Can Scientists Define Life ?

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marc.t...@wanadoo.fr

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Feb 10, 2012, 6:27:13 PM2/10/12
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I would like to challenge you with the following controversial
statement: we can nothing about the origin of life.
I think it is true, perhaps for the same reason as the creationists,
but I am sure that these won’t agree with the next statements!
When scientists consider life as a scientifically sound concept they
are in a very difficult position, actually an impossible one.
Everybody can argue them: how can you assert that you will find how
life began when nobody can define it?
Actually there is a seeming consensus among the specialists in the
search for the origin of life (chemists, geochemists, biochemists,
biologists, exo/astrobiologists, computer scientists, philosophers and
historians of science) that there is an “obvious need for a definition
of life”. In spite of this wish everybody can observe the amazingly
high number of definitions of life, leading to reflect that skepticism
is multiplied by the above number, leaving almost no chance for new
formulations which, however, continue to appear!
Wouldn’t be that any definition of life is subjective and arbitrary as
is the boundary between living and nonliving systems or the moment
when nonliving systems would have become living? It is true that the
statement that any such boundary or moment exists is not falsifiable:
no experiment can be considered to prove that it can be false.
Therefore, if the distinction between living and nonliving systems is
a matter of belief and not science, it is not only hopeless but
useless to try to define this indefinable state related to a
metaphysical question!
If the concept of life is metaphysical then, it is true to say that we
can know nothing about the origin of life, as it is true to say that
we can know nothing about the origin of the soul, about the origin of
God etc.
On the contrary I don’t think it is true that we can know nothing
about the origin of the primordial ancestor on Earth, i.e. the origin
of all the terrestrial systems stemming from Darwinian evolution: we
can know about the origin of Darwinian evolution!

John S. Wilkins

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Feb 10, 2012, 7:01:23 PM2/10/12
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You are making a mistake here that is quite common: confusing studying a
thing with defining it. We can study things we do not know how to
define, and we can define things that are not (scientifically)
investigable, like unicorns and fairies.

It may turn out, and I think it will, that we can give a blow-by-blow
description of the kind of chemical process that led from non-organic
chemical reactions ("inorganic" and "organic" have special meanings in
chemistry) to organic ones, and that at no stage is there a discrete
step from "not-life" to "life". We may decide that the very term "life"
is a nonscientific term, but I bet people will continue to use it.

We do not have to be able to define "life", so long as we can point to
standard examples of life. I can point to my children and say "life is
like *them*" - this is called an "ostensive definition" (to ostend is to
point). The desire for a hard and fast definition is a hangover from the
days when people tried to do science by definition.

By the way, the poeple who seem to want a definition of life most
ardently are the exobiologists at NASA, who think, wrongly, that if they
can define the sorts of chemical reactions and dynamics that all and
only life can do, they can build a detector for their probes. I think
they are doing science by definition.
--
John S. Wilkins, Associate, Philosophy, University of Sydney
http://evolvingthoughts.net
But al be that he was a philosophre,
Yet hadde he but litel gold in cofre

James Beck

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Feb 10, 2012, 8:39:15 PM2/10/12
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Another very good reply.

Josh Miles

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Feb 10, 2012, 11:30:15 PM2/10/12
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On 2/10/2012 5:27 PM, marc.t...@wanadoo.fr wrote:
> I would like to challenge you with the following controversial
> statement: we can nothing about the origin of life.

That's not controversial. It's just stupid.

Friar Broccoli

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Feb 10, 2012, 11:50:21 PM2/10/12
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.

> You are making a mistake here that is quite common: confusing studying a
> thing with defining it. We can study things we do not know how to
> define, and we can define things that are not (scientifically)
> investigable, like unicorns and fairies.

Is this an example of "category error"? Or does it belong in a (or
perhaps several) different philosophical "box(es)"?

>
> It may turn out, and I think it will, that we can give a blow-by-blow
> description of the kind of chemical process that led from non-organic
> chemical reactions ("inorganic" and "organic" have special meanings in
> chemistry) to organic ones, and that at no stage is there a discrete
> step from "not-life" to "life". We may decide that the very term "life"
> is a nonscientific term, but I bet people will continue to use it.
>
> We do not have to be able to define "life", so long as we can point to
> standard examples of life. I can point to my children and say "life is
> like *them*" - this is called an "ostensive definition" (to ostend is to
> point). The desire for a hard and fast definition is a hangover from the
> days when people tried to do science by definition.
>
> By the way, the poeple who seem to want a definition of life most
> ardently are the exobiologists at NASA, who think, wrongly, that if they
> can define the sorts of chemical reactions and dynamics that all and
> only life can do, they can build a detector for their probes. I think
> they are doing science by definition.


--
Friar Broccoli (Robert Keith Elias), Quebec Canada
I consider ALL arguments in support of my views

Bill

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Feb 11, 2012, 1:18:38 AM2/11/12
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On Feb 11, 11:50 am, Friar Broccoli <elia...@gmail.com> wrote:
> On 2012-02-10 19:01, John S. Wilkins wrote:
>
>
>
>
>
>
>
>
>
> > <marc.tess...@wanadoo.fr>  wrote:
.   .
>
> > You are making a mistake here that is quite common: confusing studying a
> > thing with defining it. We can study things we do not know how to
> > define, and we can define things that are not (scientifically)
> > investigable, like unicorns and fairies.
>
> Is this an example of "category error"?  Or does it belong in a (or
> perhaps several) different philosophical "box(es)"?
>

You are making a mistake that is quite common here. We can refute
errors without categorizing them.


J. J. Lodder

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Feb 11, 2012, 4:50:11 AM2/11/12
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<marc.t...@wanadoo.fr> wrote:

Of course they can. How many do you want?

Counter question:
Is it possible for you to understand
that science isn't about definitions?

Or that talking about science isn't science?

Jan

Athel Cornish-Bowden

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Feb 11, 2012, 5:31:04 AM2/11/12
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Yes, and the last sentence is particularly good.


--
athel

Steven L.

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Feb 11, 2012, 7:08:37 AM2/11/12
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"marc.t...@wanadoo.fr" <marc.t...@wanadoo.fr> wrote in message
news:a11c3a2c-aec8-4c02...@v2g2000vbx.googlegroups.com:

> Actually there is a seeming consensus among the specialists in the
> search for the origin of life (chemists, geochemists, biochemists,
> biologists, exo/astrobiologists, computer scientists, philosophers and
> historians of science) that there is an "obvious need for a definition
> of life". In spite of this wish everybody can observe the amazingly
> high number of definitions of life, leading to reflect that skepticism
> is multiplied by the above number, leaving almost no chance for new
> formulations which, however, continue to appear!
> Wouldn't be that any definition of life is subjective and arbitrary as
> is the boundary between living and nonliving systems or the moment
> when nonliving systems would have become living? It is true that the
> statement that any such boundary or moment exists is not falsifiable:
> no experiment can be considered to prove that it can be false.
> Therefore, if the distinction between living and nonliving systems is
> a matter of belief and not science, it is not only hopeless but
> useless to try to define this indefinable state related to a
> metaphysical question!
> If the concept of life is metaphysical then, it is true to say that we
> can know nothing about the origin of life, as it is true to say that
> we can know nothing about the origin of the soul, about the origin of
> God etc.

Is God (if He exists) a "life form"?

He is supposed to be some disembodied spirit. But science-fiction
writers have had a field day writing about hypothetical life forms that
exist as pure energy or something else can perform the usual functions
of life without biochemical bodies.

Nevertheless, right here on Earth, though we may argue about viruses and
prions, there is universal agreement that things like procaryotes are
life forms. A single cell is a life form even if a virus may not be.

And how the first cell got started is still a legitimate scientific
question.



-- Steven L.


marc.t...@wanadoo.fr

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Feb 11, 2012, 8:51:58 AM2/11/12
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"We can study things we do not know how to define"
I would be grateful if you could give us examples of material,
physical (in one word 'real') things that scientists cannot define
scientifically but that they can study?

"We do not have to be able to define "life", so long as we can point
to standard examples of life. I can point to my children and say "life
is like *them"
Your example (your children) belong to the category of "animals".
Indeed animals are among the most sophisticated extant terrestrial
systems being the outcome of more than 4 billions years of Darwinian
evolution! Then it is easy to say that they are different from, let's
say, minerals. Nevertheless, among the extant terrestrial systems
stemming from Darwinian evolution, there are also virus and above all
prions, for which the status of 'living' systems is very much debated,
isn't it?
The other major issue with the concept of life, as you admitt it ("at
no stage is there a discrete step from "not-life" to "life"), is the
miraculous moment when nonliving systems would have become living.
Moreover I would appreciate your reply to my statement that the
hypothesis that any such boundary or moment exists is not falsifiable
because no experiment can be envisaged to prove it to be false.

"By the way, the people who seem to want a definition of life most
ardently are the exobiologists at NASA, who think, wrongly, that if
they can define the sorts of chemical reactions and dynamics that all
and only life can do, they can build a detector for their probes."
You don't give your reasons why exobiologists at NASA are wrong, do
you?
These scientists are not the only ones who seem to want a definition
of life: scientists who are working on the origin of life too!

marc.t...@wanadoo.fr

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Feb 11, 2012, 9:09:13 AM2/11/12
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"A single cell is a life form even if a virus may not be"
I suppose that, by "a cell", you mean a complex vesicle with all the
genetic machinery?
But what about lipid vesicles without this complex genetic machinery
but nevertheless with the capacity to reproduce and to transmit some
of their caracteristics to their daughter vesicles: are they living?

AGWFacts

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Feb 11, 2012, 12:08:16 PM2/11/12
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On Fri, 10 Feb 2012 15:27:13 -0800 (PST), marc.t...@wanadoo.fr
wrote:

> I would like to challenge you with the following controversial
> statement: we can nothing about the origin of life.

Is this (above) a campaign for Chez Watt?


--
"I am not ignorant simply because I choose to believe one
theory over another." -- Madison Murphy

Bob Casanova

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Feb 11, 2012, 12:53:31 PM2/11/12
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On Sat, 11 Feb 2012 06:09:13 -0800 (PST), the following
appeared in talk.origins, posted by marc.t...@wanadoo.fr:
As others have pointed out, definitions are sometimes
tricky. Do you think that everything that exists has a fixed
and unique definition? If you do, you're mistaken. The lack
of a universally-recognized and fixed definition for "life"
is no real handicap for those investigating abiogenesis
since they're investigating natural processes, not
dictionaries.

And please learn to set up attributions; it makes the thread
much easier to follow. No, I don't know how to do this in a
post via GurgleGroups, but I'm sure there's a help file.
--

Bob C.

"Evidence confirming an observation is
evidence that the observation is wrong."
- McNameless

marc.t...@wanadoo.fr

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Feb 11, 2012, 1:18:44 PM2/11/12
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On 11 fév, 18:53, Bob Casanova <nos...@buzz.off> wrote:
> On Sat, 11 Feb 2012 06:09:13 -0800 (PST), the following
> appeared in talk.origins, posted by marc.tess...@wanadoo.fr:
Ok, but usually definitions help, particularly in science. In
mathematics, for instance, definitions are a prerequisite.
Indeed I just ask the following question: Are lipid vesicles without
the complex genetic machinery but with the capacity to reproduce and
to transmit some of their characteristics to their daughter vesicles
'living' systems? The answer can be: "yes" or "no" or "I don't know".
Of course any arguments with the response would be welcome.

Steven L.

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Feb 11, 2012, 6:08:41 PM2/11/12
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news:5c2f3b47-cb89-4267...@w4g2000vbc.googlegroups.com:
I've always liked Isaac Asimov's own definition of biochemical life:

"Life is that which can effect a temporary and local decrease in entropy
by means of *catalyzed* chemical reactions."
-- Isaac Asimov


IOW, when thinking about what a life form is, you need to put at least
as much emphasis on metabolism as on reproduction.

Now a self-sustaining network of biochemical reactions capable of
extracting energy from the environment gives you the metabolism. One of
the things a life form can do with metabolism is make a copy of
itself--reproduce.

Try reading some of Stuart Kauffman's stuff. He takes the
dynamical-metabolism problem seriously.



-- Steven L.


John S. Wilkins

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Feb 11, 2012, 7:21:41 PM2/11/12
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<marc.t...@wanadoo.fr> wrote:

> "We can study things we do not know how to define"
> I would be grateful if you could give us examples of material,
> physical (in one word 'real') things that scientists cannot define
> scientifically but that they can study?

Life

Gene

Species

Region

Niche

Mountain

Ecosystem

Disease

Society

Cognition

Planet

Star

Galaxy

Cloud

Climate

...


>
> "We do not have to be able to define "life", so long as we can point
> to standard examples of life. I can point to my children and say "life
> is like *them"
> Your example (your children) belong to the category of "animals".
> Indeed animals are among the most sophisticated extant terrestrial
> systems being the outcome of more than 4 billions years of Darwinian
> evolution! Then it is easy to say that they are different from, let's
> say, minerals. Nevertheless, among the extant terrestrial systems
> stemming from Darwinian evolution, there are also virus and above all
> prions, for which the status of 'living' systems is very much debated,
> isn't it?

Animals are alive if anything is. So what?

> The other major issue with the concept of life, as you admitt it ("at
> no stage is there a discrete step from "not-life" to "life"), is the
> miraculous moment when nonliving systems would have become living.


Objection, your worship. Facts not admitted in evidence!

> Moreover I would appreciate your reply to my statement that the
> hypothesis that any such boundary or moment exists is not falsifiable
> because no experiment can be envisaged to prove it to be false.

That is, to be sure, the very definition of "not falsifiable". But it is
not required for there to be a fact of living systems. Look up
"black and white" fallacy, and "sorites".
>
> "By the way, the people who seem to want a definition of life most
> ardently are the exobiologists at NASA, who think, wrongly, that if
> they can define the sorts of chemical reactions and dynamics that all
> and only life can do, they can build a detector for their probes."
> You don't give your reasons why exobiologists at NASA are wrong, do
> you?
> These scientists are not the only ones who seem to want a definition
> of life: scientists who are working on the origin of life too!

Really? I had no idea:

http://www.springerlink.com/content/h475867185551688/

Bill

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Feb 11, 2012, 8:06:25 PM2/11/12
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Are they living? Who cares? If we can describe them accurately and
understand how they work, who cares whether we decide to call them
living or almost living or pseudo living or not living? The question
as to whether a virus is a living thing is a question about language,
not about viruses.

Burkhard

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Feb 11, 2012, 8:06:05 PM2/11/12
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On Feb 11, 1:51 pm, marc.tess...@wanadoo.fr wrote:
> "We can study things we do not know how to define"
> I would be grateful if you could give us examples of material,
> physical (in one word 'real') things that scientists cannot define
> scientifically but that they can study?
>

"illness" and "health" woudl be two obvious examples, and medicine is
doing fine without them.
"I know it when I see it" is often good enough o get off the ground

<snip>

James Beck

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Feb 11, 2012, 11:00:33 PM2/11/12
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I see that you are a troublemaker. What a superb teacher and mentor
you must be.

Arkalen

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Feb 12, 2012, 2:25:38 AM2/12/12
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And while science DOES often define things in very precise ways so that
people can understand each other when they study them, those definitions
are limited to a certain field or context; it's the only way to get that
kind of precision. Take for example the different definitions of
"species" that apply to different situations (and then there are the
situations where scientists avoid the word entirely)

--
Arkalen
Praise be to magic Woody-Allen zombie superhero telepathic vampire
quantum hovercraft Tim! Jesus.

John S. Wilkins

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Feb 12, 2012, 2:36:22 AM2/12/12
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Bill <broger...@gmail.com> wrote:

> On Feb 11, 11:50 am, Friar Broccoli <elia...@gmail.com> wrote:
> > On 2012-02-10 19:01, John S. Wilkins wrote:
...
> > > You are making a mistake here that is quite common: confusing studying a
> > > thing with defining it. We can study things we do not know how to
> > > define, and we can define things that are not (scientifically)
> > > investigable, like unicorns and fairies.
> >
> > Is this an example of "category error"? Or does it belong in a (or
> > perhaps several) different philosophical "box(es)"?

There are indefinitely many ways to carve up errors in reasoning,
because an error is the absence of correctness, and you can divide
privative classes many ways.

Taxonomies of fallacies are in general unenlightening.
> >
>
> You are making a mistake that is quite common here. We can refute
> errors without categorizing them.

Unless you are making some kind of mistake in saying that :-)

Arkalen

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Feb 12, 2012, 2:40:24 AM2/12/12
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I know someone who thinks hurricanes are life forms.

Look, the way your brain creates "meaning" is to associate a bunch of
concepts with each other more or less strongly, based on your experience
and observations. When you create a definition, what you do is try to
impose a line in the world that neatly separates that association of
concepts from other concepts. Problem is, there is no reason for that
line to actually exist in the world. You can either create your
definition, and train your brain into making its idea of "meaning" match
the definition perfectly, or you accept there is no perfect definition,
but many different definitions that will apply in different contexts
(depending on which concepts we're emphasizing at any given time), all
with fuzzy borders.

marc.t...@wanadoo.fr

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Feb 12, 2012, 4:21:46 AM2/12/12
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On 12 fév, 01:21, j...@wilkins.id.au (John S. Wilkins) wrote:
> John S. Wilkins, Associate, Philosophy, University of Sydneyhttp://evolvingthoughts.net
> But al be that he was a philosophre,
> Yet hadde he but litel gold in cofre

I begin by what I am the most interested in your response: I would be
grateful if you could send me the pdf of your article entitled
"Selection without replicators: the origin of genes, and the
replicator/interactor distinction in etiobiology.": I would like to
read it and send you my comments if you like it.

Your examples of material, physical (in one word 'real') things that
scientists cannot define scientifically but that they can study:
- Life: for me it is a metaphysical concept;
- Species: as Arkalen is saying, there are "different definitions of
'species' that apply to different situations and then there are
situations where scientists avoid the word entirely";
- Region: I supposed you mean that we cannot define an absolute
boudary for a 'region' in general but we must for a specific region;
- Niche: aproximatively the same situation as for 'species''
- Mountain: I supposed you mean that we cannot define an absolute
distinction between these different categories as 'rise in the
ground', 'hill', 'mountain' etc. However, when scientists are dealing
with such a specific 'rise in the ground' they will specify its
altitud accurately;
- Ecosystem: it is true that such a concept is vague but when
scientists are dealing with it they must specify their definition for
the given situation they are studying;
- Disease: I am physician and I can assert that physicians must define
a particular disease when they study it (e.g. consensus documents such
as the consensus document of The Joint European Society of Cardiology/
American College of Cardiology Committee for the redefinition of
myocardial infarction);
- Society: the same as for 'Ecosystem';
- Cognition: the same as for 'Ecosystem';
- Planet: a clear definition exists!
- Star: the same as for 'planet'!
- Galaxy: the same as for 'planet'!
- Cloud: the same as for 'Ecosystem';
- Climate: the same as for 'Ecosystem'.
I am a little puzzled by your view of what science is: is it because
you are a philosopher? For me 'philopsophy' is between science and
metaphysics: why didn't you choose 'philosophy' in your examples?

Animals:
You do not want to see the point: the fact you are taking the example
of the most complex extant terrestrial systems which is the result of
more than 4 billion years of Darwinian evolution and that it is far
easier that to make a distinction with minerals than for prions, for
example!

"The miraculous moment when etc."
Sorry, but I do not understand your objection and what you are meaning
by "Facts not admitted in evidence!": can you specify it?

Fasifiability of the concept of life:
"Black-or-white fallacy is a false dilemma fallacy that unfairly
limits you to only two choices" (Internet Encyclopedia of
Philosophy).
The distinction between nonliving and living systems is not a false
dilemma fallacy: it is necessary if you want to know something about
the origin of life.
As, for me, it is not possible to make such a distinction this is the
reason why I suggest to work on the origin of Darwinian evolution
instead, as you seem to do in your article entitled "Selection without
replicators: the origin of genes, and the replicator/interactor
distinction in etiobiology" but I would like to read it before, to be
sure, because the abstract is not so clear.

"Really? I had no idea"
Don't be too condescending: I am doing research in this domain too
(see http://en.wikipedia.org/wiki/Abiogenesis - the paragraphs "Lipid
world" and "Origin of Darwinian evolution rather than origin of
life")

marc.t...@wanadoo.fr

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Feb 12, 2012, 4:25:54 AM2/12/12
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Of course, as a physician, I totally disagree with you: see my
response to John S. Wilkins about the word 'disease'.

Message has been deleted

Burkhard

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Feb 12, 2012, 4:32:21 AM2/12/12
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Your answer was that you can define a specific disease. That is the
same thing that John did before for specific living things, so you are
really proving his point.

marc.t...@wanadoo.fr

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Feb 12, 2012, 4:23:19 AM2/12/12
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I totally agree with you!

Message has been deleted

marc.t...@wanadoo.fr

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Feb 12, 2012, 6:28:16 AM2/12/12
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I see your point. You are right that the word 'disease' in general has
no clear and universal definition, such as "good health'. In France,
for example, it is an important point because French have what is
called "Sécurité Sociale" which is free for everybody. Then, indeed,
only specific diseases (with definitions as precise as possible) are
taken care of by the "Sécurité Sociale"!
There is the same kind of problem with the distinction between
'normality' and abnormality'. However, when dealing with a practical
issue you must define as exactly as possible, what you intend by
abnomelity: e.g. abnormal values for glycaemia.

In the case of the word' life' there is no problem for people to use
it in the ordinary life (!). But if scientists want to know about the
origin of life I don't see how they can if they can't make a clear
distinction between living and nonliving systems.
By contrast I think it is possible to make such a clear distinction
between systems with the possiblity to evolve by natural selection
(e.g. lipid vesicles without this complex genetic machinery but with
the capacity to reproduce and transmit some of their caracteristics to
their daughter vesicles) and systems without this possiblity (e.g.
current experimental lipid vesicles).

Arkalen

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Feb 12, 2012, 8:22:55 AM2/12/12
to
(2012/02/12 19:59), marc.t...@wanadoo.fr wrote:
> I totally agree with you!
>
The question "Who cares?" is usually a rhetorical question meant to say
that nobody SHOULD care. It is pretty obviously the case here. Yet you
care about the question quite a lot, and you think scientists should
care about the question too. So what is it you're agreeing with here ?

Arkalen

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Feb 12, 2012, 8:20:46 AM2/12/12
to
What does "metaphysical" mean ?

> - Species: as Arkalen is saying, there are "different definitions of
> 'species' that apply to different situations and then there are
> situations where scientists avoid the word entirely";

... And the same is true of life ! If you're satisfied with my response
about species, why are you looking for an absolute all-encompassing
definition of "life" ?

> - Region: I supposed you mean that we cannot define an absolute
> boudary for a 'region' in general but we must for a specific region;
> - Niche: aproximatively the same situation as for 'species''
> - Mountain: I supposed you mean that we cannot define an absolute
> distinction between these different categories as 'rise in the
> ground', 'hill', 'mountain' etc. However, when scientists are dealing
> with such a specific 'rise in the ground' they will specify its
> altitud accurately;

And when scientists are dealing with a system they can specify to what
extent it reproduces, metabolizes, dissipates energy, locally reduces
entropy, consists of catalyzed chemical reactions, behaves
teleologically, etc etc.

> - Ecosystem: it is true that such a concept is vague but when
> scientists are dealing with it they must specify their definition for
> the given situation they are studying;
> - Disease: I am physician and I can assert that physicians must define
> a particular disease when they study it (e.g. consensus documents such
> as the consensus document of The Joint European Society of Cardiology/
> American College of Cardiology Committee for the redefinition of
> myocardial infarction);
> - Society: the same as for 'Ecosystem';
> - Cognition: the same as for 'Ecosystem';
> - Planet: a clear definition exists!

Which is somewhat arbitrary ! As is the definition of "mountain"
(something higher than 1000m above sea level IIRC), and tons of those
limited definitions scientists work with.

> - Star: the same as for 'planet'!
> - Galaxy: the same as for 'planet'!
> - Cloud: the same as for 'Ecosystem';
> - Climate: the same as for 'Ecosystem'.
> I am a little puzzled by your view of what science is: is it because
> you are a philosopher? For me 'philopsophy' is between science and
> metaphysics: why didn't you choose 'philosophy' in your examples?
>
> Animals:
> You do not want to see the point: the fact you are taking the example
> of the most complex extant terrestrial systems which is the result of
> more than 4 billion years of Darwinian evolution and that it is far
> easier that to make a distinction with minerals than for prions, for
> example!

That IS the point. "life" as we think of it has a collection of
attributes. Some things undisputably have all those attributes and we
have no problem calling them "alive"; moreover enough of these things
have all those attributes, and enough things have none of them, that
they form a cluster and it is a perfectly useful term.

Thing is, none of those attributes are absolutely dependent on one
another, so we get lots of "fuzzy" cases where something will have some
attributes of life and not others (whether in the real world, or in
potentia and mostly the realm of science-fiction writers, but who knows
what's out there. And what we might come up with in the future).

There is simply no unambiguous set of characters we can imagine that
will result in everything we naively think of as "life" being covered
and everything we naively think of as "non-life" being excluded. That's
because our naive concepts of the word are formed by our everyday
experiences, which don't include things like the detailed lifecycle of
the virus or prion or intelligent androids.

By the way, it isn't the 4 billion years of evolution that make
"animals" the easiest thing to define as "alive". It's that "animals"
(and even more : "large tetrapods") are our brains' template for what
"alive" IS. It's why people will sometimes attribute intentionality to
things that move and call them "alive", but will forget that plants are
alive too.

>
> "The miraculous moment when etc."
> Sorry, but I do not understand your objection and what you are meaning
> by "Facts not admitted in evidence!": can you specify it?
>
> Fasifiability of the concept of life:
> "Black-or-white fallacy is a false dilemma fallacy that unfairly
> limits you to only two choices" (Internet Encyclopedia of
> Philosophy).
> The distinction between nonliving and living systems is not a false
> dilemma fallacy: it is necessary if you want to know something about
> the origin of life.

Not so. As with the mountain example, people can look at what attributes
a borderline system has and see which attributes usually found in living
things it has, and which attributes it has that aren't in living things,
and thus characterize it fully and study it AS a possible step in the
formation of life, without having to decree which side of the
living/nonliving boundary it falls in.

> As, for me, it is not possible to make such a distinction this is the
> reason why I suggest to work on the origin of Darwinian evolution
> instead, as you seem to do in your article entitled "Selection without
> replicators: the origin of genes, and the replicator/interactor
> distinction in etiobiology" but I would like to read it before, to be
> sure, because the abstract is not so clear.
>
> "Really? I had no idea"
> Don't be too condescending: I am doing research in this domain too
> (see http://en.wikipedia.org/wiki/Abiogenesis - the paragraphs "Lipid
> world" and "Origin of Darwinian evolution rather than origin of
> life")
>


Burkhard

unread,
Feb 12, 2012, 8:29:24 AM2/12/12
to
Isn't the opposite the case? If it were _always_ straightforward to
distinguish living from non-living things, explaining how one gave
rise to the other would be problematic - our definitions have created
a (semantic) chasm. Instead, what we have are things that clearly are
alive (you, trees, lions, bacteria) and things that aren't (rocks,
houses, the late Conan Doyle). To get from one to the other, we should
expect to find a substantial grey area where the call is more and more
difficult to make.

Same with origin of languages. There is no precise definition of "old
French" or "modern French". But we do ave diagnostic criteria (e.g.
the /wo/ -> /we/ shift for old French, the loss of "ne" in
negotiations (I got penalised in school, but my pen friends thought I
was writing in a funny "old fashioned" style) They are not
definitions, as they can occur on both sides of a hypothesized
boundary) but if you have several together, you can classify a text.
Then we have clear examples for both, such as the Girart de Vienne for
Old French or Didier Daeninckx for modern French. That is more than
enough to develop theories about their respective origins - (and of
course lots of problematic "border crossers" whose precise pace can be
debated no end - are the Serments de Strasbourg an example of
"speciation" that shows how the empire was breaking up and new
languages formed, or did it simply reflect much older divisions?

Arkalen

unread,
Feb 12, 2012, 8:37:32 AM2/12/12
to
My guy who thought "life" should include hurricanes pointed out that
whirlpools like that will spawn other whirlpools, which share
characteristics with their parent whirlpool. Are hurricanes subject to
Darwinian evolution ? Are they a meaningful model for the origin of life ?

Someone brought up stars as an example of things that "reproduce" in the
conversation about nested hierarchies earlier, pointing out that younger
stars are formed from the supernovae of older stars. Presumably the
younger stars share *some* characteristics with their parents, seeing as
they're made from a lot of the same stuff.

"Is subject to Darwinian evolution" itself has fuzzy borders. Again, our
everyday evolved life-forms are clear unambiguous cases, with a very
high fidelity of replication (but not quite 100%, leaving space for
variation), a very stable structure and environment that means we have
an unbroken line of descent going back billions of years, so on.

Something that has a replication fidelity of 0, or is so unstable it
only persists for a generation, isn't subject to Darwinian evolution;
indeed it doesn't reproduce at all.

But in between 0% fidelity and 99%, and 1 generation and 1 trillion...
you can get fuzziness.

Ernest Major

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Feb 12, 2012, 9:11:39 AM2/12/12
to
In message
<5d18fa0a-fe2e-4582...@g27g2000yqa.googlegroups.com>,
marc.t...@wanadoo.fr writes
>- Planet: a clear definition exists!

Recently the astronomical community concluded that it was inappropriate
to classify Pluto as a planet on the grounds that it was merely the
largest (or not even that) of a collection of bodies (kuiperoids,
plutinos) sharing several characteristics.

In doing so, they defined "clearing its orbit" as a criterion which must
be met by a planet. Unfortunately "clearing its orbit" is not an
unambiguous term, so we don't actually have a clear definition.

Furthermore, that definition is a dynamical definition - it depends on
orbits, rather than the nature of the body - and many people, myself
included, would prefer that planets be defined by intrinsic properties,
such as mass and composition. (I'd argue for 15 planets in the Solar
System.) The definition excludes "rogue planets", that is planets that
do not orbit any star. And there are other edge cases, such as a
Mars-sized object in a Trojan point of a brown dwarf, or the smaller (or
both) members of a double planet, or two bodies that periodically swap
orbits (as do two of Saturn's shepherd moons).

>- Star: the same as for 'planet'!

When does a protostar become a star? Is a black hole a star? Is a white
dwarf a star? Is a black dwarf a star? Is a brown dwarf a star? Is a
neutron star a star?

>- Galaxy: the same as for 'planet'!

As the Milky Way tears apart and cannibalises the Magellanic Clouds,
when do they stop being galaxies and become part of the Milky Way? Where
is the dividing line between an intergalactic globular cluster and a
dwarf galaxy? Is a galactic mass gas cloud a galaxy before it forms
stars?
--
alias Ernest Major

marc.t...@wanadoo.fr

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Feb 12, 2012, 9:25:47 AM2/12/12
to
On 12 fév, 14:20, Arkalen <arka...@inbox.com> wrote:
> > (seehttp://en.wikipedia.org/wiki/Abiogenesis-  the paragraphs "Lipid
> > world" and "Origin of Darwinian evolution rather than origin of
> > life")
>
> --
> Arkalen
> Praise be to magic Woody-Allen zombie superhero telepathic vampire
> quantum hovercraft Tim! Jesus.

"What does 'metaphysical' mean?"
For me the best synonym is "transcendental": i.e. which supposes the
intervention of a superior principle beyond the real world.

"And the same is true of life ! If you're satisfied with my response
about species, why are you looking for an absolute all-encompassing
definition of 'life'?"
I agree when you say: "then there are situations where scientists
avoid the word ENTIRELY", particularly in the situation where
scientists want to know about the origin of all extant and past
terrestrial systems stemming from Darwinian evolution.

"it reproduces, metabolizes, dissipates energy, locally reduces
entropy, consists of catalyzed chemical reactions, behaves
teleologically"
And what else? We do not need so much to make Darwinian evolution
working (although your description is not too far from a collection of
systems with possible natural selection and Darwinian evolution).
Within my approach it is possible to envisage less restrictive systems
and thus more likely ones, although more original.

What do think of the MAGIC moment when nonliving systems would have
become living?

marc.t...@wanadoo.fr

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Feb 12, 2012, 9:38:59 AM2/12/12
to
On 12 fév, 14:37, Arkalen <arka...@inbox.com> wrote:
Hurricanes are thermodynamically far-from-equilibrium systems but I
have never heard that they can reproduce: can you provide some good
scientific references about it?

"stars are formed from the supernovae of older stars"
More precisely new stars are formed from huge clouds of hydrogen
present in galaxies: when a big star of a galaxy reaches the end of
its 'live' (no more nuclear fuel) it explodes (= supernova) and the
explosion, if the cloud is not too close, targets the formation of a
star from the gravitational collapse of the cloud.

marc.t...@wanadoo.fr

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Feb 12, 2012, 9:50:57 AM2/12/12
to
On 12 fév, 14:22, Arkalen <arka...@inbox.com> wrote:
I agree with Bill when he says: "The question as to whether a virus is
a living thing is a question about language, not about viruses".
I would like just to add that, on the contrary, the fact that a
collection of viruses can evolve says something very important on
viruses.

Arkalen

unread,
Feb 12, 2012, 9:52:16 AM2/12/12
to
So you're some kind of vitalist ? By which I mean, you believe there's
some kind of "living force" that uniquely distinguishes the living from
the non-living ?

AFAICT the definition of life is something that would apply to life as
it is, not just to how it started. So the definition of life being
metaphysical would imply you think life itself, as it currently is, is
metaphysical. I guess things CAN be defined by their origin instead of
their characteristics but I'm not sure how it would work here.

Either way, if you think there is a very clear difference between life
and non-life, in that life supposes the intervention of a superior
principle beyond the real world to an extent non-life doesn't, then we
should EXPECT life to be easily definable. How do you account for the
fact it isn't ?

(also, and this may or may not be semantics, did you really mean to say
"beyond the real world" ? Are you saying life is caused by something
that isn't real ?)

>
> "And the same is true of life ! If you're satisfied with my response
> about species, why are you looking for an absolute all-encompassing
> definition of 'life'?"
> I agree when you say: "then there are situations where scientists
> avoid the word ENTIRELY", particularly in the situation where
> scientists want to know about the origin of all extant and past
> terrestrial systems stemming from Darwinian evolution.

But you seem to think they SHOULDN'T avoid the word, and that they
should instead define it as a prerequisite to studying that origin. If
that isn't what you think, what are we talking about here ?

>
> "it reproduces, metabolizes, dissipates energy, locally reduces
> entropy, consists of catalyzed chemical reactions, behaves
> teleologically"
> And what else? We do not need so much to make Darwinian evolution
> working (although your description is not too far from a collection of
> systems with possible natural selection and Darwinian evolution).
> Within my approach it is possible to envisage less restrictive systems
> and thus more likely ones, although more original.

See my response elsethread on why "systems that make Darwinian evolution
work" is no more well-defined than "life" is.

And you do not seem at all to address my point that people can describe
and fully characterize systems that are in the fuzzy boundary between
life and non-life without having to decree which side of the line they
fall on, and that this is enough to be able to study them.

>
> What do think of the MAGIC moment when nonliving systems would have
> become living?
>

Same thing I think of the MAGIC moment when prehistoric non-human apes
became human, or the MAGIC moment when a child becomes an adult. It's
not magic (except figuratively), and it's not a moment.

How do you account for the difficulty in distinguishing life from
non-life, if the transition happened so sharply ? Not to mention MAGICALLY.

Arkalen

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Feb 12, 2012, 10:08:18 AM2/12/12
to
No; it wasn't my idea, and I really don't have time to look it up. (I
just remembered though; the word I was looking for wasn't "whirlpool",
it's "eddy")

You can probably find something in resources on fluid dynamics or something.

>
> "stars are formed from the supernovae of older stars"
> More precisely new stars are formed from huge clouds of hydrogen
> present in galaxies: when a big star of a galaxy reaches the end of
> its 'live' (no more nuclear fuel) it explodes (= supernova) and the
> explosion, if the cloud is not too close, targets the formation of a
> star from the gravitational collapse of the cloud.
>

Yeah, but I wasn't talking about the details of star formation, I was
talking about how whether a system is subject to Darwinian evolution or
not becomes fuzzy in systems with low-fidelity reproduction or who don't
persist (or simply haven't had time to persist...) for many generations.
How about that ? We can point to the various sets of parameters under
which genetic algorithms work or don't work if you don't like my
real-life examples.

Associated question prompted by your response to my other post in this
thread : in what way does looking at Darwinian evolution instead of
"life" have anything to do with the magic moment life began ? I mean, if
we can unambiguously define systems that are subject to Darwinian
evolution, and you yourself can think of very very simple systems that
are subject to it, what makes the "moment Darwinian evolution started"
magical ?

marc.t...@wanadoo.fr

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Feb 12, 2012, 10:18:25 AM2/12/12
to
On 12 fév, 15:11, Ernest Major <{$t...@meden.demon.co.uk> wrote:
> In message
> <5d18fa0a-fe2e-4582-a43f-0c28698d6...@g27g2000yqa.googlegroups.com>,
> marc.tess...@wanadoo.fr writes
I think the correct explanation is that Pluto was captured by the
solar system later after the formation of the latter: planets should
form at the same time as the star(s) around which they orbit.

"When does a protostar become a star? "
See my explanation to Arkalen.

"As the Milky Way tears apart and cannibalises the Magellanic Clouds,
when do they stop being galaxies and become part of the Milky Way?"
Presently these galaxies belong to the Milky Way's satellite system
which is part of the Local Group (from wikipedia: "Local Group").

marc.t...@wanadoo.fr

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Feb 12, 2012, 10:24:23 AM2/12/12
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On 12 fév, 15:52, Arkalen <arka...@inbox.com> wrote:
> some kind of "living ...
>
> plus de détails »

My answer to your question about metaphysics means only that
metaphysics is different from science.

Arkalen

unread,
Feb 12, 2012, 10:43:07 AM2/12/12
to
Sadly, that is meaningless unless you explain HOW it's different from
science.

Science is about understanding the real world. In a way your second
statement is completely consistent with the first in that you seem to
say life was started by something that wasn't real, but that's just a
confusing idea I'd like to see some elaboration on.

At any given time there are tons of things in the real world that
science can't investigate... But experience has shown that's mostly for
lack of tools. The creation of things like telescopes, microscopes,
statistical analysis, MRIs, surveys, computers and so on has brought
many domains that used to be the province of philosophy, religion and
literature more into the realm of science, and the process is ongoing.

Surely when you say "metaphysics is different from science" you don't
just mean metaphysics is different from science *right now*, but it's
intrinsically different from science and will always be.
So given the continual expansion of science's field of inquiry, how do
you know whether something is metaphysical or not ?

Oh, and I'm just remembering this started when you said life is a
metaphysical concept to you. Does this mean you don't think life is
something science can investigate ? And what does THAT mean ? I mean,
abiogenesis is a tough nut to crack but biologists have been figuring
how life works for over a century. Sounds like scientific investigation
to me. That's why I asked whether you were a vitalist, because that's
the most straightforward interpretation I see of life being "metaphysical".

Or maybe I'm completely misunderstanding what you mean by "metaphysical
concept" ?

Ernest Major

unread,
Feb 12, 2012, 10:50:56 AM2/12/12
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In message
<074825af-78de-45f0...@y10g2000vbn.googlegroups.com>,
marc.t...@wanadoo.fr writes
That is not a mainstream position on the origin of Pluto. The mainstream
position is that kuiperoids are bodies which were neither expelled from
the Solar System during its formation, nor incorporated into planets.

You might also like to investigate the observations of planets orbiting
pulsars, which would seem to form a counterexample to your proposed
criterion.

Regardless, your response is not a defence of your claim that planet has
an unambiguous definition.
>
>"When does a protostar become a star? "
>See my explanation to Arkalen.

That is an insufficiently precise reference.
>
>"As the Milky Way tears apart and cannibalises the Magellanic Clouds,
>when do they stop being galaxies and become part of the Milky Way?"
>Presently these galaxies belong to the Milky Way's satellite system
>which is part of the Local Group (from wikipedia: "Local Group").
>
That is not a defence of your claim that galaxy has an unambiguous
definition.
--
alias Ernest Major

Athel Cornish-Bowden

unread,
Feb 12, 2012, 11:23:21 AM2/12/12
to
I'm not sure I understand your point here. Maybe you took my comment as
being sarcastic, but it wasn't intended to be. Actually I now realize
that the sentence i liked ("I think they are doing science by
definition") is ambiguous in a way that I hadn't previously noticed. I
took it as echoing a previous sentence ("The desire for a hard and fast
definition is a hangover from the days when people tried to do science
by definition") that was clearly not intended to treat "science by
definition" as something good. I still think that is probably what John
Wilkins meant, but the sentence could be read to mean that by the
definition of science what these people are doing is science. If that
is what he meant then I don't agree.


--
athel

marc.t...@wanadoo.fr

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Feb 12, 2012, 12:04:13 PM2/12/12
to
> >>>>> (seehttp://en.wikipedia.org/wiki/Abiogenesis-the paragraphs "Lipid
I understand your perplexity. I'll try to explain my point of view
more clearly.
When I state that the concept of life is 'metaphysical' I mean that it
is a concept that science (i.e. scientists) cannot investigate. This
is because the physical existence of the distinction between living
systems and nonliving ones is not falsifiable: nobody can imagine an
experiment to prove it to be false (Popper's condition for a
scientific assertion).
On the contrary I think that several experiments can be performed to
test the hypothesis that it is the origin of Darwinian evolution which
is interesting to investigate (and actually I imagine such experiments
in a recent publication which is accessible via Wikipedia by the
following link: http://en.wikipedia.org/wiki/Abiogenesis, reference n
°130).

marc.t...@wanadoo.fr

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Feb 12, 2012, 12:21:01 PM2/12/12
to
That is one of the main difference with 'life': we can imagine a
moment when Darwinian evolution started which is NO MAGIC AT ALL:
within the model I propose the major difference between the current
experimental lipid vesicles (which cannot evolve) and the ones which
would be able to suffer natural selection and evolve is the
heritability of specific characteristics of the latter (cf. reference n
°130).

Arkalen

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Feb 12, 2012, 12:49:18 PM2/12/12
to
I'm afraid I don't understand that sentence at all. Not that Popper is
the be-all, end-all of science anyway, but what does it mean for a
"distinction between living systems and nonliving ones" to be proven
false ? Does that mean picking a characteristic difference between
living and nonliving systems, and proving that it does indeed match our
naive concepts of living vs nonliving systems ? But that can absolutely
be proven false, like when people thought that organic molecules were
characteristic of living systems (this was proven false with the
synthesis of urea). Or when people pick some unique defining
characteristic for life and it can be shown to be unsatisfactory on its
own (like defining life by "can reproduce", which excludes organisms
that happen to be sterile for example).

Also, you are still not addressing what most people have been telling
you, which is that a clear distinction between living and nonliving is
NOT NECESSARY for the study of the origin of life. Systems can be
characterized, both from their components and from their possible
similarities to some step in the origin of life, without needing to slap
a "living" or "nonliving" label on them.

> On the contrary I think that several experiments can be performed to
> test the hypothesis that it is the origin of Darwinian evolution which
> is interesting to investigate (and actually I imagine such experiments
> in a recent publication which is accessible via Wikipedia by the
> following link: http://en.wikipedia.org/wiki/Abiogenesis, reference n
> °130).
>
And that is even stranger. "The hypothesis that it is the origin of
Darwinian evolution which is interesting to investigate" ? That sounds
like those mathematical proofs that all natural numbers are interesting
("0 is interesting. Now consider the lowest non-interesting number. Hey,
it's the lowest non-interesting number, that's pretty interesting ! QED").

Whether something is "interesting" or not is a personal judgment call,
which can be backed with various good or bad reasons that would convince
others to be interested too, but it isn't *a scientific hypothesis* for
Heaven's sake. I don't see what falsifiability has to do with it.

I'm sure you meant something different but I can't tell what, or what
metaphysics has to do with Darwinian evolution.

Also, from the abstract of your paper : "If we replace the search for
the origin of life by the one for the origin of evolution our priority
first is to find a consensus on the minimal conditions that would allow
evolution to emerge and persist anywhere in the universe."

How much do you know about genetic algorithms ? Those follow the minimal
conditions for evolution (replication, random mutations, non-random
selection), but in order to actually reproduce life-like Darwinian
evolution you need a whole lot of parameters to be in the correct ranges.

Arkalen

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Feb 12, 2012, 12:56:03 PM2/12/12
to
Is that so now. You can imagine a non-magical moment when systems that
previously didn't replicate suddenly started replicating with, say, 80%
fidelity ?

Because you won't get Darwinian evolution from systems that replicate
with 1% fidelity, I can tell you that.

But then maybe the system just before Darwinian evolution started did
replicate, it was just with a fidelity that was a teeeeeeeeny bit too
low for Darwinian evolution to happen...

So at what percentage point did Darwinian evolution suddenly start ?

Friar Broccoli

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Feb 12, 2012, 1:28:57 PM2/12/12
to
On 2012-02-12 02:36, John S. Wilkins wrote:
> Bill<broger...@gmail.com> wrote:
>
>> On Feb 11, 11:50 am, Friar Broccoli<elia...@gmail.com> wrote:
>>> On 2012-02-10 19:01, John S. Wilkins wrote:
> ....
>>>> You are making a mistake here that is quite common: confusing studying a
>>>> thing with defining it. We can study things we do not know how to
>>>> define, and we can define things that are not (scientifically)
>>>> investigable, like unicorns and fairies.
>>>
>>> Is this an example of "category error"? Or does it belong in a (or
>>> perhaps several) different philosophical "box(es)"?
>
.

> There are indefinitely many ways to carve up errors in reasoning,
> because an error is the absence of correctness, and you can divide
> privative classes many ways.
>
> Taxonomies of fallacies are in general unenlightening.

Useful comment, which helps me understand why I have found the effort to
produce such a classification system so frustrating.

I had thought my problem was an absence of any understanding of the
basic rules of logic.


>>>
>>
>> You are making a mistake that is quite common here. We can refute
>> errors without categorizing them.
>
> Unless you are making some kind of mistake in saying that :-)


--
Friar Broccoli (Robert Keith Elias), Quebec Canada
I consider ALL arguments in support of my views

marc.t...@wanadoo.fr

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Feb 12, 2012, 1:29:14 PM2/12/12
to
On 12 fév, 18:49, Arkalen <arka...@inbox.com> wrote:
My statement that the physical existence of the distinction between
living systems and nonliving ones is not falsifiable and cannot be
tested is related to the fact that nobody can formulate an universal
definition of life. Thus, if somebody is doing a given experiment
based on HIS definition of life anybody, with a DIFFERENT definition
of life, can refute the relevance of his experiment ... and so on.
On the contrary, I think it is possible to find a consensus on the
minimum prerequisite for making Darwinian evolution working (I can
specify you my proposal). If my statement that such a consensus is
true then any experiment based on this prerequisite would be relevant
to prove that a given model is false or not.

"How much do you know about genetic algorithms ? Those follow the
minimal conditions for evolution (replication, random mutations, non-
random selection), but in order to actually reproduce life-like
Darwinian evolution you need a whole lot of parameters to be in the
correct ranges."
One the main consequences of my approach (i.e. to focus on the origin
of Darwinian evolution) is that the minimum prerequisite I propose
doesn't require the existence of nucleic acids (on which I think
genetic algorithms are based, aren't they?) nor the existence of amino-
acids. This is actually the case of the model of lipid vesicles with
an heterogeneous membrane I propose (you must read the full paper to
understand better what I mean).

marc.t...@wanadoo.fr

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Feb 12, 2012, 1:46:18 PM2/12/12
to
On 12 fév, 18:56, Arkalen <arka...@inbox.com> wrote:
I must specify that the ONLY difference between the two kinds of
vesicles is the heritability of specific characteristics: actually
these specific characteristics, which are not related to nucleic acids
or amino-acids, are transmitted to the daughter vesicles WITHOUT ANY
CHANGE: then 100% of the information is transmitted.
Indeed, within such a model, there are possibilities for a KIND of
mutations (which is not described in the article because I found it
later on): when such a mutation occurrs the change is weak but
significant in term of what can be called a phenotypic change, i.e. a
possible occurrence of a NEW property.

Arkalen

unread,
Feb 12, 2012, 2:10:44 PM2/12/12
to
As far as I can tell those two statements are contradictory. If we can't
formulate a universal definition of life, then any one distinction we
draw between living systems and nonliving ones is false, i.e.
falsified... which means they have to be falsifiable.

> Thus, if somebody is doing a given experiment
> based on HIS definition of life anybody, with a DIFFERENT definition
> of life, can refute the relevance of his experiment ... and so on.

I don't see the logical link here at all. You might be talking about how
there are many different ways of distinguishing life from non-life, and
different ones are preferred by different people, in different contexts,
for different purposes. I don't see how that makes such distinctions
"unfalsifiable". It looks to me as if you're taking a word that applies
to scientific hypotheses, and applying it to the meta-questions of
whether a scientific hypothesis is relevant or interesting. I don't
think that works at all.

> On the contrary, I think it is possible to find a consensus on the
> minimum prerequisite for making Darwinian evolution working (I can
> specify you my proposal). If my statement that such a consensus is
> true then any experiment based on this prerequisite would be relevant
> to prove that a given model is false or not.

That's nice, but you haven't responded to any of my objections to there
being such a simple consensus, except for nitpicking a few examples
which I don't think affects my larger point much.

>
> "How much do you know about genetic algorithms ? Those follow the
> minimal conditions for evolution (replication, random mutations, non-
> random selection), but in order to actually reproduce life-like
> Darwinian evolution you need a whole lot of parameters to be in the
> correct ranges."
> One the main consequences of my approach (i.e. to focus on the origin
> of Darwinian evolution) is that the minimum prerequisite I propose
> doesn't require the existence of nucleic acids (on which I think
> genetic algorithms are based, aren't they?)

I don't think it's relevant. The "genes" in a genetic algorithm have
about as much resemblance to actual genes as the "neurons" in a neural
network have to actual neurons. As all things with computers it all has
to come down to series of ones and zeros at some point, but at the end
of the day they're entities that replicate imperfectly, which is what
your vesicles are right ?

Arkalen

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Feb 12, 2012, 2:27:35 PM2/12/12
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In that case Darwinian evolution is impossible. I don't think perfect
replication is even possible especially as the number of generations
increases, there must be a thermodynamics thing at work there. But if it
were, perfect replicants would never evolve.

> Indeed, within such a model, there are possibilities for a KIND of
> mutations (which is not described in the article because I found it
> later on): when such a mutation occurrs the change is weak but
> significant in term of what can be called a phenotypic change, i.e. a
> possible occurrence of a NEW property.
>

So... there IS change.

And how do you go from non-replicating vesicles to near-perfectly
replicating vesicles ? I notice you said the ONLY difference between the
two kinds of vesicles (by which I assume you mean current experimental
vesicles, and your theoretical vesicles) is that the latter reproduce
with perfect heritability. But that... is not a small difference !
Nothing in the Universe replicates near-perfectly the way life does, and
life needs a buttload of complex machinery to achieve that. Do those
reproducing vesicles have specific characteristics that make them
reproduce the way their current experimental comrades don't ?

It reminds me a bit of when I was a kid and I wondered why we had blood
instead of just water that contained all the stuff necessary to serve
whatever purposes blood served. Is it possible that something that's
just like the current experimental vesicles, with only the differences
necessary to make it replicate... would be a proto-cell ?

marc.t...@wanadoo.fr

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Feb 12, 2012, 2:43:55 PM2/12/12
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Actually If we can't formulate a universal definition of life that
doesn't mean that any distinction drawn between living systems and
nonliving ones is false: that means that it is impossible to just
imagine any one distinction between living systems and nonliving ones.
Then this the reason why it is not falsifiable.

"That's nice, but you haven't responded to any of my objections to
there being such a simple consensus, except for nitpicking a few
examples which I don't think affects my larger point much."
Sorry, but could you tell me again your objections?

"As all things with computers it all has to come down to series of
ones and zeros at some point, but at the end of the day they're
entities that replicate imperfectly, which is what your vesicles are
right?"
- First, my model has nothing to do with a computer approach.
- Second, the fact that the vesicles are able to reproduce is not a
specific property of my model as the current experimental vesicles are
able to reproduce too.
- Third, the specificity of my vesicles is that they are able to
transmit specific characteristics (related to specific phenotypic
properties) to their descendants.

Arkalen

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Feb 12, 2012, 3:34:11 PM2/12/12
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I still don't see the logical link between those two sentences. Maybe it
would help if you explained what it means for a distinction to be "false" ?

>
> "That's nice, but you haven't responded to any of my objections to
> there being such a simple consensus, except for nitpicking a few
> examples which I don't think affects my larger point much."
> Sorry, but could you tell me again your objections?

That "systems subject to Darwinian evolution" isn't much better defined
than "life" is. Mostly because Darwinian evolution requires imperfect
replication, but not TOO imperfect replication, and that there probably
isn't a single value at which a "switch" happens.

>
> "As all things with computers it all has to come down to series of
> ones and zeros at some point, but at the end of the day they're
> entities that replicate imperfectly, which is what your vesicles are
> right?"
> - First, my model has nothing to do with a computer approach.

I never said it did. But a computer approach modelling the evolution of
abstract replicators can apply to the evolution of many different kinds
of replicators, so your objection that your vesicles don't use nucleic
acids is completely irrelevant.

> - Second, the fact that the vesicles are able to reproduce is not a
> specific property of my model as the current experimental vesicles are
> able to reproduce too.
> - Third, the specificity of my vesicles is that they are able to
> transmit specific characteristics (related to specific phenotypic
> properties) to their descendants.
>

When I say "replicate" or "reproduce" I implicitly mean "pass on
specific characteristics to their descendants". That's why I talked
about the fidelity of replication or reproduction.

Maybe you should tell me what you think a few minimal criteria for
Darwinian evolution are, because I've been going on about imperfect
replication as if it were an obvious one but maybe you disagree on that.

marc.t...@wanadoo.fr

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Feb 12, 2012, 3:40:47 PM2/12/12
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Actually I think Darwinian evolution is possible: there is no absolute
requirement of a kind of mutations (i.e. changes) for natural
selection operating. If the model allows the emergence of several
distinct lineages of vesicles then natural selection can operate on
these lineages. Of course, if a kind of mutation is possible then the
number of distinct lineages would be much higher, during a period of
time much shorter. Then Darwinian evolution would be much faster and
much more efficient.

"So... there IS change."
At the beginning I didn't realise that the model had the capacity for
a a kind of mutations but, later on, I found out it actually had it.

"And how do you go from non-replicating vesicles to near-perfectly
replicating vesicles ?"
- The vesicles reproduce by simple division.
- However the lipid composition of their membrane is not stable: this
composition is fully dependent on the nutriments provided by the
environement.
- Then vesicles do not self-replicate.
- Only some specific characteristics replicate and are hereditary:
specific membrane sites and specific molecules. Each membrane site/
molecule couple forms a mutually catalytic process which is the most
simple hypercycle you can imagine.
- These site/molecule couples represent the hereditary information.

marc.t...@wanadoo.fr

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Feb 12, 2012, 3:57:42 PM2/12/12
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be'"false'"
A distinction can be proved to be false if it is possible to draw a
precise and commonly accepted boundary between living and nonliving
systems.

"Mostly because Darwinian evolution requires imperfect replication,
but not TOO imperfect replication, and that there probably isn't a
single value at which a "switch" happens."
See the last point.

"Maybe you should tell me what you think a few minimal criteria for
Darwinian evolution are, because I've been going on about imperfect
replication as if it were an obvious one but maybe you disagree on
that."
There are three conditions:
1. Local conditions allowing the emergence of dissipative systems,
organized on a macroscopic level, generated by a flow of matter and
energy that is continuously supplied. These open far-from-equilibrium
systems are self-sustained and thus can maintain themselves far-from-
equilibrium because they are able to exchange energy, matter, and
information with the external environment;
2. The systems must be able to reproduce;
3. The systems must be capable of acquiring heritable structure/
function properties that are relatively independent from the local
environment, i.e., the fact that they belong to a specific lineage
should not depend on the nature of the nutriments they receive from
the local environment. This last condition is required for the
emergence of distinct lineages allowing natural selection.

Arkalen

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Feb 12, 2012, 4:08:00 PM2/12/12
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Of course natural selection doesn't require mutations. Thing is, without
mutation there are no distinct lineages. Or if you're thinking of
distinct lineages that arose independently (not from a common ancestor),
those lineages *don't change*. Once something is culled by natural
selection it's gone, and the remaining lineages don't diversify to
compensate for the loss in diversity. And in fact, given at generation
zero the individuals aren't very-well adapted to the environment at all,
given enough time every single one of those unchanging lineages will be
wiped out and that's all she wrote.

Basically what you have is evolution over one generation only. And
that's no evolution at all.

> Of course, if a kind of mutation is possible then the
> number of distinct lineages would be much higher, during a period of
> time much shorter. Then Darwinian evolution would be much faster and
> much more efficient.

I am baffled as to how Darwinian evolution could happen at all without
mutation. Maybe you could explain. And without mutation, how does your
number of "distinct lineages" go higher than one ? If they all arise
independently it's not evolution; there's no progression.

>
> "So... there IS change."
> At the beginning I didn't realise that the model had the capacity for
> a a kind of mutations but, later on, I found out it actually had it.
>
> "And how do you go from non-replicating vesicles to near-perfectly
> replicating vesicles ?"
> - The vesicles reproduce by simple division.
> - However the lipid composition of their membrane is not stable: this
> composition is fully dependent on the nutriments provided by the
> environement.
> - Then vesicles do not self-replicate.
> - Only some specific characteristics replicate and are hereditary:
> specific membrane sites and specific molecules. Each membrane site/
> molecule couple forms a mutually catalytic process which is the most
> simple hypercycle you can imagine.
> - These site/molecule couples represent the hereditary information.
>

And how much simpler are these site/molecule couples than ribosomes/RNA?
And if they're as simple as I can imagine, how come no abiogenesis lab
has come upon them yet ?

Besides I'm not seeing the difference between those vesicles and any
other hypothesized kind of proto-cell, or what the difference of your
approach is in practice. Lots of people are looking at precursors for
life that don't use DNA or even RNA, and they don't worry about whether
they're looking at the origin of "life" or "Darwinian evolution".

John S. Wilkins

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Feb 12, 2012, 4:10:25 PM2/12/12
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