Newsgroups: comp.ai.alife
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!udel!gatech!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!ub!galileo.cc.rochester.edu!prodigal.psych.rochester.edu!stevens
From: stevens@prodigal.psych.rochester.edu (Greg Stevens)
Subject: Re: "What is Life?"
Message-ID: <1995Feb7.151910.21325@galileo.cc.rochester.edu>
Sender: news@galileo.cc.rochester.edu
Nntp-Posting-Host: prodigal.psych.rochester.edu
Organization: University of Rochester - Rochester, New York
References: <jhansen-120195102007@cetq10.coe.uga.edu> <1995Jan30.224310.1099@galileo.cc.rochester.edu> <3gmelc$j40@engnews2.Eng.Sun.COM> <1995Feb2.161422.3233@galileo.cc.rochester.edu> <3h5snd$9p2@engnews2.Eng.Sun.COM>
Date: Tue, 7 Feb 95 15:19:10 GMT
Lines: 117

In <3h5snd$9p2@engnews2.Eng.Sun.COM> holtz@netcord.Eng.Sun.COM (Brian Holtz) writes:
>In article <1995Feb2.161422.3233@galileo.cc.rochester.edu>,
>Greg Stevens <stevens@prodigal.psych.rochester.edu> wrote:

>>>The requirement of generational change excludes as non-living a lot of
>>>phenomena -- galaxies, stars, continental plates, weather systems,
>>>fire -- that do not seem very alive.  
>>
>>Well, that seems kind of ad hoc to me.

>...If you define evolution as simply "adaptive change", you have to say
>that an individual organism "evolves" if it, say, changes to a white
>coat during winter.  Are you willing to say that?

I never said I wanted to define "evolution" as merely "adaptation."  I was
implying in different parts of the post that I didn't think constraining
"life" to things that showed evolutionary adaptation was quite capturing
what is intuitively meant by "alive."

When you mourn the death of your pet dog, you do not mourn the loss of its
ability to reproduce or the loss of it ability to participate in the
evolution of dogs.  You mourn its ongoing behavior DURING its life time,
those adaptations it shows which are interpreted as goal-directed 
behavior, such as begging for food, fetching sticks, etc.

>>it makes sense to me that something in the STRUCTURE
>>of the organism could be distinguished in determination of whether it is
>>alive, without resorting to the criterion of evolution

>But what sort of structural criterion could include viruses and
>exclude fires?  

Well, autopoiesis theory has a shot at it.  A system of self-producing 
componants which maintain a relation-static organization within physical
boundries.

Note that "self-production" is a superset of "reproduction" but does not
entail it.

>Life seems more about dynamic behavior than static
>structure.

Yes, it seems to be about dynamics behavior of ORGANISMS, not populations.
See my earlier comment about the pet dog.

And I never said "static" structue, either -- like is specified in the
autopoiesis criterion stated above, dynamic structural relations in each
individual should be able to account for the behaviors by which you judge
each INDIVIDUAL to be alive. 

"Life" is a catagory that applies to individuals.  As such, a definition of
life which refers by necessity only to populations and not individuals seems
kind of strange.

>>(we had notions of life long before notions of evolution).

>Weren't those notions uniformly vitalist? 

Actually not.  You can go back even into early Norse and other mytholodies to
find kinds bringing to life constructions made of flowers woven together and
the like WITHOUT having enchanted them or breathed life into them or
whatever.  These were the first proper "robots."

>>But let's say it is self-building, self-modifying, adapting and maintaining.
>>Let's say it responds to stimuli in a way such that its structure alters
>>to maintain a homeodynamisis, and undergoes permanent change so that its
>>structure reflects its experiential history.  Lets say it repairs itself
>>and grows even.
>>Is it alive?

>I'm enough of an engineer to believe that what can be built (or
>self-built, or born) once can be built (or self-built, or born) as
>many times as resources will permit.  So if your entity can be
>produced it can be reproduced, presumably with modifications, and so
>is alive.

Yet then anything which can be built can be reproduced and therefore is
alive by your criterion.  If you are not requiring that what produces it
is of the same species or type of organism, then cars are VERY alive because
they are produced en mass!


>So viruses are not alive?  Why do so many biologists study viruses,
>but so few study fire?

Many biologists also study amino acid structure.  Once you get low-level
lines blur between biology and molecular biology and biochemistry, so
talking about "Life is what biologists study" is not very constraining.

>Doesn't Roget's already have enough? :-)  I'm interested in
>what I would call life or vitality.  What you are interested in I
>would call vivacity, or perhaps animation or (your?) homeodynamisis
>(but probably not exactly autopoiesis).

"Vitality"?  So when someone says, "That person lost some vitality" it means
the person has suddenly been transformed into something that is 
irreproducible?

When experimental evidence of data is "reproduced" -- yet changing because
of experimental conditions just as organisms change as a result of mutation
and environmental change -- does that mean it is alive?

When you see someone dies, is it their having come about through a process of
reproduction that the person has lost, or the person's ability to reproduce
that it has lost, or the normal state of "humans" of reproducing and evolving
that "it" has lost (showing one of the oddities of defining indivdiual life
in terms of populations)?

When you mourn someone's death, which of these is it that you miss?  Or is
it possible that you miss something about thir INDIVIDUAL behavior, the
individual STRUCTURE of their behavior which is governed by their biological
structure as an INDIVIDUAL?

Greg Stevens

stevens@prodigal.psych.rochester.edu

