Thanks to David for continuing this discussion.
>> LH: "I suggest that some of us do a little experiment: Find half
>> a dozen biochemists / molecular biologists and ask each of them
>> to specify a (theoretical) situation which would convince them
>> that humans didn't evolve (without some intelligent intervention
>> and/or tinkering with the genetic code). Ask them not to offer
>> "extreme" examples. Instead, challenge them to think of
>> _potentially_ realizable data."
> DT: In principle, this is an acceptable experiment. However, the
> question is one that is never asked within the orthodox paradigm
> - so I'm not sure the reactions from the half-dozen would be
> meaningful.
>
> Perhaps the first question might be - do you accept the premise
> of the experiment? That is, would ANY evidence be allowed
> against evolution? This seems to be the main thrust of Dembski's
> pulsar (quoted by Stephen in his post of 17th Jan) - a
> hypothetical situation which Dembski argues allows ID to be
> considered a legitimate scientific theory.
To answer your question, we need to make it more specific. What do you
mean by, "Would ANY evidence be allowed against evolution?"
1. "Would ANY evidence be allowed against certain evolutionary MECHANISMS
playing a major role in macroevolution?" The answer here is clearly,
"yes." Biologists are constantly arguing over which evolutionary
mechanisms are most important. Neutral or adaptive mutations? Entire
populations, or small, isolated sub-populations? Point mutations, gene
duplication, copy errors, or gene transfer? The evidence can favor one
evolutionary mechanism over another. And here is the important point:
the right kind of evidence can all but _rule_out_ certain evolutionary
mechanisms from playing any significant role beyond microevolution.
2. "Would ANY evidence be allowed against the theory that certain species
evolved from certain other species?" Again, the answer is yes.
Evolutionary biologists are constantly arguing about which species
descended from which, and how long ago, and which anotomical structure in
one species corresponds (genetically and developmentally) to which
structure in another species. Biologists are constantly looking at the
fossil, developmental, and genetic evidence to argue that species A
descended from species B (rather than C or D), and structure W arose from
alterations in structure X (rather than Y or Z).
Those questions were tame. You probably want to ask this one:
3. "Would ANY evidence be allowed against a PURELY NATURALISTIC theory of
common descent by modification?" Given the answers to questions one and
two, I believe that the answer to this one must be, "Yes." Evolutionary
pathways and evolutionary mechanisms can be "ruled out" by the evidence.
This allows the possibility for scientists to eventually be "backed
into a corner" --- leaving them with _no_ plausible mechanism.
Imagine discovering that in a certain species, the fossil record indicates
a certain line of descent, but the genetic/developmental data is stronly
at variance with this, and all known evolutionary mechanisms are
considered incapable of accounting for that variance. This WOULD be
considered evidence against a _purely_ naturalistic theory of common
descent by modifcation (for that species). (Of course, entire theories
are seldom rejected on just one piece of evidence, unless that evidence is
particularly robust.)
And finally....
4. "Would ANY evidence be allowed in favor of the idea that biological
life was designed?" As we've already discussed, the issue of
design-of-component-pieces is, IMO, much more philosophical than
scientific, so I don't see how scientific evidence would favor Intelligent
Design vs. Anthropic Principle design here.
As for method-of-assembly, scientific evidence might indeed accumulate to
argue that no known natural mechanisms could account for certain aspects
of biological history. But of course, the determined Naturalist could
fall back upon extra-terrestrials, Unknown Natural Mechanisms, or cosmic
fluke.
-------------------------------------------
> DT: I personally have a problem with this kind of question - because
> I cannot relate it to the world around me (even though I am an
> advocate of intelligent design!) Dembski's pulsar is not the way
> God works! Design is to be found everywhere - not in the
> extreme, nor the non-extreme! Design is in the "ordinary" and
> familiar ingredients of the world around us.
I agree that we see design all the ordinary and familiar ingredients of
the world around us. But we also see two different kinds of systems:
systems whose physical histories includes clear instances of intelligent
intervention, and systems whose histories do not. Thus, I have no problem
with using the evidence to classify biological life into one category or
the other.
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> DT: Rather than ask whether these people can think of such a
> compelling example, it might be more interesting to get them to
> assess the arguments of "Darwin on Trial". In this book, they
> are faced with a challenge: that there is no satisfactory natural
> explanation of origins. The data/evidences do not warrant the
> conclusions of evolutionary biologists. It seems to me that this
> is where evidences of paradigm blindness will be revealed.
>
> As a follow-up, maybe Walter Remine's "The Biotic Message" could
> be used. Are the evidences of design (the Creator's message)
> really so prevalent?
Let's be more specific about what we mean by the phrase, "... no
satisfactory natural explanation of origins." If you mean, "... no
detailed and empirical model which starts from agreed-upon intial
conditions and arrives at present-day data," then you are correct.
Stellar evolution has recently achieved this, but biological evolution has
not.
But perhaps you mean, "... empirical evidence renders natural explanations
of biological history extremely improbable." ReMine argues this, and
Johnson comes close to doing so.
But herein lies the problem: do we really understand the natural
mechanisms with sufficient empirical accuracy to make such a claim?
Historical science cannot make stronger empirical claims than the
empirical content of the disciplines upon which it depends. This is where
astrophysicists and geologists have an advantage over evolutionary
biologists. The natural mechanisms of physics and geology are understood
with much greater empirical content than those of molecular biology,
developmental biology, and complex population dynamics. Empirical models
of the formation of stars, planets, oceans, and atmospheres are now
possible. Interestingly enough, empirical models of the formation of
galaxies and galactic clusters have not yet been achieved. Thus, in one
sense, "there is no satisfactory natural explanation of the formation of
galaxies." However, I think you agree that a "natural explanation" of
galactic formation is not ruled out by the data, either. We still have
sufficient "error bars" on our understanding to expect that such an
explanation could, and probably will, be forthcoming. I suggest that the
"error bars" in our understanding of organic chemistry and biology are
still so broad, that it is far too premature to claim that natural
explanations of biological history are "extremely improbable."
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>> LH: "True, you cannot "prove" a paradigm is wrong from within
>> that paradigm. However, most scientists are willing to step
>> outside their paradigms from time to time, and most scientists
>> can specify data which would make them seriously question their
>> paradigm."
> DT: I am all for encouraging this - with the proviso that we are not
> looking for our design signatures and messages, but God's. I
> hope you are right. But do you really find much evidence of it
> within the evolutionary biology community?
Well, I don't hang out with many evolutionary biologists, but I do hang
out with plenty of physicists, neuroscientists, and molecular biologists.