>>Hello Russell, thanks for your comments. I'd like to throw in my
>>own $0.02 here.
>>
>>First, I agree with what you wrote above. The problem though is
>>that the argument from imperfection is often guilty of the same
>>type of fallacy.
>>
>>Nevertheless, the argument can be valid depending on the situation.
>>I'll call this the "who says what first principle". Suppose a
>>creationist says something like "look at X. It's obviously designed
>>blah blah". In this situation it is perfectly legit to counter
>>with "oh yeah, what about this, it doesn't look designed to me".
>
>RS>This is how the "argument from imperfection" arose. Creationists
>have been talking for a long time about how life must have been
>designed, because it works so perfectly. Then others responded by
>pointing out many instances in which the fucntioning of organisms
>is (sometimes significantly) less than perfect.
>
This is undoubtedly true for many creationists but is certainly
not true for all. For example Beheian design is based on the
idea of irreducible complexity which may or may not involve
"perfection" or even optimality in function.
As another example, let's look at your statement:
'This is how the "argument from imperfection" arose'
I'm not enough of an historian to attempt a guess at when the
argument from imperfection arose. If we go as far back as Darwin
we'll find one of Darwin's contemporaries, Richard Owen, making
extensive use of the argument. It is clear that Darwin borrowed
some of his examples of imperfections from Owen. Interestingly,
Owen was a creationist who used the argument from imperfection
as an argument *for* design. It seems quite possible then that
the argument from imperfection originated with creationists ;-).
The point of these examples is that context is essential. For
someone like Owen, the argument from imperfection is obviously
knocking down a strawman.
The problem as I see it is that appropriate context is
practically never given. For example, the talk.origins FAQ
<Evidence for Jury-Rigged Design in Nature> has the following
as its opening paragraph:
Many organisms show features of appallingly bad design.
This is because evolution via natural selection cannot
construct traits from scratch; new traits must be
modifications of previously existing traits. This is
called historical constraint. A few examples of bad
design imposed by historical constraint:
There is no mention whatsoever of the appropriate context of
the argument from imperfection here. We do, however, see a
very strong claim being made "appallingly bad design" with
absolutely no supporting analysis except stuff like "looks
like bad design to me". If the writers of this FAQ want to
maintain their position of "appallingly bad design", then
they also need to define exactly what design is and how its
idntified and measured objectively. Otherwise they're just
giving their opinions, which are no better than the "wow
this looks designed to me" opinions of creationists.
>>BH>For example, one says "the eye would obviously be better designed
>>without a blind spot". This involves the implicit (and ridiculous)
>>assumption that one can change one aspect of a complicated design
>>keeping everything else constant.
>
>RS>It was done with the squid. Squids don't have a blind spot.
>
>>BH>Of course, one could say that
>>God could accomplish this feat if he wished. But now you're supporting
>>your argument with theology. This is taking the easy way out that
>>creationists are so often condemned for. To really support the
>>case that the blind spot is bad, one has to come up with an alternate
>>design and demonstrate that it is better. No one has done this.
>
>RS>Nature has. We have merely pointed it out.
>
Are you saying squid eyes are actually better than
human eyes? If so, by what criteria?
>>BH>What I mean here, of course, is an alternate design of a human
>>eye, and not something completely different like a cephalopod
>>eye.
>
>RS>Why not? The designs (so to speak) are very similar.
>
>>BH>I'm pretty sure that I still have all the relevant posts from the
>>t.o thread that I could forward to you if you are interested in
>>all the gory details. If memory serves the crucial points were:
>>
>>1) a complicated interdependence between the various structures.
>>included in this is the importance of the relative locations of
>>some of the structures. One cannot simply change or move one thing
>>without producing a whole host of changes in other things. To
>>remove the blind spot one would have to move a lot of stuff.
>
>RS>So it is your argument that it would be impossible to make this
>minor change in the layout of blood vessels in the retina?
>
No. My argument is that the consequences of this change upon the
performance of the eye are not known.
Brian Harper
Associate Professor
Applied Mechanics
Ohio State University
"Aw, Wilbur" -- Mr. Ed