Loren tells us that Progressive Creation is basically Theistic
Evolution with an "extra degree of freedom". He also explains how it
is not always a good idea to add an extra degree of freedom simply
because it fits the data better.
The first thing I would like to note is that there is no "right" way
to do data fitting. The theory of data fitting is half based on
logic, the other half on heuristics (rules of thumb). We have
developed these heuristics because "they seem to work", not because
they are inherently the right thing to do. This does not completely
invalidate Loren's points about data fitting, but it does mean we need
to think very carefully about it.
Eventually I want to argue that Progressive Creation does _not_ have
more degrees of freedom than Theistic Evolution, but first, some
preliminaries.
There is more than one way to skin a cat.
-----------------------------------------
Loren tells us that, when fitting some data, we shouldn't neccessarily
choose a cubic fit over a linear fit just because it fits the data
better. Let's examine why. A cubic fit has more "free variables"
than a linear fit. This means that there are far more _possible_ data
fit lines for cubic fitting than for linear fitting. Cubic fitting
encompasses all the straight lines and lots and lots of curvy ones
besides. Even if the _true_ data is _not_ cubic, there is a good
chance that a cubic will be found which fairly closely matches the
data. The same is not so true for linear fitting.
As a result, if I find data that matches a linear fit well then this
will be much more of a surprise than discovering that the data matches
a cubic fit well. If I predict that some data will be linear, then I
am making a much stronger claim than if I predicted that the data will
be cubic. This is because the chance of being proven wrong if I
really am wrong is much higher in the former case than in the latter.
In other words, a theory that predicts everything doesn't say
anything.
Now that I have apparently bolstered Loren's point, I wish to make a
subtle, but very important, observation: linear fitting is not the
only way to reduce the number of degrees of freedom. With linear
fitting, we try to fit the data to a line, namely:
y = a + bx
We have two degrees of freedom, namely a and b. Why not consider
the following, alternative, type of fitting:
2 3
y = 1 + x + ax + bx
Again, we only have two degrees of freedom, a and b. There is
no inherent reason why we should reject this alternative over the
linear alternative. Both make strong claims about the form of the
data. People generally choose linear rather than something like this
because it "looks simpler" and because in the past people have
discovered that there are a lot of linear relationships in the world.
So in summary, yes a theory that has "few degrees of freedom" is
preferable to one with more, but there is more than one way to develop
a theory with few degrees of freedom. To choose one type of "few
degrees of freedom" model over another, you need extra information
from somewhere. If you don't have this extra information, then you
are probably better off with more degrees of freedom - you are just as
likely to get it right and you will probably match the data better
(but of course, don't claim your theory has achieved more than it
has).
Does PC have more degrees of freedom than TE?
---------------------------------------------
Evolution seems to have quite a few degrees of freedom. Evolution
claims that life came about through the process of one animal evolving
through a series of small morphological changes into another animal
(or in fact, several other animal species). As far as I know, it
doesn't say very much about what _morphological_paths_ these
transitions must travel along. So it seems to me that there are
plenty of degrees of freedom here. As way of illustration, suppose
evolution said the "animal" "F" evolved into "P". Someone postulates
that the way it happened was that the lines on the right of the F grew
a bit longer, curled round and joined up to form a P. But then
someone discovers that the fossil record shows that the animal "J"
must have been an intermediate. Well, evolution can accomodate this.
It just means that we got the original transition path wrong. What
really happened was: F -> E -> L -> J -> U -> D -> B -> P. So here we
have a gradual morphological transition path from F to P which
accomodates the new data. Of course, PC suffers from this same flaw.
The important thing to see is that both theorys have plenty of degrees
of freedom to spare.
Ahha, someone will say, but you are forgetting about genetics.
Evolution, or at least neo-evolution, says that these morphological
changes are a result of the underlying genetics. But does this
actually reduce the degrees of freedom? Biologists have been puzzled
by apparently large morphological jumps. Well genetics has the
answer. It can be shown that small changes in DNA can sometimes give
rise to large morphological changes. But this, rather than decreasing
the number of degrees of freedom, increases them! For now we are no
longer restricted to smooth morphological changes, but we can allow
jumps!
The problem is that we currently have only a small idea of how change
in DNA gives rise to change in morphology. As a result, it places few
restrictions on morphological transition - in fact, perhaps it
actually has more of degrees of freedom than Darwin's original theory.
Genetics tells us that we should expect some amount of morphological
change through DNA change, but until we know more about the
relationship between DNA and morphology, it doesn't say much about how
large scale transitions would occur, or even if they would be
possible.
So we can see that there are still plenty of degrees of freedom left
for the theory of evolution. What about Progressive Creation? Well
yes, there are plenty of degrees of freedom here also, but are there
more? God's supernatural intervention at various stages of history
says neither more nor less about morphological paths than genetics. I
dispute the claim that "God" is an extra variable. What large scale
morphological _transition_paths_ does "genetics" rule out that "God
altered DNA changes" does not? It is conceivable that some time in
the future, genetics may be able to do this, but as far as I know
currently it does not. In this case, PC and TE have roughly the same
number of degrees of freedom.
PC and TE obtain their degrees of freedom in different ways, just like
y = a + bx and
2 3
y = 1 + x + ax + bx do. If you have reason to
suspect that linear relations are more likely to be at work then you
will take the linear. If you believe relations of the second form
are more likely, then you will take that one. The point is, without
refering to additional information, there is no inherent reason for
prefering one over the other. People who believe that everything has
a natural description will tend to choose TE, whereas people who
believe God works supernaturally on occasion, will lean more towards
PC. But an argument on number of degrees of freedom, in my opinion,
will not rule either out.
Are there any theological reasons to support PC?
------------------------------------------------
Loren raised the Genesis 1 account. I am running out of time, so I
will leave that for now. However, I can think of a different
theological reason for at least considering PC, and that is the
occurence of supernatural miracles in scripture.
Talk to any medically minded atheist and he will tell you that
scientifically, dead people don't rise. There is no known physical
explanation for the reversal of decay processes - something neccessary
to bring someone who has been dead for some time, back to life. If a
"supernatural" explanation is neccessary to understand Jesus being
raised from the dead (and countless other miracles), then it seems
quite natural to think that creation of life had a supernatural
component also.
Just as our observance of lots of linear relationships in the world
leads us to think that linear interpolation might be a good thing to
do, so too, our observance of supernatural miracles in the world and
in scripture can lead us to think that Progressive Creation might be a
good model.
Conclusion
----------
Loren writes:
>If Progressive Creation fits the data at least as well as Theistic
>Evolution, why not embrace it and advocate it as the "antidote" to
>Naturalistic Evolution? Progressive Creation, when carefully formulated,
>is not equivalent to "God-of-the-Gaps." But there is a significant danger
>that, if biological evolutionary theory ultimately achieves a firm
>empirical grounding (as stellar evolutionary theory has done), Progressive
>Creation could fall into the same apologetic demise as God-of-the-Gaps.
>That is why I advocate Theistic Evolution as the antidote to Naturalistic
>Evolution.
I agree that PC and TE seem to fit the data equally well. It seems to
me, contrary to your claim, that both have about the same number of
degrees of freedom. It may be that biological evolutionary theory
achieves a firm empirical grounding - but it hasn't done so yet.
Let's not jump the gun. There are theological arguments suggesting
that PC might be right, not conclusive perhaps, but reason enough for
not discarding PC prematurely. Naturalistic evolutionists have
overplayed their hand - this should be pointed out. Let us not be
guilty of the same by dismissing evolution without due cause, but let
us also be honest about the exact state of knowledge about origins,
and not feel pressured to jump one way or the other unless there are
good reasons to do so.
Yours in Christ,
Mark Phillips.