Finally, a few words about scarecrows and lactose intolerance.
---------------------------
In Walter Remine's latest response to me, he gave a sort of
historico-logical explanation of how the patterns of life (reproductive
isolation / absence of certain kinds of vitalistic forces / presence of
apparent design) lead evolutionists to certain hypotheses -- hypotheses I
tentatively called the "central core" of evolution. (Descent through
modification / random variation / selection.) I liked Walter's analysis
for the most part; I found it insightful.
(Minor point: Walter also suggested that other hypotheses belong in the
central core --- e.g. Lamarckian inheritance, genetic throwbacks,
atavisms, transposition, convergence, sexual selection, "evolutionary
progress." I did not include those in the "central core" because the
relative importance of each of them has been debated. Some versions of
evolution relied heavily on one or more of them, some versions only
slightly, and some versions excluded some of them altogether. Since their
relative importance has historically been a subject of debate, I think
they properly belong in "auxilliary hypotheses" category.)
It almost sounded like praise when Walter said,
WR> Evolutionists continually adapt their ...
> theory to fit the available data. As the data refutes their
> simplest, easiest, most plausible explanations, they move onward....
and I would like to leap in and say, "Yes, it sounds like those scientists
are acting properly and responsibly." ;-)
---------------------------------
However, that was not really Walter's point. Walter's point was about the
great flexibility of evolutionary theory.
WR> Let me sum up this parade. Evolutionists continually adapt their
> smorgasbord theory to fit the available data. As the data refutes their
> simplest, easiest, most plausible explanations, they move onward to the
> deeper reaches of their smorgasbord. This gives life (and legs) to their
> theory.
> ...
> In practice, natural selection is countless degenerative auxilliary
> hypotheses serving only to explain a specific observation. Each instance of
> organism and environment gets is own special definition of fitness.
> There is no coherent theory.
> ...
> To refute punctuated equilibria, for example, you
> would have to find lots of gradual evolution, or ancestors and lineages. In
> other words, punc eek is defined so the only way you can "refute" it is by
> finding compelling evidence that evolution ACTUALLY HAPPENED. That's
> not a test of evolution.
> ...
> Evolutionary theory is a structureless smorgasbord of every conceivable
> naturalistic mechanism. And evolutionists *select* those *natural*
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> mechanisms that seem to match (and therefore "explain") the data....
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> They ignore the mechanisms that don't fit.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is a serious point, and deserves a careful answer. I would suggest
these four points:
1. An "historical" scientific theory cannot have greater empirical
content than the observational and experimental sciences upon which
it depends.
Cosmology's predictive power is limited by the empirical accuaracy of
particle theory and general relativity. "Historical" geology's predictive
power is limited by knowledge of exact rates for various processes
(erosion, uplift, drift, etc.)
In the past, evolution's auxilliary hypotheses (e.g. the elements of
genetic information, the inter-relatedness of genetic information in
determining morphology, the source of genetic variation, the frequency of
mutations, mechanisms for reproductive isolation) have been very flexible
BECAUSE OF the relatively weak empirical content of molecular biology,
cellular biology, developmental biology, and ecology / population
dynamics. This is changing, however, because the empirical content of
those disciplines is starting to grow by leaps and bounds. As it does,
the empirical content of evolutionary theory -- its ability to make
testable predictions -- will also grow.
2. When an "historical" scientific theory lacks strong empirical
bounds, it is proper to adjust its auxilliary hypotheses to match
the available data.
As new data became available, evolutionists PROPERLY selected certain
natural mechanisms as being primarily important, while de-emphasizing or
discarding certain others.
Given these first two points, we could only test (and falsify) certain
_specific_ versions of evolutionary theory. But can we test (and falsify)
evolutionary theory _generally?_ That's were these points come into play:
3. The increasing empirical content of experimental sciences and the
increasing amount of "historical" data (e.g. fossils, genetic homology
information) both work to gradually decrease the flexibility of the
auxilliary hypotheses.
4. An "historical" scientific theory is tested insofar as the
auxilliary hypotheses required to fit the "historical" data must
not contradict the bounds set from the experimental sciences.
In practice, scientists do not wait for experimental science to set
precise limits on auxilliary hypotheses before constructing "historical"
theories. Predictions and constraints flow in both directions. For
example, cosmological data sets a strong limit on the number of
"generations" of quarks and leptons which can exist. If experimental
particle physics finds more than 4 generations, the hypotheses of big-bang
cosmology will have to be re-examined.
Frequently, data from "historical" observations PRECEDES experimental
science in setting limits on auxilliary hypotheses. For example,
consider a possible set of auxilliary hypotheses for evolution:
Aa:
1) Morphologically significant non-lethal
mutations are infrequent. (Say, less than 1 per 10^9 individuals
per generation. Please note, I'm out of my expertise here, so the
numbers I choose could be off by a few orders of magnitude.)
2) All such mutations affect at most one or two morphological
characteristics.
3) Selection pressures operate to introduce a majority (>50%) of
such non-lethal mutations into the general population.
4) Modern speciation almost always occurs within geographically united
populations.
Set (Aa) would, I believe, predict lots of evidence for
morphologically _gradual_ evolution. Now consider another set:
Ab:
1) Morphologically significant non-lethal
mutations are frequent. (Say, greater than 1 per 10^6 individuals
per generation.)
2) Most (>90%) such mutations affect more than two morphological
characteristics.
3) Selection pressures operate to delete all but a small minority
(<.01%) of such non-lethal mutations from large populations (>1000
individuals).
4) Modern speciation almost always occurs within populations isolated
geographically from the original population.
Set (Ab) would, I believe, strongly favor a pattern of punc. eek.
fossilization.
Walter raised a very good point: Punc. eek. was not offered as a
prediction on the basis of discovering (Ab) to be true. Punc. eek. was
proposed _post_hoc_ to "explain" the fossil data. In effect, Punc. eek.
"forced" (Ab) rather than being predicted by (Ab). But even though punc.
eek was offered post-hoc, it serves to limit the empirical bounds of
auxilliary hypotheses. Thus, it is "progressive" rather than
"degenerative."
Thus, I disagree with Walter's statement:
WR> punc eek is defined so the only way you can "refute" it is by
> finding compelling evidence that evolution ACTUALLY HAPPENED.
Another way to refute punc. eek. is to show that the empirical data from
molecular, cellular, developmental biology and observed cases of
microevolution FAVOR set "Aa" (or something close to it) rather than "Ab."
If the experimental/observational sciences eventually favor "Aa" while the
fossil record / genetic homology data favor "Ab," evolutionary theory will
be in serious danger. Whether or not it could be rescued would depend on
whether or not additional progressive hypotheses could be constructed.
Am I giving you a "run-around" again? No, I'm being realistic about how,
in practice, scientific theories are ACTUALLY tested.
---------------
WR> In practice, natural selection is countless degenerative auxilliary
> hypotheses serving only to explain a specific observation. Each instance of
> organism and environment gets is own special definition of fitness.
> There is no coherent theory.
I agree that "natural selection" has been and often still is used in this
way. That's the problem I have with the "hot new field" of evolutionary
psychology!
But I do disagree with your characterization, "There is no coherent
theory." I would rather say that natural selection is a coherent theory
which still has frighteningly wide empirical bounds.
-------------------
In summary, Walter, I agree with you about evolution's great flexibility
and relative lack of predictive ability. I disagree with your
catch-phrase characterizations of evolution as "untestable" and
"a structureless smorgasbord."
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In previous posts, I offered two possible "tests" of evolution. In one, I
restricted myself to (what I called) the "central core." Walter rejected
that test as "the old 'dramatic observation' [which no one would expect to
see anyway] ploy."
In the other test, I also utilized auxilliary hypotheses which nearly all
biologists expect to be true. Walter rejected it, in part, as
insufficiently specific.
I suppose I could make my "functional parsimony reconstruction test" more
specific. I could dig into the molecular biology of calcium channels.
I could list all the known homologies and divergences of the same channel
type (and subunits) between different species, known pseudogenes (if any),
all the known mutations and their functional consequences. I could
specify a range over which parsimony reconstruction should be done and
what the resulting electrophysiological/functional properties should
be. I could specify a region of reconstructed genomic phase space which
(IMO) MUST code for functional channels (function specified by certain
criteria) in order for evolution to be true.
But that's a lot of work. Let me first ask this: Would such a test
fit your testability criteria?
For now I'll stick by this point: The construction of genomic libraries
and the technique of parsimony reconstruction are very powerful tools
which can be used to test evolutionary theory.
----------
It may be, as you say, that a few evolutionists would rejoice to see a new
species suddenly appear, tomorrow, in several geographically isolated
places around the globe; it may be that a few evolutionists would embrace
it as a new "natural mechanism." But does this attitude on the part of a
few scientists make evolution _unfalsifiable?_
As you lace up your boxing gloves, please tell me WHICH definition of
"evolution" is the target for the glove labelled "unfalsifiable":
1) Darwin's original theory?
2) The modern version?
3) The core of the theory which hasn't changed since Darwin?
4) The philosophical committment of some evolutionists that, no matter
what the data, everything happened/happens via natural mechanisms?
5) The practice of modifying (naturalistic) auxilliary hypotheses
to fit the data?
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Finally, a word about ice cream:
When Walter wrote what I considered to be a garish straw-man of my
position ("... the usual evolutionary run-around"), I decided I should
give that straw man a floppy hat, baggy pants, bright shirt, costume
jewelry, stick a post down its back, hang bells from it, and leave it out
in a field, so that anyone who saw it would have no doubt about what it
was. It seemed an appropriate response to a straw-man.
(I also wished to make a second point: that high-order scientific
theories are never uniformly "testable" or "untestable." They more
resemble fudge ripple ice cream.)
Walter, you defended your style of writing, saying that you value clarity
and speed of communication. Then you should be grateful if I identify
a tactic, which you frequently use, which hinders communication. Almost
every time I read one of your posts, I am bothered by what I perceive as
straw-men. (I believe many other readers share this perception.)
Straw-man spotter's guide:
--"The remainder of Loren's discussion (though nicely stated) offers the
usual evolutionary run-around."
--"Loren is trying to blame evolution's untestability onto the people
who want to replace it."
--"Loren is using the old dramatic observation ploy."
--"Loren's notion does not test evolution, it is just another run-around."
--"Loren is using reverse-logic again."
--"Anything to wear you down and take the heat off evolution.
Loren does that."
--"Loren's discussion on this point is exceedingly bland (non-existent!)."
--"In summary, Loren gave us the run-around."
Your frequent use of one-sentence (mis)characterizations hinders
communication. It is difficult NOT to interpret them as _ad_hominem_
attacks. I find myself forced to re-read your prose THREE OR FOUR TIMES
before I can filter out these perceptions and understand the actual point
you are making! (It's usually a pretty good point, so I make the effort.)
Also note:
--"Evolutionary theory is a structureless smorgasbord of every conceivable
naturalistic mechanism."
--"That is another favorite evolutionary dodge."
--"It's always been a structureless smorgasbord of conflicting mechanisms."
--"There is no coherent theory."
Even when you avoid using a person's name, these one-sentence
characterizations and catch-phrases are, in my experience, worse than
useless; they are a serious hinderance to communication.
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"You should always save hyperbole |
until you really need it." | Loren Haarsma
--Hobbes (_Calvin_and_Hobbes_) | lhaarsma@opal.tufts.edu