On Fri, 8 Nov 1996 20:48:38 +0000, Mike L Anderson wrote:
ML>There are several indications (other than the ones Nicholas
>Matzke mentioned) that mammalian eyes are less than perfect - that
>I know about. Most mammals cannot see colour. The humble goldfish
>can see across a wider range of the visible spectrum than any
>mammal including us. Many insects have multiple visual pigments.
So what? The "humble goldfish" can swim better than me too! :-)
According to this argument, presumably the only perfect human being
would be Superman, who can outdo any other living thing in
everything. Anything else would be "less than perfect"?
ML>Furthermore, in some respects some molluscs have eyes better
>designed than vertebrates.
I will asssume by "molluscs" and the example "octopus", you mean
cephalopods? I would not have a problem if cephalopods had "in some
respect...eyes better designed than vertebrates". All PCs would
maintain is that both cephalopod and vertebrate eyes *are* designed.
I would have thought it a matter of entire indifference to ID theory
in general, and PC in particular, if cephalopod eyes are designed one
way and vertebrate eyes another.
Indeed the "astonishing" thing for "blind watchmaker"
evolution is that cephalopod and vertebrate eyes are so similar:
"The surface and coastal-living cephalopods are predominantly visual
animals. Like birds, they have to depend mainly on sight because they
move too fast to rely on smell. The animals must, literally, keep an eye
on the fishes and mammals that compete with them and prey on them in
the sea. Their eyes are astonishingly like those of their vertebrate rivals.
There is a retina, a lens with muscles for focusing, a cornea and an iris
diaphragm. Laboratory experiments indicate that their visual acuity is as
sharp as our own and that they can, in all probability, see colours much
as we can." (Wells M.J., "Cephalopods", Encyclopedia of the Animal
World, Bay Books: Sydney, 1982 reprint, 4:363)
But the fact is that cephalopod eyes cannot focus as well as
vertebrate eyes:
"The cephalopod cornea does not have any focussing function. Image
formation is accomplished entirely by the lens, which is forced
forward for viewing nearby objects." (Miller W.H., "Photoreception",
Encyclopaedia Britannica, Benton: Chicago, 15th edition, 1984,
14:355)
Indeed the vertebrate eye is potentially the most efficient of all eyes:
"The large size of the camera-like vertebrate eye makes it
potentially the most efficient of all eyes because it can project a
large image on a large surface area containing a high density of
receptors." (Miller W.H., "Photoreception", Encyclopaedia
Britannica, Benton: Chicago, 15th edition, 1984, 14:353-354)
ML>In vertebrates light passes through the neural retina before
>reaching the photoreceptors. This must lower the quality of the
>image. The other consequence is a blind-spot where the nerve fibres
>leave the eye. The octopus does not have this problem.
Dawkins sets out this argument from imperfection:
"My second example of an evolutionary progression that didn't happen
because of disadvantageous intermediates, even though it might
ultimately have turned out better if it had, concerns the retina of
our eyes land all other vertebrates)...Any engineer would naturally
assume that the photocells would point towards the light, with their
wires leading backwards towards the brain. He would laugh at any
suggestion that the photocells might point away from the light, with
their wires departing on the side nearest the light. Yet this is
exactly what happens in all vertebrate retinas. Each photocell is,
in effect, wired in backwards, with its wire sticking out on the side
nearest the light. The wire has to travel over the surface of the
retina, to a point where it dives through a hole in the retina (the
so-called 'blind spot') to join the optic nerve. This means that the
light, instead of being granted an unrestricted passage to the
photocells, has to pass through a forest of connecting wires,
presumably suffering at least some attenuation and distortion
(actually probably not much but, still, it is the principle of the
thing that would offend any tidy-minded engineer!)." (Dawkins R.,
"The Blind Watchmaker", Penguin: London, 1991, p93)
But what "problem" is this exactly? Paul Nelson (?) says:
"It has been widely argued in both the technical (Thwaites 1984,
William 1992) and popular evolutionary literature (Diamond 1985,
Dawkins 1986, Miller 1994) that the vertebrate eye is poorly
designed. "In fact it is stupidly designed," writes the influential
neo-Darwinian theorist George Willams, "because it embodies many
functionally arbitrary or maladaptive features" (1972:73)...The
capstone of this argument is held to be the cephalopod (squid and
octopus) retina, which is putatively "wired correctly," with its
photoreceptors facing *towards* the light, and with its nerves
"neatly tucked away behind the photoreceptor layer" (Miller 1994:30;
see also Diamond 1985:91 and Williams 1992:74)... None of the
authors cited above provides any evidence that the cephalopod retina
is functionally superior to the vertebrate retina." (Editorial.,
"Introduction: A Popular Argument", Origins & Design, Vol. 17, No.
1, Winter 1996, pp19-20)
In fact, Ayoub argues that the vertebrate eye is not functionally
suboptimal at all:
"It has been commonly claimed that the vertebrate eye is functionally
suboptimal, because photoreceptors in the retina are oriented away
from incoming light. However, there are excellent functional reasons
for vertebrate photoreceptors to be oriented as they are.
Photoreceptor structure and function is maintained by a critical
tissue, the retinal pigment epithelium (RPE), which recycles
photopigments, removes spent outer segments of the photoreceptors,
provides an opaque layer to absorb excess light, and performs
additional functions. These aspects of the structure and function of
the vertebrate eye have been ignored in evolutionary arguments about
suboptimality, yet they are essential for understanding how the eye
works." (Ayoub G., "On the Design of the Vertebrate Retina", Origins
& Design, Vol. 17, No. 1, Winter 1996, p19)
After discussing the function of the vertbrate eye, Ayoub suggests a
thought experiment":
"...as a thought experiment, let's fix the blind spot. We will start
by turning the photoreceptors around, so their wiring isn't in the
way. We have eliminated the blind spot, providing slightly better
sight in one portion of the eye. Now, however, the blood vessels and
RPE, needed to maintain the photoreceptors, must be located on the
inner side of the retina, between it and the lens. This places a
large capillary bed (containing many red blood cells) and an
epithelial tissue in the path of the light, significantly degrading
the visual information passing to the photoreceptors. Furthermore,
since the photoreceptors continually shed material from their outer
segments, dumping this opaque waste in the path of the light would
greatly diminish the amount of light reaching the photoreceptors.
Our proposed change also reduces the quality of the light, by
refracting it with the opaque pieces of shed outer segment membrane.
We might imagine simply placing the RPE at the back of the retina,
but this raises the problem of how to dispose of spent outer segment
membranes, so that the photoreceptors can be quickly regenerated.
Or, perhaps, we could surround each photoreceptor cell by RPE cells,
but this would need increase the space between the photoreceptors,
thus decreasing the resolution of vision. These design changes may
force temporal or spatial decrements in vision. Are these
improvements? Hardly; indeed, our thought experiment has taken the
vertebrate eye rapidly downhill. In trying to eliminate the blind
spot, we have generated a host of new and more severe functional
problems to solve. Our "repair" seems far worse than the apparent
flaw we wanted to fix." (Ayoub, 1996, p22)
Ayoub concludes that, far from being suboptimal, the vertebrate
retina provides an excellent example of functional design:
"The vertebrate retina provides an excellent example of functional
though non-intuitive-design. The design of the retina is responsible
for its high acuity and sensitivity. It is simply untrue that the
retina is demonstrably suboptimal, nor is it easy to conceive how it
might be modified without significantly decreasing its function."
(Ayoub, 1996, p22)
Goodwin concurs, pointing out why the vertebrate eye develops
embryonically the way it does, and that visual system works
"extraordinarily well":
"You might ask why the inner layer of cells of the retina become the
nerve cells that conduct electrical impulses to the brain these impulses
arising from the outer layer of cells that contain the pigment which
catches photons It would seem more sensible to arrange it the other
way round, so that photons don't have to pass through a screen of
neurons before reaching the pigmented ells. Invertebrates such as the
squid and the octopus have highly developed eyes, and they organize
the retina with the pigmented cells inside and neurons outside But
invertebrates make their eyes differently: the optic cup arises directly
from the surface layer of cells (the ectoderm) by invagination, the
familiar buckling of a cellsheet that all animal embryos use to develop
internal complexity. They don't make the optic cup from an extension
of the brain the way vertebrates do So In squid and octopus the
pigmented epithelium forms from the cells that were on the surface of
the embryo, where pigmentation is often found. Vertebrates seem to
have a choice of having the pigment in the inside or the outside layer
of the retina, since both arise from cells that were originally on the
surface. However, it seems that a number of factors are involved in
committing the outer layer to being pigmented and developing into
rods and cones, among which are mechanical stresses that make the
cells go columnar and the bloody supply which comes to this layer.
And this type of visual system works well enough - EXTRAORDINARILY
WELL, IN FACT." (Goodwin B., "How The Leopard Changed Its Spots:
The Evolution of Complexity", Phoenix: London, 1994, p153. Emphasis
mine)
ML>I concur with Nicholas. These sorts of facts are difficult for
>PC's but not TE's.
I must have missed something? Why is the alleged fact that the eye
(or any other design) is "less than perfect" , supposedly "difficult
for PC's but not TE's"? I am a PC and I don't have a problem with
designs that are "less than perfect". Indeed, it has never occurred
to me that design should be perfect, and I am not aware of any PC or
ID theorist who has claimed that *any* design is "perfect". Maybe
this was based on some overenthusiastic 18th century Paleyan natural
theology argument? Indeed the only statement that life's designs are
"perfect" (that I am aware of) comes from Darwin:
"In considering the Origin of Species, it is quite conceivable that a
naturalist, reflecting on the mutual affinities of organic beings, on
their embryological relations, their geographical distribution,
geological succession, and other such facts, might come to the
conclusion that species had not been independently created, but had
descended, like varieties, from other species. Nevertheless, such a
conclusion, even if well founded, would be unsatisfactory, until it
could be shown how the innumerable species inhabiting this world have
been modified, so as to acquire that PERFECTION of structure and
coadaptation which justly excites our admiration." (Darwin C.R.,
"The Origin of Species", 6th edition 1872, Everyman's Library, J.M.
Dent & Sons: London, 1967 reprint, p18. My emphasis).
Maybe this was part of Darwin's technique, to set up a straw man that
could be more easily torn down?
Here are some reasons why this "PC" would not find it "difficult" if
"mammalian eyes" were "less than perfect":
1. in my theology, only God is perfect (Mt 5:48). According to the
Bible, God's designs are merely "good" (Gn 1:4, 10, 12, 18, 21, 25,
31), not "perfect". The only claim that I can find about the human
body is that it is "wonderfully made" (Ps 139:14), not that it is
"perfect". Perfect design would point to itself and be a temptation
idolatry, ie. to worship...the creature more than the Creator" (Rom
1:25. KJV). Near-perfect design is sufficient to infer an
Intelligent Designer (archaeology does it all the time -
witness Glenn's Golan Venus which is *definitely "less than perfect"!
:-), since there is no evidence that the alternative "blind
watchmaker" couldn't manage even that):
"While it is easy to accept that a random search might hit on
mutational routes leading to relatively trivial sorts of adaptive
ends, such as the best coloration for a stoat or ptarmigan or the
most efficient beak forms for each of the different species of
Galapagos finch. But as to whether the same blind undirected search
mechanism could have discovered the mutational routes to very complex
and ingenious adaptations such as the vertebrate camera eye, the
feather, the organ of corti or the mammalian kidney is altogether
another question. To common sense it seems incredible to attribute
such ends to random search mechanisms, known by experience to be
incapable, at least in finite time, of achieving even the simplest of
ends." (Denton M., "Evolution: A Theory in Crisis", Burnett Books:
London,1985, p61)
2. perfect design in one organism would be a problem for others, in a
*total ecological system*. It is noteworthy that in Genesis 1 it is
only *the system as a whole* that is pronounced "very good" (Gn
1:31), not the individual creations. Wise points out optimal design
in a complex interelated system is a tradeoff:
"...we are far from understanding the complexity of individual
organisms, let alone the entire ecosystem in which that organism
lives. What appears to be less than optimal design to us with our
limited knowledge may actually be an optimal design when the entire
system is considered. Consider the thickness of armor plating on the
side of a warship. Since the purpose of such plating is to protect
the ship from the puncture of an incoming warhead, it is advantageous
to make the plating as thick as possible. Yet the plating on actual
warships is much thinner than it could be made. The reason is, of
course, that an increase in plating thickness makes the ship heavier,
and thus slower. A less mobile ship is more likely to get hit more
often and less likely to get to where it is needed when it is needed.
The actual thickness of the armor on a warship is a tradeoff-not so
thin as to make the ship too easily sinkable, and not so thick as to
make the ship too slow. We know too little about the complexity of
organisms and the environment in which they live to conclude that any
one particular feature is actually less than optimal." (Wise K.P.,
"The Origin of Life's Major Groups", in Moreland J.P. ed., "The
Creation Hypothesis", InterVarsity Press: Downers Grove Ill, 1994,
pp221-222)
A designer may *optimize* his designs in a total system to take
account of other factors. Mike Behe points out that a designer might
have multiple motives, not just engineering excellence:
"The most basic problem is that the argument demands perfection at
all. Clearly, designers who have the ability to make better designs
do not necessarily do so. For example, in manufacturing, "built-in
obsolescence" is not uncommon-a product is intentionally made so it
will not last as long as it might, for reasons that supersede the
simple goal of engineering excellence. Another example is a personal
one: I do not give my children the best, fanciest toys because I
don't want to spoil them, and because I want them to learn the value
of a dollar. The argument from imperfection overlooks the
possibility that the designer might have multiple motives, with
engineering excellence oftentimes relegated to a secondary role.
Most people throughout history have thought that life was designed
despite sickness, death, and other obvious imperfections." (Behe
M.J., "Darwin's Black Box: The Biochemical Challenge to Evolution",
Free Press: New York, 1996, p223)
3. what is "perfect"? If it means "perfect in man's eyes", then
there would be no mosquitoes or blowflies! :-) A design can only be
claimed to be "less than perfect" if: 1. the designer has stated
his design goal that it was intended to be perfect; and 2. it fails
to meet the design goals of the designer. Behe observes that
arguments from imperfection depend on the critic perfectly knowing
the motives of the designer:
"Another problem with the argument from imperfection is that it
critically depends on a psychoanalysis of the unidentified designer.
Yet the reasons that a designer would or would not do anything are
virtually impossible to know unless the designer tells you
specifically what those reasons are. One only has to go into a
modern art gallery to come across designed objects for which the
purposes are completely obscure (to me at least). Features that
strike us as odd in a design might have been placed there by the
designer for a reason-for artistic reasons, for variety, to show off,
for some as-yet-undetected practical purpose, or for some unguessable
reason or they might not. Odd they may be, but they may still be
designed by an intelligence. The point of scientific interest is not
the internal mental state of the designer but whether one can detect
design." (Beh, 1996, p223)
4. PC can accept common ancestry and design through secondary causes
and a historical process. Gould's "panda's thumb" type arguments
presuppose a YEC (indeed a 19th century "separate creations")-style
creationism that few, if any creationists would believe today:
"...Miller's argument misses the mark...it arises from the confusion
of two separate ideass-the theory that life was intelligently
designed and the theory that the earth is young. Because religious
groups who strongly advocate both ideas have been in the headlines
over the past several decades, much of the public thinks that the two
ideas are necessarily linked. Implicit in Ken Miller's argument
about pseudogenes, and absolutely required for his conclusions, is
the idea that the designer had to have made life recently. That is
not a part of intelligent-design theory. The conclusion that some
features of life were designed can be made in the absence of
knowledge about when the designing took place... An art museum might
display a statue of a bronze cat purportedly made in Egypt thousands
of years ago-until the statue is examined by technologically advanced
methods and shown to be a modern forgery. In either case, though,
the bronze cat was certainly designed by an intelligent agent."
(Behe, 1996, p227)
5. if the arguments from imperfection is supposed to argue against
the existence of a Designer (or a Designer that is only able to
create "less than perfect" designs), why is that not "difficult
for...TE's"? Presumably they also believe in the same Designer that
PCs do? Darwinists are not arguing for "less than perfect" - they
are really arguing for no design whatsoever. And non-design is an
argument for *atheism*, as theistic evolutionist Harvard professor
Asa Gray acknowledged:
"The proposition that the things and events in nature were not
designed to be so, if logically carried out, is doubtless tantamount
to atheism...To us, a fortuitous Cosmos is simply inconceivable. The
alternative is a designed Cosmos...If Mr. Darwin believes that the
events which he supposes to have occurred and the results we behold
around us were undirected and undesigned; or if the physicist
believes that the natural forces to which he refers phenomena are
uncaused and undirected, no argument is needed to show that such
belief is atheistic." (Gray A., "The Atlantic Monthly", October
1860" (Noll M.A. & Livingstone D.N. (eds), Hodge C. "What Is
Darwinism?", 1874, Baker Books: Grant Rapids MI, 1994 reprint,
p156).
God bless.
Steve
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