Re: Where's the Evolution?

Brian D Harper (
Thu, 01 Apr 1999 16:15:59 -0800

At 03:24 PM 4/1/99 -0800, Ami wrote:


>As sound as the theory of evolution is, isn't it still a theory? The
>ability of things to evolve naturally, step by step, from simple to complex
>is a prediction of evolution. Therefore, to invoke the predictions of the
>theory itself to prove the theory is a bit circular, isn't it?

OK, let me make a statement that you may think is outrageous at first. :)
Evolution is both theory and fact. Creationists will often claim
that such a statement is a word game (Hugh Ross, I believe, calls
it the "shell game" of evolution). In view of this, it may be a
good idea to look at other, less controversial :), scientific fields
to see if the same use of terminology applies and it seems to me
that it does. My favorite example is the theory of plasticity as
opposed to the fact of plasticity. It is a fact that metals display
plastic behavior. Many theories have been proposed to try to
explain this fact. It turns out, interestingly enough, that none
of those theories really works except in the simplest of cases.
<<i.e. they might be useful in explaining microplasticity but
not macroplasticity :)>> If there were a committed anti-plasticity
movement I'm sure they would publicize this failure as "plasticity's
dirty little secret" supported by all sorts of quotes from the
literature, for example:

"If you see finite strain plasticity calculations, and
even more so if they're cyclic or dynamic, and you have
an experiment and all the finite element points are on
the experimental curve, you've seen a fraud because it
just doesn't work out that way. There are too many
uncertainties. You can match certain functionals of the
solution in certain cases but it is very very difficult,
given the uncertainties in theory, the uncertainties in
measurement, even if you can do perfect calculations,
to get really good results ..."
-- Thomas J.R. Hughes, <Plasticity of Metals at Finite
Strain>, Proceedings of Research Workshop held at
Stanford University July 29 - June 1, 1981, p.719.

OK, I'm getting sidetracked ;-). What I'm trying to show
is that using the same word to refer to both theory and
facts is not a practice unique to evolution.

Wrt to evolution we have the fossil record which exhibits
significant changes in the types of organisms that have
lived on this earth through time. This record shows, in
many instances, significant increases in complexity.
This is a fact. There are many theories that have been
proposed to try to explain this and other facts about
the evolution of life. Even if all the theories fail, the
facts regarding what has occurred remain. This is an
important point as many will try to refute a phenomena by
trying to undermine a theory which is trying to explain
the phenomena.

BTW, don't be too influenced by Cummins :). The "ability of things
to evolve naturally, step by step, from simple to complex" is not,
actually, a prediction of evolution. Believe it or not, it is
still a point of controversy as to whether evolution (the actual
process as opposed to a theory) results in a *general* trend
toward increasing complexity. Yes, of course, there are cases
where this has occurred. But it is not certain that this is a
generally anticipated outcome for all evolutionary change. Note
here that we are talking about the facts of the matter (what has
actually occurred?, does complexity always increase?, usually?).

More details on this controversy can be found at:

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