>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.
>
>Furthermore, in some respects some molluscs have eyes better
>designed than vertebrates. 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.
>
This type of observation is very common and I think also very
naive from the standpoint of design. Paul Nelson has written
a really great article about the argument from imperfection
that I suggest everyone should read. I understand it has now
been published, so if Paul is listening maybe he could give
us the reference.
The reason I say the above is naive is that it assumes one
can change one aspect of a design keeping everything else
the same. This might be possible with simple designs but
almost certainly is not for complicated ones. I did a lot of
reading on eyes awhile back and from what I read it seemed
to me (a non-expert on eyes) that the at first seemingly
irrational arrangement alluded to above actually allows
the pigment epithelium (I hope I'm remembering this
correctly) to perform several different functions that it
otherwise would be unable to perform. One might then
argue that any loss in image quality is offset by the improved
efficiency of having one component perform multiple functions.
Besides, the deleterious effects of the actual arrangement are
very slight.
Now, one might counter the above by saying that God is not
constrained in the way human engineers are and that He
could optimize all aspects of a design simultaneously without
having to do trade-offs such as that above. Now things get
tricky I think. If the conversation began with the creationist
saying "look, this is perfect, God must have designed it", then
the counter is perfectly legit, IMHO. On the other hand, if
the conversation begins with the evolutionist saying "look,
this design is imperfect, it couldn't be designed" then the
counter is not legit since it introduces a theological question
regarding what God would or wouldn't do. The evolutionist
has made the charge that the design is not perfect, the onus
is on him to prove it by finding a better design without
appealing to theological arguments.
Brian Harper | "If you don't understand
Associate Professor | something and want to
Applied Mechanics | sound profound, use the
The Ohio State University | word 'entropy'"
| -- Morrowitz
Bastion for the naturalistic |
rulers of science |