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Re: Feduccia's allegations and logical arguments



HP Jeff Hecht observed:
Remember that Microraptor is at least 20 million years after Archaeopteryx,
so the fossils Xu et al found cannot be ancestral.  Either it's an
evolutionary throwback (living fossil), or it's an evolutionary dead-end.
It's fascinating in either case, but it can't [] provide a definitive proof
of how flight originated in birds.
to which HP Ekaterina A responded:
...the Sinitic fossils do provide good approximations for the ancestral
states in the emergence of birds, though they may be co-eval or later than
A'pteryx.
An early Jurassic fossile would surely be great but there is little doubt
that the Yixian forms greatly
clarify the actual steps in the emergence of birds...

There may be 'little doubt', but unfortunately that doubt is sufficient to
leave the issue unsettled.  For logic fans, this is, in my view, equivalent
to the argument from analogy:

A logical argument by analogy relies upon an inductive inference from the
supposition that things are similar is certain known respects to the
likelihood that they are also similar in some further unknown respect.
...
The degree of reliability achieved by such an argument depends upon the
extent and nature of the similarities that hold between the instances in its
premises and the new case in its conclusion.
http://www.philosophypages.com/dy/a4.htm

Because the extent and nature of the connection between the known and
unknown conditions is easy to question, this is not considered one of the
stronger arguments.

Put another way, a supposedly primitive condition cannot be strongly
identified by looking at the conditions in subsequent versions.  Traits can
arise in too many different ways and for too many different reasons to
identify them indisputably as continuations from an unknown previous
version.
My guess is that this problem is the reason why some versions of cladistics
overlook time as a factor, substituting logical rules about what must be the
ancestral condition.
It's an important objection, and one I think has to be overcome on other
grounds.  It can't just be dismissed.
My own view, for what it's worth, is that the available evidence supports
the dinosaurian ancestry of birds while little supports an alternative.  The
preponderance of evidence thus supports accepting the dino-to-bird
hypothesis, though recognizing that a single new fossil from the right time
could eliminate that preponderance.