Fair questions.
Let me explain my reasoning.
1. "Synthetist": I wanted a term that covered the views of the
Modern Synthesis of the period from 1940-1960 or so.
"Synthesists" sounded like industrial chemists. Hence the
term...
2. Of course we need to demonstrate that macroevolution
happens. This has been done, inferring in cases where the degree
of change would take, ex
hypothesi, too long to observe directly.
But the arguments against macroevolution are usually offered
along the lines that there are mechanisms that do prevent
it from occurring (at some level - choices range from the
impossibility of speciation through to the impossibility of very
large "kinds" evolving from each other, at the phylum level).
Everything we know about genetics, development, and so on
shows us that there are no barriers of the kinds claimed (and we
know a lot more now than when I wrote this). So my argument here
is that the burden of proof, or rather substantiation, has been
met and no plausible reason for thinking that macroevolution at
level N is impossible has been offered.
3. It is not the case that genetic processes are by definition
microevolutionary. This is often said, but never defended.
Genetic processes are implicated in speciation (whether by
isolation and subsequent independent evolution leading to
developmental incompatibility, or by "sudden speciation" in
hyrbidisation), and so any higher level of macroevolutionary
change must be, at the bare minimum, a series of genetic
evolutionary steps. This is at least additive (some say, and I am
inclined to agree, that macroevolution is more than
additive).
We have seen the sorts of morphological changes occur
that are held up as "impossible". Some have been sports, and some
are variable forms of a species that are greater than the
differences between other species. So I stand by my statement of
7 years ago.
Science is not about faith. It is about theoretical
explanations of the natural world. A theory that accounts for
observations, which offers predictions or expectations (for
example, if whales and hippos share traits no other groups do,
they will be derived from common ancestors, and this predicts all
kinds of shared traits with undiscovered fossils - this is an
actual case - google for "Whippo"), and which posits nothing in
direct contradiction with known science, among other things -
this is the best explanation in a science and it will be accepted
as correct, for the moment. This is true in any science, not just
the historical ones.
Macroevolution - by which I mean Darwin's idea of common
descent, also known today as phylogeny - is such a theory. It
therefore is the accepted theory because it explains so much.
Nothing else does. So the onus at the moment is on anyone who
wishes to reject it to show that it fails in some way. At the
time Darwin proposed it, and for a relatively short time after,
macroevolution needed to be shown to be the preferred theory
against the prior views of Owen, Oken and von Baer, which was
effectively a view of form causing organisms to be what they were
- an Aristotelian and Platonist view. Special creation was
employed scientifically only as an instance of this acocunt, by
Cuvier, 50 years before Darwin.
Science changes. What is accepted at one time needs to be
proven not to be the best knowledge bet, as it were. Once it has
been, it is no longer a viable hand in the card game that is
science (to stretch a metaphor). Creationism is not viable now,
because it explains and predicts nothing and is in contradiction
to the rest of known science. But to challenge existing theories
of macroevolution (although not the fact of macroevolution) you
have to show they fail to explain something, or that something
explains it better, or that it contradicts (perhaps newly-) known
science. Hence my argument in the FAQ.
Some ideas are just not open to demonstration in a way that
will satisfy the extreme skeptic (not just in science; a suitably
extreme skeptic could doubt I exist, for instance); but they can
be demonstrated to scientific satisfaction. Science is not, as I
said, about faith, but about knowing. We know macroevolution
occurs to a degree of certainty that will satisfy anyone but the
extreme skeptic. There is no arguing against that approach.
Nevertheless, as Galileo said in another context, still it (life)
moves.
I hope this clarifies the argument for you.