"Guy Hoelzer"  wrote in message
news:c9b74g$t6$1{at}darwin.ediacara.org...
> in article c955m8$134c$1{at}darwin.ediacara.org, Perplexed in Peoria at
> jimmenegay{at}sbcglobal.net wrote on 5/27/04 9:40 AM:
>
> > "Guy Hoelzer"  wrote in message
> > news:c9389m$e25$1{at}darwin.ediacara.org...
> >> in article c92cvt$3s4$1{at}darwin.ediacara.org, John Wilkins at
> >> john_SPAM{at}wilkins.id.au wrote on 5/26/04 8:26 AM:
> >>> I have already delivered myself of my dismissal of emergence as a
> >>> metaphysically interesting feature of physical systems, so I won't
> >>> rehearse it here. Flocking behavior, though, is a property of
individual
> >>> birds (or boids) and their genetic and developmental
programs, not of
> >>> flocks...
> >>
> >> I'm afraid that I don't understand your objection to my example.  I
agree
> >> that flocking behavior is a property of individual birds, and not of
> > flocks.
> >> Similarly, flocks are a property of a species, not of individual birds.
> >> Therefore, a single genetic mutation can lead to heritability of
flocking
> >> behavior at the individual level, and flocks at the species level; so
> >> changes in the frequency of this mutation can potentially be influenced
by
> >> selection at both the individual and species levels.  Do you agree?
> >
> > I have already delivered myself of my middle-ground position
> > between Guy and John, but, what the hell, I will repeat it here.
>
> I am afraid that I must have missed your "delivery" post the
first time
> around.  My apologies for making you repeat yourself.
>
> > If a deme of swallows does well because it flocks, then the
> > individual swallows also do well.  If the flocking behavior
> > is due to individuals heading toward concentrations of
> > other birds sighted visually, then individual selection
> > seems to be the explanation of choice.
> >
> > If a deme of peacocks does poorly because runaway sexual
> > selection has caused the males to carry outlandish tails,
> > then the individual peacocks also do poorly.  But an
> > individual peacock has no opportunity to do well in this
> > situation.  If it doesn't grow a tail, it can't reproduce.
> > If it does grow a tail, it cannot survive predation.  The
> > tail is a deme-level property, and deme-level selection
> > is the explanation of choice.
> >
> > Notice that this is just the opposite of what intuition
> > would say about where the property resides.  A flock
> > seems to be collective, whereas a tail seems to be
> > individual.  Ignore the guidance of intuition!  Instead,
> > pay attention to whether an individual can do better
> > than the deme as a whole by bucking the system.  If
> > he can, then blame the individuals.  If not, then
> > blame the system.
> >
> > Another example:  If the swallows flock because of sound
> > signals emitted expressly for the purpose of attracting
> > birds to the flock, then we have a borderline case.
> > An individual has no particular reason to signal, if
> > it lives in a deme of birds that ignore the signal.
> >
> > Whenever you see frequency-dependent selection at the
> > individual level, there is the possibility that the
> > trait is maintained by feedback loops at the demic
> > level, and demic-level selection may be the best
> > explanation for what is happening.
>
> I have no problems with any of this, but I don't think that it touches on
> the point I made above.  I am arguing along the lines that Jim McGinn has
> frequently argued on sbe.  Natural selection can have traction influencing
> the fate of any mutation (defined as any change in heritable information;
> need not be genetic) at several levels simultaneously.  The hypothetical
> mutation I described above causing individuals to behave in ways leading
to
> flock formation was used to illustrate how selection at the individual
level
> and deme (or species) level could interact in either complimentary or
> antagonistic ways to form a net effect on the frequency of this mutation.

Hmmm.  There are three different accounts of multi-level selection.
One is that effects of selection at the different levels must be
added to find the net effect.  That seems to be the account that
you are following.  The second account is that the same effect
of selection can be described at multiple levels.  You don't
add the effects of the different levels - they are all the same
effect.  This second account is, I thought, the one that Jim
McGinn is promoting.  You seem to think otherwise, and you are
probably correct since you have been reading his posts longer than
I have.

The third account, the one that I was trying to adhere to in my
post, is that selection at different levels is neither additive,
nor is it simply an alternate viewpoint.  Different traits are
selected at different levels.  There is no addition of selective
effects at various levels, because the effects apply to different
traits.  While there is the possibility of an alternate viewpoint,
that possibility is rejected for philosophical reasons.

(Incidentally, I don't personally subscribe to a philosophy that
rejects alternate explanations, but I am willing to accept the
single-best-viewpoint rule in my campaign to convince John that
demic and species levels of selection are explanatorially
necessary.)

If you adopt the "single-best-viewpoint" rule, the second account
of multi-level selection is outlawed, and the first, additive,
account becomes seriously weakened.  After all, the partition
of the net effect among the various levels is fairly arbitrary.
It becomes very difficult epistemically to demonstrate that
higher-level effects actually exist.

Therefore, I have voluntarily limited myself to the third
account, because a demonstration that there are selective
phenomena that cannot be explained any other way breaks the
back of John's intransigence and makes it possible to move
toward a mature multi-level selection that incorporates aspects
of all three accounts.
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