"Below, I respond to Kevin O'Brien and Steven Schimmrich."
"As someone who is comfortable with evolution, let me convey my belief that
this is a misleading response. For the stakes were higher than merely the
validity of or falsity of Haig's theory. For Haig's theory assumes the
validity of evolution, a negative result could indicate problems with any
link in the chain -- including the evolutionary model."
Einstein's theory of gravity, that it is a result of curved space, assumes
the validity of gravity. If we were to prove that curved space cannot
account for gravity, would that invalidate the concept of gravity? No,
because "gravity" is the fact -- the natural phenomenon -- that needs to be
explained while "curved space" is the theory offered to explain that fact.
If that theory turns out to be wrong, the fact is still valid.
"Had the results come up positive, one can be confident that it would have
been heralded not as a vindication of Haig's theory within a theory, but as
(an) experimental confirmation of evolution theory itself -- and reasonably
so."
The lay public would have seen it that way, but scientists would have been
more restrained; to them it would be the verification of an individual
explanation for how evolution works, not for the fact of evolution.
"But that is not what happened. So, the theory must be scored as some
(modest) evidence against the evolutionary model."
A model is an overall hypothetical description of a known, accepted natural
phenomenon that is then used to generate theories to explain how the
phenomenon works. As the theories are verified or refuted, the description
of the phenomenon changes, but the phenomenon itself remains constant.
"I do agree with Kevin (except for his wording) that it does not 'invalidate
the historical fact of evolution.' (There is lots of other evidence
supporting evolution.) But calling a theory a 'fact'...."
I did not call a theory a fact. Evolution is the phenomenon -- the
historical fact -- that needs to be explained. Your confusion stems from
the fact that the model invented to described this phenomenon is also called
"evolution". The theories that have been developed from this model include
Lamarckism (now refuted), natural selection (now combined with genetics to
form the synthesis theory), saltation (now largely abandoned except for
homeodomain mutations), punctuated equilibrium, genetic drift and sexual
selection, among others. The refutation or abandonment of any of these
theories will change how we describe "evolution", but it won't invalidate
the natural phenomenon itself, which is an historically verifiable fact.
To avoid future confusion I would be willing to call the model by another
name, but for now we need to keep in mind that there is evolution the
historical fact and evolution the hypothetical model.
"...in no way excuses it from empirical challenges to its validity...."
Facts are indesputable; models are not. The fact of evolution is
indesputable; the current model being used to generate theories and
experiments is not. Haig's experiments invalidated a part of the current
model, so now the model will have to be revised; his results do not
invalidate the fact of the natural phenomenon itself.
"...(any more than calling Newtonian mechanics a 'fact'; we no longer
believe this.)"
Newtonian mechanics was never a theory, because Newton refused to theorize
an explanation for why his laws acted the way they did. His laws, however,
are still accepted as facts because they still describe natural phenomena.
Inertia is still the tendency of an object -- whether at rest or moving
uniformly in a straight line -- to resist a change in its motion;
acceleration (change in motion) is still proportional to the net force; and
every force still produces a counter force that is equal in magnitude and
opposite in direction. On top of that, every mass still attracts every
other mass in the universe with a force that is directly proportional to the
product of the masses and inversely proportional to the square of the
distance between the masses.
You are probably thinking of the modifications made to the descriptions of
these laws imposed by relatively, but in fact relativity did not invalidate
these laws. Relativity simply altered the proportionality constants for the
second motion and universal gravitation laws, and stated that it was the
curvature of space that made objects obeying the first motion law to move
along non-linear paths. As far as I know, the third motion law is
unmodified.
"...and the recent research does provide such a challenge."
Only to the model, not the natural phenomenon.
"Let us be clear about it. Intellectual honesty can lead to no other
conclusion."
Just as long as we understand what is being discussed.
"Steven's response was similar: [snip Steven's response]"
"Good response. 'That's the purpose of science' -- even if her work were to
contribute to the toppling of evolution."
The curent model may be toppled, but the natural phenomenon can never be
refuted, any more than one can refute the existence of gravity, lightning or
tornadoes, to name only three natural phenomena for which there are yet no
clear theories to explain how they work.
Kevin L. O'Brien