On Wed, 25 Feb 1998 02:56:12 -0800, Cliff Lundberg wrote:
>>CL>Since all three of you agree on this, could one of you
>>>elaborate a little? What are Neo-Darwinian mechanisms?
>>>Which mechanisms are excluded?
>SJ>I will try to answer this as simply as possible.
CL>Stephen, your long and patient response did not address
>what I was getting at, which has nothing to do with
>creationism. I see the terms 'Neo-Darwinism' and
>'Darwinism' thrown around in these discussions in a
>fairly interchangeable manner, and I wonder about the
>distinction between these two, in the minds of the
>participants.
Sorry I misunderstood. Technically "Darwinism" could be distingished
from "Neo-Darwinism" by contrasting the original 19th Century
Darwinism of Charles Darwin (sometimes called Classical Darwinism)
with modern Neo-Darwinism, which incorporates Mendel's Genetic
theory, which Darwin apparently did not find out about (Mendel was
actually a contemporary of Darwin but was apparently unknown to
Darwin). But today the words "Darwinism" and "Neo-Darwinism" mean
basically the same thing-in a scientific sense.
However, in a more general and philosophic sense the word
"Darwinism" is still used, to refer to any theory of evolution that
has variation and natural selction at its core. Thus Dennett is
attracted to a sort of Cosmic Darwinism:
"Hume imputes the "continued improvement" to the minimal selective
bias of a "stupid mechanic," but we can replace the stupid mechanic
with something even stupider without dissipating the lifting power:
a purely algorithmic Darwinian process of world-trying. Though Hume
obviously didn't think this was anything but an amusing
philosophical fantasy, the idea has recently been developed in some
detail by the physicist Lee Smolin (1992 ). The basic idea is that
the singularities known as black holes are in effect the birthplaces
of offspring universes, in which the fundamental physical constants
would differ slightly, in random ways, from the physical constants
in the parent universe. So, according to Smolin's hypothesis, we
have both differential reproduction and mutation, the two essential
features of any Darwinian selection algorithm. Those universes that
just happened to have physical constants that encouraged the
development of black holes would ipso facto have more offspring,
which would have more offspring, and so forth-that's the selection
step. Note that there is no grim reaper of universes in this
scenario; they all live and "die" in due course, but some merely
have more offspring." (Dennett D.C., "Darwin's Dangerous Idea:
Evolution and The Meanings Of Life", Penguin: London UK, 1995,
pp176-177)
CL>Personally, I feel that Neo-Darwinism represents a
>sort of fundamentalist revival of Darwinism, as a
>reaction to creationism. But I would like to know if
>people think there are real technical distinctions
>between D. and Neo-D.
Neo-Darwinism *is* modern-day Darwinism. But Gould argues that
there is a "strict" Neo-Darwinism that overemphasises natural
selection and adaptation, and underplays other factors (like sudden
appearance, stasis, mass-extinction, etc). Gould likes to call
himself a "pluralist", as opposed to the so-called "strict"
Darwinists like Dawkins, Dennett and Maynard Smith.
Like a religion, the "strict" Darwinists and the "pluralists", appeal
to their founder, in this case Charles Darwin. Unfortunately, Darwin
sent so many different and contradictory messages in his writings
that both sides can legitimately claim his support. The pluralists
can claim that Darwin never said that natural selection was the only
means of modification:
"Furthermore, I am convinced that Natural Selection has been the most
important, but not the exclusive, means of modification." (Darwin
C., "The Origin of Species", [1872], 6th Edition, Everyman's Library,
p20)
On the other hand, the "strict" Darwinists can claim that the full
title of Darwin's Origin of Species was: "The Origin of Species BY
MEANS OF NATURAL SELECTION, or The Preservation of Favoured Races in
the Struggle for Life" (my emphasis), and Darwin in the Origin of Species
over 40 times called his theory "The Theory of Natural Selection", and
Darwin repeatedly declared that his theory stood or fell by natural
seelction:
"If it could be proved that any part of the structure of any one
species had been formed for the exclusive good of another species,
it would annihilate my theory, for such could not have been produced
through natural selection." (Darwin, 1872, p186)
"If it could be demonstrated that any complex organ existed which could
not possibly have been formed by numerous, successive, slight
modifications, my theory would absolutely break down." (Darwin, 1872,
p170)
The problem here is that Darwin protected his theory from
falsification at the price of ambiguity and vagueness in the
relative importance of natural selectiuon. Both the "stricts" and
the "pluralists" can therefore lay claim to be Darwin's true
followers. The "stricts" can claim that "Darwin said that, `Natural
Selection" is "not the exclusive, means of modification.'"
On balance, I think the so-called "strict" Darwinists are closer to
what Darwin thought. Although Darwin allowed an escape-hatch by
claiming that natural selection was not the only means of
modification, he never quantified just how much modification he
would allow by mechanisms other than natural selection.
And he consistently maintained that his theory stood or fell by
natural selection, and he rejected saltations (big jumps):
"As natural selection acts solely by accumulating slight, successive,
favourable variations, it can produce no great or sudden
modifications; it can act only by short and slow steps. Hence the
canon of "Natura non facit saltum," [nature doesn't make jumps -SJ]
which every fresh addition to our knowledge tends to confirm, is on
this theory intelligible." (Darwin, 1872, p447)
But IMHO, the *real* problem that was behind Darwin's ambiguity and the
modern-day argument between the "strict" and "pluralist" Darwinists
is that step-by-tiny-incremental-step natural selection is the *only*
naturalistic way, even in principle, to develop life's complex designs,
yet the evidence from the fossil record is that it didn't happen
that way. As Julian Huxley, co-founder of Neo-Darwinism pointed
out, if creationism is rejected out of hand, then natural selection
is all that's left:
"In any case, if we repudiate creationism, divine or vitalistic guidance,
and the extremer forms of orthogenesis, as originators of adaptation,
we must (unless we confess total ignorance and abandon for the time
any attempts at explanation) invoke natural selection-or at any rate
must do so whenever an adaptive structure obviously involves a
number of separate characters, and therefore demands a number of
separate steps for its origin. A one-character, single-step adaptation
might clearly be the result of mutation; once the mutation had taken
place, it would be preserved by natural selection, but selection would
have played no part in its origin. But when two or more steps are
necessary, it becomes inconceivable that they shall have originated
simultaneously. The first mutation must have been spread through the
population-by selection before the second could be combined with it,
the combination of the first two in turn selected before the third could
be added, and so on with each successive step. The improbability of
an origin in which selection has not played a part becomes larger with
each new step." (Huxley J., "Evolution: The Modern Synthesis", 1942,
pp473-474)
IMHO the Darwinists' main problem is in their faulty first premise:
"if we repudiate creationism, [and] divine...guidance". If God is
real and has indeed intervened in an guided life's development, then
all Darwinists (whether "strict" or "pluralists" are permanently stuck
with less than best explanations.
Steve
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Stephen E (Steve) Jones ,--_|\ sejones@ibm.net
3 Hawker Avenue / Oz \ Steve.Jones@health.wa.gov.au
Warwick 6024 ->*_,--\_/ Phone +61 8 9448 7439
Perth, West Australia v "Test everything." (1Thess 5:21)
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