Re: [Phys-l] About the "why" and "how questins."

[William Robertson <wrobert9@ix.netcom.com>]

Comments below.

Bill





On Dec 21, 2010, at 4:45 PM, Robert Cohen wrote:

> William Robertson wrote:
>
> > What seldom is
> > presented to the public is the fact that the Earth would be
> > warming at this point (according to ice core data) if humans
> > never existed.
>
> Is that a fact?  Why?
Granted this is not a true fact. I'm basing this comment on where we  
are currently on the ice core data from the last 500,000 years. We're  
on the upswing but not at the crest. I should properly say that if we  
assume the oscillations of temperature indicated by ice core data were  
to continue as before, then we would expect the Earth to continue  
warming for a while.

> > One could actually make a case that
> > the mechanism of Darwinian evolution, natural selection, is a
> > fact.  We have seen natural selection both in nature and in
> > the laboratory. It happens.
>
> What did we observe?  Natural selection or evolution?  Both?  Neither?

We have observed natural selection. Peppered moths is the classic  
natural example of the environment selecting out certain  
characteristics. In the lab, organisms subjected to different  
environmental pressures result in the elimination of certain  
characteristics in the population. I would not call either of these  
evolution, because evolution occurs over long periods of time. It is  
clear, though, that the mechanism of natural selection occurs in  
nature and in the lab, and can be reproduced.
> > What is not a fact, but rather a
> > theory, is global evolution, the evolution of species via
> > natural selection throughout the Earth's history. We have a
> > fossil record (fact) and a mechanism (natural selection), but
> > all that does is make global evolution a very good theory, as
> > you say. So, scientists should present evolution as a very
> > good theory, not a fact.
>
> So, global evolution is a theory, but natural selection is a fact?

That's my claim. Of course one should qualify that by natural  
selection I mean the mechanism in isolated instances, not that the  
mechanism clearly has been at work throughout history.
> I don't disagree with your contention that scientists need to be
> careful.  However, I'd feel better about following your arguments if  
> you
> could provide a definition of a fact vs. a theory.  Also,  
> definitions of
> evolution vs. natural selection vs. global evolution would be nice.

Facts, for me, are observations on which anyone with a clear and fair  
mind agrees. Theories are composed of inferences from facts. No fair  
minded person can argue that the fossil record is not a fact. We find  
fossils, and unless you believe that they have been placed there by  
aliens, you would have to consider the fossils as a factual record.  
The inferences of the theory of evolution are good inferences, but I  
would not call them facts. Hope that makes things clearer.
> ----------------------------------------------------------
> Robert A. Cohen, Department of Physics, East Stroudsburg University
> 570.422.3428   rcohen@po-box.esu.edu    http://www.esu.edu/~bbq
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