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Philosophy (was Re: Cladistics)

At 02:04 PM 2/24/98 EST, Dinogeorge wrote:

><< Then perhaps I might suggest a field other than science?  We don't get
> "right" answers in science, any field of science.  We get the best
> approximations we can with current data and methodology, subject to
> falsification with new data and methods.  I know some people are
> uncomfortable with this, but that's how science works. >>
>Yes, we do get "right" answers, even in science. It all depends on what you
>mean by "right."

Granted: see below.

>If you really, really believe that truth is an undiscoverable
>ideal, then its pursuit is pointless, and you might as well become a mystic.
>It is irrational to continue pursuing an unreachable goal.
In fact, many philosophers of science would argue that it is the mystic who
can assert that they find the truth.  Scientists are limited only to
approximations of the truth, potentially falsifiable on the basis of
additional data.

To give an example, what is the absolute true answer to the shape of the
Earth?  This is a nice, scientific question, as it asks for a geometric
description of a particular object.

Is it a plane?  A cube?  A sphere?  An oblate spheroid?  All these are
closer and closer approximations of the true surface, but none (even the
last) is the TRUE answer, as even that one fails to account for differences
in continental, regional, and local topography.  (And then, of course, there
would be the question regarding the local sea and land fall due to tides,
changes in shorelines, rise and fall of mountain ranges, etc., etc., etc.).

Because the oblate spheroid model is the Truth doesn't mean that it is not
useful.  Just because it isn't the Truth doesn't mean that it is less useful
than the spherical, cubic, or planar models.  (To paraphrase Isaac Asimov,
as I've been doing here, just because two models are "wrong" doesn't mean
that they are both equally "wrong").

On the other hand, for some questions of particularly limited scope, it is
possible to set up the problem so that one (and only one) solution is
potentially correct.  Either fossil specimen A shared a more recent common
ancestor with fossil specimen B than it did with C, or B and C shared a more
recent common ancestor, or they all split off simultaneously from the same
ancestor.  There are only these three possibilities.  Only one of them could
be correct.

However, we can only reconstruct these events: they are gone now.  We might
have some model (parsimony, maximum likelihood, biomechanical, etc.) to
choose one of the three schemes over the other, but we cannot stop there and
say "This is the *right* answer."  The best we can say is "This is the right
answer, given current data".  The addition of new data could potentially
cause us to reject the currently accepted scenario in favor of one of the
other two.

So, to bring things back to dinosaurs: the concept that birds and
dromaeosaurids are sister taxa isn't an article of faith.  It isn't
necessarily right.  It IS the best answer given certain criteria and
methodologies.  However, it is falsifiable and could be rejected with new data.

This is why I tell people that I am willing to be convinced that dinosaurs
were not ancestral to birds.  It is a possibility we have to accept.
However, it would require an amazingly huge megabuttload (to coin a phrase)
of additional data to a) demonstrate that all the features in common shared
between birds and dinosaurs at various level are convergences and b) to show
a whole humongous more bunch of data that some other group was closer to birds.

Thus, to say that we know that the dinosaurian ancestry of birds is the
"right" answer is not scientific.  It is an amazingly strong, robust
hypothesis, but it is potentially wrong and potentially falsifiable.

So, anybody heard about any new dinosaurs lately...

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661