Is 'Natural Selection' A Tautology?
Richard Wein
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
>
>It has to be true...
>
>That's the beauty of a tautology.
>
>He is talking about Natural Selection, isn't he?
A tautology is an assertion which is true by logical necessity. A
non-tautological conclusion is one which follows necessarily from
independent premise(s). Ewald's conclusion is of the latter variety. The
premise in this case is that there exists heritable variation in
survival/reproductive ability. There is no logical necessity that this be
the case.
The whole issue of tautology in "natural selection" is, in any case, a red
herring, arising from confusion over what is meant by "natural selection".
Are critics referring to the *expression* "natural selection" or to the
*assertion* that natural selection occurs?
- An expression (as opposed to an assertion) is considered tautological if
it contains redundant information. For example, "to return back again" is
tautological because the sense of "back again" is already fully contained
within the word "return", and so is redundant. The expression "natural
selection" is clearly *not* tautological, because neither word necessarily
entails the other: selection may be non-natural (artificial), and many
things other than selection may be natural.
- The *assertion* that natural selection occurs may be obvious, but it's
not a tautology. It may be a practical necessity, but it's not a logical
necessity. In any case, there is a lot more to the theory of evolution than
merely the assertion that natural selection occurs, so, even if this
assertion were a tautology, that would be of no real interest.
The fact that creationists like to raise this red herring simply indicates
their lack of relevant arguments.
I don't expect Scott to be the slightest bit influenced by this, as he's
shown so often that he's not open to reasoned argument. However, it may be
of interest to other evolutionists, who, I feel, are not always clear about
the meaning of tautology.
Richard Wein (Tich)
--------------------------------
Please change "nospam" to "rwein" in my email address.
Howard Hershey
sc...@home.com wrote:
>
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
> It has to be true...
>
> That's the beauty of a tautology.
>
> He is talking about Natural Selection, isn't he?
Yes. But the above is not formulated as a tautology where it is
merely noted that the 'survivors survived'. He does not say that
'survival and reproduction' is all that is required for natural
selection. He does say that the *differential* 'survival and
reproduction' must be related to genetic differences among organisms.
That is, the genetic variations are the cause of the differential
'survival and reproduction'. Differential survival tells us something
about the utility of different genotypes (actually the phenotypes
caused by those genotypes) in a particular environment. Survival of
half of genetically and phenotypically identical organisms is not due
to natural selection and one does not describe the survivors as 'more
fit', even though there are survivors and losers.
In what way is the above a tautology (which would be merely the
statement that the survivors survived rather than that they
differentially survived because of genetic variation)?
>
> Scott
Mark Isaak
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
>It has to be true...
>
>That's the beauty of a tautology.
Among other things. Correspondence with reality makes things true, too,
though creationists try their best to forget this.
>He is talking about Natural Selection, isn't he?
No, he is talking about life.
What you quoted does NOT say that natural selection is a tautology.
A tautology is a repetition of words or ideas. Where do you see such
repetition in the quote above?
--
Mark Isaak atta @ best.com http://www.best.com/~atta
"The commonest fallacy is to suppose that since the state of doubt
is accompanied by a feeling of uncertainty, knowledge arises when
this feeling gives way to one of assurance." - John Dewey
mel turner
>
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p.45.
>
>It has to be true...
>
>That's the beauty of a tautology.
Definitions do tend to be tautologies.
If the conditions needed for evolution by natural selection are
present, then yes, it will have to occur. That's also true for
most other natural phenomena.
>He is talking about Natural Selection, isn't he?
You can't tell?
So, if evolution by natural selection is a 'tautology' and thus is
something that is obviously and necessarily true, then what have all
those creationists been talking about for so long? They all should
give up immediately, right...?
But where is the actual tautology in:
"Differential reproductive success among individuals in a particular
environment, that is due to heritable differences in phenotypic
traits, will over generations cause adaptive evolutionary changes* in
the population".
[*or prevent non-adaptive changes, as in the case of stabilizing
selection.]
What's a bit amusing is to see creationists claim that natural
selection is a "has to be true" tautology, but simultaneously argue
that it nevertheless has to be false...
cheers
Richard Harter
wrote:
Your example,"to return back again", is an unhappy one. The "again"
is definitely not redundant because it asserts that this is not the
first time that one has returned. The "back" is, AFAICT, redundant.
>- The *assertion* that natural selection occurs may be obvious, but it's
>not a tautology. It may be a practical necessity, but it's not a logical
>necessity. In any case, there is a lot more to the theory of evolution than
>merely the assertion that natural selection occurs, so, even if this
>assertion were a tautology, that would be of no real interest.
"Natural selection" is not a self contained expression; it is a label
for a description of a process. When you unpack the description you
run into a difficulty with the concept of fitness. If you define
fitness as reproductive fitness (as measured by actual reproductive
success) then the definition of natural selection is circular. If you
define fitness in terms traits which "ought" to be superior then it is
not circular.
>The fact that creationists like to raise this red herring simply indicates
>their lack of relevant arguments.
That is as it may be. It remains that the formulating the principle
of natural selection in a non-tautological form is a task with serious
difficulties.
>I don't expect Scott to be the slightest bit influenced by this, as he's
>shown so often that he's not open to reasoned argument. However, it may be
>of interest to other evolutionists, who, I feel, are not always clear about
>the meaning of tautology.
There are two different usages of the word "tautology". One is
classical and refers to redundancies in expressions, e.g., "an
unmarried bachelor". The "unmarried" is redundant because a bachelor
is unmarried by definition. The other usage is much more modern and
apparently is due to Wittgenstein. It refers to propositions that are
true by virtue of their logical form irrespective of the truth or
falsity of the variables contained within the proposition. Thus,
according to this usage, "A or ~A" is a tautology.
The difficulty (and it is a real one) is that the principle of natural
selection can be formulated both in tautological and non-tautological
forms depending on how fitness is defined. The error of logic is to
define natural selection tautologically and then argue for its
empirical content.
Richard Harter, c...@tiac.net
http://www.tiac.net/users/cri
"It was half way to Rivendell when the drugs began to take hold"
Hunter S Tolkien "Fear and Loathing in Barad Dur" - Iain Bowen
Howard Hershey
Only if you do so without the requirement that the only form of
fitness relevant to natural selection is comparative fitness, the
*differential* reproductive success of *different* phenotypes. The
'actual' or 'absolute' reproductive success of a single group with a
given phenotype does not tell us which of two or more groups is fitter
in natural selection, although calculating the absolute reproductive
success of both groups is necessary to determine which is fitter. The
success of one group relative to another group with a different
phenotype does matter to the concept of natural selection. The
absolute reproductive success of any single group does not.
Fitness = measured reproductive success of a group is a tautology in
the same way that every definition is a tautology. But the definition
of natural selection requires a comparison of at least two such
measures of 'fitness'. Natural selection is an inherently comparative
process. One simply does not have natural selection in the absence of
a comparison. And if you have a comparison that shows no difference
in fitness of the two groups you examine (that is fitness
(reproductive success) of group A/fitness B =1), you won't have
natural selection occurring there either. For natural selection you
need fitness A/fitness B to be significantly different from 1. In
fact, that is not a bad definition of natural selection if you want a
nice short one: natural selection is defined as and occurs when the
measured reproductive success of intraspecies variants with phenotype
A/ measured reproductive success of variants with phenotype B in the
same environment is significantly different from 1. Which phenotype
is fitter is determined by the direction of the difference. Of
course, as all good definitions should be, mine is a tautology, as
indicated by the = sign.
> If you
> define fitness in terms traits which "ought" to be superior then it is
> not circular.
That would be relative fitness, which is not a measure of which
"ought" to be more successful but a measure of the "observed"
*difference* in reproductive success correlated with the phenotypic
difference of the two groups. The superior or fitter one (in any
pairwise examination) is obviously the one with greater reproductive
success. "Ought" implies that there is some _a priori_ way of
predicting which phenotype would be more successful. Granted that one
can often predict, on biological and engineering grounds, which
phenotype will be 'fitter' in a particular environment, but the only
way to know which is fitter is to do the measurements and make the calculation.
I agree that the term 'fitness' is used for the directly measureable
quantity 'reproductive success'. But I have no problem with that
being a tautology, since it is a definition of a specific calculated
quantity. But absolute 'reproductive success' or 'fitness', _per se_,
tells us nothing about whether natural selection is occurring. Only
*differential* reproductive success does.
wilkins
<nos...@lineone.net> wrote:
Post of the Month, IMO...
--
John Wilkins, Head, Graphic Production, Hall Institute
<http://www.users.bigpond.com/thewilkins/darwiniana.html>
Otto: Apes don't read philosophy.
Wanda: Yes they do, Otto, they just don't understand it.
che...@my-deja.com
sc...@home.com wrote:
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
> It has to be true...
>
> That's the beauty of a tautology.
>
> He is talking about Natural Selection, isn't he?
>
The tautology is: That which survives is the fittest. What is the
fittest? That which survies.
What's not a tautology is: In a situation where the population is
greater than the resources can provide for, the ones who will survive
are those most able to exploit the (limited) resources.
Brian
Sent via Deja.com http://www.deja.com/
Before you buy.
rokimo...@my-deja.com
sc...@home.com wrote:
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
> It has to be true...
>
> That's the beauty of a tautology.
>
> He is talking about Natural Selection, isn't he?
>
> Scott
Just because it has to be true and is a part of nature doesn't make it
a tautology. You have been informed of this many times by now. Just
answer this question if natural selection is a tautology why can we
design experiments to determine when genetic changes have not occurred
due to natural selection? Have you ever heard of genetic drift? If we
can tell the two apart how can natural selection be a tautology?
Trying to support an unreasonable creationist assertion to this extent
seems stupid and probably unethical. It makes you look as sleezy as
the people like Johnson that must know better by now too. What do you
gain by supporting a creationist lie?
Ron Okimoto
Richard Wein
Fair point. The "again" is ambiguous. In British colloquial usage, at least,
"to come back again" can mean the same as "to come back", without any
implication of this happening more than once. But I agree that my use of the
word "again" confuses the issue, and I should have omitted it.
>>- The *assertion* that natural selection occurs may be obvious, but it's
>>not a tautology. It may be a practical necessity, but it's not a logical
>>necessity. In any case, there is a lot more to the theory of evolution
than
>>merely the assertion that natural selection occurs, so, even if this
>>assertion were a tautology, that would be of no real interest.
>
>"Natural selection" is not a self contained expression; it is a label
>for a description of a process.
To clarify, what I mean by an expression is a noun, or a phrase which
collectively takes the place of a noun, as opposed to a complete proposition
(aka "assertion"). In this sense, "natural selection" *is* an expression.
Perhaps what you're getting at is that I only considered whether the term
"natural selection" is tautological, and not whether the *definition* of
that term is tautological. That would be a good point, and I'll deal with it
below. First we need a definition of "natural selection".
>When you unpack the description you
>run into a difficulty with the concept of fitness.
So, I guess you're defining "natural selection" as "survival of the
fittest". I'm not sure this is the best definition, but let's go with it.
>If you define
>fitness as reproductive fitness (as measured by actual reproductive
>success) then the definition of natural selection is circular.
If I understand you correctly, this defines "fitness" in a retrospective
way, referring to those organisms which actually have had most reproductive
success. With this definition, "natural selection" would indeed be a
tautology. But I consider this a useless definition in the current context,
and contrary to our usual sense of the word. Even the
fittest individual, in the usual sense, may have the misfortune to meet with
an accident and fail to reproduce at all. A more useful definition of
"fitness" in this context would be "inherited propensity for reproductive
success".
>If you
>define fitness in terms traits which "ought" to be superior then it is
>not circular.
I dislike your use of the word "ought", which can imply a purpose or moral
imperative. I think my "inherited propensity for reproductive success" is
better.
Unpacking the expression "survival of the fittest" then gives us the
following: "tendency to reproductive success of those with the greatest
inherited propensity for reproductive success". This expression *is*
tautological, because it contains redundancy. It could, without loss of
meaning, be reduced to "inherited propensity for reproductive success". Note
that the presence of redundancy does not deprive the expression of
significant meaning.
Note also that the *proposition* that some organisms have a greater
inherited propensity for reproductive success than others is certainly not a
tautology.
>>The fact that creationists like to raise this red herring simply indicates
>>their lack of relevant arguments.
>
>That is as it may be. It remains that the formulating the principle
>of natural selection in a non-tautological form is a task with serious
>difficulties.
>
>>I don't expect Scott to be the slightest bit influenced by this, as he's
>>shown so often that he's not open to reasoned argument. However, it may be
>>of interest to other evolutionists, who, I feel, are not always clear
about
>>the meaning of tautology.
>
>There are two different usages of the word "tautology". One is
>classical and refers to redundancies in expressions, e.g., "an
>unmarried bachelor". The "unmarried" is redundant because a bachelor
>is unmarried by definition. The other usage is much more modern and
>apparently is due to Wittgenstein. It refers to propositions that are
>true by virtue of their logical form irrespective of the truth or
>falsity of the variables contained within the proposition. Thus,
>according to this usage, "A or ~A" is a tautology.
This is the same distinction that I made, between a tautological
*expression* and a tautological *proposition* (or assertion), e.g. between
"an unmarried bachelor" and "all bachelors are unmarried".
The tautological *expression* ("an unmarried bachelor") contains a
redundant word ("unmarried"), but has meaning and can be used to form a
meaningful proposition, e.g. "John is an unmarried bachelor". This
proposition is *not* a tautology--it gives us real information about John,
albeit in an unnecessarily verbose manner.
The tautological *proposition* ("all bachelors are unmarried"), on the other
hand, gives us no information that is not already contained in the
definition of the word "bachelor".
Similarly, "survival of the fittest" may well be a tautological expression,
but this does not deprive it of meaning.
>The difficulty (and it is a real one) is that the principle of natural
>selection can be formulated both in tautological and non-tautological
>forms depending on how fitness is defined. The error of logic is to
>define natural selection tautologically and then argue for its
>empirical content.
I assume that, by "empirical content", you mean empirical support for a
proposition. You cannot have empirical support for an expression or
definition, and the empirical data are not necessarily *contained* in the
proposition.
So what proposition are you referring to here? Presumably you're referring
to the proposition that natural selection occurs. But this proposition is
not, in itself, an interesting or controversial one, so it's not important
whether it's tautological or not.
The interesting proposition is that natural selection plays a significant
role in evolution. And this proposition is non-tautological even if the
expression "natural selection" is tautologous. Unpacking the proposition, we
get: "the tendency to reproductive success of those with the greatest
inherited propensity for reproductive success plays a significant role in
evolution". The first 10 words of this proposition are redundant, as we
could just as well write: "inherited propensity for reproductive success
plays a significant role in evolution". But the fact that part of the
proposition is redundant does not make the proposition itself a tautology.
Thus, the issue of tautology of "natural selection" only arises in the
context of:
(a) the possible tautology of a proposition which is of no interest; or
(b) the possible tautology of an expression, and I've shown that tautology
in an expression does not deprive it of meaning.
I therefore stand by my assertion that arguments about the possible
tautological nature of "natural selection" are nothing but a red herring.
Thomas Scharle
being described as a tautology was Newton's famous F=ma.
It was said that force and mass were defined in such
terms that that equation was a tautology. If natural
selection were a tautology in that sense, it sure wouldn't
be in bad company.
You see, tautologies can explain things. Remember in
geometry class how they explained why a three-legged stool
is stable: Three points determine a plane. Or why girders
have triangular braces: If the sides of a triangle are
fixed, the angles are fixed.
Isn't, in a sense, the application of mathematics to
science and engineering just the use of tautologies to
explain things about the natural world?
--
Tom Scharle scha...@nd.edu "standard disclaimer"
Stew Dean
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
> It has to be true...
>
> That's the beauty of a tautology.
>
Urm - not really. There are different creatures and these creatures
have different chances of survival. These two parts are different.
This would not be true if all creatures and all individuals where the
same. For this to happen all chemical reaction would be 100% reliable
in all situations. All interactions would be ordered and beyond the
influence of external items.
Urm.
> He is talking about Natural Selection, isn't he?
Well is he wrong? Are we all different? Do these difference lead to
each of us being more or less likely to create new idividuals?
--
Stewart Dean
http://www.webslave.dircon.co.uk
Richard Harter
>"Natural selection" is not a self contained expression; it is a label
>for a description of a process. When you unpack the description you
>run into a difficulty with the concept of fitness. If you define
>fitness as reproductive fitness (as measured by actual reproductive
>success) then the definition of natural selection is circular. If you
>define fitness in terms traits which "ought" to be superior then it is
>not circular.
As a note the quoted "ought" was not meant to refer to teleology.
Rather it was meant as shorthand for traits that are presumed to be
superior by criteria of functionality. For example we judge that
speed in antelopes and cheetahs (each for their own reasons) is a
trait with functional merit. The fast escape or eat as the case may
be; the slow get eaten or starve as the case may be.
Presumed functional fitness of traits (with heritability and
variation) is a fundamental element in Darwin's aragument.
==
Howard and Richard each made extensive comments which I will respond
to in due course.
Iain
Are we saying circular reasoning, or are we saying that the terse form of
expressing Natural Selection is tautologous in the same way that Newton's
second law is, i.e in an irrelevant manner relative to its truth?
<rokimo...@my-deja.com> wrote in message
news:8p4atb$4f2$1...@nnrp1.deja.com...
sc...@home.com
>Could someone please tell me what definition of tautology we are using here?
>Are we saying circular reasoning, or are we saying that the terse form of
>expressing Natural Selection is tautologous in the same way that Newton's
>second law is, i.e in an irrelevant manner relative to its truth?
>
_The Biotic Message_, I believe that we
are speaking of the circular reasoning
definition.
Regards,
Scott
sc...@home.com
actually explains anything and whether something
that is true by definition has any empirical content.
Scott
sc...@home.com
to exploit the (limited) resources?
So to you, natural selection is that which delimits
those who are most able to exploit the limitied
resources from those who are less able to exploit
the limited resources?
Scott
sc...@home.com
>In article <39b46...@news1.prserv.net>,
> sc...@home.com wrote:
>> "Darwin only had a couple of basic tenets...
>>
>> You have heritable variation, and you've got
>> differences in survival and reproduction among
>> the variants. That's the beauty of it. It has to be
>> true - it's like arithmetic. And if there is life on
>> other planets, natural selection has to be the
>> fundamental organizing principle there, too"
>>
>> - Paul Ewald, Amherst College biology professor
>> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
>> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>>
>> It has to be true...
>>
>> That's the beauty of a tautology.
>>
>> He is talking about Natural Selection, isn't he?
>>
>
> of nature doesn't make it a tautology.
<snip>
Just because it has to be true does not make
it a tautology?
I'm open to the idea that that could be the case.
The question is, how is it being used?
Can the way in which a statement is formulated
turn it into a tautology?
Some members of a population will reproduce
before they die, others will not reproduce
before they die.
Is this a tautology?
Scott
John Segerson
sc...@home.com wrote:
> Some members of a population will reproduce
> before they die, others will not reproduce
> before they die.
>
> Is this a tautology?
>
> Scott
Only if the statement has but one meaning that is trivially true. However,
in an arbitrary population, the statement could be true in an infinite number
of variations. What matters in the real case is the actual differences
between the two subsets of the population and why these lead to differential
survival.
John
Vincent Maycock
<sc...@home.com> wrote in message news:39b6c...@news1.prserv.net...
Yeah, it's "A or not A," which is always true. So why say "A or not A"? Why
not just say "A"? I.e., "Some members of a population will reproduce before
they die." There's no reason to turn the statement into a tautology.
--
Vince
Gavin Tabor
>
> The first time that I heard of a scientific theory
> being described as a tautology was Newton's famous F=ma.
This is not a tautology. Its a definition of inertial
mass. The really interesting thing though is that
m(inertial) = m(gravitational).
>
> It was said that force and mass were defined in such
> terms that that equation was a tautology. If natural
> selection were a tautology in that sense, it sure wouldn't
> be in bad company.
>
> You see, tautologies can explain things. Remember in
> geometry class how they explained why a three-legged stool
> is stable: Three points determine a plane. Or why girders
> have triangular braces: If the sides of a triangle are
> fixed, the angles are fixed.
>
> Isn't, in a sense, the application of mathematics to
> science and engineering just the use of tautologies to
> explain things about the natural world?
No.
Gavin
>
> --
> Tom Scharle scha...@nd.edu "standard disclaimer"
--
Dr. Gavin Tabor
School of Engineering and Computer Science
Department of Engineering
University of Exeter
Gavin Tabor
No. It may be a statement of the bleeding obvious, but it
isn't tautological. Neither is the observation that those
that reproduce will pass on genes that in some sense are
beneficial to their progeny, and that this may alter the
overall genetic composition of the species. Some loose
statements of this may be tautological, but that doesn't
detract from the theory itself.
Speaking personally, I have other problems with the statement
"survival of the fittest", of rather greater (IMHO) import than
philosophical discussions of semantics.
Gavin
>
> Scott
Richard Wein
Vincent Maycock wrote in message <39b71b3b$0$21099$45be...@newscene.com>...
><iain...@btinternet.com> writes:
>> >Could someone please tell me what definition of tautology we are using
>here?
>> >Are we saying circular reasoning, or are we saying that the terse form
of
>> >expressing Natural Selection is tautologous in the same way that
Newton's
>> >second law is, i.e in an irrelevant manner relative to its truth?
>
not
>tautological unless one turns around an substitutes B for A in the
>statement.
>
>>In the context of Walter ReMine's book,
>>_The Biotic Message_, I believe that we
>>are speaking of the circular reasoning
>>definition.
>
>because the statement which is being shown to be true in the circular
>reasoning, is already known to be true on empirical grounds (namely, that
>some living things leave more offpsring than others, more so than we would
>expect on the basis of chance).
"Natural selection" cannot contain circular reasoning because it's an
*expression*, not a *proposition*.
The proposition "natural selection occurs" may contain circular reasoning
(depending on how you define natural selection) but it's a straw man. The
fact that natural selection occurs is obvious, whether it's a tautology or
not. The proposition made by the theory of evolution is that natural
selection plays a significant role in evolution, and that is certainly not a
tautology.
Richard Wein (Tich)
Howard Hershey
Then you don't learn anything by reading the name of the winner of a
race in the newspaper? After all, the winner is the person who comes
in first. And who is the person who comes in first? Why, the winner,
of course! What a worthless tautology! And I suppose you would argue
that knowing who the winner was says nothing about his absolute speed
(measured as the time it took to do the course). I would agree; it
doesn't, although you do have to at least qualitatively measure
absolute speed (qualitative in the sense of at least knowing the rank
ordering of finishing the course) to determine anything useful.
Knowing which person is 'the winner' *does*, I would argue, indeed
tell you something about his/her speed relative to the other entrants
in that specific race. Any analogical similarities between this and
the 'race' for reproductive success is purely intentional.
Howard Hershey
It is a truism in the real world. But it is certainly possible to
have populations so phenotypically and genetically equivalent and in
so rich an environment that very few die before reproduction and any
deaths are purely chance events and do not involve selection, natural
or artificial. Bacteria in a rich culture during log phase growing
from a clonal isolate, for example, comes quite close to this ideal.
Of course, in the real world, the good times cease to roll eventually
and variants do arise.
>
> Scott
Howard Hershey
Vincent Maycock wrote:
>
> <sc...@home.com> wrote in message news:39b6c...@news1.prserv.net...
> > In <8p69p9$ovf$1...@plutonium.btinternet.com>, "Iain"
> <iain...@btinternet.com> writes:
> > >Could someone please tell me what definition of tautology we are using
> here?
> > >Are we saying circular reasoning, or are we saying that the terse form of
> > >expressing Natural Selection is tautologous in the same way that Newton's
> > >second law is, i.e in an irrelevant manner relative to its truth?
>
> Newton's second law is not a tautology; it's a definition. Saying A=B is not
> tautological unless one turns around an substitutes B for A in the
> statement.
>
> >In the context of Walter ReMine's book,
> >_The Biotic Message_, I believe that we
> >are speaking of the circular reasoning
> >definition.
>
> Right; but it's not important if NS is phrased as circular reasoning,
> because the statement which is being shown to be true in the circular
> reasoning, is already known to be true on empirical grounds (namely, that
> some living things leave more offpsring than others, more so than we would
> expect on the basis of chance).
Of course, the fact that some living things leave more offspring than
others does not *necessarily* mean that selection was involved. As
the use of the word 'selection' implies, the fact of there being
differences in number of offspring only becomes selection if it is
significantly correlated to some phenotypic difference. Not all cases
of living things leaving more offspring than others is due to
phenotypic differences. Those cases due to chance alone are not due
to selection of any kind.
>
> --
> Vince
Ken Cox
> Some members of a population will reproduce
> before they die, others will not reproduce
> before they die.
>
> Is this a tautology?
Yes, because it is of the form (A or not A). However, that's
not what natural selection states, so it doesn't help answer
the question in the thread title.
Hint: You're not going to get anywhere until you start working
in that business about inheritable variations.
--
Ken Cox k...@research.bell-labs.com
hrgr...@my-deja.com
Gavin Tabor <G.R....@exeter.ac.uk> wrote:
> Thomas Scharle wrote:
> >
> > The first time that I heard of a scientific theory
> > being described as a tautology was Newton's famous F=ma.
>
> This is not a tautology. Its a definition of inertial
> mass. The really interesting thing though is that
> m(inertial) = m(gravitational).
>
> >
> > It was said that force and mass were defined in such
> > terms that that equation was a tautology. If natural
> > selection were a tautology in that sense, it sure wouldn't
> > be in bad company.
> >
> > You see, tautologies can explain things. Remember in
> > geometry class how they explained why a three-legged stool
> > is stable: Three points determine a plane. Or why girders
> > have triangular braces: If the sides of a triangle are
> > fixed, the angles are fixed.
> >
> > Isn't, in a sense, the application of mathematics to
> > science and engineering just the use of tautologies to
> > explain things about the natural world?
>
> No.
Isn't "If [Maxwell's equations] then [there will be electromagnetic
waves which travel at the speed of light]" a tautology ?
Further examples on request :-)
HRG.
> Gavin
>
> >
> > --
> > Tom Scharle scha...@nd.edu "standard disclaimer"
>
> --
>
> Dr. Gavin Tabor
> School of Engineering and Computer Science
> Department of Engineering
> University of Exeter
>
>
Jonathan Stone
Thomas Scharle <sch...@berlin.helios.nd.edu> wrote:
> The first time that I heard of a scientific theory
>being described as a tautology was Newton's famous F=ma.
>
> It was said that force and mass were defined in such
>terms that that equation was a tautology. If natural
>selection were a tautology in that sense, it sure wouldn't
>be in bad company.
>
> You see, tautologies can explain things. Remember in
>geometry class how they explained why a three-legged stool
>is stable: Three points determine a plane. Or why girders
>have triangular braces: If the sides of a triangle are
>fixed, the angles are fixed.
Within euclidean plane geometry, yes. In some other geometries (such
as on the surface of a sphere): yes.
In other circumstances (such as a "saddle", or negatively-curved
surface): no, I dont think so.
> Isn't, in a sense, the application of mathematics to
>science and engineering just the use of tautologies to
>explain things about the natural world?
No, and the distinction is important.
"Tautologies" are, by definition, deductive: like mathematics, one
starts with a set of axioms and sees what one can derive from them via
deductive logic. Tautologies are those things which are always true
(usually via propositional calculus), such as "all black crows are
black", that sort of thing.
Science is about forming theories with explanatory and predictive
power. Useful scientific theories are without exception[*] inductive,
and therefore non-tautological.
The standard textbook example is the sentence "all crows are black":
no matter how often we see crows and note that all the crows we've
seen are all black, we cannot rule out the possibility that,
somewhere, lurks a white crow (perhaps an albino). Scientific
theories amount to constructing a theory "all crows are black"'
and seeing what we can deduce, given "all crows are black" as an
assumption. One can use deductive reasoning to look for "tautological"
implications of a theory, or to develop a theory; but any theory
about the real world inevitably has inductive steps (such as, generalizing
from the exact experiments conducted in a lab to all similar experiments)
which are not tautological.
[*] I can't think of any. If John W. or Mr. Harter can suggest some,
I'll write them down for future reference.
Tim Tyler
: "Darwin only had a couple of basic tenets...
: You have heritable variation, and you've got
: differences in survival and reproduction among
: the variants. That's the beauty of it. It has to be
: true - it's like arithmetic. And if there is life on
: other planets, natural selection has to be the
: fundamental organizing principle there, too"
Probably not so. There /could/ be other, organising principles
that better deserve the adjective "fundamental".
In particular, if organisms have evolved to the point where they have
taken control of their own design and development - through something
like genetic engineering - the "fundamental organising principle" might be
intelligent design - in the sense that this is responsible for most
aspects of the organism.
Intelligent design may involve large numbers of other, non-genetic
strategies for creating optimisations. Natural selection will still
inevitably be involved - but it might not be wise to call it fundamental,
if other forces are primarily more directly responsible for most of the
observed adaptations.
--
__________ Lotus Artificial Life http://alife.co.uk/ t...@cryogen.com
|im |yler The Mandala Centre http://mandala.co.uk/ Namaste.
Gavin Tabor
>
> In article <39B752D0...@ex.ac.uk>,
> Gavin Tabor <G.R....@exeter.ac.uk> wrote:
> > Thomas Scharle wrote:
> > >
> > > The first time that I heard of a scientific theory
> > > being described as a tautology was Newton's famous F=ma.
> >
> > This is not a tautology. Its a definition of inertial
> > mass. The really interesting thing though is that
> > m(inertial) = m(gravitational).
> >
> > >
> > > It was said that force and mass were defined in such
> > > terms that that equation was a tautology. If natural
> > > selection were a tautology in that sense, it sure wouldn't
> > > be in bad company.
> > >
> > > You see, tautologies can explain things. Remember in
> > > geometry class how they explained why a three-legged stool
> > > is stable: Three points determine a plane. Or why girders
> > > have triangular braces: If the sides of a triangle are
> > > fixed, the angles are fixed.
> > >
> > > Isn't, in a sense, the application of mathematics to
> > > science and engineering just the use of tautologies to
> > > explain things about the natural world?
> >
> > No.
>
> Isn't "If [Maxwell's equations] then [there will be electromagnetic
> waves which travel at the speed of light]" a tautology ?
No. The Online Webster gives as a definition of tautology :
"needless repetition of an idea, statement, or word"
The link between Maxwells equations and em waves is either
a. the experimental observation and the underpinning theory
(reverse order) or
b. the mathematical theory and its manipulation into shape
for a specific instance.
In neither case is either part needless repetition.
Gavin
Thomas Scharle
[...snip...]
> No. The Online Webster gives as a definition of tautology :
> "needless repetition of an idea, statement, or word"
> The link between Maxwells equations and em waves is either
> a. the experimental observation and the underpinning theory
> (reverse order) or
> b. the mathematical theory and its manipulation into shape
> for a specific instance.
> In neither case is either part needless repetition.
[...snip...]
My point is that ... at worst ... "natural selection is
a tautology" is something like "Newtonian mechanics is a
tautology".
In the Library Of Congress cataloging system for books,
Newtonian mechanics is treated as a division of mathematics
(it's in the QA division) rather than physics (QB).
*If* we treat Newtonian mechanics/natural selection/
Maxwellian electromagnetism as a tautology, these are not
tautologies in the sense of "needless repetition", but in
some sort of quasi-technical logical jargon: where anything
which is logically provable is a "tautology".
Those who try to debunk evolutionary biology by calling
the principle of natural selection a tautology ... *insofar
as* they might be on to something ... contribute nothing
more significant than the observation about many sciences,
that sciences do use logically provable statements as part
of their explanatory mechanisms.
In brief: If natural selection is a tautology, so what?
Robert Grumbine
Thomas Scharle <sch...@thomas.helios.nd.edu> wrote:
Nice article, in which a particular bete noire is mentioned:
> In the Library Of Congress cataloging system for books,
>Newtonian mechanics is treated as a division of mathematics
>(it's in the QA division) rather than physics (QB).
LC also does not consider oceanography to be a science, it's
GC, G being geography/mythology primarily. Interesting to see
geography lumped with mythology as well; says something about
what LC thought of maps, I guess.
Dewey was an attempt to organize the books in a library into
content-related order. LC, I finally found out after whining
at the science librarian at my grad school following my 50th
or so catalog search that put 4 books on the same subject in to
four different campus libraries, was meant to make it relatively
easy to assign _some_ number to a book. Not necessarily a good
number in the sense of placing the books near their content neighbors,
but a number. Dewey involved a bit of work (thought) to assign
numbers. My dissertation (on physical oceanography) got put in
to one of the not-science libraries on the grounds that the title
(horrid thing that) included some geographic terms, and most of
the geographic holdings were not in the science library. I was
able to persuade a revision to the filing that got it under
GC for the oceanography, rather than the G for place names mentioned.
I think. (Anyone at U. Chicago, please check the holdings and
see where it is these days. Mine is the 1989 one. There are other
Grumbine theses there.)
--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences
ted reichardt
Robert Grumbine <bo...@Radix.Net> wrote:
> (Anyone at U. Chicago, please check the holdings and
>see where it is these days. Mine is the 1989 one. There are other
>Grumbine theses there.)
>
>--
>Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur
>activities notes and links.
Author Grumbine, Robert W.
Title Formation of high salinity shelf water on polar continental shelves
/ by Robert W. Grumbine.
Imprint 1989.
Description viii, 80 leaves : ill. ; 28 cm.
Notes Thesis (Ph. D.)--Univ. of Chicago, Dept. of Geophysical Sciences,
December 1989. Thesis (Ph. D.)--Univ. of Chicago, Dept. of Geophysical
Sciences, December 1989.
Includes bibliographical references.
Subjects Salinity --Antarctica--Weddell Sea--Mathematical models.
Regenstein Stacks GB9999.G88 copy: 1
Richard Harter
wrote:
>
>
>Richard Harter wrote:
[snip]
>> "Natural selection" is not a self contained expression; it is a label
>> for a description of a process. When you unpack the description you
>> run into a difficulty with the concept of fitness. If you define
>> fitness as reproductive fitness (as measured by actual reproductive
>> success) then the definition of natural selection is circular.
>
>Only if you do so without the requirement that the only form of
>fitness relevant to natural selection is comparative fitness, the
>*differential* reproductive success of *different* phenotypes. The
>'actual' or 'absolute' reproductive success of a single group with a
>given phenotype does not tell us which of two or more groups is fitter
>in natural selection, although calculating the absolute reproductive
>success of both groups is necessary to determine which is fitter. The
>success of one group relative to another group with a different
>phenotype does matter to the concept of natural selection. The
>absolute reproductive success of any single group does not.
>Fitness = measured reproductive success of a group is a tautology in
>the same way that every definition is a tautology. But the definition
>of natural selection requires a comparison of at least two such
>measures of 'fitness'. Natural selection is an inherently comparative
>process. One simply does not have natural selection in the absence of
>a comparison. And if you have a comparison that shows no difference
>in fitness of the two groups you examine (that is fitness
>(reproductive success) of group A/fitness B =1), you won't have
>natural selection occurring there either. For natural selection you
>need fitness A/fitness B to be significantly different from 1. In
>fact, that is not a bad definition of natural selection if you want a
>nice short one: natural selection is defined as and occurs when the
>measured reproductive success of intraspecies variants with phenotype
>A/ measured reproductive success of variants with phenotype B in the
>same environment is significantly different from 1. Which phenotype
>is fitter is determined by the direction of the difference. Of
>course, as all good definitions should be, mine is a tautology, as
>indicated by the = sign.
Er, Howard, nobody was talking about "absolute fitness" except you.
It is understood that fitness is comparative. The question at hand is
whether natural selection defined in terms of measured relative
reproductive success is tautological. You seem to agree.
>> If you
>> define fitness in terms traits which "ought" to be superior then it is
>> not circular.
>
>That would be relative fitness, which is not a measure of which
>"ought" to be more successful but a measure of the "observed"
>*difference* in reproductive success correlated with the phenotypic
>difference of the two groups. The superior or fitter one (in any
>pairwise examination) is obviously the one with greater reproductive
>success. "Ought" implies that there is some _a priori_ way of
>predicting which phenotype would be more successful. Granted that one
>can often predict, on biological and engineering grounds, which
>phenotype will be 'fitter' in a particular environment, but the only
>way to know which is fitter is to do the measurements and make the calculation.
>I agree that the term 'fitness' is used for the directly measureable
>quantity 'reproductive success'. But I have no problem with that
>being a tautology, since it is a definition of a specific calculated
>quantity. But absolute 'reproductive success' or 'fitness', _per se_,
>tells us nothing about whether natural selection is occurring. Only
>*differential* reproductive success does.
Now here I have no notion of what you mean by "absolute reproductive
success". What on Earth are you talking about.
The issue at hand is that natural selection as propounded by Darwin
and as regularly treated in evolutionary theory selects for
adaptation, fitness on a priori grounds of superior functionality.
This is a major claim of Darwinian theory.
The difficulty here is with arguing on one hand that "fitness" is
synonymous with whatever happens and on the other that "fitness" is
adaptive.
[snip remainder]
Richard Harter
wrote:
>Richard Harter wrote in message <39b54265...@news.SullyButtes.net>...
>>On 5 Sep 2000 10:34:35 -0400, "Richard Wein" <nos...@lineone.net>
>>wrote:
>>
>>>sc...@home.com wrote in message <39b46...@news1.prserv.net>...
>>>> "Darwin only had a couple of basic tenets...
>>>>
>>>> You have heritable variation, and you've got
>>>> differences in survival and reproduction among
>>>> the variants. That's the beauty of it. It has to be
>>>> true - it's like arithmetic. And if there is life on
>>>> other planets, natural selection has to be the
>>>> fundamental organizing principle there, too"
>>>>
>>>> - Paul Ewald, Amherst College biology professor
>>>> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
>>>> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>>>>
>>>>
>>>>It has to be true...
>>>>
>>>>That's the beauty of a tautology.
>>>>
>>>>He is talking about Natural Selection, isn't he?
>>>
>>>A tautology is an assertion which is true by logical necessity. A
>>>non-tautological conclusion is one which follows necessarily from
>>>independent premise(s). Ewald's conclusion is of the latter variety. The
>>>premise in this case is that there exists heritable variation in
>>>survival/reproductive ability. There is no logical necessity that this be
>>>the case.
>>>
>>>The whole issue of tautology in "natural selection" is, in any case, a red
>>>herring, arising from confusion over what is meant by "natural selection".
>>>Are critics referring to the *expression* "natural selection" or to the
>>>*assertion* that natural selection occurs?
>>>
>>>- An expression (as opposed to an assertion) is considered tautological if
>>>it contains redundant information. For example, "to return back again" is
>>>tautological because the sense of "back again" is already fully contained
>>>within the word "return", and so is redundant. The expression "natural
>>>selection" is clearly *not* tautological, because neither word necessarily
>>>entails the other: selection may be non-natural (artificial), and many
>>>things other than selection may be natural.
>>
>>Your example,"to return back again", is an unhappy one. The "again"
>>is definitely not redundant because it asserts that this is not the
>>first time that one has returned. The "back" is, AFAICT, redundant.
>
>Fair point. The "again" is ambiguous. In British colloquial usage, at least,
>"to come back again" can mean the same as "to come back", without any
>implication of this happening more than once. But I agree that my use of the
>word "again" confuses the issue, and I should have omitted it.
Agreement.
>>>- The *assertion* that natural selection occurs may be obvious, but it's
>>>not a tautology. It may be a practical necessity, but it's not a logical
>>>necessity. In any case, there is a lot more to the theory of evolution
>than
>>>merely the assertion that natural selection occurs, so, even if this
>>>assertion were a tautology, that would be of no real interest.
>>
>>"Natural selection" is not a self contained expression; it is a label
>>for a description of a process.
>
>To clarify, what I mean by an expression is a noun, or a phrase which
>collectively takes the place of a noun, as opposed to a complete proposition
>(aka "assertion"). In this sense, "natural selection" *is* an expression.
>
>Perhaps what you're getting at is that I only considered whether the term
>"natural selection" is tautological, and not whether the *definition* of
>that term is tautological. That would be a good point, and I'll deal with it
>below. First we need a definition of "natural selection".
>>When you unpack the description you
>>run into a difficulty with the concept of fitness.
>
>So, I guess you're defining "natural selection" as "survival of the
>fittest". I'm not sure this is the best definition, but let's go with it.
I appreciate your qualms. May I point out that it is easy to confuse
fitness of individuals and fitness of traits. Darwinian theory really
is about the natural selection of traits in populations by virtue of
the superior fitness of the traits.
>>If you define
>>fitness as reproductive fitness (as measured by actual reproductive
>>success) then the definition of natural selection is circular.
>
>If I understand you correctly, this defines "fitness" in a retrospective
>way, referring to those organisms which actually have had most reproductive
>success. With this definition, "natural selection" would indeed be a
>tautology. But I consider this a useless definition in the current context,
>and contrary to our usual sense of the word. Even the
>fittest individual, in the usual sense, may have the misfortune to meet with
>an accident and fail to reproduce at all. A more useful definition of
>"fitness" in this context would be "inherited propensity for reproductive
>success".
Well, now, there you've illuminated the difficulty. Howard, if I
understand him correctly, is quite happy, indeed insists upon, the
definition that you are calling useless. However it does seem that
you are mixing up fitness of individuals and fitness of traits. Be
that as it may you seem to be arguing for a concept of intrinsic
fitness.
>>If you
>>define fitness in terms traits which "ought" to be superior then it is
>>not circular.
>
>I dislike your use of the word "ought", which can imply a purpose or moral
>imperative. I think my "inherited propensity for reproductive success" is
>better.
(See other followup.) The difficulty with "inherited propensity for
reproductive success" is with establishing that there is such a thing
in any meaningful sense. Suppose, to be slightly more specific, you
have a species with two alleles A and a of a gene. At one particular
time you measure the prevalence of the two alleles and discover that
the populations are dominated by allele A and that, in the current
generation, those with allele A (prokaryotes for convenience) have a
better track record at reproducing. Does this tell you that allele A
has superior fitness? Alas, no. At a later time you may make the
same measurement and discover that allele a now appears to be
superior. How do you determine these propensities?
>Unpacking the expression "survival of the fittest" then gives us the
>following: "tendency to reproductive success of those with the greatest
>inherited propensity for reproductive success". This expression *is*
>tautological, because it contains redundancy. It could, without loss of
>meaning, be reduced to "inherited propensity for reproductive success". Note
>that the presence of redundancy does not deprive the expression of
>significant meaning.
>Note also that the *proposition* that some organisms have a greater
>inherited propensity for reproductive success than others is certainly not a
>tautology.
>
>>>The fact that creationists like to raise this red herring simply indicates
>>>their lack of relevant arguments.
>>
>>That is as it may be. It remains that the formulating the principle
>>of natural selection in a non-tautological form is a task with serious
>>difficulties.
>>
>>>I don't expect Scott to be the slightest bit influenced by this, as he's
>>>shown so often that he's not open to reasoned argument. However, it may be
>>>of interest to other evolutionists, who, I feel, are not always clear
>about
>>>the meaning of tautology.
>>
>>There are two different usages of the word "tautology". One is
>>classical and refers to redundancies in expressions, e.g., "an
>>unmarried bachelor". The "unmarried" is redundant because a bachelor
>>is unmarried by definition. The other usage is much more modern and
>>apparently is due to Wittgenstein. It refers to propositions that are
>>true by virtue of their logical form irrespective of the truth or
>>falsity of the variables contained within the proposition. Thus,
>>according to this usage, "A or ~A" is a tautology.
>
>This is the same distinction that I made, between a tautological
>*expression* and a tautological *proposition* (or assertion), e.g. between
>"an unmarried bachelor" and "all bachelors are unmarried".
The notion of tautological propositions is a dubious one for reasons
that Mr. Wilkins will be happy to explain.
>The tautological *expression* ("an unmarried bachelor") contains a
>redundant word ("unmarried"), but has meaning and can be used to form a
>meaningful proposition, e.g. "John is an unmarried bachelor". This
>proposition is *not* a tautology--it gives us real information about John,
>albeit in an unnecessarily verbose manner.
>
>The tautological *proposition* ("all bachelors are unmarried"), on the other
>hand, gives us no information that is not already contained in the
>definition of the word "bachelor".
>
>Similarly, "survival of the fittest" may well be a tautological expression,
>but this does not deprive it of meaning.
>
>>The difficulty (and it is a real one) is that the principle of natural
>>selection can be formulated both in tautological and non-tautological
>>forms depending on how fitness is defined. The error of logic is to
>>define natural selection tautologically and then argue for its
>>empirical content.
>
>I assume that, by "empirical content", you mean empirical support for a
>proposition. You cannot have empirical support for an expression or
>definition, and the empirical data are not necessarily *contained* in the
>proposition.
>
>So what proposition are you referring to here? Presumably you're referring
>to the proposition that natural selection occurs. But this proposition is
>not, in itself, an interesting or controversial one, so it's not important
>whether it's tautological or not.
No. I'm referring to the thesis that adaptation is a consequence of
natural selection. This is fundamental to evolutionary theory. It is
generally agreed (except possibly by Moran) that genetic drift does
not explain adaptation. You cannot defend this thesis if you are
using a circular definition of natural selection.
>The interesting proposition is that natural selection plays a significant
>role in evolution. And this proposition is non-tautological even if the
>expression "natural selection" is tautologous. Unpacking the proposition, we
>get: "the tendency to reproductive success of those with the greatest
>inherited propensity for reproductive success plays a significant role in
>evolution". The first 10 words of this proposition are redundant, as we
>could just as well write: "inherited propensity for reproductive success
>plays a significant role in evolution". But the fact that part of the
>proposition is redundant does not make the proposition itself a tautology.
>
>Thus, the issue of tautology of "natural selection" only arises in the
>context of:
>(a) the possible tautology of a proposition which is of no interest; or
>(b) the possible tautology of an expression, and I've shown that tautology
>in an expression does not deprive it of meaning.
>
>I therefore stand by my assertion that arguments about the possible
>tautological nature of "natural selection" are nothing but a red herring.
The trouble is that there two definitions of natural selection
floating about, one of which is essentially circular, and one which is
not. The objection is that evolutionary arguments slide back and
forth between the two.
howard hershey
There are different things called 'fitness'. There is the mean
population fitness, Wp (usually W with a bar over it), which is a direct
measurement of the mean reproductive success of an entire population in
a specific environment. Such a measurement is a tautology by
definition, since the way you measure this 'fitness' is to measure the
observed reproductive success of the population. Then there is the
'fitness' of specific phenotypic subgroups within that population.
These fitness values may be the same as or significantly different from
(either higher or lower) the mean population fitness. The fitness that
is relevant to natural selection, however, is 'relative fitness', where
the fitness of a subgroup is compared to either that of a phenotypically
different subgroup or to the mean population fitness (usually by
dividing the subgroup fitness by mean population fitness and normalizing
all values to the case with highest 'relative fitness'). If there is no
significant difference in relative fitnesses, there is no selection
going on that can distinguish between these phenotypes.
What that means is that natural selection is *not* going on when there
is no significant *difference* in measured fitness. What is going on in
these cases where there is no significant difference in measured fitness
is pure blind luck and chance. And it is in cases where the *only*
reason for differential survival is luck (where there is no correlation
to phenotypic difference) that one has pure "the survival of
survivors". Otherwise one has *differential* survival correlated to a
particular phenotype (aka, selection). Of course, one still has the
responsibility to present an argument that the correlational
relationship between phenotype and differential reproductive success is
causal rather than casual; that the specified phenotype is the reason
for the differential reproductive success.
>
> >> If you
> >> define fitness in terms traits which "ought" to be superior then it is
> >> not circular.
> >
> >That would be relative fitness, which is not a measure of which
> >"ought" to be more successful but a measure of the "observed"
> >*difference* in reproductive success correlated with the phenotypic
> >difference of the two groups. The superior or fitter one (in any
> >pairwise examination) is obviously the one with greater reproductive
> >success. "Ought" implies that there is some _a priori_ way of
> >predicting which phenotype would be more successful. Granted that one
> >can often predict, on biological and engineering grounds, which
> >phenotype will be 'fitter' in a particular environment, but the only
> >way to know which is fitter is to do the measurements and make the calculation.
>
> >I agree that the term 'fitness' is used for the directly measureable
> >quantity 'reproductive success'. But I have no problem with that
> >being a tautology, since it is a definition of a specific calculated
> >quantity. But absolute 'reproductive success' or 'fitness', _per se_,
> >tells us nothing about whether natural selection is occurring. Only
> >*differential* reproductive success does.
>
> Now here I have no notion of what you mean by "absolute reproductive
> success". What on Earth are you talking about.
I meant the non-comparative measurement of reproductive success in a
*particular* environment (not in *all* possible environments, which is a
creationist argument of "absolute"). In other words, a calculation of
mean population fitness or the fitness of a particular phenotypic
subgroup by direct measurement of reproductive success in a particular
environment.
>
> The issue at hand is that natural selection as propounded by Darwin
> and as regularly treated in evolutionary theory selects for
> adaptation, fitness on a priori grounds of superior functionality.
> This is a major claim of Darwinian theory.
One can only truely argue that a phenotypic difference is responsible
for greater measured 'relative fitness' (see above for how one does
this) *after* one has, in fact, demonstrated that those phenotypes are
indeed correlated with measured greater relative fitness. Which is not
to say that one cannot make _a priori_ *predictions* about which of two
phenotypes is going to be correlated with significantly higher relative
fitness based on engineering or other reasoning. And, of course, the
reason for asking whether or not a particular phenotype is correlated
with higher relative fitness is often in this reverse direction (one
makes a prediction that these phenotypes differentially cause a
selective difference and then one gathers the evidence that either
confirsm or disconfirms this hypothesis). But if the measurements of
relative fitness show no significant difference between the two
phenotypes, you discard your hypothesis that natural selection is
discriminating between these phenotypes. That is the way science is
supposed to work, isn't it?
Making a claim that a particular phenotype is more fit than another in a
particular environment is mere speculation (albeit that some such are
almost so obvious that it is hard to believe that it will be dicarded)
*until* there is supporting evidence that these phenotypes (note the
plural) do indeed make at least a correlational difference in the
reproductive success of their bearers.
>
> The difficulty here is with arguing on one hand that "fitness" is
> synonymous with whatever happens and on the other that "fitness" is
> adaptive.
"Fitness", _per se_, is indeed measured as whatever happens (that is,
one measures reproductive success empirically). But it is 'relative
fitness' and not the directly measured 'fitness' that produces the
significant correlation between different phenotypes and greater
reproductive success that is required to make the claim that natural
selection has occurred. Further evidence, of course, is required to
demonstrate what it is about thsee correlations that is causal.
'Adaptive' is *defined* as those phenotypic features that result in the
most (reproductively) success in a particular environment. I certainly
think it would make little sense to call such features "maladaptive", as
that would run counter to most people's notions of what "success" or
"beneficial" mean when you look at life. One can always argue that the
'goal' of life ought not to be maximal reproductive success, but that is
a religious argument that doesn't seem to apply to, say, insects, but is
*certainly* one that humans can and do consider for themselves.
Richard Wein
>On 6 Sep 2000 07:47:39 -0400, "Richard Wein" <nos...@lineone.net>
>wrote:
>
>>Richard Harter wrote in message
<39b54265...@news.SullyButtes.net>...
[...]
>>>If you define
>>>fitness as reproductive fitness (as measured by actual reproductive
>>>success) then the definition of natural selection is circular.
>>
>>If I understand you correctly, this defines "fitness" in a retrospective
>>way, referring to those organisms which actually have had most
reproductive
>>success. With this definition, "natural selection" would indeed be a
>>tautology. But I consider this a useless definition in the current
context,
>>and contrary to our usual sense of the word. Even the
>>fittest individual, in the usual sense, may have the misfortune to meet
with
>>an accident and fail to reproduce at all. A more useful definition of
>>"fitness" in this context would be "inherited propensity for reproductive
>>success".
>
>Well, now, there you've illuminated the difficulty. Howard, if I
>understand him correctly, is quite happy, indeed insists upon, the
>definition that you are calling useless. However it does seem that
>you are mixing up fitness of individuals and fitness of traits. Be
>that as it may you seem to be arguing for a concept of intrinsic
>fitness.
Yes. Such a concept is essential to the theory of evolution. However, it may
not necessarily be essential to the definition of "natural selection" (see
below).
Howard seems to be very much concerned with *measuring* fitness, and so has
provided a measure of observed fitness. However, for purposes of describing
the theory of evolution, we need a concept of intrinsic fitness.
>>>If you
>>>define fitness in terms traits which "ought" to be superior then it is
>>>not circular.
>>
>>I dislike your use of the word "ought", which can imply a purpose or moral
>>imperative. I think my "inherited propensity for reproductive success" is
>>better.
>
>(See other followup.) The difficulty with "inherited propensity for
>reproductive success" is with establishing that there is such a thing
>in any meaningful sense. Suppose, to be slightly more specific, you
>have a species with two alleles A and a of a gene. At one particular
>time you measure the prevalence of the two alleles and discover that
>the populations are dominated by allele A and that, in the current
>generation, those with allele A (prokaryotes for convenience) have a
>better track record at reproducing. Does this tell you that allele A
>has superior fitness? Alas, no. At a later time you may make the
>same measurement and discover that allele a now appears to be
>superior. How do you determine these propensities?
It isn't possible to measure intrinsic fitness precisely. Observed fitness
is only a statistical approximation to intrinsic fitness. But that's no
reason why we can't define a concept of intrinsic fitness.
I think the theory of evolution is clear on this point. Organisms have a
propensity for reproductive success which includes a hereditary element. Or,
to put it another way, fitness is partly inherited.
Inheritance of fitness is a vital part of the theory of evolution, but isn't
always explicitly mentioned. The mechanisms of adaptation are usually given
as random mutation and natural selection, without any explicit mention of
inheritance. You might argue that this concept should be included in the
definition of "natural selection", or you might argue that it's implied by
the inclusion of "random mutation".
So, if some people are defining "natural selection" as merely the fact that
some individuals have more offspring than others, without mentioning that
the differential reproductive success is partly based on inheritance, then I
think this is unfortunate, but not necessarily serious, as long as the full
description of the theory of evolution mentions inheritance. In any case,
this limited definition is not circular.
If you still think that there is a circular definition of "natural
selection" in circulation, please tell us exactly what it is, and show how
it's circular. When you elaborate it in full, you might find that it's not
circular after all.
Note that a definition which is tautologous (i.e. contains redundant terms)
is not necessarily circular (i.e. is self-referential, or refers to a
concept which in turn is defined in terms of this one).
che...@my-deja.com
sc...@home.com wrote:
[snip]
> >> It has to be true...
> >>
> >> That's the beauty of a tautology.
> >>
> >> He is talking about Natural Selection, isn't he?
> >>
> >> Scott
> >
> >
> >The tautology is: That which survives is the fittest. What is the
> >fittest? That which survies.
> >
> >What's not a tautology is: In a situation where the population is
> >greater than the resources can provide for, the ones who will survive
> >are those most able to exploit the (limited) resources.
> >
> And which are the ones that are most able
> to exploit the (limited) resources?
>
> So to you, natural selection is that which delimits
> those who are most able to exploit the limitied
> resources from those who are less able to exploit
> the limited resources?
>
> Scott
More or less. To be more accurate natural selection preserves the
traits of those who generate the most descendants over many
generations. Thus if trait X is a great aid in producing descendants
then over time trait X will be found in almost all members of a
population.
Theoretically the best exploiters of limited resources don't _have_ to
be the best descendant producers. But they usually are.
Brian
Robert Grumbine
Ok, they fibbed. It was supposed to have been reclassed in GC and
moved to Crerar (the science library). As well. Maybe I can use
the GB classification to get myself hired as a geographer.
--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
rokimo...@my-deja.com
You are evading again. Answer my question, if we can tell the
difference between natural selection and genetic drift can natural
selection be considered a creationist tautology? A simple yes it is a
tautology or no it is not will do.
You should know by now that it doesn't matter how you can twist
someones words it is the results that count. By your own definition we
are talking about the creationist strawman argument pertaining to
circular reasoning. If we can tell when natural selection is not the
instrument of genetic change through time in particular systems how can
it be a creationist tautology?
You might also explain to me how someone that seems reasonably
intelligent can stoop to this base level of creationist sophistry. We
expect this type of useless argument from lawyers in court rooms. What
good can it possibly do to spread misinformation in the name of the God
that you seem to have so much faith in, but not enough faith to face
the facts as they fall? Shouldn't you be trying to bring up the level
of creationist argument instead of wallowing in the muck of your
predecessors.
We can observe natural selection working. We can tell when it hasn't
been working. Shifty statements will not change this. Your
creationist tautological argument is bogus and counts for nothing but
propaganda value for the simple reason that natural selection has been
documented to occur. How can calling it a tautology change that fact?
You might want to think about prefacing this argument the next time you
want to trot it out. Something like, "I know that natural selection
has been observed, but I'm going to try and throw dirt on the idea by
quibbling about how some people talk about it." Wouldn't this be the
honest thing to do even if it made you look like a fool? Isn't this
exactly what you are admitting in your above non response, but for some
reason you can't seem to come out and say it?
Ron Okimoto
Matt Silberstein
sc...@home.com:
> "Darwin only had a couple of basic tenets...
>
> You have heritable variation, and you've got
> differences in survival and reproduction among
> the variants. That's the beauty of it. It has to be
> true - it's like arithmetic. And if there is life on
> other planets, natural selection has to be the
> fundamental organizing principle there, too"
>
> - Paul Ewald, Amherst College biology professor
> Jill Cooper, "A New Germ Theory," The Atlantic, February 1999.
> as quoted in _The Wedge of Truth_ by Phillip E. Johnson, p. 45.
>
>
>It has to be true...
>
>That's the beauty of a tautology.
Is gravity a tautology?
>He is talking about Natural Selection, isn't he?
Yes and it is fundamental to how the world works. The world is finite.
If you have replicators and you have imperfect replication (and
Shannon shows us that all replication is imperfect) you will have
inherited differences. And if the world is finite then some
replicators will do better than others.
--
Matt Silberstein
A simple man comes home and wonders what is for dinner
A complex man comes home and wonders about the complexities of the universe
An enlightened man comes home and wonders what is for dinner
A murderer on _Homicide: Life on the streets_
Howard Hershey
Depending on what you mean by "intrinsic fitness" I might or might not
agree. "Natural selection" can certainly occur in such a way that
there is no evolutionary impact (selection only works on phenotypes
directly, and not all phenotypes are caused by genotypes). Only the
heritable fraction of phenotypic selection will have an *evolutionary*
impact. But natural selection cannot distinguish between an organism
who is a runt for genetic reasons and one who is a runt because of
starvation. It descriminates against (or for) both equally in a
particular environment. But only the discrimination against (or for)
that portion of the phenotype due to genetic differences will have any
evolutionary impact. Although natural selection certainly plays a
major evolutionary role, it is not synonymous with evolution. You can
have natural selection without evolutionary impact and you can have
evolution (of the neutral kind) without natural selection. If that is
what you mean by "intrinsic fitness", I agree, but would prefer that
it be called the "heritable component of fitness". The "heritable
component of fitness" is important for evolution.
OTOH, if by 'intrinsic fitness' you mean the idea that a phenotype has
an 'intrinsic' fitness value in the sense that that value or
directionality will adhere to the phenotype in any other environment,
I would disagree most strongly.
>
> >>>If you
> >>>define fitness in terms traits which "ought" to be superior then it is
> >>>not circular.
> >>
> >>I dislike your use of the word "ought", which can imply a purpose or moral
> >>imperative. I think my "inherited propensity for reproductive success" is
> >>better.
> >
> >(See other followup.) The difficulty with "inherited propensity for
> >reproductive success" is with establishing that there is such a thing
> >in any meaningful sense. Suppose, to be slightly more specific, you
> >have a species with two alleles A and a of a gene. At one particular
> >time you measure the prevalence of the two alleles and discover that
> >the populations are dominated by allele A and that, in the current
> >generation, those with allele A (prokaryotes for convenience) have a
> >better track record at reproducing. Does this tell you that allele A
> >has superior fitness? Alas, no. At a later time you may make the
> >same measurement and discover that allele a now appears to be
> >superior. How do you determine these propensities?
>
> It isn't possible to measure intrinsic fitness precisely. Observed fitness
> is only a statistical approximation to intrinsic fitness. But that's no
> reason why we can't define a concept of intrinsic fitness.
The concept described above as being 'intrinsic fitness' is precisely
the type of idea with which I disagree strongly. Fitness is
determined by the interaction of phenotype and environment. It is not
an intrinsic property of phenotype alone.
>
[snip]
>
> I think the theory of evolution is clear on this point. Organisms have a
> propensity for reproductive success which includes a hereditary element. Or,
> to put it another way, fitness is partly inherited.
Fitness is *often* partly inherited because phenotypes are *often*
partly a consequence of genotypes. Selection, however, is independent
of whether or not the phenotype is or is not a consequence of
genotype. But evolutionarily relevant fitness most certainly is not
independent of whether the phenotype is or is not a consequence of
genotype. Selection occurs at the phenotypic level and that is where
fitness is determined as well. The environment does not 'read'
genotypes; it does 'read' phenotypes.
>
> Inheritance of fitness is a vital part of the theory of evolution, but isn't
> always explicitly mentioned. The mechanisms of adaptation are usually given
> as random mutation and natural selection, without any explicit mention of
> inheritance. You might argue that this concept should be included in the
> definition of "natural selection", or you might argue that it's implied by
> the inclusion of "random mutation".
Natural selection and random mutation are different phenomenon. The
definition of natural selection does not include random mutation
because selection, as a mechanism, does not *directly* involve or
require random mutation. Natural selection *does* require the
existence of phenotypic variation (no phenotypic variation, no
selection). One way to generate phenotypic variation is via genotypic
variation (this is the only evolutionary relevant type of phenotypic
variation). The only way known by which genotypic variation is
generated in nature is through random mutation. That, of course, is
how natural selection is connected to evolutionary change over time.
But it does not mean that "natural selection" requires "random
mutation" to be included in its definition.
>
> So, if some people are defining "natural selection" as merely the fact that
> some individuals have more offspring than others, without mentioning that
> the differential reproductive success is partly based on inheritance, then I
> think this is unfortunate, but not necessarily serious, as long as the full
> description of the theory of evolution mentions inheritance. In any case,
> this limited definition is not circular.
I described what "natural selection" is. The term is not simply a
synonym for "evolution". One can have natural selection that has no
evolutionary consequences. One can also certainly have natural
selection that does have evolutionary consequences. Whether the
phenotypes have a genetic basis is what determines this. You can also
have evolutionary consequences in the absence of natural selection
(neutral drift, founder effects, etc.). Natural selection is a
mechanism that is not identical to evolution. It is one mechanism by
which evolutionary change can occur.
Netcom jimhumph
Richard Wein wrote
> "Natural selection" cannot contain circular reasoning because it's an
> *expression*, not a *proposition*.
> The proposition "natural selection occurs" may contain circular reasoning
> (depending on how you define natural selection) but it's a straw man.
>
No, this is hopelessly confused. The term 'straw man' is applied to
*arguments* : "Natural selection occurs" is not an argument.
Futhermore 'circular reasoning ' occurs in an argument when
one of the premises is identical to the conclusion - but again
""Natural selection occurs" is not an argument.
jimh
sc...@home.com
>
>Richard Wein wrote
>
>> "Natural selection" cannot contain circular reasoning because it's an
>> *expression*, not a *proposition*.
>> The proposition "natural selection occurs" may contain circular reasoning
>> (depending on how you define natural selection) but it's a straw man.
>>
>*arguments* : "Natural selection occurs" is not an argument.
>Futhermore 'circular reasoning ' occurs in an argument when
>one of the premises is identical to the conclusion - but again
>""Natural selection occurs" is not an argument.
>
mel turner
[snip]
>>""Natural selection occurs" is not an argument.
Right, it's a statment of fact.
>Neither is "natural selection occurs" a definition.
Yes, and they didn't say it was a definition.
And "natural selection causes adaptive evolution" is a central concept
of biological science.
cheers
sc...@home.com
in the above "central concept of biological sceince"?
Is there any explanation for HOW "natural selection"
causes adaptive evolution, or does it just happen "by
definition"?
Scott
mel turner
>In <8q1bbr$9sn$2...@news.duke.edu>, mtu...@snipthis.acpub.duke.edu (mel
turner) writes:
>>In article <39c42...@news1.prserv.net>, sc...@home.com wrote...
>>>>""Natural selection occurs" is not an argument.
>>
>>Right, it's a statment of fact.
>>
>>>Neither is "natural selection occurs" a definition.
>>
>>Yes, and they didn't say it was a definition.
>>
>>And "natural selection causes adaptive evolution" is a central concept
>>of biological science.
>>
>Is "natural selection" defined as differential survival
>in the above "central concept of biological sceince"?
Differential reproductive success among individual geno/phenotypes
in the population. Not quite the same thing as 'survival'.
>Is there any explanation for HOW "natural selection"
>causes adaptive evolution,
Yes, of course. There are a great many such explanations, and many
investigations into details, and many studies of specific cases.
Textbooks full. Research journals full. Libraries full, no doubt.
>or does it just happen "by definition"?
Of course not. It happens, and it's not 'just by definition'.
Why? Is "natural selection causes adaptive evolution" somehow
a tautology? How, exactly?
cheers
Howard Hershey
I will repeat part of a reply to a post that I tried to e-mail to you,
but got returned.
Perhaps an analogy is in order. The environment's role in the
selection process is like that of a seive in the sorting process of
mixed gravel and sand (a mixture of size phenotypes, if you will). A
seive blindly sorts the mixture and you wind up with larger gravels
being largely retained and smaller gravels being largely lost by
passing through. Notice that there is a directionality to this
sorting process. It is the *larger* gravels that are retained by the
seive. To claim that it is the *smaller* gravels that get retained by
the seive would be to distort the common meaning of "larger" and
"smaller" so that they mean the opposite of what most people
understand. In the same way, the environment retains those organisms
best adapted to that sorting environment. Natural selection can no
more selectively retain the phenotypes maladapted to its environment
than a seive can selectively retain the smaller gravels. To retain
maladapted organisms, you have to have an intelligent designer
intervene to save them (as humans sometimes do in artificial
breeding). Retention of well-adapted organisms is not evidence for
intelligent design; selective retention of maladapted organisms is.
>
>
> Scott
sc...@home.com
>In article <39c59...@news1.prserv.net>, sc...@home.com wrote...
>>In <8q1bbr$9sn$2...@news.duke.edu>, mtu...@snipthis.acpub.duke.edu (mel
>turner) writes:
>>>In article <39c42...@news1.prserv.net>, sc...@home.com wrote...
>
>>>>>""Natural selection occurs" is not an argument.
>>>
>>>Right, it's a statment of fact.
>>>
>>>>Neither is "natural selection occurs" a definition.
>>>
>>>Yes, and they didn't say it was a definition.
>>>
>>>And "natural selection causes adaptive evolution" is a central concept
>>>of biological science.
>>>
>>Is "natural selection" defined as differential survival
>>in the above "central concept of biological sceince"?
>
>in the population. Not quite the same thing as 'survival'.
>
individual geno/phenotypes in the population causes
adaptive evolution."
Correct?
>>Is there any explanation for HOW "natural selection"
>>causes adaptive evolution,
>
>Yes, of course. There are a great many such explanations, and many
>investigations into details, and many studies of specific cases.
>Textbooks full. Research journals full. Libraries full, no doubt.
>
>>or does it just happen "by definition"?
>
>Of course not. It happens, and it's not 'just by definition'.
>Why? Is "natural selection causes adaptive evolution" somehow
>a tautology? How, exactly?
>
Sigh.
What is "adaptive evolution"?
Is there evolution that is NOT adaptive?
Isn't ALL evolution adaptive?
What definition of "evolution" are you using today?
Please explain the difference between natural selection
and evolution. It sounds to me like they are the same
thing, changes in allele frequencies in a population.
Scott
Adam Noel Harris
[...]
:Sigh.
:
:What is "adaptive evolution"?
Evolution which increases the fit of organisms to their environment. To
avoid tautology, let's say that it's evolution caused by natural
selection, or evolution which results in the increase of genotypic
variants which are better able to utilize the resources of their
environment to increase their reproduction.
:Is there evolution that is NOT adaptive?
Yes.
:Isn't ALL evolution adaptive?
No. You claim to have a textbook written by Motoo Kimura. Kimura's most
famous argument is that MOST evolution is non-adaptive.
:What definition of "evolution" are you using today?
Let's stick with "Changes in the heritable characteristics of populations
of organisms over generations."
:Please explain the difference between natural selection
:and evolution. It sounds to me like they are the same
:thing, changes in allele frequencies in a population.
Evolution is changes in allele frequencies in a population. Natural
selection is one cause of such changes. Natural selection results in
changes that are adaptive. But not all evolution is adaptive.
Do you really want to learn this stuff or are you trying to engineer new
ways to be difficult?
-Adam
--
Opinions expressed are not necessarily those of Stanford University.
PGP Fingerprint = C0 65 A2 BD 8A 67 B3 19 F9 8B C1 4C 8E F2 EA 0E
mel turner
>In <8q4lm8$1l0$1...@news.duke.edu>, mtu...@snipthis.acpub.duke.edu (mel
turner) writes:
>>In article <39c59...@news1.prserv.net>, sc...@home.com wrote...
[snip]
>>>Is "natural selection" defined as differential survival
>>>in the above "central concept of biological sceince"?
>>
>>Differential reproductive success among individual geno/phenotypes
>>in the population. Not quite the same thing as 'survival'.
>>
>So we have "differential reproductive success among
>individual geno/phenotypes in the population causes
>adaptive evolution."
>
>Correct?
So far. All the terms in the statement could be expanded on greatly, of
course.
>>>Is there any explanation for HOW "natural selection"
>>>causes adaptive evolution,
>>
>>Yes, of course. There are a great many such explanations, and many
>>investigations into details, and many studies of specific cases.
>>Textbooks full. Research journals full. Libraries full, no doubt.
>>
>>>or does it just happen "by definition"?
>>
>>Of course not. It happens, and it's not 'just by definition'.
>>Why? Is "natural selection causes adaptive evolution" somehow
>>a tautology? How, exactly?
>>
>Sigh.
>
>What is "adaptive evolution"?
The evolution of adaptations. The evolution of changes that result in
increases in the overall fitness of the population's members in their
environment. The evolution of those features many folks think look
"designed"...
>Is there evolution that is NOT adaptive?
Of course.
http://www.talkorigins.org/faqs/faq-intro-to-biology.html
http://www.talkorigins.org/faqs/genetic-drift.html
>Isn't ALL evolution adaptive?
No. See above. Some think most evolution is non-adaptive.
>What definition of "evolution" are you using today?
Change in allele frequency within a population over time. Why? Have I
used any others in this same context?
>Please explain the difference between natural selection
>and evolution.
Natural selection is one phenomenon that causes and influences
evolution. It's not the only one.
>It sounds to me like they are the same
>thing, changes in allele frequencies in a population.
Then you haven't been paying enough attention. "Change in allele
frequencies in a population" clearly isn't the same thing as
"differential reproductive success among individuals in a population,
and its effects over generations" [IMO, a pretty good brief
definition of NS].
cheers
Vincent Maycock
<sc...@home.com> wrote in message news:39c68...@news1.prserv.net...
> In <8q4lm8$1l0$1...@news.duke.edu>, mtu...@snipthis.acpub.duke.edu (mel
turner) writes:
> >In article <39c59...@news1.prserv.net>, sc...@home.com wrote...
> >>In <8q1bbr$9sn$2...@news.duke.edu>, mtu...@snipthis.acpub.duke.edu (mel
> >turner) writes:
> >>>In article <39c42...@news1.prserv.net>, sc...@home.com wrote...
> >
> >>>>>""Natural selection occurs" is not an argument.
> >>>
> >>>Right, it's a statment of fact.
> >>>
> >>>>Neither is "natural selection occurs" a definition.
> >>>
> >>>Yes, and they didn't say it was a definition.
> >>>
> >>>And "natural selection causes adaptive evolution" is a central concept
> >>>of biological science.
> >>>
> >>Is "natural selection" defined as differential survival
> >>in the above "central concept of biological sceince"?
> >
> >in the population. Not quite the same thing as 'survival'.
> >
> So we have "differential reproductive success among
> individual geno/phenotypes in the population causes
> adaptive evolution."
>
> Correct?
>
>
>
> >>causes adaptive evolution,
> >
> >investigations into details, and many studies of specific cases.
> >Textbooks full. Research journals full. Libraries full, no doubt.
> >
> >
> >Why? Is "natural selection causes adaptive evolution" somehow
> >a tautology? How, exactly?
I was thinking about defining an adaptation to be "the cause of natural
selection," but in some cases it isn't. All adaptations, at the very least,
can be broken down into simpler adaptations which are causes of natural
selection, but these conglomerate adaptations themselves must logically be a
result of natural selection. So I guess an adaptation would be anything that
causes or is caused by natural selection.
> Sigh.
>
> What is "adaptive evolution"?
Evolution that results from natural selection.
> Is there evolution that is NOT adaptive?
Yeah, genetic drift.
> Isn't ALL evolution adaptive?
No.
> What definition of "evolution" are you using today?
>
> Please explain the difference between natural selection
> and evolution. It sounds to me like they are the same
> thing, changes in allele frequencies in a population.
No, natural selection is one mechanism for inducing allele frequency
changes; the other mechanism is genetic drift.
--
Vince