Don Page is one of the world’s leading experts on theoretical gravitational physics and cosmology, as well as a previous guest-blogger around these parts. (There are more world experts in theoretical physics than there are people who have guest-blogged for me, so the latter category is arguably a greater honor.) He is also, somewhat unusually among cosmologists, an Evangelical Christian, and interested in the relationship between cosmology and religious belief.
Longtime readers may have noticed that I’m not very religious myself. But I’m always willing to engage with people with whom I disagree, if the conversation is substantive and proceeds in good faith. I may disagree with Don, but I’m always interested in what he has to say.
Recently Don watched the debate I had with William Lane Craig on “God and Cosmology.” I think these remarks from a devoted Christian who understands the cosmology very well will be of interest to people on either side of the debate.
Open letter to Sean Carroll and William Lane Craig:
I just ran across your debate at the 2014 Greer-Heard Forum, and greatly enjoyed listening to it. Since my own views are often a combination of one or the others of yours (though they also often differ from both of yours), I thought I would give some comments.
I tend to be skeptical of philosophical arguments for the existence of God, since I do not believe there are any that start with assumptions universally accepted. My own attempt at what I call the Optimal Argument for God (one, two, three, four), certainly makes assumptions that only a small fraction of people, and perhaps even only a small fraction of theists, believe in, such as my assumption that the world is the best possible. You know that well, Sean, from my provocative seminar at Caltech in November on “Cosmological Ontology and Epistemology” that included this argument at the end.
I mainly think philosophical arguments might be useful for motivating someone to think about theism in a new way and perhaps raise the prior probability someone might assign to theism. I do think that if one assigns theism not too low a prior probability, the historical evidence for the life, teachings, death, and resurrection of Jesus can lead to a posterior probability for theism (and for Jesus being the Son of God) being quite high. But if one thinks a priori that theism is extremely improbable, then the historical evidence for the Resurrection would be discounted and not lead to a high posterior probability for theism.
I tend to favor a Bayesian approach in which one assigns prior probabilities based on simplicity and then weights these by the likelihoods (the probabilities that different theories assign to our observations) to get, when the product is normalized by dividing by the sum of the products for all theories, the posterior probabilities for the theories. Of course, this is an idealized approach, since we don’t yet have _any_ plausible complete theory for the universe to calculate the conditional probability, given the theory, of any realistic observation.
For me, when I consider evidence from cosmology and physics, I find it remarkable that it seems consistent with all we know that the ultimate theory might be extremely simple and yet lead to sentient experiences such as ours. A Bayesian analysis with Occam’s razor to assign simpler theories higher prior probabilities would favor simpler theories, but the observations we do make preclude the simplest possible theories (such as the theory that nothing concrete exists, or the theory that all logically possible sentient experiences occur with equal probability, which would presumably make ours have zero probability in this theory if there are indeed an infinite number of logically possible sentient experiences). So it seems mysterious why the best theory of the universe (which we don’t have yet) may be extremely simple but yet not maximally simple. I don’t see that naturalism would explain this, though it could well accept it as a brute fact.
One might think that adding the hypothesis that the world (all that exists) includes God would make the theory for the entire world more complex, but it is not obvious that is the case, since it might be that God is even simpler than the universe, so that one would get a simpler explanation starting with God than starting with just the universe. But I agree with your point, Sean, that theism is not very well defined, since for a complete theory of a world that includes God, one would need to specify the nature of God.
For example, I have postulated that God loves mathematical elegance, as well as loving to create sentient beings, so something like this might explain both why the laws of physics, and the quantum state of the universe, and the rules for getting from those to the probabilities of observations, seem much simpler than they might have been, and why there are sentient experiences with a rather high degree of order. However, I admit there is a lot of logically possible variation on what God’s nature could be, so that it seems to me that at least we humans have to take that nature as a brute fact, analogous to the way naturalists would have to take the laws of physics and other aspects of the natural universe as brute facts. I don’t think either theism or naturalism solves this problem, so it seems to me rather a matter of faith which makes more progress toward solving it. That is, theism per se cannot deduce from purely a priori reasoning the full nature of God (e.g., when would He prefer to maintain elegant laws of physics, and when would He prefer to cure someone from cancer in a truly miraculous way that changes the laws of physics), and naturalism per se cannot deduce from purely a priori reasoning the full nature of the universe (e.g., what are the dynamical laws of physics, what are the boundary conditions, what are the rules for getting probabilities, etc.).
In view of these beliefs of mine, I am not convinced that most philosophical arguments for the existence of God are very persuasive. In particular, I am highly skeptical of the Kalam Cosmological Argument, which I shall quote here from one of your slides, Bill:
- If the universe began to exist, then there is a transcendent cause
which brought the universe into existence. - The universe began to exist.
- Therefore, there is a transcendent cause which brought the
universe into existence.
I do not believe that the first premise is metaphysically necessary, and I am also not at all sure that our universe had a beginning. (I do believe that the first premise is true in the actual world, since I do believe that God exists as a transcendent cause which brought the universe into existence, but I do not see that this premise is true in all logically possible worlds.)
I agree with you, Sean, that we learn our ideas of causation from the lawfulness of nature and from the directionality of the second law of thermodynamics that lead to the commonsense view that causes precede their effects (or occur at the same time, if Bill insists). But then we have learned that the laws of physics are CPT invariant (essentially the same in each direction of time), so in a fundamental sense the future determines the past just as much as the past determines the future. I agree that just from our experience of the one-way causation we observe within the universe, which is just a merely effective description and not fundamental, we cannot logically derive the conclusion that the entire universe has a cause, since the effective unidirectional causation we commonly experience is something just within the universe and need not be extrapolated to a putative cause for the universe as a whole.
However, since to me the totality of data, including the historical evidence for the Resurrection of Jesus, is most simply explained by postulating that there is a God who is the Creator of the universe, I do believe by faith that God is indeed the cause of the universe (and indeed the ultimate Cause and Determiner of everything concrete, that is, everything not logically necessary, other than Himself—and I do believe, like Richard Swinburne, that God is concrete and not logically necessary, the ultimate brute fact). I have a hunch that God created a universe with apparent unidirectional causation in order to give His creatures some dim picture of the true causation that He has in relation to the universe He has created. But I do not see any metaphysical necessity in this.
(I have a similar hunch that God created us with the illusion of libertarian free will as a picture of the true freedom that He has, though it might be that if God does only what is best and if there is a unique best, one could object that even God does not have libertarian free will, but in any case I would believe that it would be better for God to do what is best than to have any putative libertarian free will, for which I see little value. Yet another hunch I have is that it is actually sentient experiences rather than created individual `persons’ that are fundamental, but God created our experiences to include beliefs that we are individual persons to give us a dim image of Him as the one true Person, or Persons in the Trinitarian perspective. However, this would take us too far afield from my points here.)
On the issue of whether our universe had a beginning, besides not believing that this is at all relevant to the issue of whether or not God exists, I agreed almost entirely with Sean’s points rather than yours, Bill, on this issue. We simply do not know whether or not our universe had a beginning, but there are certainly models, such as Sean’s with Jennifer Chen (hep-th/0410270 and gr-qc/0505037), that do not have a beginning. I myself have also favored a bounce model in which there is something like a quantum superposition of semiclassical spacetimes (though I don’t really think quantum theory gives probabilities for histories, just for sentient experiences), in most of which the universe contracts from past infinite time and then has a bounce to expand forever. In as much as these spacetimes are approximately classical throughout, there is a time in each that goes from minus infinity to plus infinity.
In this model, as in Sean’s, the coarse-grained entropy has a minimum at or near the time when the spatial volume is minimized (at the bounce), so that entropy increases in both directions away from the bounce. At times well away from the bounce, there is a strong arrow of time, so that in those regions if one defines the direction of time as the direction in which entropy increases, it is rather as if there are two expanding universes both coming out from the bounce. But it is erroneous to say that the bounce is a true beginning of time, since the structure of spacetime there (at least if there is an approximately classical spacetime there) has timelike curves going from a proper time of minus infinity through the bounce (say at proper time zero) and then to proper time of plus infinity. That is, there are worldlines that go through the bounce and have no beginning there, so it seems rather artificial to say the universe began at the bounce that is in the middle just because it happens to be when the entropy is minimized. I think Sean made this point very well in the debate.
In other words, in this model there is a time coordinate t on the spacetime (say the proper time t of a suitable collection of worldlines, such as timelike geodesics that are orthogonal to the extremal hypersurface of minimal spatial volume at the bounce, where one sets 
) that goes from minus infinity to plus infinity with no beginning (and no end). Well away from the bounce, there is a different thermodynamic time 
(increasing with increasing entropy) that for 
increases with 
but for 
decreases with (so there becomes more positive as becomes more negative). For example, if one said that is only defined for 
, say, one might have something like
the positive square root of one less than the square of . This thermodynamic time only has real values when the absolute value of the coordinate time , that is, 
, is no smaller than 1, and then increases with .
One might say that begins (at 
) at 
(for one universe that has growing as decreases from -1 to minus infinity) and at 
(for another universe that has growing as increases from +1 to plus infinity). But since the spacetime exists for all real , with respect to that time arising from general relativity there is no beginning and no end of this universe.
Bill, I think you also objected to a model like this by saying that it violates the second law (presumably in the sense that the coarse-grained entropy does not increase monotonically with for all real ). But if we exist for 
(or for 
; there would be no change to the overall behavior if were replaced with 
, since the laws are CPT invariant), then we would be in a region where the second law is observed to hold, with coarse-grained entropy increasing with 
(or with 
if ). A viable bounce model would have it so that it would be very difficult or impossible for us directly to observe the bounce region where the second law does not apply, so our observations would be in accord with the second law even though it does not apply for the entire universe. I think I objected to both of your probability estimates for various things regarding fine tuning. Probabilities depend on the theory or model, so without a definite model, one cannot claim that the probability for some feature like fine tuning is small. It was correct to list me among the people believing in fine tuning in the sense that I do believe that there are parameters that naively are far different from what one might expect (such as the cosmological constant), but I agreed with the sentiment of the woman questioner that there are not really probabilities in the absence of a model. Bill, you referred to using some “non-standard” probabilities, as if there is just one standard. But there isn’t. As Sean noted, there are models giving high probabilities for Boltzmann brain observations (which I think count strongly against such models) and other models giving low probabilities for them (which on this regard fits our ordered observations statistically). We don’t yet know the best model for avoiding Boltzmann brain domination (and, Sean, you know that I am skeptical of your recent ingenious model), though just because I am skeptical of this particular model does not imply that I believe that the problem is insoluble or gives evidence against a multiverse; in any case it seems also to be a problem that needs to be dealt with even in just single-universe models.
Sean, at one point your referred to some naive estimate of the very low probability of the flatness of the universe, but then you said that we now know the probability of flatness is very near unity. This is indeed true, as Stephen Hawking and I showed long ago (“How Probable Is Inflation?” Nuclear Physics B298, 789-809, 1988) when we used the canonical measure for classical universes, but one could get other probabilities by using other measures from other models.
In summary, I think the evidence from fine tuning is ambiguous, since the probabilities depend on the models. Whether or not the universe had a beginning also is ambiguous, and furthermore I don’t see that it has any relevance to the question of whether or not God exists, since the first premise of the Kalam cosmological argument is highly dubious metaphysically, depending on contingent intuitions we have developed from living in a universe with relatively simple laws of physics and with a strong thermodynamic arrow of time.
Nevertheless, in view of all the evidence, including both the elegance of the laws of physics, the existence of orderly sentient experiences, and the historical evidence, I do believe that God exists and think the world is actually simpler if it contains God than it would have been without God. So I do not agree with you, Sean, that naturalism is simpler than theism, though I can appreciate how you might view it that way.
Best wishes,
Don
Since TY just put in a personal note, I would like to as well. I am greatly enjoying this discussion, even though of course I disagree with many of you. I do recognize that many of these issues are not clear, so it is not surprising that we can have a variety of opinions about them.
I am advocating Christian theism first because I believe it is true and second because I believe that faith in it can lead to a better life. I don’t think God will judge anyone just because he or she comes to the wrong conclusion about theism, though I do believe that God will discipline us if we fail to show love to others in order to cleanse us to make us eventually into perfect (though not infinite) beings who can fully enjoy God’s love and express it to others.
I have recently become 99% convinced that God will in the afterlife eventually save everyone, though we may have to for a sufficient season undergo discipline and cleansing by God’s holy fire that is in the Bible called hell. This does not mean that I am giving up the traditional Christian doctrine that Jesus Christ is the means to salvation, so that “there is salvation in no one else, for there is no other name under heaven given among men by which we must be saved,” as the Apostle Peter said in Acts 4:12. However, I believe that the ambiguity of this life will eventually be brought to a close, so that all will see that indeed Jesus is the Son of God and will willingly follow Him.
So I do not believe that there is an everlasting divide between those of us who have different opinions about theism in this life, and I look forward to having eternal fellowship with God and with all of you. However, I do believe that the earlier one enters into this fellowship, the better (both for the person and for those he or she affects), and this is a motivation for me to try to explain why I believe that faith in Jesus Christ as the Son of God is reasonable.
I think Don has explained the most important motive for Christian evangelism/apologetics here. The life we were intended for by our creator is actually the best, and is only available through a relationship with Christ (which, when truly functioning, is a different thing to religious observance). The flip side is what people are capable of when estranged from God.
The pivotal force in human existence is I believe, a spiritual one. It is our inequity (want of inner justice) in Adam. We have inherited an overly self-centred, self-justifying, self-preserving, self-important spirit which guarantees eternal turmoil. God’s answer to this condition is Christ. (Evolution by Natural Selection happens to provide a naturalistic hypothesis/justification for why people are like this).
I work with people for whom this is obvious. We work in a community with gangs who practice satanism, sodomy and violent initiation rites. A young man I prayed with last week had 10 bullets fired at him and seven hit, with one going straight through his thigh. He spent a month in intensive care and is now attending rehab. Recently a ten year old boy was killed in crossfire. Last night I did a Bible Study with a young man who has been in prison three times, together with an older man who became a Christian after years of (and generational) gang membership.
This is obviously all part of my ‘data set’.
TY (April 6, 2015 at 9:50 am) returned to the cosmological question of whether the universe had a beginning, writing the following: “It seems to me there is more theoretical support for the “FOR” side and a comment from Don Page would be welcome.”
Let me preface this with a quote from Aron Wall’s excellent summary that TY cited:
“The main point of the doctrine of Creation, I think, is that God is real, and that everything else is derived from his power and will. We know this doctrine is true because we know God. Not because of the Big Bang, as natural as it is to connect the two ideas.”
I don’t personally think that evidence for a beginning of the universe is strong evidence for the Creation of the universe, so theologically I do not care much whether or not the universe had a beginning. (I should perhaps admit that I have a weak personal motivation for not believing that Creation implies a beginning, in that I have my own Symmetric-Bounce model, arXiv preprint here for a universe without a beginning.) However, if the possibility of a beginning can motivate someone to consider other evidence for Christian theism, I am not opposed to someone making an argument for a beginning, so long as it is made clear that not only is this highly tentative evidence, but also if this evidence were refuted, many Christian theists such as myself would not see that counter-evidence as any evidence at all against the existence of God.
So far as whether or not the cosmological evidence supports a beginning or not, the evidence seems very unclear to me. I do think it highly plausible that the thermodynamic arrow of time does have some (perhaps rather fuzzy) beginning, so that entropy has not been increasing forever (though I am not sure even about this), but it also seems to me plausible that spacetime could have existed before this point, perhaps even infinitely long before this point with a contracting universe that had entropy decreasing. (However, if there are ordinary observers in that contracting part of the universe, I think they would remember times when the size and entropy of the universe is smaller and think that the future is in the opposite direction of time where they are, so that they would experience an expanding universe with growing entropy, just as we do.)
Prof. Don Page:
I have been reading these debates with lot of interest. I am delighted to know that a physicist of your caliber is theist. I do not want to make any comments on Christianity because my limited knowledge about Christianity is obtained only from watching TV shows!! However, I want to make one point. Why not separate the two issues: (1) why would a scientist believe in divinity? (2) Whether God appears on earth from time to time looking like a human being. I believe, no matter what religion you practice, the case for the second issue would be weaker than for the first issue. Although my religion (Hindu) has also mythological stories about God coming to earth in several kinds of human or even animal forms, I have hard time reconciling that with something identified with laws of nature and basically shapeless, formless, attributes less entity. It is not clear what it means. For one thing, there may be billions of planets on which life might arise. On some other planet the highest species may look like crocodile or something we have not seen! Laws of nature may be completely different in different multiverse. The omnipotent God can achieve his goal without coming to a particular planet. Although you have discussed these issues at length, I would appreciate some comments.
Don: thank you for that reply of April 7, 2015 at 1:23 am. How you (and professor/St Aron) find the time for responding (with thoughtful arguments) in the blogs, questions coming from all corners, and for academia (not to mention time for God and relations) boggles the mind. But I shouldn’t be the pot calling the kettle black as my waking hours are fully utilised. Sometimes, not enough hours for sleep!
I’m satisfied with your answer, Don. I was just trying to understand your position on the connection between creation and evidence of the beginning of time and the universe, the latter being neither necessary nor sufficient reason for the former. My views on this subject accord with yours, with Professor Aron, with Professor/St. Stephen Barr, and with so many others down long line of reputable theistic physicists.
St. Simon: I thought I wasn’t going to enter the debating hall after my counsel to you on April 5, 2015 at 10:51 am, to stay out, but I had to get professor/ St Don’s reply to my cosmology question.
From Matthew Matthew 22:36-40:
36 “Teacher, which is the greatest commandment in the Law?”
37 Jesus replied: “‘Love the Lord your God with all your heart and with all your soul and with all your mind.’[a] 38 This is the first and greatest commandment. 39 And the second is like it: ‘Love your neighbor as yourself.’[b] 40 All the Law and the Prophets hang on these two commandments.”
Continue the good work in South Africa.
Bill Jefferys (April 6, 2015 at 3:57 pm) wrote the following:
P(“D is consistent with physical law”|G) < 1
Therefore, the likelihood ratio in favor of H [naturalism] and against G [theism] of such an observation D is:
P(“D is consistent with physical law”|H)/P(“D is consistent with physical law”|G) > 1
Therefore, observed over and over again, the combined likelihood ratio (the product of the individual likelihood ratios of the individual independent data) approaches infinity. And, so long as you do not assume a prior that rules out either G or H a priori, the posterior probability of H approaches 1 in the limit.
There are many objections I can raise to this. First, even within the assumptions of this model, the conclusions do not follow. For example, suppose that for the nth observation
p_n = P(“D of the nth observation is consistent with physical law”|G) = 1 – 1/n^2 < 1.
Then if one starts with the observation n = m for some integer m much larger than unity, and takes the infinite set of observations with all integer n this large and larger, the ratio of likelihoods for naturalism versus theism would be the reciprocal of the products of the factors 1 – 1/n^2 for all n from m to infinity, which is finite and is approximately 1 + 1/m, not infinite as claimed.
Furthermore, even if the product of the likelihood ratios diverged as one takes an infinite number of observations, so long as no individual likelihood ratio were infinite, the product would remain finite for any finite number of observations. That is, the limit of an infinite number of observations is physically unrealistic, so conclusions drawn from this assumption are not realistic. We really want to know what we can conclude from our finite number of observations.
Yet another problem with the argument is that the observations usually used to test physical law are not in circumstances in which a theist would strongly suspect that God would probably do a miracle to produce data D inconsistent with physical law. Therefore, even if no miracles are seen in even an infinite set of such observations, that would tell us very little about the probability of miracles in different circumstances in which theists might expect them to occur.
An analogy in testing between two different hypothesized laws of nature would be doing a large number of observations of whether or not Newton’s theory of gravity holds to within 1% here on earth. Even if all of these observations obeyed Newton’s theory to this accuracy, that would not rule out violations in other circumstances.
Bill Jefferys (April 6, 2015 at 5:59 pm) wrote the following:
“Just briefly, TY, fine-tuning does not in any way support theism, as Michael Ikeda and I demonstrated in our paper on the subject (citation in previous comments). The fine-tuning argument completely misunderstands Bayesian inference.”
I’m not a great fan for fine-tuning arguments for the existence of God, since it seems possible that a suitable multiverse theory can explain the fine tuning (though I might still think that the existence of God may be the simplest explanation for why our multiverse is described by such a theory that does lead to life and observership). But I think your paper with Ikeda missed the point of the argument. It is not that given life, fine tuning is evidence for theism, but rather than life itself is evidence for theism, particularly now that we have found that life in a lawful universe seems to require fine tuning.
As I understand it, your way of calculating likelihoods assumes life, so it could not give the likelihood of a theory that does not permit life. But this seems rather odd. Surely we should be able to conclude from our observations that we are alive (even if we have to be alive to make the observation) that the likelihood of a theory that predicts no life is zero. Then if theism is assumed to give a higher probability for a theory with life than naturalism does (since naturalism might not be seen to have any preference for leading to a theory with the fine tuning it needs to produce life), the observation of life would be at least some evidence for theism over naturalism.
Don, it’s true that you can “trick up” a sequence of observations as a special case such that the combined likelihood ratio won’t go to infinity, but that assumes an awful lot. It’s a pretty artificial and unrealistic notion that you’d just happen to make only observations that form a convergent series such as you suggest.
Don’t think I hadn’t already thought of this before you wrote it. I just didn’t think you’d have the chutzpah to suggest something so blatantly artificial, and didn’t want to complicate things unnecessarily.
But since you bring it up…
From my point of view, since I don’t know when this god is going to interfere with an observation, I have to assign a value of
P(“D of the nth observation is consistent with physical law”|G)<k
for some unknown constant k<1. This reflects my view that for any of these observations there is a finite probability, bounded from below by some number >0, that god is going to interfere. This reflects my ignorance about what such a god might do more than anything.
It says, in particular, that I don’t believe that it would be the case that god would sneakily decide to interfere with probabilities that are smaller and smaller as I get older and just happen to form a convergent series. It says that I think that would be a bit much.
I don’t think you can make a convincing case that your artificial example would actually happen in real life. Why, out of all the possible observations that one could make, would one only observe those that happen to form a convergent series as you age and ignore all the others? Remember, just the experience of daily life is a series of a large number of observations…it’s not just stuff we do in the lab.
As far as I can see, your suggestion is mere question-begging. It cannot be taken seriously.
Don, Michael and I know very well what the point of the “fine tuning argument” for theism is; our point is that their point is simply wrong.
The fine-tuners misunderstand the point of the anthropic principle as first stated by Brandon Carter and others (e.g., Bob Dicke). That point was that our own existence implies that we should observe certain ranges for certain physical constants and not other ranges. In some cases we may be able to predict what should be observed using the fact of our own existence.
1) Finding that the constants of physics were not compatible with our own existence (i.e., that some of them violated those ranges predicted by the anthropic principle) would be proof positive that we could not exist except by the action of some deity that is powerful enough to override physical law.
2) Therefore our observing that the universe is not fine-tuned would be evidence against naturalism.
3) Therefore our observing that the universe is fine-tuned cannot be evidence against naturalism and (this is proved in the paper, it’s straightforward application of probability theory) is evidence against theism (it’s not merely neutral as regards theism).
Basically, the fine-tuners want to have it both ways. They want fine-tuning to be evidence for theism, but at the same time it’s self-evident that discovering that fine-tuning did not hold would obviously be evidence for theism. That’s a logical error. The fine-tuners are wrong because they don’t understand logic.
BTW on the anthropic principle, this recent paper just came to my attention. Makes many of the same points that Michael and I did. Clearly points out the error that the theistic fine-tuners are making.
http://philsci-archive.pitt.edu/11399/1/FTA.pdf
Bill, Luke Barnes critiqued yout paper in two sets of articles in Letters to Nature:
Terms and Conditions – A Fine-Tuned Critique of Ikeda and Jefferys (Part 1 and Part 2). A lot of water has fowed under the brdge since 2010.
https://letterstonature.wordpress.com/2010/10/26/terms-and-conditions-a-fine-tuned-critique-of-ikeda-and-jeffreys-part-1/
https://letterstonature.wordpress.com/2010/11/05/what-do-you-know-a-fine-tuned-critique-of-ikeda-and-jefferys-part-2/
It was a rather comprehensive and, to me, a devastatiung critique from a steadfast Fine Tuner theorist; so would you care to update us on how things got resolved (or not resoved)?
Thnaks.
TY, I am very familiar with Luke Barnes’ critique. It is completely bogus.
The basic problem is this. As the late physicist and Bayesian statistician Ed Jaynes has pointed out, it is absolutely necessary to condition all probability statements on any relevant data that is already known as prior information before the experiment, whatever it is, is carried out. By “relevant” he means that the data from the experiment is not independent of this prior information.
Jaynes points out that failure to condition on such data is a fruitful source of error in probability arguments. Failure to do this conditioning properly only produces garbage, and that is the case for Barnes’ arguments.
In the case of anthropic arguments, you cannot ignore your own existence as an observer. In most probability experiments (like coin tossing, high-energy physics, etc.), your existence as an observer doesn’t matter so it is OK to leave that out of the conditions. But in the anthropic case, the fine-tuning observations do depend on your existence as an observer, and therefore it is necessary to condition all probability statements on your own existence, which, it cannot be denied, you knew about from a very early age, way before you did any physics or entertained any anthropic ideas.
This is in fact the whole point of Brandon Carter’s original observations about the anthropic principle.
Since Luke Barnes’ argument (and the arguments that Don referenced) do not condition on this fact, those arguments are wrong.
I’ve discussed the error of failure to condition on known data in a completely different context. See here:
http://bayesrules.net/papers/OldData.pdf
I have, by the way, had a back-and-forth with Barnes some years ago on this. You will not be surprised that I wasn’t able to convince him of his error even though I was able to refute the arguments he made to me. After a couple of tries I gave up.
This seems like such an obvious point to me – well, perhaps someone can enlighten me as to why it has not immediately blown the use of fine-tuning as an argument for theism out of the water long ago:
With different physical laws, our form of life, based on the chemical properties of carbon and other elements as they behave in this universe, would not be possible -agreed. How does this prove that in some other universe with different properties, some other form of life could not occur? For that matter, if there is another form of life that can inhabit gas-giant planets, rather than small, rocky planets with relatively large moons where water is liquid, that other form would have a much better claim to having a universe fine-tuned for them, since so far our planet is unique, and very close to 100% of this universe consists of environments not even coarsely tuned for us.
Other universes might not have stars, but they might have self-reproducing electr0-magnetic fields, or things we cannot even imagine. For the fine-tuning argument to make sense, all other forms of life that might be possible under different rules of nature would have to be somehow ruled out, and I have never seen this attempted by any theist. I guess it is just one of their “priors”.
In Conway’s “Game of Life”, simple forms of self-reproducing cellular automata evolve, and grow more complex over time. The simple, tautological rule which explains this is: if something can evolve in a given universe, and is given enough time, it will. I find this much simpler and understandable than an omniscient god.
As I see it, we are fine-tuned by evolution to suit the small, rare environment of this planet, rather than it (much less the whole universe) being fine-tuned for us. It’s an application of what I will call “Mario’s Sharp Rock” (to distinguish it from Ockham’s Razor): of two competing hypotheses, yada yada yada, always chose the more humble one.
Thank you Bill.
Jeffries,
I like your sharp rock. How about the “Skeptic’s Sad Slicer,” in which you choose the theory you like the least.
On the topic of fine-tuning, I’ve never accepted its premise perhaps somebody can elucidate it for me. The way I see it, when we have a n-parameter statistical model that we fit to data, we accept the best fit values to be the best description of reality. We don’t go on to say, that for any set of parameters in the model, all values are potentially, physically realizable and with equal prior probability. The language/formalism may treat all such parameter combinations as equal, but that doesn’t mean physical reality does. It’s quite an assumption that other values of physical constants are realizable, that they correspond to physical realities and are not just descriptions permitted by the formalism.
Bill Jefferys
I think we are agreed that in all this we need to be extremely clear about exactly what we are attempting to calculate and to disclose/realize what our assumptions are.
Earlier you referred first causes back to the anthropic principle, i.e. we are here to observe a universe that could make us. I do not see any necessarily atheistic implications for this, merely a strong reductionist case. My point at April 6, 1:31 pm was that success in complete naturalistic reduction, certainly with physics as the paradigm, if it happened, still leaves you with a lot of questions to answer, such as how did our math(s) arise, and how do we know that math is actually necessarily paralleled by a physical reality.
You have elaborated on the fine tuning debate. This is how it looks to me.
If we knew all the physics and had the analytic power, and looked backward with an atheistic bias in the prior belief, checking for possible divine intervention on the way, we could find nothing. We could extrapolate back to the starting conditions I mentioned as a hypothetical future physics understanding. But all you would have really proven is that no outside entity succeeded in intervening by deviating from the physics. Your atheistic prior could be seen as having been re-enforced. The assumption in here is that God would intervene, and that would be detectable as a deviation from physics.
Alternatively, if you start with a fairly open prior assumption on theism, and see the appearance of man as a design goal associated with the theistic case, and look forward in time, at many possible evolving universes within various physics parameter spreads, then ours looks very highly tuned indeed to facilitate life as we know it and therefore gives a very high post bias toward theism if it is the only one.
Simon, your comment ignores the point of my last posting, on the need to condition probability statements on all relevant prior information.
Bill
I simply do not see why my existence affects the validity of my second argument. My potential future existence is neutral regarding theism in the prior when projecting forward in time.
Simon, then I do not understand your argument. Please restate it more clearly.
Simon,
Be careful that you’re not assuming a positive atheistic bias here. Many of us here may be atheists, but we don’t necessarily assume there’s not a god (how could we prove it?). The arguments against fine-tuning arise (or at least easily can and do arise) rather from a skeptical bias instead (being inclined to not believe something without evidence).
To put it another way, also making use of Mario’s Sharp Rock, the laws of this universe also produced this pebble I just found on a walk, and probably lots of other pebbles like it (at different scales) all over this universe, and would not have produced said pebbles with different laws. Why do theists assume a creator god would want people instead of pretty pebbles? Mario’s Sharp Rock says pebbles. (A similar argument applies to beetles, and bacteria, and many other things.)
I know the Bible (written by men) says that men are the most important part of the universe, but if we presume the Bible in order to support the fine-tuning argument, isn’t that one of those “circular faith positions”?
Daniel Kerr, I may well not understand what theists mean by their fine-tuning argument either, but am trying to critique it on their own terms, which I think is something like: here we are (after 13+ billion years) as one result of the Big Bang (and in their minds the most important result, on this one, small planet), so post hoc, propter hoc. This presumes things could have been different but were constrained to be as they were so as to produce life, culminating in us, with our poorly-designed knee joints and varying capacities for empathy and thought (as would result from evolution), from which my previous objection follows.
(Dr. Page is not a big fan of the fine-tuning argument either, so it’s not germane to his post, but I keep hoping those who do like it will explain why, in the light of the obvious objections that I and others have stated.)
Don Page writes,
To eminent physicists like Sean and Don, the above may be dead obvious, but I can just barely begin to grasp it. I plead to anyone who knows a good explanation of the points in those two sentences, aimed at the science-literate but not PhD-in-physics level, to provide some reference(s). I’ve got thermo for engineers under my belt, some graphical and equation-based learning of (mostly special) relativity, and the Wiki on CPT invariance. And Hawking’s argument about psych and thermo arrows of time. What next?
Paul,
Causation, logic, etc. is learned from nature in the sense that we consistently see these concepts being played out. There is nothing absolute about them. Rather, we are indoctrinated into believing that there are “causes before effects” and “logic” because everything abides by these rules (disregarding some mystical interpretations of quantum mechanics). We generally take this for granted, but that’s where it comes from. We also tend believe that time must move forward (and not backward) because we expect entropy to increase (due to the second law), and thereby to move backwards, in some sense we might expect to decrease it (and thereby violate the law). This is how much of our common sense about what is “logical” is formed and thus goes to show that much of what we think is “logical” is observed in nature. Such discussion is relevant because, in some sense, the recognition can be used to support a naturalistic worldview. There are some odd-balls to this though such as CPT-invariance, wherein physics doesn’t care if you run the equation backwards, and if it doesn’t, why doesn’t nature show similar strange behavior(?).
That’s a naive explanation of what you quoted– hope that helps.
JimV writes April 7, 2015 at 3:51 pm
“I know the Bible (written by men) says that men are the most important part of the universe, but if we presume the Bible in order to support the fine-tuning argument, isn’t that one of those “circular faith positions”?”
Yes JimV, written by men but inspired by the Holy Spirit. So from this fundamental Christian belief, I don’t see a logical circularity there. Of course non-Christians and atheists don’t have to buy this premise.
On fine tuning, I wish I understood this subject to be able to speak intelligently on it rather than babble incoherence or nonsense. But I’m humble enough to listen to the experts and I did a few hours ago. I share with blog writers this site:
http://www.closertotruth.com/series/does-fine-tuned-universe-lead-god
One thing for sure, physicist are divided on the mutiverse explanation. I really liked Freeman Dyson’s interview. He makes a heck of a lot of sense.