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The Evidence Room · The Drawing Board

How do we know God exists?

Summary

Nobody has a proof, and the Bible never offers one: what there is instead is a set of features of the world that are far easier to explain if a mind is behind it than if nothing is, each one weighed here against the best answer its critics give.

  • These are reasons rather than proofs, and each one has a serious answer printed beside it.
  • The universe appears to have had a beginning, which is a claim about physics and could be revised.
  • The physical constants sit in narrow bands, which physicists themselves call a problem.
  • Saying how improbable that is needs a measure over the values the constants could have taken, and nobody has one.
  • Taken together they reach a maker at most. They do not reach Jesus.

THE CLAIM

Several features of the world are far easier to explain with a mind.

  1. 1What kind of question this isManuscript
  2. 2Why is there something rather than nothing?The data
  3. 3The dialsThe numbers
  4. 4The one thing you cannot get behindThe data
  5. The remaining 2steps →

WHERE IT STANDS

Reasons, not proofs, and each one has a serious answer.

moderate confidence

Nothing on this page is a proof. That word belongs to mathematics, and almost nothing outside mathematics has one.

What follows are reasons: several independent features of the world that a person can weigh, the way you weigh reasons for anything that matters. Individually none is decisive. The claim is about how they add up.

How the question is being taken here75 words

It is worth noticing that the Bible works this way too. It does not open with an argument. It opens with a statement, and when it does argue it points at the sky and at conscience rather than at a syllogism.

Every objection below is real, several of them are strong, and a few of the best objections to these arguments come from people who believe in God and think the arguments are bad ones.

The numbers, and who counted them

Walking it through

  1. 01Manuscript

    What kind of question this is

    People sometimes expect this question to work like a math problem: line up the premises, turn the crank, and the conclusion is forced.

    The rest of this step111 words

    Almost no interesting question works that way. Whether a defendant is guilty, whether a theory in physics is right, whether a person loves you: all of these are settled by weighing evidence and comparing explanations, not by deduction.

    So the honest form of this question is comparative. Given what we find (a universe that had a beginning, physical constants that sit in a narrow band, minds that experience things, and a stubborn sense of right and wrong), which overall picture leaves the least unexplained?

    Someone can weigh all of it carefully and land the other way. That is not stupidity, and treating it as stupidity is how these conversations go bad.

  2. 02The data

    Why is there something rather than nothing?

    The oldest argument in the file has a simple shape. Whatever begins to exist has a cause. The universe began to exist. So the universe has a cause.

    The rest of this step145 words

    The second line used to be a purely philosophical claim. In the twentieth century, physics made it a scientific one: the expansion of space, the background radiation left over from an early hot state, and the abundances of the lightest elements all point back to a beginning.

    The honest note, and it matters: a beginning is a claim about physics, and physics can revise its claims. There are serious cosmological models (bouncing universes, eternal inflation, quantum-gravity proposals) in which our expansion is one episode rather than the start of everything. None is established, and neither is the alternative.

    So the argument is genuinely open at that point. What it does establish, if the beginning holds, is that the universe is not the kind of thing that explains itself, and that a cause outside of space and time is at least the right shape of answer.

  3. 03The numbers

    The dials

    Physics contains a set of numbers that the theory does not predict. They are measured, not derived, and several of them sit in narrow bands where life is possible.

    The rest of this step265 words

    The starkest is the cosmological constant, the energy of empty space, which drives cosmic expansion. Its value is of order ten to the minus one hundred twenty-second in the natural units physicists use: that is, one followed by a hundred and twenty-two zeros beneath it. Larger, and expansion tears matter apart before a single star or galaxy forms.

    Then there is carbon, which every living thing is built from. Carbon is made inside stars through a process that depends on a very particular energy match. The strong nuclear force appears to be tuned to within about half a percent for it to work, and the strength of electromagnetism (the fine-structure constant, about 0.007297) to within a few percent, roughly four, on the same argument.

    The astronomer Martin Rees gathered several of these into a short list of dimensionless numbers, including the ratio of gravity to electromagnetism, around ten to the thirty-sixth. His point was that a handful of numbers set the character of the whole cosmos.

    Roger Penrose put a number on the starkest one of all. In The Emperor's New Mind (Oxford University Press, 1989), page 344, he worked out how precisely the universe's starting state had to be selected out of the space of states it could have had, and got one part in ten to the power of ten to the one hundred and twenty-third. The exponent alone has more digits than the observable universe has particles.

    What this does and does not show is the subject of the first four objections below, and they are the strongest set on the page.

  4. 04The data

    The one thing you cannot get behind

    Everything science studies, it studies from the outside. Brains can be measured, scanned, and mapped, and the mapping has been spectacularly successful.

    The rest of this step175 words

    But there is one thing that is not available from the outside: what it is like to be you. The redness of red. The particular ache of a memory. Philosophers call this the hard problem, and it is called hard because the usual method does not obviously reach it: you can give a complete physical account of what a brain is doing and it seems not yet to have said why any of it is experienced.

    The argument here is modest, and overstated versions of it deserve the ridicule they get. It is not brains are mysterious, therefore God. It is that on a picture where reality is fundamentally mindless, conscious experience is a genuine puzzle, whereas on a picture where mind is fundamental, minds appearing in the world is what you would expect.

    The honest counterweight: several serious philosophers think the hard problem is a confusion rather than a discovery, and others answer it without God, by holding that experience is a basic feature of matter itself. Neither of those is a fringe position.

  5. 05Manuscript

    And then there is right and wrong

    The fourth reason has its own page, because Marcus Brown considers it the strongest one: if some things are genuinely wrong (not merely disliked) then goodness needs a ground that is not human opinion.

    The rest of this step59 words

    That argument is walked in full, with the classic objection from Plato and the best modern answers, at its own door below.

    It is worth noting the shape it shares with the others. Each of these arguments points at something ordinary (a beginning, a constant, an experience, a conscience) and asks which picture of reality makes it least surprising.

  6. 06The text

    How the Bible actually argues

    Here is something people notice with surprise. Scripture never argues for God's existence the way this page does.

    The rest of this step107 words

    It begins with a flat statement (in the beginning God) and everywhere else it points. It points at the sky. It points at rain and harvests. It points at conscience. It treats the evidence as public and already in front of everyone.

    Paul's line to Rome is the clearest case: the invisible things are perceived through the things that are made. That is an appeal to creation, not to a chain of premises.

    Which sets the real size of the arguments above. They answer the claim that belief is unreasonable. They are not the road most people actually walk to God, and Scripture never says they are.

The objections, at full strength

Each objection below is stated the way the people who hold it state it, at the same type size as the answer. If you hold one of these and think it is put unfairly here, tell us.

  1. THE OBJECTION01Ours is one universe among an enormous numberIf there are vastly many universes with different constants, then some of them will have life-permitting values, and of course we find ourselves in one of those. The idea is not invented to escape design; it falls out of physics people were doing anyway. Eternal inflation produces bubble universes as a consequence of inflationary cosmology, and string theory's landscape allows an enormous number of possible low-energy configurations. On this picture, asking why our constants are life-permitting is like asking why the planet you live on has liquid water. Somebody had to be on one that did.

    THE ANSWER

    This is the main response to fine-tuning and it is a serious one, held by serious physicists for reasons internal to their field. Its honest limit (and physicists say this themselves) is that there is currently no empirical evidence for other universes and no accepted way to test for them. A hypothesis that explains the data but cannot presently be checked is not thereby false; it is a promissory note.

    Two further points, and one of them cuts against this page's own side. Against the multiverse: some philosophers press the inverse gambler's fallacy: that many other trials elsewhere does not raise the probability of this particular trial coming out well, any more than learning that many people play the lottery explains your own winning ticket. In favor of fairness: a multiverse would in fact explain the tuning, and a Christian who waves it away as desperate is not arguing honestly.

    Where this lands: two explanations of the same data, one of which posits an unobserved designer and one of which posits unobserved universes. Neither side gets to call the other unscientific for free.

  2. THE OBJECTION02Of course the constants permit life: you are here to notice themThis is the observer-selection point and it is logically airtight as far as it goes. Any observer, in any universe, will necessarily find conditions compatible with observers. There are no reports from the universes where nothing formed. So the fact that we observe life-permitting values carries no information at all about how surprising those values are. The appearance of fine-tuning is a selection effect, and selection effects are one of the most reliable sources of illusory significance in all of statistics.

    THE ANSWER

    The logic is correct and should be granted immediately. What it establishes is that we could not have observed anything else. What it does not establish is why there is anything to observe. The standard illustration is the firing squad: twelve marksmen fire and you survive. It is certainly true that you could not be puzzling about it unless you had survived, and it remains entirely reasonable to suspect the outcome was arranged. Observer selection removes the surprise only if there were many trials, which is why this objection is strongest when it is paired with the multiverse and much weaker standing on its own.

  3. THE OBJECTION03You cannot say the odds are long without knowing the rangeThis is the most technically serious objection and it rarely gets printed in popular material. To say a constant is finely tuned, you need a probability, and a probability needs a measure over the space of possible values. Nobody has one.We do not know which constants are genuinely independent and which are fixed by deeper physics not yet discovered: historically, numbers that looked arbitrary have repeatedly turned out to be derivable. We do not know whether the possible range is infinite, in which case normalizing a probability over it is not merely hard but mathematically undefined. Without a unified theory there is no way to say a value is improbable.The whole argument may be a probability claim with no probability in it.

    THE ANSWER

    There is no clean answer to this and this page will not manufacture one. It is the objection that ought to make anyone cautious about stating fine-tuning in numerical terms, which is why the figures above are given as measured precisions rather than as odds. Two things can still be said.

    First, the physics community's own language (physicists routinely describe the cosmological constant as the worst fine-tuning problem in science) is not apologetics; it reflects a real sense within the field that these values call for explanation. Second, the argument can be run without a measure, as a comparison of explanations rather than a calculation: a life-permitting universe is more expected on a designing mind than on no mind, and that comparison does not require assigning a number to the alternatives. That is a weaker argument than the one usually presented.

    It is the one that survives.

  4. THE OBJECTION04A God able to tune a universe is more improbable than the universeRichard Dawkins put this at the center of The God Delusion (Bantam, 2006), and stripped of its rhetoric it is a real challenge. Design arguments work by saying that complex, organized things need an explanation. A being capable of designing physical constants and monitoring every conscious creature would have to be at least as complex and organized as anything it made. So the explanation is more in need of explanation than the thing explained, and you have not simplified anything: you have added an entity and moved the problem up one level.

    THE ANSWER

    The objection is a good one against a certain picture of God, and Christians who imagine God as an extremely large and complicated engineer have earned it. The classical reply is that it misidentifies what is being claimed. In traditional theism God is not a composite of parts and processes: that is precisely what the doctrine of divine simplicity denies.

    Complexity of the sort that requires explanation is complexity of assembly, of things put together out of other things, and that is the sort of complexity the argument says needs a cause. A mind's ideas can be complex without the mind being an assembled object. Whether that reply works is genuinely disputed and a reader should not be told it settles the matter.

    What can be said is that the objection assumes a definition of God that classical theism rejected long before Dawkins wrote, and an argument is only as good as its target.

  5. THE OBJECTION05This is a god of the gaps: you are naming what science has not explained yetThe pattern is old and the record is bad. Lightning was divine anger; now it is electrostatics. Disease was judgment; now it is microbiology. The complexity of the eye was proof of design; then Darwin explained it. Each time, the gap where God lived was filled, and belief retreated to the next unexplained thing. Consciousness and cosmic beginnings are simply where the gaps currently are. The reasonable inference from the history is not that this time is different. It is that the gaps keep closing.

    THE ANSWER

    The history is accurate and the warning is a fair one, and Christians ought to feel its weight rather than deflect it. Two distinctions matter. The first is between a gap in current knowledge and a limit in the kind of explanation available.

    Why does electricity behave this way? is a gap. Why is there any law-governed universe at all? is a different sort of question, and it is not obvious that more physics is the sort of thing that answers it, since physics presupposes a universe to describe. The second is about the direction of the inference.

    The strongest arguments here do not run from we cannot explain this; they run from this is what you would expect on one picture and not the other, which is an argument from what is known rather than from what is missing. Both distinctions can be disputed. What cannot be disputed is the track record, and any believer who has not felt the force of it is not paying attention.

  6. THE OBJECTION06Even if some designer exists, that is not the God of the BibleGrant every argument on this page. What you have is a cause outside space and time, apparently intelligent, apparently interested in a universe that supports carbon. That is a very long way from the God who called Abraham, gave the law at Sinai, and raised Jesus of Nazareth. The gap between a first cause and a personal God who forgives sins is not a small one, and moving across it takes something these arguments cannot supply. Hume said this centuries ago and it was never answered: a design inference at best delivers a designer, not a deity with a character or a history.

    THE ANSWER

    This is correct, and this page agrees with it without qualification. The arguments here get you at most to a mind behind the world. They do not get you to the cross.

    Christianity has never claimed otherwise: its distinctive claim is a historical one: that this God acted, in public, in a particular place, and that the action can be investigated. That is why the resurrection has its own page in this wing and why it does more work than anything here. The proper role of these arguments is narrower than they are usually given: they answer the charge that belief in God is irrational.

    They do not identify which God, and honest apologetics says so at the start rather than being caught at it.

WHERE IT STANDS

Reasons, not proofs, and each one has a serious answer.

moderate confidence

These are reasons, not proofs, and anyone who presents them as proofs has misled you. Each one has a serious answer, and several of the answers are strong.

The universe appears to have had a beginning, which is a claim about physics and could be revised. The physical constants sit in narrow bands, which is real and which physicists themselves call a problem, though saying how improbable that is requires a measure nobody has. Consciousness is a genuine puzzle for a purely physical picture, though not everyone agrees it is a puzzle at all.

The strongest of the group, in the founder's judgment, is the moral one, and it has its own page.

The rest of the summing-up63 words

Taken together they do not force a conclusion. They shift the comparison, and a comparison is what a reasonable person is actually working with on any question this size.

And they get you at most to a maker. They do not get you to Jesus. For that the door is history, not physics, which is why the resurrection file sits beside this one.

What would overturn this A theory that fixes the constants from physics alone would take the fine-tuning reason off this page, and the page would say so.

The limits

What the evidence does not settle

  1. Whether the universe had an absolute beginning is a live question among cosmologists.

    What would settle it A model with observational support that carries the history back past the apparent beginning.

  2. How improbable the fine-tuning is cannot be stated as a number without a measure over the possible values.

    What would settle it A physical theory that fixes the range the constants could have taken.

  3. Whether consciousness is a puzzle for a purely physical account is itself disputed.

    What would settle it A physical account of experience that its critics accept, or a demonstration that none can be given.

The works this page is built on

11 works, each named in full. Follow one into the registry to see everything else on the site that leans on it.

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If there's no God, is anything really wrong?→

Did Jesus rise from the dead?→

Why does God allow suffering?→

The creation week, read closely→

The flood→

The apologetics room→

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