Text 243, 101 rader
Skriven 2004-09-29 22:00:00 av Tim Tyler (1:278/230)
Ärende: Re: Testing Evolution Via
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John Edser <edser@tpg.com.au> wrote or quoted:

> > > JE:-
> > > Drift is just a defined random 
> > > process of sampling error.
> > > All random processes remain ubiquitous.
> > > Therefore, if you define any gene freq.
> > > changes via genetic drift as "evolution"
> > > and not as strictly "temporal variation" the 
> > > theory of evolution becomes a non refutable.
> > > You end up reducing evolutionary theory
> > > to just a non scientific "iron man" proposition
> > > on par with so called "creation science".
> 
> > TT:-
> > Huh?!?
> > Evolution is certainly normally defined as I described.
> > It's been the subject of many experimental tests over the years.
> > It's not "non refutable".  Rather it's proven beyond reasonable doubt.
> > I'm afraid that what you are saying makes no sense.
> 
> JE:-
> I would suggest you read anything by Karl Popper. 
> A valid point of refutation is required for any valid
> scientific theory. This requirement is just common sense.
> If I am accused of being a witch then I must have the right
> to ask what test is definitive for refuting that 
> proposition, i.e. what test can I make that could demonstrate
> I am not a witch? In the middle ages the accused were
> tied in a chair and dunked. If they drowned this proved
> they were not a witch but if they survived this proved that
> they were! It's just the W.C. Fields syndrome: "there is a sucker
> born every minute". Political manipulation of reasoning and
> logic has always been endemic. _Rational_ tests have to exist
> to refute any proposition otherwise the proposition just becomes
> a dictate (again, mostly for political reasons). 
> 
> A point of refutation is _not_ a point of non verification.  
> If something is supposed to be observed but fails to show
> up this does not refute a proposition. However, if something
> should never be observed but is, then this may refute a 
> proposition. If a proposition cannot provide at least one
> such prohibited observation, then the view constitutes an iron man
> proposition because it remains irrefutable. The "drift as evolution
> without selection" viewpoint cannot be refuted it can only 
> be non verified. This is because you cannot delete a
> random processes, they remain _ubiquitous_. Unless you can
> delete it you cannot test it to refutation. However selection
> can be deleted for a significant period of time using the
> experiment I have described so it can be refuted.

The issue of to what extent selection and drift are responsible
for observed features of organisms is quite subject to 
experimental investigation - the hypothesis that selection is involved 
predicts a lot of convergent evolution - whereas the hypothesis that drift 
is involved predicts much greater morphological diversity.

There have been attempts to examine the relative contributions of 
selection and drift to evolution - e.g. see "Life's Solution:
Inevitable Humans in a Lonely Universe" by Conway Morris.

> > TT:-
> > Apparently random processes form the foundation of many scientific laws. 
> > I refer you to the Boyle's law and the theory of ideal gasses - which
> > are based on the hypothesis that gas molecules interact at random.
> > What might be "non-refutable" is whether the mutations (or whatever)
> > are *really* random - but frankly, nobody cares two hoots about that.
> 
> JE:-
> Random _patterns_ can be produced by _either_, random or non
> random processes.  Thus random _patterns_ can be employed all
> the time as just ONE PART of "of many scientific laws" but
> not random processes because these can only produce random patterns.

Genetic drift is a process with undirected componets.  Nothing
stops it from producing non-random patterns.

Recall the experiment where you fire ball bearings "at random" into
a grid of vertical spikes on an inclined plane - and the ball bearings
wind up forming a normal distrubution in buckets at the bottom of
the slope?

That's a classic example of random processes producing a non-random 
pattern.

> This means that such processes cannot, just on their OWN, constitute
> a valid causative process within the sciences.

It doesn't follow.  The whole argument is nonsense :-(
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