Re: Alvin Plantinga's paper/Predictions

Moorad Alexanian (
Fri, 22 Jan 1999 08:41:24 -0500 (EST)

At 03:07 PM 1/21/99 -0400, David Campbell wrote:
>[pieces of longer message]
>>>What does evolutionary theory predicts man to look like in the future? Will
>>>man remain bipedal? Will he evolve to become a flying animal? Evolutionary
>>>theory assumes man evolved from situation A to situation B and the
>>>predicative power is limited to finding evidence along that particular
>>>trajectory in time. It cannot predict anything beyond B or earlier than A.
>>The main issue is if by tinkering with living organisms one can generate a
>>new organism that is totally different, a difference in kind not degree,
>>from the original one. If the latter could be accomplished, then that would
>>lend credence to the theory of common descend.
>What constitutes a difference in kind? New species have been generated, as
>has at least one new genus, by tinkering with living organisms.
>Actually, the difficulty of such predictions as you are asking for from
>evolutionary theory is a lack of data, not a lack in the theory. If I knew
>what selective pressures people are going to face and what the
>probabilities of various mutations are, I could predict whether we will
>evolve the ability to fly. Based on what evidence is available, I think we
>are able to avoid such selective pressures by building machines that allow
>us to fly. In a closely controlled situation, it is possible to predict
>how things will evolve, although the apparently random nature of mutations
>and the usual existence of multiple solutions to any given problem make a
>definitive (as opposed to probabilistic) prediction nearly impossible. The
>same is true of physics. The formulas for gravity are well-known, but
>predicting the exact behavior of enough objects over a long enough time
>becomes impossible.
>David C.

By difference in degree I mean something that can be gotten from something
else in a continuous fashion. For instance, by breading all sorts of dogs,
we only get different looking dogs but dogs nonetheless. Difference in kind
require some sort of discontinuous transition. Of course, on the molecular
level, there is no true continuous change since all changes are of a finite
nature--e.g., exchanging some strands in a DNA.

Weather study, or the model for the solar system, is based on mathematical
models that give rise to chaotic behavior and in that sense we cannot make
long range predications--but can make excellent short term predictions. I
do not think such models exist in evolutionary theory even to make short
range predictions. For instance, given a particular DNA, and whatever else
you need to determine the organism involved, can you tell me what will be
the outcome if I tinker with the DNA in a particular fashion? For instance,
is the resulting organism even viable?