William Morse  wrote:

> wilkins{at}wehi.edu.au (John Wilkins) wrote in
> news:blt3go$2g9t$1{at}darwin.ediacara.org: 
> 
> > Paul Gallagher  wrote:
> 
> >> Now I'm not sure I understand Sober correctly. I think he's saying
> >> fitness is a real  (but non-physical) property of the organism, 
> >> even if it can't be precisely measured. The analogy to temperatue 
> >> is interesting, but isn't temperature precisely measurable, and
> >> isn't it independent of context? 
>  
> > It's an analogy of ontology. Temeperature is not relative, to be sure,
> > but it *is* a *physical* property that applies to differing physical
> > substrates.
>  
> > Sober thinks, and I concur, that fitness is a physical property.
> > Supervenience was proposed initially to deal with consciousness in the
> > philosophy of mind - if minds were all physically different, how did
> > they instantiate a physical property of - say - "seeing red" or
> > "knowing that it will rain"? Jaegwon Kim proposed
supervenience as a
> > solution - these things can be multiply realised physically, but if
> > any two physical systems were identical, they *had* to be in that
> > state. 
> 
> >> Clearly there are different properties of organisms that can be
> >> passed on to offspring and that can affect the properties of future
> >> populations. Assigning fitness values is a way of predicting the
> >> effects of these properties. But beyond that I'm confused...
> >> I think it makes sense to say temperature is the cause of a 
> >> physical process. But does it make sense to say fitness is a 
> >> cause of natural selection?
>  
> > Ultimately, in each particular case (this is critical), no. Neither
> > does it in each particular case of temperature.
> 
> But from a statistical standpoint it does make sense, just as from a 
> statistical standpoint we can say that temperature is the cause of a 
> physical process. I think it is possible to compare fitnesses - if 
> individual A can run ten miles an hour, and animal B can run eleven miles
> an hour, with no other meaningful differences between them, then one can
> predict that whatever gives individual B that edge will "be
selected", the
> good lord willing and the creek don't rise. Is this what Sober is getting
> at?

I think so. He gives the example of identical twins, one walking
slightly higher on a slope than the other and getting hit by lightning.
There is no selection here, he says, because there is no physical
property of the dead twin that caused the death that the other twin
doesn't have.
> 
>  What causes, say,
> > paper to combust at 451°F is the binding of sufficient free oxygen to
> > the carbon and other reactive molecules of the paper such that they
> > release energy that causes still more molecules to so bind and release
> > energy. To entify "temperature" is to run into the same
problems as
> > when we generalise the properties of a particular case of selection -
> > say the ability of one moth morph to evade capture due to confusing
> > the visual acuity of the major predator - to all cases. We note a
> > similar dynamic, and we assign a variable - fitness - into which we
> > pour the specifics of the physical case one by one.
>  
> Well, even in statistical mechanics that is the case (at least if Tsallis
> is right about the proper equation for entropy). But I can still make
> predictions based on the statistics, so even if the actual cause is 
> historical the net cause is teleological.

Now that I have choked on "teleological" (are you reading my diatribe
against teleology in That Other Group?), let me just note that fitness
is also a statistical property, just like entropy. As to whether this
is, as Darwin thought, following Laplace, randomness due to our
ignorance or there is some contingent randomness in the physical
properties of organisms, I leave to another, more philosophical,
discussion.
> 
> Yours,
> 
> Bill Morse


-- 
John Wilkins wilkins.id.au
For long you live and high you fly, 
and smiles you'll give and tears you'll cry
and all you touch and all you see is all your life will ever be
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