map to make predictions. What does God have to say about supersymmetry, or the mass of the Higgs boson, or the amplitude of gravitational-wave perturbations of the cosmic microwave background? If we claim that God “explains” the known laws of physics, the same method of explanation should work for the unknown laws. It’s not going to happen.

It’s not clear to me that anyone who believes in God should actually want it to happen. There is a very strong tension between what scientists look for in a theory — clear and unambiguous connections between premises and predictions — and the way that religious believers typically conceive of God, as a conscious being that is irreducibly free to make choices. Does anyone really want to reduce God to a simple set of rules that can be manipulated by anyone to make clear predictions, like we can in theories of modern physics? If not, God will always remain as a theoretical option of last resort — something to be invoked only after we are absolutely convinced that no possible naturalist option can explain the universe we see.


Obviously these very simple points don’t come anywhere near addressing all the possible issues in this area. In particular, I haven’t made any real attempt to argue that a purely naturalistic explanation actually is a better fit to the observed universe than God or similar ideas. Instead I’ve just tried to explain the mindset of someone like me who does end up coming to that conclusion. In my paper I’ve tried to lay out why invoking God doesn’t seem to provide an especially promising explanation of the world around us. Others may disagree, but I hope this has made things more clear.

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83 Responses to Preaching to the Unconverted

  1. Ian Ward says:

    I’m pretty sure I saw a Goddess, anyway, just the other day :’)

  2. Tyro says:

    Good work at taking a stab at presenting a clear, coherent response. From my perspective it seems to be bending backwards to be respectful and courteous and to avoid even the hint of offence. I’m interested to see what sort of responses will be posted at UD (none were up when I checked).

  3. A. Moony Sun says:

    It would seem to follow, that concepts and ideas of any type of deity would be sub-set to the laws of nature; a product of, rather than progenitor to natural laws. In this way a deity is quantifiable by the output or byproduct of its “existence”. One, “in theory” could then surmise its mass, calories spent and even the energy needed to maintain its existence.

  4. Sili says:

    How long before your guest post slips down the memory hole?

  5. Cristi says:

    Congratulations for openness and for explaining the methodology of science with patience, even if some may think it’s a lost cause. I think that the “against dialog” positions of some from one side or the other is not constructive, even making them look arrogant, dogmatic or cowards. It is always better to have an open dialog. Even if for the moment most humans are tempted to reject arguments contradicting their own precious opinions, these arguments are like seeds that in time will grow up. One possible explanation for long-term changes is that good and straight arguments, even if rejected by the conscious mind, reside somewhere in the unconscious mind, and reveal themselves initially in situations which are less personal, gaining weight in time and eventually surpassing superstition and dogmatism. I think that the best toolbox is critical thinking, promoted with neutrality, as a powerful and useful toolbox, not as a mean to attack. This kind of changes takes time.
    Again, congratulations for promoting dialog and believing in the human reason, while respecting the individual freedom.

  6. DaveH says:

    I have been reading Uncommon Descent recently (I used to browse the Flat Earth Society forums but no-one there seemed to be taking it seriously), so I look forward to being amused by some of the responses over at UD.

  7. DaveH says:

    Commenter “Mung” at UD wants to know if you think a reductionist explanation of your blog post is the best possible explanation. Apparently anyone who can grasp the point of that question will be closer to understanding Intelligent Design.

    …ID is more like Sociology or English Lit than Physics or Biology?

    (There’s no point me posting this at UD – It’s very heavily moderated)

  8. Tyro says:

    Some of the comments on UD have made it through moderation and they’re hard to read over the deafening whooshing noise.

    Most of the responses totally ignore everything Sean wrote and just try to pipe up with logical arguments, weird semantic arguments, or conspiracy theories. Very few seemed to think that anything in Sean’s piece actually applied to them. One of the weirdest responses was from DonaldM who says that, when talking about simplicity, Sean was really talking about the simplest naturalistic explanation even though DM actually quotes Sean when he explicitly considers God.

    Two of the comments really stand out. First is Mung who asks about definitions of “the universe” and concludes by saying that if you understood his question you’d understand ID. Since ID has always ostensibly been about inferring design based on genetics not cosmology, I don’t think that even Mung understand ID. Second is DonaldM who, after a long discussion saying that scientists reject God a priori and generally attacking naturalism, he concludes by saying that ID has nothing to do with gods at all and is about determining cause. Aside from the absurdity of defending God and then saying it has nothing to do with God, there’s the big whoosh that Sean wasn’t talking about ID at all, he was simply explaining science. The fact that Sean’s points missed some subtleties about ID when he wasn’t talking about ID in the first place is really not a failing of his.

    Oy. I was hoping that a couple of them would show more signs of having “got it” but so far, it looks like a blank. I mean, only one or two seem to have even read it.

  9. spyder says:

    You might think that if there were such a thing as ID, the believers would be more, i don’t know, intelligent?

  10. Sean Strange says:

    Warning: irrational, non-scientific, marginally off-topic ranting ahead

    “The primary sin a scientist can commit is to decide ahead of time that the universe must behave in certain ways.”

    Doesn’t this include assumptions like “the world is comprehensible” and “everything is measurable via the scientific method”? Isn’t science founded on such unprovable assumptions? If I start from different assumptions, such as “the universe is incomprehensible”, or “everything that matters is unique and irreproducible (i.e. magic)”, then I get an entirely different worldview – probably the default one for all of human history prior to the Enlightenment.

    Science is spectacularly effective at delivering hydrogen bombs precisely and reliably on target, or systematically converting the world’s resources into garbage, but as a basis for a lasting civilization it is very much in doubt. It may turn out that rolling back the Enlightenment and placing strict limits on human inquiry is the only thing that can save us from the destructive powers science has unleashed!

    Leaving aside theism vs. non-theism, the big blind spot of science is thought itself. Since all scientific observations are filtered through consciousness, any comprehensive science needs to start there. This is where the pre-scientific mystics were ahead of us in many ways, and why scientific materialism scares so many people. If you have no place for thought in your models, you have no place for the things we really value as human beings. You might as well rearrange the atoms of the entire universe into paperclips — what’s the difference? Why should anyone care how random particles interacting in a void behave, independent of human consciousness? I know I don’t. For that matter, given that our lives are so short, why do we need science at all? Isn’t a good myth that gives meaning to our lives enough?

  11. cybertraveller777 says:

    Two as yet not fully understood phenomena could make GOD the simpler
    explanation. The fact that all galaxies are accelerating outward
    hence dark matter/dark energy. If a being/entity/ultimate power repository,
    exists as a hemispherical containment of the universe, and this absolute
    infinitely dense beings energy, pervades and impells all things, then this
    would explain why the gravity calculation cannot account for the missing
    matter. What if GOD deposits a small part of himself as he departs
    instataneously outward spherically creating the void, and his energy
    left in the center of the void becomes all matter, which is now in the
    process of being pulled outward toward that energy from which it originates.

  12. TimG says:

    @Sean Strange: Science is certainly based on assumptions, but it uses a minimal set of assumptions. Mostly stuff like “The world follows consistent laws”, and “inductive reasoning is valid” that everyone already assumes implicitly just to live their lives.

  13. Daniel says:

    Unable to finidh the article at this time. Yet and still, there are 11 dimensions according to string theory. Who says there is absolutey nothing in those other 7 or 8 dimensions, is etiher no scientist or no clear thinker. my opinion only…sometimes I believe in direct observation only, sometimes I let my intuition carry me away to the land of new ideas, and sometimes I just sit and think nothing.
    “i just don’t believe in Zimmerman”

  14. Ronald Lett says:

    @TimG: Everyone does not assume those “basic” assumptions. Just today, I was debating with a very religious older gentleman who would not back down from an abstract argument that “anything is possible”, which contradicts “The world follows consistent laws.”

  15. JonJ says:

    I shot this post over to my Facebook page with a comment roughly saying that this guy (Prof. Carroll) is one of the best writers on the Intertubes for my money, and I don’t even have to shell out any of it to read him! Keep up the good fight!

  16. TimG says:

    @Ronald Lett: People certainly might *argue* against those assumptions, but their actions suggest they still believe them. Someone might claim to dispute the idea that the world follows consistent laws, but the next time they get hungry, they’re still going to reach for a snack. Why? Because food always cured hunger before. No one thinks, “Well, I’m hungry, but maybe this time the answer is to stand on my head for an hour.”

  17. Mila says:

    How much synaptic self-(creating)-indulgence must we ejaculate before we arrive at “om”?

    Just sayin’.

  18. rob j says:

    I am both an avid Christian and scientist, and after painstaking side by side study of both Jewish and Christian creation accounts, and quantum physics, I have found that they actually operate very well together, and the studies have actually complemented eachother wonderfully. I am a scientist simply because I am intelligent and curious, a Christian simply because I have experienced things I cannot deny, with proof that cannot be discounted. Convenient? Maybe. But I find this an excellent topic.I think Max Planck had a lot to say in the topic aswell. It’s a good research topic.

  19. Darth Dog says:

    You are a brave man Sean. Well done though.

  20. Alan says:

    For me the universe is God-like if this kind of evidence is true:

    “…Fontana believes that many claims to the paranormal are true and that they provide credible evidence that a soul or spirit survives beyond physical death.”

    “Scholarship, personal experience and high quality always show. This highly accessible, detailed and authoritative book will become a classic. After reading it and assessing the evidence, there can no longer be any doubt that there is life after death. David Fontana’s book should be mandatory reading for all those involved in the care of the dying – and of course for the rest of us who know we will have to face it one day! Dr Peter Fenwick, Britain’s leading clinical authority on Near-Death-Experiences.

    Prof. David Fontana was as distinguished a psychologist as any scientist is distinguished in his/her field, yet looked and concluded after years of investigations that there probably is an afterlife. This is why Stephen Hawking cannot be taken seriously, for instance, as an authority on this issue – no look, no see. I remember meeting Fontana briefly at a few talks in London and had discussions with his colleagues. They were fascinated by this evidence.
    Also many physical scientists don’t like this kind of evidence – but it’s there, waiting for an explanation.

    So again there is this question – if this is true why is the universe structured in such a way that allows meaning generated during a lifetime to continue in another “realm”.
    A little like the recent film Solaris, it creates another level of reality (or our universe has this built in) and that’s where you go – but also maybe one of many alternatives.

    People’s definition of God vary but for me there is something God-like about this universe with evidence like this.

  21. Solitha says:

    “Would you also agree that the best way to answer questions like “Why does God favor three generations of elementary particles, with a wide spectrum of masses?” is to try and establish whether a universe built in this way exhibits a higher degree of Kolmogorov simplicity than one which does not?”

    Is it just me, or did Mr. Torley imply here that God is bound by Kolmogorov simplicity? Doesn’t that kind of… well, totally… derail the idea of the creator making all the rules?

  22. DaveH says:

    I must just comment on this syllogism that’s appeared in the comments at UD:

    1. Either there is a natural or non-natural explanation for the origin of nature.
    2. A natural explanation is logically impossible (due to the circular fallacy)
    3. Therefore, there is a non-natural (i.e., supernatural) explanation for the origin of nature.

    This is a restatement of the cosmological argument, with the assumption of First Cause built in.

    My favourite comment at UD so far is the statement that solipsism is even simpler than a theory that does not invoke God. I think we can grant the point that a non-explanation of the world is simpler than an explanation.

  23. Scientist says:

    Great post, Sean, congratulations!

  24. Tyro says:


    “My favourite comment at UD so far is the statement that solipsism is even simpler than a theory that does not invoke God. ”

    In a weird way, he’s sort of onto something though I’m sure it’s an accident. Look into some of SC’s great books about entropy for a long discussion on Boltzman Brains. I’m sure I’ll mangle something key but AFAIR, this is the idea that, in a universe which extends sufficiently far into the future, random movement of particles will assemble to form disembodied brains with the illusion of memory. Under a naive description of the universe, these are more likely than imagining the whole universe had an extremely low entropy past.

    I don’t know if (and don’t think that) the commenter had any clue about any of this but even if it was sheer coincidence, he happened to stumble onto the first passably interesting reflection. And like all ID comments, it takes a few sentences to ask and a chapter or more to answer.

  25. Tyro says:


    “Doesn’t that kind of… well, totally… derail the idea of the creator making all the rules?”

    Re-read what Sean said about “rules” in science. They aren’t like traffic laws which sufficiently powerful things can break, they’re more like descriptions of how things work. In this case, complexity and information theory isn’t even like physical theories which rely upon fundamental constants which we can imagine a god bending but actually relies upon mathematics which can’t be bent.

    One commenter on UD just said that God was described as simple, case closed. Instead of undermining complexity, that just seems to show that this description of God is wrong.