Darwinian and panbiogeographic frameworks

[John Grehan]

Stuart Poss responded with a number of thoughtful and interesting
comments that indicate how we appear to have considerably different
perspectives on evolution and evolutionary theory. I have offered
further response below, for those interested.

  For this reason, science focuses almost exclusively with "facts" or
>"evidence' that can not be explained by theory, since it is precisely this
>information that permits us to discard one hypothesis for another.

My feeling about these matters of evoltution is that they are more complex than
simple tests of individual hypotheses so its not possible to reduce the
research activity to this simple criterion. What might constitute evidence
that cannot be explained by a theory might not be regarded the same way
by someone else. Research programs can be remarkably adaptive in
accomodating anomolies, and philosophers of science have pointed out
that research programs can end up representing views that are contradictory
to those help by earlier members of the same research program.

 A discussion of the falsification of this
>theory requires us to pay particular attention to evidence that  it
>"cannot explain".
 I thought you were making a scientific assertion by suggesting that you
had such evidence.

It seems to be to be the nature of the Darwinian research program that it can
explain anything and everything. My view of science is that the requirement of
this kind of evidence may be less critical to question of how and why there
are particular research perspectives and how they demonstrate their
productivity.
On this I and Stuart Poss would naturally be in disagreement.

>If you are unable to "force" a disagreement among your hypotheses then you are
>dealing with what scientists would call a either a hypothesis with limited
>predictive power and consequently of less general interest, or a
>hypothesis that
>is not sufficiently well-conceived to formulate a scientific test of its
>potential veracity.

I forget what I said exactly, but I did not intend to say that it was not
possible
to force a disagreement among hypotheses. I think I was refering to what
decisions were made in relation to those choices.

>In science evidence can not be regarded a matter of individual judgement.
>It is
>only the interpretation of the meaning of evidence that is subject to
>discussion.

I guess I look at the "evidence" as someting that is a matter of
interpretation. For
someting to constitute "evidence" is a matter of interpretation so I see no
difference
between evidence and interpretation. Perhaps an inconsequential difference.


 In order to disprove Darwinian theory one needs to demonstrate that there
exist observations that can not so exist according to theory.

I see this as one possible criterion for disproof. The difficulty with the
requirement
of demonstrating this criterion is that one might always come up with an
ad hoc hypothesis to disqualify the disproof as disproof. Research programs
can be tenacious in this respect. Planetary motions observed by astronomers
could not exist according to Newton's theory, but since the theory was so
elegant the theory was not thrown out and an appeal was made for an undiscovered
planet affecting gravitional effects. So long as the planet was not found
the theory
could be sustained by the view that the planet existed but had not been
found, or
that there was some other factor. The planet was found, and a great victory for
science was proclaimed.


>> My understanding is that he did not observe this differential selection, but
>> interpreted the process this way.
>>
>
>No.  I would disagree with you.  Darwin observed the results of differential
>selection and was correct in his interpretation.

I repeat, I said my understand was that he did not observed the differential
selection. You concur by stating that he observed the results of differential
selection. Quite a different thing.

  However, his observations with regard to differential selection taking
>place among these birds remain largely verrified by subsequent evidence,
>in this
>case a variety of beak lengths, not to mention a consistent pattern of
>change in
>allelic frequencies.

I have no problem with the possibility that the differences may be the result of
selection and that investigators have made a good case for this.

  The point I was trying
>to make is that most differentiated from geographically proximate relatives,
>which would be predicted by Darwinian theory.

If by Darwinian theory you are referring to the theory of natural selection I
would point out that such a prediction is not unique to Darwinian theory. If you
are, however, referring to Darwinian theory in terms of the prediction that
relative forms have a common ancestor then I would agree, and in this sense
I would be a Darwinian.


>I don't know what specfic misrepresentation of orthogenesis you are
>referring to,
>but there is little if any support to the notion that evolution proceeds to
>endpoints that are predetermined by the intrinsic nature of the organism,
>independent of external factors (environmental factors) that might select for
>particular hereditable characteristics.

You have just stated the misrepresentation. The view that orthogenesis is
teleological
has been supported by some of its practioners, but in general it has not.
The teleological
assertion was made by Mayr, Eldredge, and Gould to name a few. Teleology was not
asserted by Haacke, and neither by other supporters of the model.


>> It was in sufficient in that it did not lead to corroborated novel
>> predictions about
>> biogeography or geology.
>
>What novel prediction?  Cooborated with what?  I guess I will have to consult
>your book.

That would be the least confusing approach I think.

The fact that your observation may be new and not known to Darwin, is
>hardly a scientific test of his ideas

That is not the point. The point is that the observation was unknown even
at the time it was predicted. Non-Darwinain biogeography made the prediction,
Darwinian biogeography did not. It is possible that the prediction could neve
be made by Darwinian biogeography since the latter lacked the necessary
conceptual tooks, but now the prediction has been made and corroborated, its
always possible for Darwinian biogeographers to claim otherwise.

, since the fundamental correctness of his
>thesis both preceeded and suceeded him.  His conclusions are as true today as
>they would have been 100 million years before he was born.  We can expect they
>will be true tomorrow.

The uncertaintly about this proposition keeps me interested in the future.


>No, but the fact that natural selection occurs and that it is intimately
>related
>to the origins of life's mechanisms permits us to understand how such mechanims
>are constructed, how they came into being, and how they function.

I would agree that it permits us to investigate the selection hypothese in
relation to phylogeny and construct phylogenetic models of their origin.

 Without an
>understanding the nature of selection on these mechanisms through time, one can
>not realistically expect to fully understand the causal relationships between
>structure and function that have existed through time to organize such systems.

And one might assert that without understanding orthogenetic mechanisms
would could not expect to fully understand structure and function.


>Science is not about holding committed opinions or ideologies, but about the
>search for specific kinds of information that will permit us to
>distinguish among
>them.

It seems to me that much of science has been about holding committed opinions
or ideologies.


A scientist should in principle should always want to impose their best
>(most predictive) theories (or those of others that he/she finds correct) on
>their colleagues for their own good

For their own good? I try not impose. I am more interested in exploration for
my curiosity, and to make the view known for those who wish.


, although we must certainly keep in mind how
>easy it is to be wrong about complex biological systems and how costly and
>difficult it is to obtain evidence vital to the disproof of particular
>hypotheses.

I think the main difference between us is that Stuart focuses on hypotheses
while I focus on research programs, and consequently we emphasise different
things and refer to different decision-making criteria.

Consequently, some generosity toward the sincerity of our colleagues
>efforts to "hawk their scientific wares" is in order, even though we may
>in some
>cases feel that they have nothing to sell us that we are interested in buying.

Again, this appears to be a difference in persepctive. I'm not in the market
for "selling" my view, just sharing it with those interested.

John Grehan