> He says that if creationists - "they do not make me laugh, they make
> me weep"- really wanted to embarrass evolutionary scientists they
> would put up their hands and simply ask what a species is. "Every
> evolutionist would hum and ha and splutter, and I do quite a bit of
> spluttering on that one in the book, " Jones says.
Chris
Not *every* evolutionist.
The problem only arises in those cases where a person is taking some kind of
metaphysical essentialist view of species and speciation (for example,
implicit Platonism). A species is simply whatever categorization we find
convenient for a certain level of thought and discourse. Turkeys and dogs
are considered to be different species because they are too different to be
considered the same at the level of thought and discourse in which we
normally use the word "species." But, two turkeys from the same parents are
considered to be of the same species as the parents because they (generally)
*are* sufficiently like their parents and each other to be considered the
same at this level of thought and discourse.
The "problem" is the result of Really Bad Epistemology, not a *biological*
problem. It is a problem about the nature and use of concepts. "Species" is
a word like "large." It is contextual. Just as "large" in one context might
mean as big as a proton, it might mean as big as a trillion times our
apparent Universe in another context. We designate what is and is not a
species on the basis of cognitive usefulness, not on the basis of some
magical actual difference between species.
If Jones is "humming and ha-ing and spluttering," it's not because the
concept is difficult, but because he is thinking about it wrongly. In fact,
evolutionary theory suggests that speciation would be about what it is, that
the only cases where "adjoining" species would really be kept apart would be
cases where genetics or environment *keep* them apart, like the arctic
terns. Speciation simply proceeds until it reaches a locally-viable maximum
for the organisms involved. If there is enough of the certain kinds of
culling, we will get species that differ from each other in "larger" ways.
If there is usefulness in a more finely-grained speciation, then, speciation
will continue up to the limits of distinguishability, causing biologists
with Platonic epistemological theories some discomfort, but not bothering
the more reality-oiented ones a bit.
Jeez, do I have to explain *everything*? :-)