Multiverse ? — Christian Theology and Scientific Rationality

( Would a multiverse be compatible with Christian theology and scientific rationality? )

Appendix: Universe or Multiverse and/or Intelligent Design of Nature?

( Would a multiverse explain why our universe is “fine tuned” to support life? )

This page supplements my page about The Anthropic Principle & Fine Tuning: Multiverse and/or Intelligent Design? and an overview-summary that I recommend reading first, before this page.

Here is a brief summary of
key concepts about a multiverse:

Explaining the Fine Tuning: We live in a universe where the properties of nature are fine tuned so they are “just right” for life. Why? Two currently plausible theories propose that either...

• we live in a universe that is intelligently designed, or

• our universe is part of a huge multiverse (containing many universes with different properties of nature, thus letting us "beat the odds" against fine tuning); this multiverse may or may not be designed.

It seems that neither of these theories can be proved or disproved,* so our evaluations of these theories can be strongly influenced by personal preference for a particular worldview and its associated way of life, plus other factors that include philosophy of science, and more.

* Speculations: Currently the most popular proposals for a multiverse claim theoretical support from cosmological inflation (early in the Big Bang) and string theory, but multiverse proponents acknowledge that direct observational evidence for their theory seems to be impossible, so we can ask “is it really science?” We should not think of a multiverse as an actual reality, but as a potential reality, a speculative proposal (with some scientific support) that we can imagine.

Beating the Odds: In a 5-card hand of poker, getting a royal flush (XJQKA of same suit) is highly improbable, so the odds against it are high. But if you deal a large number of hands, observing a royal flush becomes highly probable, so the odds favor it. Similarly, the odds against a fine-tuned universe are extremely high, but if we live in a huge multiverse (containing many universes with varying properties of nature) having one or more life-allowing universes becomes highly probable so the odds favor it, and we live in one of these life-allowing universes.
Universe-Types and Universe-Actualizations: When we ask “how many universes are in a multiverse?” we must consider two factors. Using calculations based on M-theory (which unifies 5 earlier string theories), scientists estimate that a multiverse might contain 10⁵⁰⁰ different types of universes; and each universe-type might occur in an immense number of actualized universes of the same type that would all have the same properties of nature but (due to having different initial conditions, plus the divergences allowed by quantum uncertainties and described by chaos theory) different histories of nature, with variations on similar basic developmental histories. / I say "might contain... types of universes" and "might occur... actualized universes" to remind you that these should be considered potential types and potential actualizations because, as explained above, there is no direct observational evidence for a multiverse.

Single-Universe or Multiverse-Universe: We might live in a single-universe (that exists independent from any other universes, so it's not part of a multiverse) or in a multiverse-universe (that is part of a multiverse).

The Anthropic Principle — which states that because humans exist, we must observe a universe with properties that allow our existence — is logically valid, and this anthropic selection effect (placing a limit on WHAT can be observed) is compatible with either the presence or absence of intelligent design and a designer, because it doesn't explain WHY our universe is fine tuned for life. But in a multiverse, beating the odds might explain WHY a universe with fine tuning exists, and a second selection effect might explain WHERE fine tuning is observed. { Can we also use a Canine Principle? }

Part 1 — A Multiverse: Christian Theology and Scientific Rationality

The Puzzle of Existence by Robert Mann, is an excellent overview of interesting ideas (scientific, philosophical, theological) that help us understand current thinking about a multiverse. After a summary and brief introduction, Mann continues by asking why is there Something instead of Nothing? (a traditional question) and (in a new question that can be imagined for a multiverse) Something instead of Everything? He then describes (using the mass of neutrons as one example of the many life-permitting features in our universe) the science of Our Atypical Universe with its Biophilic Selection, and explains Cosmic Fine-Tuning, Cosmic Inflation, and how String Theory allows this proposal for a multiverse:

"There could be as many as 10⁵⁰⁰ kinds of ground states to [string] theory, each with its own particular properties and features. Our universe is presumably described by one of these kinds. ... Perhaps all of these different kinds of ground states — in other words, different kinds of universes — actually exist, with ours being one amongst this vast set."

For this part of the paper (the first 6 pages) mainly I just learned from Robert in the science parts, and generally appreciated his skill as a thinker-and-writer who can effectively teach a coherent system of ideas that I find fascinating and intellectually stimulating.
But the final part of his paper (in the last 3 pages) — The Multiverse Paradigm, Theology's New Challenge, The Duplication Dilemma, and Summary — raises important questions about Christian Theology and Scientific Rationality that I will respond to, based on...

Four Rational Principles we should use when asking
“Wouldn't it be strange if EVERYTHING happens?”
This objection — claiming “it would be much too strange” if everything happens in a multiverse — is based mainly on philosophical preference rather than theological necessity. Here are some reasons to think we should say “wait a minute” and put the strangeness into perspective by thinking rationally:

• Rational Principle #1 (re: physical possibility) — There are important differences between an immense multiverse (where MANY THINGS happen) and an infinite multiverse (where EVERYTHING happens). The mathematics of infinity produces results that seem absurd in our normal non-infinite ways of thinking. An argument based on converting these mathematical absurdities into philosophical absurdities will seem much less impressive when we think about the important differences between an infinite multiverse (which is physically impossible, and would be very strange) and an immense multiverse (which might be possible, and would be less strange). ...[a concluding comment from AP/MaoID, about the difference between immensity and infinity, is not included here]... [recently, in 2016, I've added a paragraph about non-infinite mathematics for Probabilistic Resources versus Probabilistic Requirements]

• Rational Principle #2 (re: actual experience, here-and-now) — If we imagine an omnipresent super-observer who is simultaneously EVERYWHERE and who thus can observe all of the many things that would happen in an immense multiverse, this super-observer might see some strange things. But this would not occur with normal physical creatures like you and me, because we would observe things in the same way we do now, as one creature living in one universe. The strangeness of a multiverse is only in your imagination; in your actual experience, nothing would be different. There would not be a duplication dilemma.
• Rational Principle #2h (re: humility) — As a theological supplement to Principle #2, a humble theist should acknowledge that if God — who is an omnipotent super-observer, contrary to Principle #2 for creatures — understands the "many things" happening, and approves, that should be sufficient for us, whether or not we understand or approve.

• Rational Principle #3 (re: theology) — An essential principle of Judeo-Christian theology is our claim that God is sovereign. Therefore, Christians should believe that in an immense multiverse the "many things" that happen would include only what God allows to happen.

note: These 4 principles are quoted from the "Philosophy and Theology" section of my page about Anthropic Principle: Multiverse and/or Intelligent Design? that is abbreviated AP/MaoID in this page, and is summarized here.

Would a designed multiverse be a worthy way for God to create? ( yes, but... )
Yes, I agree with Robert in preferring (aesthetically and theologically) a single universe — cleverly designed by God so it will support human life — instead of a cleverly designed multiverse.
But whatever way God chose to create, we should say (and I'm sure Robert agrees) that "You are worthy, our Lord and God, to receive glory and honor and power, for you created all things, and by your will they were created and have their being." (Revelation 4:11, NIV)

And I agree with Robert that, despite this ultimate humility, in our current state of “not knowing how God created” we should use whatever we do know (when all things are considered, theologically and scientifically) to think about how God created, and to explain what we're thinking. That is what Robert and I are trying to do, in his paper and my page, and in other ways. {more about methods of creation and appropriate humility}

Parts-of-Paper and Whole Paper: Although I've tried to describe Robert's views accurately, I want to help you understand quickly so I've been selective by quoting some parts but not others. Therefore, if you want to know what he says and how, you should read his paper, The Puzzle of Existence.
Quotations in this page are from my page AP/MaoID== and The Puzzle of Existence by Robert Mann. {other presentations by Robert Mann}
Locations for Quotations: To help you know “where to look” so you can see the context of the parts I'm quoting, and what he says in-between, I'll use a system to show the quotation-location. For example, the first citation below is labeled "147L6-147R9" in two parts that show the beginning & ending of the quoting. The right-side table shows 18 parts of page 147, including 147L6 and 147R9. The location of "147 L 6" is on page 147, on the left side (L), a little more than halfway down (6). Similarly, "147R9" is on page 147, on Right side, near the bottom (9). I've assembled the paragraph below by using excerpts within this range, from 147L6 to 147R9.

Formats for Quotes & Non-Quotes & Comments: In this page, regular quotation marks (like "these two") show that I'm quoting Robert's paper or my AP/MaoID; and “smart quotes” are used for non-quotations; and my comments are in [square brackets]. To clarify who is saying what, many paragraphs begin with RM (Robert Mann) or CR (Craig Rusbult) so you'll know whose ideas are being described. {other papers & talks by Robert Mann}

page 147
147L1	147R1
147L2	147R2
147L3	147R3
147L4	147R4
147L5	147R5
147L6	147R6
147L7	147R7
147L8	147R8
147L9	147R9

A Duplication Dilemma ? (this would not be a problem for Christian theology)
RM: As an example to illustrate "a number of subordinate interrelated problems that science and theology must both contend with in the context of a multiverse paradigm," Robert Mann describes {in 147L6-147R9} the Duplication Dilemma: "Consider a universe that is infinite in spatial extent and in which there is an unbounded amount of energy [note by CR: this is one of the proposed mechanisms for producing an "infinite" multiverse, and it correctly illustrates the weirdness that would occur in the infinite multiverse that is proposed by some scientists], everywhere obeying the laws of physics in our observable patch. ... By simply allowing matter and energy to realize all possible configurations that are permitted by the known laws of physics [which would produce an infinite number of actualized universes, each having different initial conditions and thus different histories, even though each actualized universe is the same universe-type and thus has the same properties of nature]... there is enough time, space, and matter to realize all possible known configurations of every allowed physical system" so "any given physical system, individual, or society will experience everything it can experience." And what about you? "Since human DNA has a finite number of configurations, your body will have a duplicate in this infinite universe." In fact, "such duplicates will occur infinitely many times" so you (via your duplicates) will experience everything you can experience, because "all possible social, psychological, and physical outcomes occur" so "at any given instant in which you made an apparent choice, there is an equivalent situation somewhere out there in which your duplicate made a different choice. If you have ever wondered what life might be like if you had not met your spouse, taken that job, or passed that test, you can be confident that somewhere else in the multiverse your duplicates have had these experiences."
CR: This does seem strange, until we remember Principle #2 which is the fact that YOU only experience what is happening to you here-and-now in our universe. IF there is an immense multiverse, your experience would not be any different than it is now. Even though the potential "duplication" sounds strange when it's described in vivid language, the strangeness is only in your imagination; in your actual experience, nothing would occur that is unusual in any way.
CR: And when RM asks you to "Consider a universe..." he should say (and he would agree) “Imagine a universe...” because any type of multiverse is speculative (so it must be imagined) and an infinite multiverse is physically impossible, as explained in Principle #1. Therefore we should ask, “Would duplication be an actual problem, or only an imagined problem that occurs only in imaginative speculations about ‘everything’ (not just many things) happening in an impossible infinite multiverse?”

If Duplicates Exist, We Are Not Unique (this would not be a problem)
RM: "Duplication poses interesting theological challenges,... [especially] a loss of uniqueness. If I am replicated many times in the multiverse, in what sense can I be understood to be a child of God, being worth more than many sparrows? To be sure, loss of uniqueness is a theological issue, one too easily dismissed by its critics. {148L4-148L5}"
CR: No, duplication is not a "theological challenge." Yes, it can be "easily dismissed" because we have a common practical precedent in our world (where ‘duplication’ is not considered a problem for identical twins) plus three logical reasons (based on three rational principles for thinking about an imaginary strangeness if “everything happens”) that are explained in my AP/MaoID:

First, remember Principle #1 and ask, “Would duplication be an actual problem, or only an imagined problem that occurs only in imaginative speculations about ‘everything’ happening in an infinite multiverse that is physically impossible?”
Second, remember Principle #2. Even if duplicates exist, this would not be a theological problem because each person (you and the genetic duplicate) would be living independently — with no knowledge of the other person — in different universes, and God would hold each of you morally accountable for the way you live, for your decisions and actions in your own here-and-now situations. This would be similar to identical twins (having the same DNA, and usually the same family environment) living in our world now, which causes no theological problems because God holds each twin accountable, as an individual person, for the way they live. If identical twins are not a problem for God (if He "approves" of these humans, as described in Principle #2h) then we should not consider twins to be a theological problem; and if actual twins (that do occur) are not a problem, potential duplicates (that might occur) are also not a problem.
Third, remember Principle #3. Judeo-Christian monotheists who believe the Bible will believe that God is sovereign. We should reject an atheistic interpretation of a multiverse. Instead, when we think about “many things happening” we should view this as “only things allowed by God” because God has sovereign control over everything that occurs everywhere in His creation. If God created an immense multiverse, He could decide that life will exist only on our Earth — and He could achieve this goal in two ways, either by miraculously creating life only on Earth (if life cannot be naturally produced by a chemical evolution from non-living chemicals) or (if life can and does naturally evolve) by “killing the life” whenever it occurs on other planets — and this is what would occur, no more and no less; or God could also create life, or allow life, in other places in our universe, or in more than one universe, perhaps in an immense number of universes. And whatever God decides — whether it's life only on Earth, or also on other planets, or also in other universes — that is fine with me, and is compatible with what the Bible teaches.

a general comment: In agreement with Robert, I personally would prefer (for aesthetic and theological reasons) to live in a designed single-universe. But, to a greater extent than Robert, I think a designed multiverse-universe is compatible with Bible-based Christian theology. By contrast, I think one type of proposed multiverse is not compatible with Christian theology:

MWI - Duplicates in Quantum-Split Histories? (this WOULD be a major problem)
As explained above and below, "duplicates" would not be a problem (practical, philosophical, or theological) in a normal multiverse. But in one very strange type of proposed multiverse — which is not mentioned in Mann's paper — duplicates would be a theological problem, although not a practical problem. { In a common classification system what I'm calling a "normal multiverse" is Levels 1 or 2, and the "very strange" multiverse is Level 3. }
Going beyond the scientific assertions of quantum physics, a Many Worlds Interpretation (MWI) proposes that during each quantum interaction every possible result is physically actualized in a different branch of history, with each branch actually happening in its own physical universe. { Why is MWI not necessary, and not useful? }
If this quantum-splitting occurs, it would produce an unimaginably immense number of branching histories because the universe contains a huge number of elementary particles, and these are continually (often zillions of times each second) involved in quantum-interactions that would produce MW-Splitting, and each interaction has a huge number of possible quantum-results; IF every possible result, from each quantum interaction in the universe, produces a different branch of history during one instant of time, during the following instant each of these branches will be split-again into an immense number of different results, and this continuous sequential branching would have occurred zillions of times every second for the past 13.8 billion years, producing an exponentially growing number of history-branches. Wow!
All of these histories would occur in worlds having the same universe-type, and all begin with the same initial conditions, so an MWI-multiverse would not be useful in a non-design explanation for the fine tuning of our universe. But MWI is useful for arguing against design-directed action during the history of nature, since everything that (with non-zero probability) could happen — including a natural origin of life and all of its possible developments during biological evolution — would happen in some branches of history, and these branches would be (due to anthropic selection) where we are.

[[ update in 2023: This page was written in 2010. Maybe there were minor changes in 2016, but none since then. If there are any changes in the near future, each will be labeled an "update" and it will be inside double brackets, like what you're reading, [[ update in 2023: ..... ]]. But I have made major changes in two other places: in the "theology" part (especially 2b) of Fine Tuning in a Universe or Multiverse – and a new page for MWI Science & Theology. ]]

What theological problems occur with a Many Worlds Interpretation?

A. Identity and Accountability: In an MWI-multiverse,

in almost all branches of mwi-history, you were never born;

but in a few branches, you were born and then during your life you “say YES to God” and are reconciled with Him;

and in a few branches, you were born and then you “say NO to God.”

In this situation, which “history of you” would be used by God for accountability, for evaluating your moral/spiritual thoughts and actions? The basic problem is that an MWI-multiverse (if it really exists, but I don't think it does) would destroy the here-and-now principle that makes duplication a non-problem in other types of hypothetical multiverses where "you only experience what is happening to you here-and-now" (this would stay the same with MWI) and (here is the big difference with MWI) if duplicates exist, "God would hold each of you morally accountable for the way you live, for your decisions and actions in your own here-and-now situations." By contrast, with MWI you have zillions of duplicates that really are YOU (sort of) because YOU are thinking every possible thought while making every possible decision, and physically doing every possible action, in each here-and-now; and these differing thoughts-and-actions (mega-schizophrenia!) lead to an immense number of divergent future histories that will be experienced by some form of “you” without any control by you, that all begin with your current here-and-now and continue diverging in your future here-and-nows.

B. Uncontrolled Evil and Suffering: The essence of MWI, with every possible quantum-result happening, seems to deny the possibility of divine control. But in Christian theologies (Arminian or Calvinistic) God is sovereign, and whatever happens is only what God allows and/or causes to happen. Without any divine control, MWI would allow the existence of history-branches with a wide variety of uncontrolled evils and sufferings, thereby violating Principle #3: "in an immense multiverse the ‘many things’ that happen would include only what God allows to happen."

For both A and B, there is a major difference between an MWI-multiverse and non-MWI multiverses:

With MWI there is not control, either by people or God.*

With other proposed multiverses, in each universe every person makes choices in their here-and-now reality; and according to conventional Judeo-Christian theology, God makes choices and has ultimate control.

The choices in A are denied by those who propose a determinism that eliminates human free will, and the choices in B are denied by atheists who declare that God does not exist, and by deists who think that God does not interact with His creation; but whatever choices do exixt, there would be no difference between these choices in a single-universe and a non-MWI multiverse. Whatever choices can be made by humans and by God in a single-universe, the same choices can be made in a non-MWI multiverse. But with an MWI-multiverse the possibility of any choice (by people in A, or by God in B) is declared to be impossible in the basic definition of MWI, as the essence of MWI.
* MWI does propose some control-by-nature because actions that are more probable, according to quantum physics, will occur in more mwi-branches of history. But there is no explicit control, by people or God. Of course, we can propose theistic interpretations of MWI, but these changes would modify its essential foundation, which is allowing quantum wave-functions to develop with total freedom.

What are my responses?

There are no scientific reasons to think an MWI-multiverse exists, and I don't think it exists.

But if MWI does occur so this produces an MWI-Multiverse,

I believe (re: Problem A) that God would somehow convert the basic-MWI into a modified-MWI by giving a special reality status to one branch of history — it's the one we have been experiencing, are experiencing here-and-now, and will continue to experience, in which our thoughts-and-actions will be accountable to God — to prevent one potential theological problem (A) from becoming an actual theological problem.

But (re: Problem B) if the other branches actually exist and are being experienced by people — even if they are not the “us” who are accountable to God) — there would be uncontrolled evil and suffering in some history-branches, thus causing Problem B. This could be solved if God exerted some control over the MWI-multiverse, but I can't understand how this could happen in a way that is consistent with the usual definition of MWI, which prposes that EVERYTHING (with no exceptions) really does happen.

Whatever is happening, at our level and God's level, for us an appropriately humble response is to faithfully follow Principle #2h by acknowledging that "if God ... understands [and wisely evaluates] the ‘many things’ happening [in our single-universe or in any kind of multiverse-universe], and approves, that should be sufficient for us, whether or not we understand or approve."

Now we'll return to Robert Mann's ideas about a non-MWI multiverse (which may or may not exist in reality, we both agree) and my responses.

Christs who Refuse to Die on the Cross (this would not be a problem)
RM: "Duplication presents a serious challenge to Christology. If there are many duplicate worlds, then presumably there are many duplicate Christs. Pursuing the line of reasoning that follows from allowing all initial conditions, in some parts of the multiverse Jesus dies on the cross and in others he does not. [this would happen with MWI but not necessarily with other kinds of multiverse] What then do we make of the concepts of atonement and salvation? Do they only apply to those ‘lucky’ parts of the multiverse where Jesus chose the path of sacrifice? Is Christ to be identified with God only in those sacrificial sectors? Does God so love only certain parts of this multiverse?" {148L5}
CR: If the tri-une God — Father, Son (Christ), Holy Spirit — is sovereign over a multiverse, instead of saying "presumably there are many duplicate Christs" it would be more correct to say “presumably there are many incarnations of Christ.”
CR: This concern — proposing that God might love some parts of the multiverse, but not others — would be a profound violation of Principle #3, regarding the sovereignty of the tri-une God (including Christ) who decides whether Christ will or will not die in each incarnation. Based on the Bible, we have no reason to think that an incarnated Christ would ever refuse to die on the cross by changing His attitude from His actual humble obedience — "My Father, if it is possible, may this cup be taken from me. Yet not as I will, but as you will. (Matthew 26:39)" — to a sinful disobedience, “... not as you will, but as I will, and I'll decide to not drink this cup of death on the cross.” I'm sure that Robert agrees, and in this "challenge" he is describing a question that could be asked by others.* In fact, in a continuation of the quotation above, Robert states this principle of sinless obedience by incarnated Christs, but then (speaking for others) he rejects it:
RM: "These problems [of sinfully disobedient Christs] can be avoided (or at least ameliorated) if one imposes the theological constraint that all the duplicate Christs choose the path of sacrifice. This is fine, but it undermines the motivation behind this simple multiverse in the first place, which was to generate universes by random initial conditions. To impose such a constraint is to eliminate this randomness." {148L8}
CR: By saying "this is fine," Mann agrees that we should expect Christ to always "choose the path of sacrifice." But a Christian does not have to avoid this theological constraint, just to "generate universes by random initial conditions." In a multiverse, God would exert sovereign control over what happens during the history of that universe, after its initial conditions have been established. Christians should strongly affirm it because we believe that God will do what is needed to offer a way for people to be saved, whether this is Christ choosing sacrifice or in some other way.
CR: Even if multiverse-universes were generated with "random initial conditions," God would be sovereign over the history that develops in each universe.

* These others might legitimately claim that disobedient Christs would be one type of "uncontrolled evil" that would occur in some branches of an uncontrolled MWI-multiverse.

Multiverse Interpretation

Should we accept an atheistic interpretation of a multiverse? No.
RM: An interpretation of a multiverse based on conventional Christian theology, which acknowledges the sovereignty of God by affirming that Christ will always behave in the way that Christ (who is part of the tri-une God) decides to behave, "undermines the motivation behind this simple multiverse in the first place, which was to generate universes by random initial conditions. To impose such a constraint is to eliminate this randomness." {148L8}
CR: Above, I ask "why should a Christian avoid this theological constraint?" and explain why we should affirm the constraint. A theistic interpretation of a multiverse is analogous to a theistic interpretation of evolution in theistic evolution. Although atheists can claim that “natural = without God” for natural neo-Darwinian evolution, this is not the way “natural” should be viewed by Judeo-Christian theists. Instead, Jews and Christians should define natural process as being designed, created, sustained, and guided (occasionally or continually) by God. And we should call attention to atheistic interpretations when we see them. For example, in April 1995 the National Association of Biology Teachers (NABT) declared that biological evolution was "unsupervised," thus adopting an atheistic interpretation of evolution. But in October 1997, non-NABT outsiders persuaded the leaders of NABT to acknowledge that their claim (about a lack of supervision) was not scientifically justifiable, so they dropped this claim. {read the story of NABT and its Biology-Theology} We also should not propose an atheistic interpretation of a multiverse, and we should not uncritically accept this proposal by others; instead we should challenge it by asking, “Can your interpretation be justified by scientific evidence-and-logic? If not, then you should explicitly state that your interpretation of the science is non-scientific.” / note: non-scientific does not mean un-scientific, it means outside science which is not necessarily against science. / also: Jews and Christians who believe what is taught in the Judaic Scriptures that we both accept (these scriptures are often called the Old Testament) are Judeo-Christian theists who should agree about the essentials of Judeo-Christian theology, although followers of Judaism and Christianity will disagree about some aspects of Christian theology; therefore, when I say "Christians" or "Christian theology" this usually is the same as “Judeo-Christian theists” or “Judeo-Christian theology” but sometimes it is different.
Our interpretations of natural process are important. In one part of my Creation-FAQ, in Sections 5A-5G I ask "What can a Christian believe about evolution?" and explain why, even though evolutionary creation (i.e. theistic evolution) is not my own view, I defend its theological acceptability. Here is one reason, quoted from Section 5E of my FAQ for Creation, Evolution, and Design:

A nontheistic interpretation of neo-Darwinian science will see the process of evolution as being not designed by God, using matter not created by God, driven by only chance and selection that were not guided by God. But these claims are theological, not scientific, and a theistic interpretation of the same science can disagree by viewing the evolutionary process as being designed by God, using matter created by God, and (at least sometimes) guided by God. {Divine Guiding of Natural Process} In most fields of science — ranging from the physics of rain to the biochemistry of embryology and physiology — there are no theological criticisms of scientists who accept naturalistic theories proposing “only natural process.” A proposal for theistic evolution [evolutionary creation] just extends this acceptance into another area of science.

And a proposal for a theistic multiverse just extends our theistic interpretations of nature into one more area of science.
When a theory is criticized because it can be interpreted atheistically, this is a good starting point for an evaluation. Then, to decide whether it's a good ending point for a conclusion that the theory must be interpreted in the way proposed by atheists, we should critically evaluate each proposed Christian interpretation (or more generally, Judeo-Christian interpretation) and ask whether it is acceptable, theologically and scientifically. If the answer is “yes, this interpretation is acceptable” and if there is no logically compelling reason to accept an atheistic interpretation, we should reject the atheistic interpretation, explaining why it is being rejected and why instead we are choosing to interpret the theory in the context of our Christian worldview. Christians should interpret a multiverse theory in ways that are acceptable to us; our views of a multiverse should not be determined by the proposals of atheists, by the interpretations they prefer.

Would a multiverse be “too much” for God to govern? ( no )
RM: "The classic picture has been that of a finite creation whose origin, existence, and fulfillment depend on the limitless power of God [who is "omnipotent, omniscient, and omnibenevolent"]. ... The creation is subordinate to God and is limited." By contrast, "It is difficult to regard the multiverse as being anything other than a limitless creation. Adopting this viewpoint, the classic picture must be discarded, and a theological tension arises between the power of the Creator and the creation." {146R6-146R8}
CR: Again, notice the equating of potential immensity (in a vast creation) with potential infinity (in a "limitless" creation) by ignoring Principle #1. Also, despite the common assumption that a life-allowing universe will also be life-producing, we should remember the distinction between life-allowing and life-producing and we should believe that a sovereign God decides where and when life will occur. Concerns about multiverse-duplicates assume that life will begin by natural process, because either an origin of life isn't difficult, or any improbabilities will be overcome by immense probabilistic resources.
CR: There is no Bible-based theological reason to conclude that God can cope with a universe but not a multiverse, that a multiverse filled with life would be “too much” for a semi-omniscient God who has limited observational-and-computational abilities so He could not cope with the complexity. But even if this divine limitation does exist (and there is no biblical evidence to support this claim), if we believe that God is omnipotent, then we should believe that He could “limit His focus” by limiting life so it exists only on Earth, or only in this universe, or only in a limited number of universes, because God decides where life will (and will not) occur. Or maybe — and a humble “maybe” is all we can claim to know — God would decide to create a huge number of intelligent creatures throughout a multiverse, by using natural evolution and/or miracles.

Would a designed multiverse be a worthy way for God to create? ( yes )
RM: "In a situation where all possible outcomes are realized it is difficult to avoid a complete degeneration into absurdity. For example, the intelligibility of God reflected through a putatively elegant mathematical description of the multiverse [for a designed universe] is undermined [with a designed multiverse] by the imbecilic generation of all conceivable outcomes." {146R9-147L1}
CR: Again, many conceivable outcomes (which might be possible) would not be "all conceivable outcomes" (this is not possible), using Rational Principle #1 about the impossibility of physical infinities.
CR: Aesthetically and theologically, I also would prefer a designed single-universe. But, as explained in Principle 2h, "a humble theist should acknowledge that if God ... understands the ‘many things’ happening, and approves, that should be sufficient for us, whether or not we understand or approve." Therefore, we should express our personal preferences with appropriate humility, as I urge in the conclusion of my Creation-FAQ asking "What can a Christian believe about evolution?":

In science and theology, our humility should be appropriate, not too little and not too much. We can make some claims, but not others, with confidence. ..... Instead of criticizing either possibility [if God created “with or without miracles” or, in the context of cosmology, created a universe or multiverse] as being a less worthy way for God to create, it seems wise to be humble by deciding that, either way, God's plan for design-and-creation was wonderful and is worthy of our praise. You and I should say in public — and believe in our hearts and minds — that “IF God created using another method (differing from the way I think He created, regarding either age or evolution [or universe or multiverse]), then God is worthy of our praise.” But this humility (if... then...) is compatible with humbly explaining, using arguments from theology and science, why we think a particular view is most likely to be true.

I think Robert agrees with this, and he is simply explaining why he thinks "a particular view [with a designed-and-created universe that is not part of an immense multiverse] is most likely to be true."

Appropriate Humility in Creation Theology
Part of my motivation for writing this page is to avoid a creation theology that is too restrictive, that goes beyond what the Bible teaches. Here are two examples. In the 1600s, some Christians (including leaders of the Roman Catholic Church) insisted that God had created a motionless earth at the center of the universe, not an earth that is orbiting the sun and is rotating once every 24 hours. In 2010, some Christians (including leaders with influence) are continuing to claim — even after hearing many explanations of why their views are not scripturally warranted or scientifically supported — that “if the Bible is true, the earth is young” so “if the earth is not young, the Bible is not true.” These two claims, about a stationary earth and a young earth, are not biblically supported so they are too restrictive, and (according to current science) they are wrong. We should avoid unnecessary restrictions on creation theology, whether the proposed restrictions are based on specific biblical passages (as with a stationary earth or young earth) or (as in Robert Mann's opposition to a multiverse) are based on general biblical principles about the characteristics of God and His creation.
I think the Bible does not support a claim that our universe must be the only universe, that God would not create our universe as part of a multiverse so the only theologically acceptable type of creation is a single universe. The Bible seems to say nothing directly about this question, one way or the other, and current science (when this was written in April 2010) says “we don't know for certain, and maybe we cannot know.”
We should try to avoid restrictions on creation theology unless these restrictions are necessary, based on what the Bible clearly teaches. If a claim really does contradict our Bible-based theology — as in an unscientific assertion that “according to science, divine miracles are impossible” so God could not use any miracles during the history of creation or the history of human salvation — we should challenge this claim and explain why we think it is wrong. But we should avoid “drawing a line in the sand and taking a stand” where this is not necessary. If a creation view is compatible with what is clearly taught in the Bible, this makes the view a theologically acceptable possibility for creation.
But an appropriate creation humility is compatible with humbly explaining, using arguments from theology and science, why we think a particular view is most likely to be true. And this is the goal of Robert in his paper.

Would a MULTIVERSE be compatible with SCIENTIFIC RATIONALITY? ( yes )
RM: "All possible experimental outcomes occur for a given physical system somewhere in the multiverse. Two sets of near-identical observers could measure wildly different outcomes from the same set of conditions, with one set of observers inferring quite distinct forms of scientific regularity. In what sense can we then say science is left with any predictive power? ... Indeed, since everything that can occur does occur, one is ultimately left with a reasonless explanation for any given phenomenon." {147R9-148L3}
For this section it will be useful to review the concepts of universe-types and universe-actualizations and Rational Principle #2.
CR, quoting from my AP/MaoID: Will reliable science be impossible because scientists cannot reject a claim for any event even though it seems extremely improbable, if the event might occur somewhere else in an immense multiverse? For example, will we have to accept implausible claims for a “perpetual motion machine” that violates the probability-based Second Law of Thermodynamics? ..... No, because scientists in a multiverse would not be omnipresent super-observers; they would live in a single universe, and in every universe, whatever is most likely to happen is what is most likely to be observed. Although strange things might be happening somewhere in a multiverse, it's extremely unlikely that strange things will be happening where you are, at the particular here-and-now location in space-and-time where you are making your observations. Therefore, in any universe-type where nature is reliable (where natural process is consistent, as in our universe) science can be based on “the best ways to bet” and it will be reliable, because scientists will not observe frequent highly improbable events (on a “tail” of a probabilistic distribution) that would threaten confidence in their science. We have no reason to think that tail-of-the-distribution events — such as perpetual motion machines (defying the Second Law) or wingless flying cows (defying gravity and aerodynamics) or everyday improbabilities such as Aunt Bertha winning 20 consecutive state lotteries — would be more probable in other universe-types with science (if they exist) compared with our universe-type. And we can imagine some events (such as wingless cows flying around the world?) so improbable that they would NEVER occur in any universe, even in an extremely immense multiverse. Our own science can continue as usual, based on our own universe-specific observations, whether or not we live in a multiverse. What about science and miracles?
RM: "If we decide to restrict science only to our observable patch, then what is the point of introducing the multiverse in the first place? One is also left with the question of how one rules out unlikely outcomes on the basis of chance. Any phenomenon contradicting known science within a patch might just as well be attributed to being in a quirky location in the multiverse. {148L2}"
CR: All actualized-universes of the same universe-type (if different types and actualizations really exist) should develop the same basic scientific principles, although in actualized-universes the differences in initial conditions would lead to different details in their histories of nature, and differences in worldviews-and-culture would produce some variability in the formulations of these principles. But if more than one universe-type has intelligent beings and science, each distinct universe-type will have different scientific principles. {quoted from AP/MaoID}
As explained above, we can "restrict science only to our observable patch." It's not necessary for us to develop a generalized multiverse-science that could explain phenomena everywhere in a multiverse (*) because we can only observe what is happening in our universe, in "our observable patch" where the properties of nature are consistent. Therefore, I don't understand why Mann is protesting against this localized universe-science by asking "what is the point of introducing the multiverse in the first place?" But in addition to developing our localized universe-science, some areas of science (e.g. string theory and multiverse cosmology) could try to develop a “bigger picture” science whose goal is an overall perspective, in the context of multiverse cosmology, on what is happening both inside and outside our universe. But this is different than trying to imagine what science would be like for a universe with nature-properties that differ from our own nature-properties; while this might be possible, it is not necessary.
And phenomena that contradict science could not be attributed to a "quirky location" because, as explained above, we are not omnipresent super-observers so "our own science can continue as usual, based on our own universe-specific observations, whether or not we live in a multiverse."
* In the most popular models of a multiverse, the properties of nature are different in each universe-type (with perhaps 10⁵⁰⁰ type-variations?) so the science developed in one universe would not be correct in a universe of a different type, re: the results of science. And re: the process of science, developing a generalized multiverse-science would be very complicated and difficult, maybe impossible, because it would be purely theoretical with no empirical foundation using data from other universe-types. But for practical functionality a generalized multiverse-science (that describes the properties of nature in 10⁵⁰⁰ universe-types, plus their universe-actualizations that have differing initial conditions) would not be necessary; instead, a localized universe-science (including multiverse cosmology) would be sufficient, and it is a worthy goal.

A Change in Science: Although in the excerpts above this is not Mann's concern (re: changes in scientific rationality), one actual change in science is the fact that scientists are now thinking, talking, and writing about a multiverse. Current cosmology is much different now than it was in the 1960s before scientists began developing their sophisticated theories about big bang inflation, string theory, and multiple universes. But there is a difference between human theories and the physical realities that may or may not match our theories. For example, the physical reality of actual orbits did not change between 1500 (when most scientists thought “planets orbit the earth”) and 1700 (when most scientists thought “planets, including earth, orbit the sun”). In this case the new theory was correct, but in other cases a theory is incorrect, as in the 1800s when a theory about luminiferous ether proposed that space is filled with an ether which serves as a medium for the transmission of light waves, and their theory was wrong. Currently it seems that “the jury is still out” on the new cosmological theories, so appropriate humility is justified.

Multiverse Theory — Is it scientific?
Some scientists (and nonscientists) claim that a multiverse theory is not scientific. These claims, made by theists and non-theists, are motivated by wanting to uphold the integrity of science. For some people, but not others, another motive is a desire to defend claims for a designing of nature. Quoting from my AP/MaoID page:

Currently there is no direct observational evidence for a multiverse. But according to most multiverse theories, other universes are in a different space-time framework so in principle they cannot be observed, or they are very far away so in practice they are unobservable. Therefore, the fact that we do not observe any other universe does not count as scientific evidence against theories proposing the existence of many other universes.
Because empirical testing is the foundation of scientific method, but multiverse theories cannot be empirically tested using direct observational evidence, many scientists and philosophers (both theists & non-theists) claim that untestable multiverse theories are philosophical speculations rather than authentically scientific theories.
But could we find indirect observational evidence? The logical foundation of modern science is hypothetico-deductive logic, which permits a theory to propose unobservable entities if these help the theory explain observable outcomes. This is why modern scientific theories proposing the existence of unobservable electrons (in chemistry) and ideas (in psychology) are widely accepted, because these theories — which propose that unobservable causes (electrons and ideas) help to produce the effects we observe — are the most satisfactory explanations for our observations. {Science and Unobservables - The Demise of Positivism}
Why could the if-then logic of hypothetico-deductive reasoning make more people consider a multiverse theory to be more acceptable as being authentically “scientific” ? We'll look at the if-and-if-then reasoning for a specific type of multiverse theory: [IOU - I'll finish this paragraph soon, probably late-night February 6] IF some scientists think that probably String Theory (M-theory) is true and/or scientifically useful, and IF String Theory seems to offer a good explanation for the cosmological inflation we do observe, and IF in these situations many universes (to form a multiverse) would be produced, THEN a multiverse seems probable. [should this be if-if-if-then, or if-if-then?] / the paragraph is very rough from here onward (based on this application of String Theory to inflationary situation) combo of M-theory plus multiverse is useful in hypothetico-deductive logic, and if a combination of “M-theory plus inflation” makes a multiverse possible (or even probable) as a cause and/or effect, this would provide indirect observational evidence for a multiverse.

Science and Miracles
Some people think that science would be impossible if miracles can occur. Although in some ways miracle questions are similar to the multiverse questions examined above, they differ in a very important way. By contrast with a multiverse and its imaginary non-problems, miracles could potentially be an actual problem that would provide a practical reason for us to lose confidence in the reliability of science. In reality, however, this potential problem is not an actual problem for everyday science, because (quoting from my page explaining why claims for inherent conflict between science and religion are exaggerated) "although science would be impossible if we lived in a world with constant ‘Alice in Wonderland’ surprises and no reliable cause-effect relationships, if despite occasional miracles the universe usually operates according to normal natural patterns, science will be possible and useful."

Should scientists distinguish between Imaginative Speculation and Physical Reality? ( yes, we agree )
RM: "The question [for science, philosophy, and theology] is whether all that exists is equivalent to all that is possible. ... A given multiverse theory posits some kind of universe-generating mechanism, and then argues the case for the special features of our universe [being produced naturally without design due to “beating the odds” with a huge number of universes] by contending that the mechanism does generate whatever it can generate... [so] whatever can exist, does exist. ... Is it credible to believe that God created everything [that we can imaginatively propose]? Does God create (by whatever means) whatever can be created, or does the Creator make particular choices? ... What line should be drawn between the possible and the existent? ... These questions cannot be decided by observation and experiment, in that the multiverse paradigm — by definition — asserts that all that exists extends well beyond the capacity of observation. ... It is also far from clear that these questions can be settled by mathematical self-consistency arguments, though there is much effort being expended in this direction. ... Are there theological criteria for drawing a line, even tentatively, between the possible and the existent? If so, what are they? If not, can theology have anything useful to say about the multiverse?" {145R8-146R4}
CR: Agreeing with Robert, I also think we should be asking these questions.

A Summary:
Would a multiverse be scientifically uncontrollable and theologically lethal? ( no )
RM: "The multiverse approach is a conceptual Pandora’s box: once you get started on the idea, it is not clear how or where to stop. Scientifically it can run out of control, and it can be theologically lethal." {145R7}
CR: A multiverse will not seem to be scientifically uncontrollable or theologically lethal if we remember four rational principles: 1 (many things are not everything, because immensity is not infinity); 2 (we are not omnipresent super-observers, we see only what is here-and-now); 2h (if it's OK with God, it's ok with me); 3 (just relax, God is in control). Yes, the concept of a multiverse is difficult to understand or even imagine, especially for people who don't have a scientific background, but we should not exaggerate the weirdness by accepting atheistic multiverse-interpretations that deny the existence and power of God. As explained above (Humility in Creation Theology), we should "avoid a creation theology that is too restrictive, that goes beyond what the Bible teaches."
RM: Listing miscellaneous potential problems with a multiverse, "further examples [in addition to the duplication dilemma] include problems with scientific elegance, empirical testability, spontaneous creation, unbounded evil, purpose, and free will." {148R9}
CR: I don't think these are actual theological problems, for reasons explained earlier. Here are brief comments about where these issues are addressed: scientific elegance and empirical testability (is a multiverse theory scientific? I think Robert will agree that good pro-and-con arguments can be made; to see some of these, and my conclusion that we should be patient and learn what we can rather than prematurely labeling multiverse proposals as non-science so we can ignore them, search for “elegance” and “testing” in my page about The Anthropic Principle: Multiverse and/or Design); unbounded evil, purpose, and free will (these are no more problematic in a multiverse than in a universe; see Principles 3, 2h, and 2, respectively, and their applications for the duplication dilemma & worries that we are not unique); spontaneous creation (I'm not sure what this means, but I think it's about many universes being created “automatically” due to the cosmological physics, which does make me a little uneasy because I prefer the idea of God creating each world individually for a purpose, but if God created our world by using a multiverse that's fine with me, as in the humility of Principle 2h; I don't think Robert is asking about creating massive amounts of mass-energy in many gigantic universes because he is an expert physicist and evidently he and his fellow physicists are satisfied that this is possible, or about creating life - which is discussed in Principle 3 above and Part 2 below).
RM: Mann wonders whether "the multiverse paradigm is scientifically beneficial... [or] can be reconciled with any reasonable form of Christian theology. A far more critical analysis from scientific, philosophical, and theological perspectives needs to be applied in examining the multiverse paradigm." {149L2}
CR: I agree. These questions — about fine tuning and intelligent design, universe and multiverse, regarding science, philosophy, and theology — are important, so they should be carefully examined and thoughtfully discussed. I hope this page makes a useful contribution to our collective logical evaluations.

APPENDIX 1

Multiverse and/or Intelligent Design?

What are the implications of a multiverse and/or intelligent design for the “fine tuning” that allows our universe to naturally support life, and for natural evolutions to produce us?

Background Reading: It may be easier to understand the ideas below if you review the summary of central ideas (Fine Tuning in a Universe or Multiverse, Beating the Odds, Anthropic Principle, Speculations) and four useful concepts (life-allowing universe and life-producing universe, universe-types and universe-actualizations) plus 4 rational principles (immensity ≠ infinity, and many things ≠ everything; we are not omnipresent super-observers; if God approves that is sufficient, and God is in control) for thinking about “everything” happening. And for a more detailed explanation of two ideas — Defining Intelligent Design (in 4 ways!) and Beating the Odds (illustrated using examples from Poker and Evolution) — you can read this part of Anthropic Principle: Multiverse and/or Intelligent Design.

Table of Contents for Appendix 1
You can read these sections in any order you want:
•• Would a multiverse weaken arguments for design? / Anthropic Principle and Canine Principle;
•• No Confident Conclusions; Motivations for Accepting or Rejecting a Multiverse Theory; Appropriate Humility in Science and Theology.

• and in Appendix 2: energy in an mwi-multiverse; questions to explore, continuous miracles; papers & talks by Robert Mann.

Would a multiverse weaken arguments for design? — YES, for two kinds of design, for...

A Designing of Nature before History: Some people are motivated to either accept or reject claims that “a multiverse exists” because an immense multiverse could weaken a claim for an intelligent design of nature.
This weakening would occur because the properties of nature — which seem fine-tuned to allow life — could occur without design IF we live in a non-designed multiverse (containing multiple universe-types with their properties-of-nature distributed across a wide range) that is extremely large so the odds favor having one or more universes with intelligent life, and one of these universes is where we live.
Currently we cannot know whether a multiverse would have to be designed or could be non-designed, so IF a multiverse exists our conclusion about a design of nature (within a designed multiverse) would be that “we cannot know.”

Design-Directed Action(s) during History: A multiverse with multiple universe-actualizations (of a universe-type that is fine tuned for life) also would weaken claims for detectable intelligent design-directed action during history if we allow appeals to “beating the odds for evolution” with a multiverse. Quoting from my page about The Anthropic Principle: Multiverse and/or Intelligent Design (AP/MaoID).

We might consider “beating the odds” to be a valid logical argument for only one type of scientific question — when we ask about ingredients of reality (such as life-allowing properties of nature, plus a life-producing history of nature) that would be necessary for our existence — because only in this case [or perhaps also when we observe other historically contingent features of nature, such as dogs *] could anthropic selection provide a logical reason to reject a probability-based scientific claim for an intelligent design of nature before history began, or for intelligent design-directed action (= design-action) during history.
For these questions about anthro-essential design,
IF (and this “if” is currently disputed) scientists in the future ever conclude that any stage in a natural history leading to humans — in the physical evolution of planets, or an initial origin of life, or an evolution of life into humans — would be extremely improbable without intelligent design-action, thus making design-action seem probable, THEN their probabilistic logic might require that they propose two if-then conditional conclusions, one for each type of universe:
• IF we live in a single-universe, THEN a claim that “design-action seems probable” is scientifically supported; but...
• IF we live in a multiverse-universe within an extremely large multiverse (not just a moderate-sized multiverse), THEN scientists can remain agnostic by saying “we don't have the certainty of indisputable scientific evidence either for or against design-action.” Why? Because although a multiverse would be relevant for evaluation — by weakening a claim that “design-directed action did occur” (due to beating the odds logic) so these kinds of claims could not be scientifically proved true — the claims for design-action also could not be proved false if we're not certain whether there are enough universes to beat the unfavorable odds to produce the observed feature. { an escape clause: But claims for an infinitely large multiverse can be used as a “trump card” that can automatically defeat any claim for design-directed action, because the math-of-infinity urges us to conclude that EVERYthing will happen, infinitely many times, even if a particular thing is extremely improbable. } / Also, a multiverse could be either designed or non-designed, although this design of nature before history is different than design-directed action during history.

* Anthropic Principle and Canine Principle
In any universe where natural process is reliable, a multiverse would not affect our experiences because in either a single-universe or multiverse-universe, whenever we observe (in everyday life and in science) "whatever is most likely to happen is what is most likely to be observed."
So... why could this principle be changed when we're evaluating claims for design-directed action? In an immense multiverse, why would we able to claim beating the odds for anthro-essential features that appear improbable (definitely in the fine tuning of nature, or maybe in a natural origin of life) but not for other improbable features, such as perpetual motion machines or wingless flying cows? Basically, it's because we observe humans but not flying cows, and (re: anthro-essential features) because WE are doing the observing so obviously we exist.
If we live in a multiverse-universe (a universe that exists within a multiverse) our science would be constructed by scientists who observe only what happens in our universe, so rational science would be possible in a multiverse. Due to observational reasons (we've never seen a wingless flying cow) and theoretical reasons (re: gravity, aeronautical physics, anatomy & physiology,...) we conclude that a flying cow is extremely unlikely and we won't propose it in our science. But we do observe humans, so we construct theories to describe-and-explain the origin of humans during the history of nature.
Of course, we also should use our observations about non-anthropic features of our universe — such as the fact that it includes Cairn Terriers (like Toto in The Wizard of Oz) and a wide variety of other dogs — as part of the empirical basis for our theories about nature and its history. Thus, in addition to the anthropic principle we could define a canine principle: because dogs exist, we must observe a universe with a history of nature (including suitable properties of nature) that allows the existence of dogs, and (more specifically) this history must allow both humans and Cairn Terriers, because we observe them. But the existence of dogs is not anthro-essential. We also could define a Feline Principle, Kangaroo Principle, Lilac Principle, Blue Sky Principle, and so on.
These logical principles, regarding our observations of historically contingent features that include humans and dogs and other observed phenomena — including marsupials in Australia, the extinction of dinosaurs by a meteorite, and more — lead to other questions we can ask.

No Confident Conclusions (about a Multiverse or Evolutions or God)
Here are quotes from my AP/MaoID regarding our ability to reach confident conclusions, our lack of certainty for a theory proposing that we live in a multiverse:

Theistic and atheistic worldviews propose descriptions of reality — and explanations for why and how things happen — that agree in most ways but differ in some important ways, including different ideas about what existed before the beginning of our universe. An atheist assumes the existence of a materialistic capability for creating our universe. A theist assumes the existence of God, who has this creative capability. Each asks the other, “Can you explain what caused the existence of what you assume as the starting point?” Neither offers an answer that satisfies the other, and neither assumption can be proved, so theism and atheism both offer an explanation that is possible but cannot be proved.
If divine design and materialism are both possibilities, and our questions about a multiverse (does it exist? would it be designed or undesigned?) cannot be decisively answered by scientific evidence and logic, our multiverse-views can be strongly influenced by our personal preference for a particular worldview and its associated way of life, plus other factors that include philosophy of science (is a multiverse theory scientific? what would be more elegant, one universe or many, a unified theory or string landscape?), and philosophy of life (would you be bothered by duplicates in other worlds?), and more.
Should this lack of proof bother us? No. In fact, I think “a state of uncertainty” is the way God wants it to be, because a lack of certainty forces each of us — no matter what we believe in our personal worldview — to live by faith in what we believe. What is the spiritual significance of this uncertainty, with humans apparently unable to logically prove or disprove the existence and actions of God? Some interesting ideas to think about are briefly outlined in two sections (A Summary, Living by Faith) in a page asking Why isn't God more obvious?

And if we accept appeals for beating-the-odds with a multiverse, we also may not be able to reach confident conclusions about totally natural evolutions, first with chemical evolution to produce the first life, and then a biological evolution of this life to produce all biocomplexity and biodiversity. For these questions about a multiverse and its effects on the probabilities of these evolutions, our views can be strongly influenced by our personal preference for a particular worldview that includes personal psychology and social-cultural factors. The types and amounts of worldview-influence vary in different areas of science, and one area that is strongly affected is our thinking about a multiverse.

Motivations for Accepting or Rejecting a Multiverse Theory
Theists who want to “win arguments for God” by their claims for divine intelligent design (before or during history) will be motivated to oppose a multiverse that can weaken (or even neutralize?) their claims for design. And atheists who want to avoid losing these arguments will be motivated to propose a multiverse; they will defend it vigorously if they think it is necessary to maintain their worldview-beliefs; a multiverse seems necessary for atheism, but (since a multiverse might be divinely designed) it would not be sufficient as a proof of atheism, or even to provide evidence for atheism. By contrast, theists who are not concerned with winning arguments can say “either way is fine, with a universe or multiverse.” They, and others who mainly just want to find truth, will try to evaluate the pro-and-con arguments — scientific (based on evidence-and-logic), philosophical, and theological — using unbiased logic, although reducing bias is difficult because none of the arguments seem conclusive so "our multiverse-views [to reject or accept it, and think of it as undesigned or designed] can be strongly influenced by our personal preference for a particular worldview and its associated way of life." (this paragraph is quoted from AP/MaoID)
As an example of this motivation, Robert Mann claims that a multiverse would weaken the persuasiveness of a theistic argument for an intelligent design of nature, saying "If we have empirical support for a compelling ecbatic [naturalistic] mechanism for explaining the origin of the constants of nature, why would we adopt a telic approach to this issue [by claiming that the constants “achieve a purpose” of a divine designer]? To rise to this theological challenge is no small task. {Mann-2005 307R5}" {note: In the main part of this page, I respond to a 2009 paper by Robert Mann.}
This is definitely an apologetics challenge, because a multiverse would weaken claims that intelligent design is an argument for the existence-and-actions of God. A theological challenge would also occur if, as Mann claims, we should say “no” when we ask would God use a designed multiverse to create our universe? Saying “no” (which I think is unwise) is declaring that the only theologically acceptable proposal for creation is a single universe; this restrictive claim-about-creation is challenged by proposals for a multiverse.

Appropriate Humility in Science and Theology
Our questions about a multiverse — does it exist? if yes, what is its size, and is it designed or undesigned? and so on — cannot be decisively answered by scientific evidence and logic, so our multiverse-views can be strongly influenced by our personal preference for a particular worldview and its associated way of life. My Creation-FAQ (Section 5G) says, "In science and theology, our humility should be appropriate, not too little and not too much. We can make some claims, but not others, with confidence." An appropriate humility — not too little, not too much, and with a good attitude — is useful when we're thinking about intelligent designs in a single-universe or multiverse-universe, and communicating with each other.

APPENDIX 2

Energy Conservation in the Many Worlds of MWI
If many universes (each with a huge mass/energy) are being produced by the process claimed by MWI many times each second, does this violate a conservation of energy? The MWI-Everett FAQ (by Price) says NO because "the energy of the total wavefunction... involves summing over each world, weighted with its probability measure." Similarly, Wikipedia says "the energy of each branch has to be weighted by its probability, according to the standard formula for the conservation of energy in quantum theory. This results in the total energy of the multiverse being conserved."
Although this is mathematically correct according to the quantum-math used to calculate probabilities, MWI claims that every MWI-world actually does physically exist in reality (with 100% probability) so every instant a near-infinite amount of mass/energy is being produced. (unless the universe being split by MWI has exactly-flat geometry and its total energy is exactly zero, as proposed in “free lunch” theories) Even though all of this new mass/energy cannot be observed (due to decoherence) with MWI the new mass/energy does physically exist, because every possibility in the quantum wave-function of our universe does physically exist. Although MWI is called "many worlds" the MWI claim is that all history-branches actually occur within our own universe, but they are hidden from our observation by decoherence. Can this vast increase of actual physical mass/energy be explained, or are MWI advocates hiding behind mathematical formalism instead of coping with the physical implications of MWI? This defense of MWI (with energy "weighted by its probability") seems to assume that mathematical description = physical reality, that the quantum-equation is physical reality because it correctly describes probabilities for what will occur in physical reality; but this interpretation-assumption is the central claim of MWI, so the defense uses circular reasoning and therefore is logically questionable.
a humble comment: This section is in the appendix because I haven't yet checked it with quantum experts, so maybe I've misunderstood something about relationships between the mathematics and claims for physical existence, about the science-and-interpretation of MWI, and the claims made by MWI.

Why MWI is not Necessary, and (I think) is Not Useful
In quantum physics, I think a Many Worlds Interpretation (MWI) is theologically unsatisfactory, as explained earlier. I also think it's not necessary and not useful.
MWI is often described in terms of experimental observations or measurements, but these words are misleading. To avoid confused misunderstandings, instead of observations (or measurements) we should think about interactions. Quantum Physics Interpretations - Schrodinger's Cat & More explains why observation is not an accurate description of what happens in nature, by using two illustrative examples: an electron passing through two slits (as a wave) before interacting (as a particle) with a detector-wall; and an electron frequently interacting with other wave-particles inside a living animal in a complex biochemical context (not a simplified experimental context) without human observation.
In both of these examples, and in all other situations, quantum interactions can occur with or without observation-knowledge by humans, and almost all interactions (certainly for billions of years before we arrived on the scene, and also in the present) do not involve human consciousness. In fact, the error of thinking “quantum physics shows that we ‘create reality’ with our human consciousness” is the main reason that Section 3B starts by saying "oops, they [the founders of quantum physics] used a bad word" because they chose a scientific term, observation, that encourages non-scientific misconceptions and false claims. { Most advocates of MWI agree that quantum interaction does not require human observation or human consciousness. For example, an MWI-Everett FAQ by Michael Clive Price says, "A measurement [aka observation] is an interaction, usually irreversible, between subsystems that correlates the value of a quantity in one subsystem with the value of a quantity in the other subsystem. ... A measurement, by this definition, does not require the presence of a conscious observer, only of irreversible processes." (italics added by me) }
MWI is not science. In modern science, quantum physics (aka quantum mechanics) is universally accepted as a successful scientific theory; but all interpretations of quantum physics, including a Many Worlds Interpretation, are nonscientific speculations. Some scientists are fascinated by the mathematical elegance of MWI, but this mental convenience requires paying a high cost in physical extravagance. And there is no scientific reason to think MWI is more likely to be true, compared with conventional interpretations. Although the physical process of decoherence is sometimes cited as support for MWI, because it explains why we (in our own here-and-now branch of history) could not observe or interact with other branches, decoherence is also consistent with other interpretations; for example, decoherence (described in Section 3A) explains why human consciousness is not necessary during observation-interactions that produce a “collapse of the wave function” in conventional non-MWI views such as the Copenhagen Interpretation. {my summary of MWI - plus comments about its physics & psychology} also, Would an MWI Multiverse require a non-conservation of energy?

Questions to Explore

Here are some interesting questions (inspired by thinking about anthropic and canine principles) for future explorations: What is special about our observations of humans, that differs from our observations of Toto or the Grand Canyon, a blue sky or thunderstorm, or liquid water? Is there a difference between our observations of historically contingent features (Cairn Terriers, Grand Canyon,...) or non-contingent features (the properties of zinc, water,...)? But is liquid water really non-contingent? (i.e. could we live in a world where we would not observe blue sky or thunderstorms, or water?) In what ways is it significant, and not significant, that humans (but not a dog, canyon, sky, or water) are asking “what, when, how, and why” and we are constructing a science to help us answer our what-when-how-why questions? Although I extended the Canine Principle to both “marsupials in Australia” and “the extinction of dinosaurs by a meteorite,” should these be viewed differently — re: beating the odds in a multiverse — if dinosaur extinction was essential for our existence (at least for our existence in 2010 using the internet) but marsupial evolution was not essential? / a bonus question-and-response: When we conclude that "because humans exist, we must observe a universe with properties that allow our existence," are we ignoring the possibility that perhaps we are being supernaturally maintained in a world where natural process would not allow our existence? This could occur if our existence is being sustained by...

Continuous Miracles: The anthropic principle claim — that "because humans exist, we must observe a universe with properties that allow our existence" — can be logically challenged, because a life-allowing universe is logically necessary (so we must observe it) only if natural process, not continuously supplied divine miracles, is maintaining our lives. Although a Judeo-Christian theist will say “miracles are possible,” almost all people, including me, are confident that this kind of “continuous miracle” is not happening, and that – based on our current scientific knowledge – it does seem that natural process (operating in biochemistry, physiology, etc) is sufficient to maintain life, that the properties of nature do allow our natural existence.

Papers and Talks by Robert Mann: In this web-page I'm responding mainly to The Puzzle of Existence by Robert B. Mann in Perspectives on Science and Christian Faith, September 2009. Although I saw similar ideas in Robert's earlier paper (Inconstant Universe) in 2005, my current responses were stimulated by hearing his talk at the Annual Meeting of ASA in July 2009. Then I read his 2009 paper, and wrote the "Philosophy and Theology" section and this response-page. Recently, in early 2016, I've listened to his later talks (alone and on panel)== at ASA's Annual Meeting in 2014 (when he was Program Chair), and an interview in 2014.

Here are some other pages with related ideas:
by me — Anthropic Principle and Fine Tuning: Multiverse and/or Intelligent Design?
plus an Overview-Summary of many ideas, but not all, in the full-length page,
and more about Multiverse and/or Intelligent Design during the History of Nature,
and by other authors — a links-page, DESIGN OF THE UNIVERSE — SCIENCE & THEOLOGY