So here goes ---
Sean Carroll, another physicist and author, writes in a review of the book:
The Hawking vs. God debate has featured prominently in the news of late. He and Mr. Mlodinow don't claim to have proved that God doesn't exist; their argument is somewhat more confined, but still important in its implications. We understand enough about the ultimate laws of physics, the authors say, to conclude that we don't need God to understand the universe.Or, as the book says,
Why is there something rather than nothing? Why does nature have the laws it does? Why do we exist? Some would claim the answer to these questions is that there is a God who chose to create the universe that way. . . . We claim, however, that it is possible to answer these questions purely within the realm of science, and without invoking any divine beings."Father Stanley Jaki, a physicist and theologian who wrote many books about the relation of science and religion, has written that physicists, if they are not careful,can confuse the operational with the ontological.
The way I understand what he is saying, good physics does not add up to good philosophy or good theology. When you have explained the steps by which you think the universe has begun, even supposing your model meets all the standards of a good model, you have perhaps accomplished a wonderful feat of theoretical reverse engineering, but you have not even started to say anything about metaphysics (which is the study of things beyond matter and motion). You are still in your own field.
Also, at the very least, the epistemological presuppositions upon which physical science is founded are metaphysical. We have to presuppose that we can say something meaningful about the physical world before we can even start writing a book of this sort. And that is a giant metaphysical presupposition. It can't be verified physically.
It's important to get that out on the table at the start, I think. I am not sure whether Hawking and Mlodinow would disagree, though I suspect that they would, and that is one of the ambiguous elements in the book. I definitely think they intended to fire a shot over the bow of traditional metaphysics, but in spite of their provocative "Traditionally these are questions for philosophy, but philosophy is dead," I don't think they have managed to fly their flag on the mast yet.
As far as physics go, Hawking and Mlodinow posit an "M-theory" which I will have to simplify even more than they already did in the book, in order to fit it in this post. They hold that any universe that can exist, will exist; that
the universe does not have just a single existence or history, but rather every possible version of the universe exists simultaneously in what is called a quantum superposition.
So, given this theory, what looks like extraordinary odds that our universe should be as it is, habitable and capable of producing beings like ourselves (I believe they give a number of 10 to the 500th power for all possible permutations of the basic physical laws, which is a number beyond staggering), is actually not a highly improbable thing at all but demonstrably inevitable for this universe. The very fact that it does exist means that it could.
The conclusions that they draw from this, if it were true, are:
- We are not special -- sentient human beings are the inevitable byproduct of the particular set of laws that exist in this particular universe.
- God did not custom-design our universe -- it's just one of a vastly, mind-boggingly number of alternate universes.
To prepare the ground for their multiverse theory, Hawking and Mlodinow explain their philosophy of model-dependent realism. They say that it is meant to short-circuit the philosophical debate between what the book calls "realists" and "anti-realists".
"There is no picture- or theory-independent concept of reality. Instead we will adopt a view that we will call model-dependent realism: the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations. This provides a framework with which to interpret modern science."
"According to model-dependent realism, it is pointless to ask whether a model is real, only whether it agrees with observation. If there are two models that both agree with observation ... then one cannot say that one is more real than another. One can use whichever model is more convenient in the situation under consideration."As I understand it, this approach allows them to speculate a bit past the normal grounds of our physical universe, while still staying within bounds of natural science.
I sort of like this concept of model-dependent realism because as they say in the book, it speaks to something we are aware of in ordinary life as well as in science. A lot of times, what we see is dependent on what we have seen and understood in the past. A new baby is awed by the swooping of the mobile above his head, whereas his mother, who has snapped it together and clipped it to the crib and turned it on, is seeing it very differently -- probably looking past the mobile watching the baby with his big eyes and dancing motions. When Hawking and Mlodinow look at a physics equation they see something very different than I do. Last year, Kieron read a book called The View from the Oak which was about the sometimes radically different ways different creatures perceive things. For example, a dog's nose is hundreds of times more sensitive than mine, so he can almost get a 3D representation of something by its smell, where I would be only vaguely aware that there is a smell at all.
Yet it strikes me that we humans do not really practice model-dependent realism even though in some ways we are somewhat subject to it and hopefully, somewhat aware of it. In other words, no one ever REALLY says, "That is just my model of reality" though they might say it to someone else "That is just YOUR model".
All of us, from the baby in the crib to the physicist, are trying to come to some absolute truth from our relative stance in the universe. We hope to transcend our model-dependence at least partly, by taking it into account and attempting to compensate for it, even though we know our attempts can never totally succeed. We may not see a whole truth given our limits (Thomas Aquinas said that a natural philosopher can never totally understand even a fly), so the understanding that our knowledge is limited induces a healthy humility and wonder that induces us to find out more, but we don't rest in our partial perspective. (A flea or dog, on the other hand, does rest in its limited knowledge, because it doesn't care to KNOW so much as to meet its biological needs).
Even the baby is striving to universalize his initial impression of the world. As soon as he is physically able to get his hands on the toy he has previously only observed, he turns it, tastes it, shakes it, pulls it, throws it. He is not content until he runs out of ways to study its behavior and sensory properties. Then he turns to something else. And we all do the same thing in our own way. Hawking and Mlodinow are not really, really content to say "this is our model and we're happy with it." They will want to defend it and refine it. They will want it to be true in some way, though they may be completely and humbly willing to admit it is not the whole truth and some future genius may springboard from their theory to a more explanatory and predictive one.
Plus, though Hawking and Mlodinow want to propose model-dependent realism as a philosophical approach that "short-circuits" the debate between realism and idealism, I don't think it can work this way. It does more and less than short-circuit (their term) -- it simply sidesteps the issue by not confronting it.
Model-dependent realism seems like it must be a form of realism -- by using the example of a goldfish bowl, it brings up an image of a "real world" out there even if we can only see it from our vantage point. The goldfish is seeing things accurately from his perspective; his perception only "works" if you are in a bowl, but it is realistic from that perspective. Knowing that he is in a bowl he could theoretically compensate for the distortion and "see" the world outside of his glass.
But model-dependent realism also echoes idealism or anti-realism in its radical subjectivity, in its agnosticism about whether what we perceive is real or not. It starts from inside our own heads. Inside our own heads, or inside a fishbowl, we can never really say anything about reality, only about what appears to our inner minds as reality. All statements then are self-reports and no more. The only way the goldfish can compensate for his subjective perspective is to presuppose that there really is a world outside the goldfish bowl, that the outside world is not just a deceptive Matrix-like stream of images on the surface of the glass.
So model-dependent realism works as a procedural or operational approach, not as an ontological or epistemological one. Or so I would think.
As a physical-scientific protocol or tool, I would imagine that model-dependent realism is quite effective. It allows physical scientists to posit certain hypotheses without getting embroiled in scientific dogma (which is, as every high school text will tell you, an obstacle to the pursuit of the physical sciences, though I have started to wonder just a bit about that). When a new model is (1) more elegant (2) more explanatory (3) more predictive it can replace the old model, no hurt feelings. Ideally it would keep the natural sciences from infringing on fields outside their own, though in practice with respect to individual scientists it doesn't seem to fully avoid this.
But as a form of philosophy, model-dependent realism seems to add up to a form of scientism -- that whatever can't be quantified, isn't really worth thinking about. Scientism unfortunately has a tendency to contradict itself -- because it tends to want to pronounce that because its procedures don't work on unquantifiables, that therefore those unquantifiables don't exist. This is illogical. You can see by drawing a Venn diagram that you can never stand inside a circle and make any pronouncements about what is outside that circle. If the goldfish holds that everything that exists is within the view of his goldfish bowl, he can't then say that this is a proof that there is nothing beyond the view of his goldfish bowl.
Hawking and Mlodinow, in fact, do not make an explicit case that nothing exists that can't be at least determined probabilistically. Neither do they, in spite of the publicity when the book was released, make a case that God does not exist. Their case is considerably more limited:
Because there is a law like gravity, the universe can and will create itself from nothing ..... Spontaneous creation is the reason there is something rather than nothing, why the universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the universe going.
I was confused when I first read this. Certainly no orthodox Christian, for example, imagines that the role of their God is to act as curator of the universe.... someone to turn on the lights in the morning and turn them off in the evening, and keep things running during the day. What God did the authors think they had pre-empted the necessity of? Surely not my God, the transcendant and yet immanent, He Who everything else is through, by and in?
I do not know if the authors are making this assumption, but I have seen some scientistis and even some theologians assume that the word "God" is a way for people to explain physical mysteries. So when there are no more physical mysteries, there is no more need for God.
I have never quite understood that line of thinking, but apparently it came about in the Enlightenment, when philosophy took a post-Cartesian credibility hit and physical science came to the fore as a presumably more realistic substitute given the terms of the Cartesian approach. Most of the scientists of the time were still Deists, though many of them weren't orthodox. And the same was true of many theologians. So God did begin to become for them a way to explain what couldn't be explained by empirical methods of the time. In that approach, God became a component of our thinking, a kind of placeholder, so as our thinking became more scientific, the place for God in our heads got smaller and smaller.
A book by Father Stanley Jaki called Miracles and Physics (short, but difficult, at least for me) discusses this history of thinking in physics and philosophy. I recommend the book. He thinks many believers inadvertently fall into the trap of using God to explain things in the natural universe that are so far not well comprehended. This is "the God of the gaps". This is a mistake because not only is it subordinating God to the universe's laws -- making Him sort of a factotum or curator or even wall-moulding material, filling in gaps in our construction-- but it leads to the discrediting of theology whenever one of these mysteries is unpacked.
God is thoroughly outside the universe, though the universe is not thoroughly outside Him. By studying science, we can learn more about Him indirectly and secondarily through His work. For example, the descriptions of magnitudes in The Grand Design gave me a better look at "infinity" by showing it as something altogether different than a "very very very large number", even an unimaginably large number.
To God, who is infinite, even 10 to the 500th power is nothing to boggle at. The only way I can picture Hawking and Mlodinow seriously supposing His agency to get lost in it as in a field of tulips would be if they really are presupposing that He is a figment of our minds. In that case, of course, quantity would boggle Him as it does us.
We can never find God while locked within physicalist presumptions, except in negative terms by finding our empiric presumptions unjustifiable (really not that unlikely, since strict empiricism runs into difficulties at every turn) and so looking outside the goldfish bowl. Certainly we can never demonstrate His absence, any more than the goldfish can demonstrate the non-existence of the rooms beyond his range of sight.
I would take it that Hawking and Mlodinow understand this, and that is why they do not pronounce the non-existence of God, though they clearly think of Him as an unnecessary hypothesis. All in all, I think they do religion a favor by debunking (or at least exposing) a few of the methodological problems that believers and non-believers alike tend to fall into when discussing religion and science. The book leaves enough questions hanging so that I am not entirely sure whether or not they are actually stating that philosophy and theology are dead and science has taken their place, or are just having fun stirring things up.
Certainly I can't imagine their book really means to settle any philosophical or theological questions -- rather, if anything, I take those elements to be an incidental part of the main objective, which is to extend the boundaries of what we think of as theoretical physics. And that part of it is the fascinating and evocative part of this book; it is their area of expertise, and they take the trouble to write it in a lively and simple way, with lots of examples and illustrations.