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Re: Speculation



At 08:27 AM 8/30/98 -0400, Larry Febo wrote:
>
>     I`ve just read Dr. Holtz article "What is Science, Anyway?"and found it
>to be somewhat enlightening. It leaves me wondering though...     When
>should one be allowed to speculate?

Go ahead, but make certain you state "This is speculation".  Furthermore, it
is probably a good idea to stop at the first level of speculation.  For
example, I could speculate that tyrannosaurids were feathered, based on
various lines of evidence.  Fair enough.  Speculating on how the feather
patterns of aublysodontine and tyrannosaurine theropods differ is going well
beyond the data...

>It seems noble to try and base all
>scientific discussion on "hard evidence" alone.

Darn tootin'!!  I'd like to see the level of "nobility" raised in general in
dinosaurian discussions!

>This makes for a firm
>foundation in such fields as chemistry and physics, where tangible evidence
>is abundant, and to an extent "universal", but when dealing with
>paleontological data, one must admit that a vast majority of the "evidence"
>is just plain missing!

Very true indeed.  This is why we should remember that our hypotheses are
just that: they should not be belief systems, they should be falsifiable
hypotheses which we will abandon if new evidence suggests otherwise (and
take up again if newer evidence supports them).  This very essential aspect
of science is one of the least well appreciated in the public eye.

>This especially holds true, (unfortunately), for the
>smaller specimens that would make up arboreal species, and extremely scarce
>(one would think) would be the forms in transition, the veritable "missing
>links" as it were. I don`t see why speculation into what these forms might
>have been is in any way "unhealthy"or why it couldn`t be considered as
>scientific, if established scientific principles were used as determining
>factors in the inquiry.

Exactly!  That's what I've been saying all along.  And, as part of
established scientific principles, we must acknowledge the possibility that
the reason we don't find lots of small feathered glider prototheropods may
be because they never existed.  Discovery of such would falsify that hypothesis.

>I think many inventions, at the forefront of the
>"unknown" have come about through this form of healthy scientific curiosity.

Of course.  Never said otherwise.

>     On the other hand, I tend to become frightened at the thought of
>establishing patterns of phylogenies based strictly on the fossils at hand
>(I mean in cases where they are obviously few in number).

Don't be frightened: cladograms LOOK like the Devil's pitchfork ;-), but are
really just a sort of graph.  Like all sorts of graphs, they represent the
best fit of a certain class of data under a certain sort of analysis: no
more, no less.  New data can overturn old phylogenetic hypotheses, or may
support them.

>As how can we
>claim to know the truth when we KNOW that most of the evidence is missing,
>and that a "universal" sampling is just not present?

Easy (and this is very important: everyone pay attention): Because we do NOT
claim it is "the truth"!!  Honestly, folks, we've had this discussion time
and again on the list here.  If you want "the truth", go to philosophy or
theology or political theory or whatever.

Science is about falsifiable hypotheses to describe the natural universe.
We hope to get closer and closer to the actual condition, but (because
omniscience is not likely) we will never know everything about everything.
We can only do as we can with what limited data we get.

Remember: cladograms are phylogenetic hypotheses; they are not "the truth".

>     So, I think its ok to speculate, and actually call it theory (or
>speculation), rather than established LAW.

It is even better to speculate, and call it a speculation.  "Theory" in
science has a very different meaning than you use it.

>I see most anything proposed in
>science to be just a "model", in constant need of refinement, and probably
>nothing, as we know it should ever become fixed dogma.

Bingo!!  Give that man a cigar!!!  Science in a nutshell!

>     Which leads me to the point that...I have a theory that I`m trying to
>refine,whose major premise is that endothermy in vertebrates, due to its
>being a highly complex metabolic process,evolved only once in the vertebrate
>line.This would lead me to conclude that the diapsid line most likely
>evolved out of the synapsid , somewhere in the early- mid Pennsylvanian,
>where they took to an arboreal habitat to develop their unique
>characteristics and send periodic offshoots to the ground to become large,
>cursorial forms, i.e., Thecodonts, right on up to Dinosaurs, and developing
>into Aves in their primary arboreal habitat .
>     Now the fossil record, (as currently interpreted), "shows" that
>Diapsids evolved separately from an Anapsid condition, late in the
>Pennsylvanian, but this is based on only a small handful of fossil
>specimens. What I am argueing is that, in a case such as this, an argument
>based upon physiological principles should take precedence over scant
>paleontological evidence. What do you think?

Okay, you've done the first step: set up your hypothesis.

Now, the second step: try and falsify it.  Note that this is, in part, YOUR
job (it is others' job as well, but you have to start it up).  Think of
methods of analysis by which to see that your hyptothesis fits the data
better than a more standard model (say, Gauthier et al. 1988).  Such a
method of analysis has to be able to choose between alternative phylogenetic
hypotheses by some criterion or criteria which others, independantly, can
also examine.

For example, you have to demonstrate why your scenario should be accepted
even though it contradicts the anatomical and biomolecular records.  You
will also have to demonstrate why physiological evidence takes precendence
over anatomical evidence.

In order to answer these questions, you will need to examine (in detail) the
anatomy of the forms in question.  You will also have to examine the
*physiology* of the living forms.  Are the biochemical pathways to produce
non-shivering thermogenesis the same in birds and mammals (i.e., is
"warm-bloodedness" in mammals the same as "warm-bloodedness" in birds?
Otherwise, you are talking about two different ways of achieving the same
thing).

You are indeed working in the scientific method: you have produce your
speculation and framed it as an hypothesis.  Now it is time to do the real work.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661