OK, I'll try :). First let me say that I'll be out of town from
June 26 to about July 5 so I may miss a lot of this thread.
If anyone has something they want me to see or respond to,
please copy to my e-mail address.
I also have to give my standard disclaimer. I've studied the
AP a lot but I'm by no means an expert, it is just one of
my favorite hobbies :).
Let me first try to explain what I believe Pim's argument is.
It's one I've seen in the literature, but unfortunately haven't
been able to track either the argument or the "answer" to it
down. I'll keep looking.
Let me first take a slight detour. In the AP literature you'll
find a proliferation of stories intended to illustrate different
aspects of the fine tuning argument. Stories about marksmen,
lotteries, firing squads, catching fish, etc. etc. I'm sure
most of us have read one or more of these. I'm not sure where that
practice began, but I suspect it might be with John Leslie's
book _Universes_ (recently reprinted in paperback by Routledge).
In any event, most of the stories (Leslie calls them parables) I've
seen can be found in his book. Oh, let me mention while
I'm thinking about it that the volume <Physical Cosmology and
Philosophy> (Macmillan, New York, 1990) edited by Leslie is
a must for anyone interested in the AP. It has all the classic
papers. Leslie himself is good example of the many surprises
that can be found in this interesting subject. Leslie is not a
theist in any form that many of us would recognize as such. He
is a neo-Platonist with the (to me:) odd view that the universe
exists because there is an ethical requirement that it should
exist. Nevertheless, he presents an argument for the existence
of God based on fine tuning. Bertvan may want to note also that
Leslie is one of the leading authorities on the AP :).
Anyway, back to the parables. The argument that I believe Pim
is making (correct me if I'm wrong Pim) was given in the form
of a parable most likely given with John Leslie in mind because of
his many parables. The parable goes like this:
Parable of the Bridges:=====================================
My, isn't it a really odd coincidence how this long and winding
river just happens to pass under all these bridges.
============================================================
Hopefully, the meaning is obvious :). I saw Leslie give an
answer to this parable somewhere but can't seem to find it.
Maybe that's just as well, since we'll have to think for ourselves.
You first ;-).
Now, about the alternative explanations. From my reading, #1 and
#2 are considered the predominant alternatives, i.e. the ones
taken most seriously in the literature. But let me say that I
think its incorrect in #2 to call fine-tuning an illusion. Fine
tuning would be a fact, where by this I mean established with
great confidence. I think the confusion here results from the
common association of fine-tuning with probability arguments.
But fine-tuning itself does not rely on probability calculations.
So, I think its best to say that the many worlds hypothesis provides
a possible explanation for fine-tuning.
I think its important to understand how this explanation works, because
not just any old set of many worlds will suffice in order to explain fine-
tuning. The many worlds hinges upon the anthropic selection principle (ASP)
which goes like this "We really shouldn't be too surprised to find
ourselves in this fine-tuned universe. We could not be in any of these
others that are not finely tuned." So, the ASP requires something to
select from which means:
(a) The other worlds must really exist as opposed to being just
logically possible.
(b) The other worlds must have widely varying laws or constants.
If they are all the same, then there is nothing to select from.
There is also a more subtle requirement associated with condition (b).
The idea that the universe is somehow special wrt life in general
or humans in particular is very unpopular with many, and supposedly
went by the wayside on account of Copernicus (Copernicus would probably
be surprised to hear about this :). The universe doesn't care about
life, it just is. Thus (b) is important so that we can conclude that
life is not special, the vast majority of all the worlds in the world
ensemble are dead etc. One reason I'm mentioning this is that some seem
to want to take the tack that life is an almost inevitable consequence
of any type universe one might have. Of course, people are welcome to
this view if they wish, but it flies in the face of the "spirit" of the
many worlds hypothesis.
OK, a lot of what I say above is a prelude to support something that
I'm sure most will find outrageous at first (hopefully only at first :).
What I would like to argue is that #3 is not really a separate option,
but will instead fall under either #1 or #2 depending upon the nature
of the theory of everything (TOE). This will seem outrageous because
in discussion groups like this, #3 is often portrayed as the advance
of science which fills in the gaps of something really naive like #1 :).
Since this will likely be controversial, let me give a reference which
outlines the arguments in a little more detail:
-- D.W. Sciama, "The Anthropic Principle and the Non-Uniqueness
of the Universe," in _The Anthropic Principle_, Proceedings
of the Second Venice Conference on Cosmology and Philosophy,
F. Bertola and U. Curi, ed., Cambridge University Press,
1993, pp. 107-109.
Before I get into the implications of TOE's wrt the AP, let me say that
Sciama is a proponent of many worlds (#2) and considers only three
alternatives, one which you do not include above but that most really don't
take seriously:
========begin quote====================================================
This simple but powerful argument leads us to ask the question:
*how much* can I deduce about the universe from the fact that
I exist? It turns out that various elementary particle, nuclear,
atomic and molecular properties of matter have to be very finely
tuned for conditions in the universe to have permitted my
development--many examples are given by Barrow and Tipler and
elsewhere in this book. These finely tuned properties will
probably also eventually be accounted for by fundamental
theory. But why should fundamental theory _happen_ to lead
to these properties?
There seem to be three possible answers to this question:
(a) It is a complete chance.
(b) God regards me as such a desirable product of the universe
that he has fine-tuned it so as to guarantee my development.
(c) There exist other, disjoint, universes with other laws
and constants of nature.
-- D.W. Sciama, ibid.
=========================================================================
We see in the quote above the introduction to the idea I want to talk
about here: "These finely tuned properties will probably also eventually
be accounted for by fundamental theory. But why should fundamental theory
_happen_ to lead to these properties?"
The problem has to do with what I mentioned above. Why should a TOE just
happen to give finely-tuned parameters? IOW, surely it is possible to have a
TOE give rise to universes where life cannot exist. Why is life so special?
etc. etc.
It is clear that the possibility of a TOE presents Sciama with problems
wrt his preferred item (c). How to circumvent? Well, you argue that many
TOE's are possible, most of which will lead to dead universes. There is a
vast ensemble of universes with a wide variety of TOE's. Some giving
universes where life is possible, most not. But, we shouldn't be
surprised ... etc etc with the anthropic selection principle.
OK, so the really interesting thing is the case where we might find that
there is only one logically possible TOE. Most would take this as the
death of the design argument from fine-tuning but this is actually
Sciama's worst nightmare. The reason is that all of the universes in the
ensemble will be the same. If they are all the same then the anthropic
selection principle can't select. Interesting.
Some may counter that we shouldn't be surprised to find ourselves in
a finely tuned universe since this is the only universe possible. To
which I would respond "of course, that's the point :)".
Sorry for going on and on. I'm trying to anticipate questions (objections:)
since I'll be going out of town shortly. Let me close by just giving
a combination of Leslie's parables aimed at #4.
We start with a fairly standard sharp shooter parable. A marksman is
some really large distance from a blank wall with a fly on it. He's
wearing a blindfold and shoots over his shoulder, hitting the fly
on the first shot. Coincidence?
Many worlds answer: No, not a coincidence. What you didn't realize is
that there are millions and millions of marksmen all firing a shot
blindfolded over their shoulders at different blank walls with a
fly on them. Surely one must hit the fly.
#4 answer: What if there is more than one fly on the wall? :)
Leslie's response: It doesn't matter how many flies there are, because
we know that there is a huge blank area surrounding the particular fly
that was hit (the carbon based life fly :). Further, if there *are* other
flies, we might expect, based on what we know about the carbon based
life fly, that those flies are also surrounded by huge areas of blank
wall.
#4 objection: But we don't know this for sure, there could be areas
on the wall that are very dense with flies.
response: Fine, so why didn't the marksman hit one of those flies instead
of the one all by itself in the middle of a huge blank area? :)
Final disclaimer: IMHO the AP lies just at the edge separating science
and metaphysics and is probably a good example of how fuzzy the edge
is :). Establishment of fine-tuning itself is, of course, scientific.
But the interpretations thereof get dangerously close, perhpas somewhat
over, the precipice. Nevertheless, its a lot of fun :).
Brian Harper
Associate Professor
Applied Mechanics
The Ohio State University
"All kinds of private metaphysics and theology have
grown like weeds in the garden of thermodynamics"
-- E. H. Hiebert