Biological fitness - What Is It? (Page 6)

CoIin
CoIin: Interesting comments, Nas.

re Dawkins, Wilson and australopithecines - Is this another case of "Just So" stories that evolutionary biologists seem to get accused of a lot?

Well, with specialist knowledge and compartmentalism being what it is, I suppose it's inevitable that scientists will often come across as being philosophically naive to philosophers of science, while the philosophers will doubtless be found wanting in their scientific knowledge by the scientists.

I'm not particularly well-versed in biology so it's nice to have someone like yourself around who knows what she's talking about and can kick me right when I stray. (sneaker + snicker )

Philosophy of science is a topic that fascinates me though. How about you? Daniel Dennett said something along the lines of "There's no such thing as philosophy-free science; only science with its philosophical baggage taken on board unchecked".

Then again, I think it was Richard Feynman who said that philosophy of science is as useful to scientists as ornithology is to birds.

P.S. I always get etymology and entomology mixed up. Etymology is about words and entomology is about ents, right?
(Edited by CoIin)
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duncan124
duncan124:
Another view of the same idea.

"Population control

Conspiracy theorists believe that the New World Order will also be implemented through the use of human population control in order to more easily monitor and control the movement of individuals.[6]

 The means range from stopping the growth of human societies through reproductive healthand family planning programs, which promote abstinence, contraception and abortion, or intentionally reducing the bulk of the world population through genocides by mongering unnecessary wars, through plagues by engineering emergent viruses and tainting vaccines, and throughenvironmental disasters by controlling the weather (HAARP, chemtrails), etc.

Conspiracy theorists argue that globalists plotting on behalf of a New World Order are neo-Malthusians who engage in overpopulation and climate change alarmism in order to create public support for coercive population control and ultimately world government.

Skeptics argue that fears of population control can be traced back to the traumatic legacy of the eugenics movement's "war against the weak" in the United States during the first decades of the 20th century but also the Second Red Scare in the U.S. during the late 1940s and 1950s, and to a lesser extent in the 1960s, when activists on the far right of American politics routinely opposed public health programs, notably water fluoridation, mass vaccination and mental health services, by asserting they were all part of a far-reaching plot to impose a socialist or communist regime.[82] 

Their views were influenced by opposition to a number of major social and political changes that had happened in recent years: the growth of internationalism, particularly the United Nations and its programs; the introduction of social welfare provisions, particularly the various programs established by the New Deal; and government efforts to reduce inequalities in the social structure of the U.S..[83]

from en.wikipedia.org/wiki/New_World_Order_(conspiracy_theory)

This account of the CTs also fails to mention the economic and anti-social aspects of population control theories.
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CoIin
CoIin: Here's another review of the fitness imbroglio that I was recommended to take a look at:-

http://docencia.med.uchile.cl/evolucion/pdf2005/LEWONTIN2004-fitness.pdf

Those hoping for a simple answer to the question "what is fitness? " ( me me me!! ) might be disappointed, but at least the article helps to clarify the distinction between the two basic interpretations of fitness that I've been calling Fitness1 (Darwin's fitness which is also our intuitive notion of fitness - a function of physical traits which can EXPLAIN reproductive success) and Fitness2 (modern biological orthodoxy - fitness IDENTIFIED with reproductive success), and their various manifestations in both qualitative and quantitative (equations! ) form.
(Edited by CoIin)
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duncan124
duncan124:
I don't think there is any real question about your play on words and bearing in mind that someone some where will use the wrong word and amongst a lot of people the same wrong word will be repeated several times I suggest a closer look at the activities of the Nazi Bishop of NY will provide an answer!

I can't remember where, and I have no link to support my memory, but I recall from somewhere that it was one of his tricks.

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nasdaquero
nasdaquero:
re Dawkins, Wilson and australopithecines - Is this another case of "Just So" stories that evolutionary biologists seem to get accused of a lot?"

I think it's mostly popularizers who get the blame here. But, yeah, I've noticed that some anthropologist or other is "rewriting" hominid phylogeny about once every other week.

"Well, with specialist knowledge and compartmentalism being what it is, I suppose it's inevitable that scientists will often come across as being philosophically naive to philosophers of science, while the philosophers will doubtless be found wanting in their scientific knowledge by the scientists"

A lot of philosophers of science are also scientists--not sure if it's a majority or not. Lewontin comes to mind, as does Ernst Mayr. I think that many scientists are aware of the philosophical underpinning of their work, and what that means for things like degrees of certainty, etc. So, maybe not so naive, even if not thoroughly versed.

"Philosophy of science is a topic that fascinates me though. How about you? Daniel Dennett said something along the lines of "There's no such thing as philosophy-free science; only science with its philosophical baggage left unpacked".

Then again, I think it was Richard Feynman who said that philosophy of science is as useful to scientists as ornithology is to birds."

I find it interesting, particularly when it comes to things I work with every day, such as species concepts. I don't think there is philosophy free science: for example, science depends on inference and inference is philosophically problematic. But a lot of what scientists do is pragmatic (in the vernacular sense, and also in the Peircian/Jamesian sense): they add to our understanding of the world in ways that seems to jibe with other things we understand about the world, and these things allow us to predict natural phenomena, and to manipulate nature. For certain there are always philosophically driven arguments and schisms in science. In biology, for example, there are definite degrees of acceptance of the orthodoxy of cladism. A lot of biologists I talk to simply ignore it altogether, although Phd students are expected to work within its constraints and to produce work under the assumption it is correct. I'm in a minority, but I think it's philosophically tenuous and essentially not a lot more than speculation. It's also 'scientistic'--it looks rigorous and its essentially reductive, which is what science likes these days.

Entomology is the study of insects. But we play a lot with etymology, too.

Cheers
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CoIin
CoIin: Sigh! How can I ever forget her beauty. Ah, those alluring yet plaintive eyes, that proud nose, those chiselled, high cheekbones, that flowing raven hair, those generous lips...

Oops . Um, where were we again? Ah yes, fitness

I'm not sure if I've convinced anyone else, but I've certainly convinced myself that this notion of fitness is plagued with confusions and circularities, if not among professional biologists and philosophers, then at least among the rest of us riff-raff. The following insight might help to explain the rampant, but no doubt inadvertant, equivocation.

Talking of which, first consider an example of less accidental equivocation. The evolutionary naysayer who cries "It's only a theory!" is often excoriated by the outraged science fan who accuses her of willfully equivocating between our vernacular usage of "theory" and the (putative) alternative and distinct use of the term in science. A scientific theory, he'll admonish, is not of the same type as "Maybe the butler did it, but I could be wrong" theory.

(I'd be inclined to argue that the difference, if there is any at all, is purely one of degree (quantitative) rather than of type (qualitative); more of a boat/ship distinction than boat/airplane, however, this avenue of inquiry will have to be left for another day. )

The point is that "theory" can be used in either sense without ringing alarm bells. It doesn't sound "odd" either way. (cf. "He's my sister" would strike any native English speaker as mighty weird whereas most of the locals where I live wouldn't bat an eyelid ). We might also note that the "It's just a theory" headache could be obviated if scientists selected another word to replace "theory", say "the General Zadonk of Relativity"?

Well, leaving technical definitions aside and approaching the issue purely from the perspective of the English language, the problem with "fitness" is that it can easily be interpreted as being "constituted" by phylogenetic traits, which is to say that fitness JUST IS the aggregate of these traits, or else it can be interpreted as being the "effect" of the traits, that is, fitness is CAUSED by the traits, or identically, the traits EXPLAIN the fitness of the organism.

Some examples might help...

1. "Wealth"

"His wealth can be explained by his money."
"His money causes him to be wealthy."

I think most of us will find these sentences counterintuitive, to say the least. It seems more correct to say that his wealth JUST IS his money; money constitutes his wealth. The relationship is constitutive rather than causal. Fifty states constitute the USA; they don't cause it.

2. "Strength"

"He's strong because he has big muscles."

This seems right. His muscles (which constitute his muscular physique) do not constitute his strength; they cause it. If you're not convinced, consider the relationship between Samson and his hair . The relationship is causal, not constitutive.


"Wealth" and "strength", then, appear quite unproblematic. Now consider a word which, like "fitness", seems to lend itself much more readily to equivocation - "beauty".

"What do you mean she's not beautiful? Just look at those eyes, that nose...." (constitutive? )

"Which of her features do you think make her beautiful and which are irrelevant?" (causal? )

Are these luscious lips and come-hither eyes et al constitutive of her beauty? Or do they cause/explain her beauty? Or both? Is the beauty in the face? Or in the eye of the beholder?

Do razor-sharp talons, visual acuity and strong wings (inter alia) constitute a fit eagle? Or do they cause the eagle to be fit? Or does the eagle's reproductive success constitute its fitness? The last one of the three is current biological orthodoxy, if I understand correctly, but at the commonsense level, none of these strikes me as counterintuitive or odd. How about you?

In fact, we could even add an extra link to the causal chain and I doubt the average man on the street, or the average poster in Wireclub ( ), would raise an eyebrow:-

"Yes, Bob, you see, the particularly resplendent tail of this peacock causes it to be especially fit, and the increased fitness explains why he's such a big hit with the peahens, and why there are so many li'l peachickens (or whatever ) running around here."

( traits >>>> fitness >>>> reproductive success )

And if you're able to figure all this out, ask yourself whether heat just is molecular motion, or whether heat is caused by molecular motion.
(Edited by CoIin)
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StarryStarryNight
StarryStarryNight: Sounds like a "which came first? chicken or egg?" kinda question..hehe...have never really given it much thought...thanks for the interesting read, colin
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nasdaquero
nasdaquero: Do razor-sharp talons, visual acuity and strong wings (inter alia) constitute a fit eagle? Or do they cause the eagle to be fit? Or does the eagle's reproductive success constitute its fitness? The last one of the three is current biological orthodoxy, if I understand correctly, but at the commonsense level, none of these strikes me as counterintuitive or odd. How about you?

It depends on the circumstances, which has been my main point all along. Fitness cannot be separated from a particular time and place. And we're generally not talking about species, but about individuals within a population relative to other individuals in that population. Because there is variability of phenotype in most populations (not speaking of clones for the moment), there is going to be variable (and predictable) fitness depending on the totality of relevant aspects of the environment: i.e. availability of resources, temperature regime, etc.

By the way, when non biologists talk about fitness, they invariably fall into the Spencerian trap of equating fitness with size, speed, strength, aggressiveness, etc. For some organisms, the superior ability to be tiny, lie still and blend into their background might be what imparts fitness.

Oh, and vernacular "theory" is much more akin to what scientists would call an hypothesis. A theory in science is an overarching model of some aspect of nature that has so much evidence in its favor that in order for it not to be true, vast areas of science would have to be revolutionized and proven wrong. Hence the theory of evolution, which depends upon and is corroborated by research in paleontology, chemistry, physics, biology, anatomy, cytology, genetics, etc etc. For evolution NOT to be true, we would need to revamp our ideas in all of those areas. Possible, sure---science always is tentative in that way-- but highly unlikely.
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CoIin
CoIin: Thanks again, Nas

The evidence for evolution does indeed seem very impressive. I think it's important to note, however, that while evidence for the theory of natural selection (TNS) constitutes evidence for evolution, the converse does not hold; evidence for evolution is not necessarily evidence for TNS. I often see the two confounded, both here in Wireclub forums and in other more salubrious environs. It seems to me that all talk of the fossil record, vestigial features, etc, etc (often adduced as a crucifix by the science fan to stave off draculian Creationists) is evidence for evolution, not for TNS per se.

Once again, this highlights the problem of equivocation, or ambiguity. When people say "evolution" it's not always clear if they're referring to the process of evolution (by any means) or Darwin's conception of evolution via (mainly) the mechanism of natural selection and ossified in the "Origin", or the neo-Darwinian synthesis, or even something else.

So when you say...

"Hence the theory of evolution, which depends upon and is corroborated by research in paleontology, chemistry, physics, biology, anatomy, cytology, genetics, etc etc. For evolution NOT to be true, we would need to revamp our ideas in all of those areas."

...what exactly are we talking about? Is there a "canonical version" of the theory of evolution stored away in a vault somewhere, so to speak, that we can pull out and refer to if the theory is challenged? Because it seems to me that the theory of evolution, like all extant scientific theories, constantly EVOLVES.

And if there's no canonical version of the theory, it's hard to see how it could ever be definitively falsified, even in principle. The cunning scientist could always indulge in a little "moving the goalposts", much as the Creationist is wont to do, and deride "Yeah yeah, yeah, Where have YOU been? No one is THAT kind of Evolutionist these days." Is everything in "Origin" still considered true? If not, is Darwinian evolution falsified?

(Watch out for that famous pre-Cambrian rabbit . C'mon now, advertising to the contrary notwithstanding, anyone who has studied the history of scientific methodology knows that scientists will stitch and tweak and patch and fiddle with a theory, but never entirely abandon it if no alternative is available. I mention this not as a criticism, but merely an observation.)

Or is "evolutionary theory" just the totality of current mainstream knowledge? (and who decides exactly what THAT is? ) And, as we both know, this is not the same corpus of knowledge as it was 150 years ago, or 15 years ago. And it won't be same 150 years from now.

P.S. I've started a thread in the Philosophy Forum for musings on evolutionary theory or anything related. I've been reading and thinking quite a lot about it lately, mainly from the conceptual rather than technical perspective. I'd be glad to hear your thoughts.
(Edited by CoIin)
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CoIin
CoIin: @ Nas - I just want to point out something, with all due respect, which I think exemplifies the whole mess of "fitness" I've been trying to unravel.

I had said:-

"Do razor-sharp talons, visual acuity and strong wings (inter alia) constitute a fit eagle? Or do they cause the eagle to be fit? Or does the eagle's reproductive success constitute its fitness? The last one of the three is current biological orthodoxy, if I understand correctly, but at the commonsense level, none of these strikes me as counterintuitive or odd. How about you?"

You responded:-

"It depends on the circumstances, which has been my main point all along. Fitness cannot be separated from a particular time and place."


It (i.e. what is fitness) cannot possibly "depend on the circumstances" if one is to remain consistent. Degrees of fitness will indeed vary according to traits and ecology, but the ROLE of fitness in the [Traits-Fitness- Reproductive Success] matrix must never change. It cannot be all three of the above.

Let's begin with a simple conceptual diagram that should not be controversial to anyone.

In a given ecology:-


Traits (teeth, camouflage, whatever) >>>>>>>> Reproductive success


The arrows represent a causal relationship. No matter what position you take on fitness, I don't think anyone denies that the traits causally affect reproductive success (the details of which needn't bother us here). This is equivalent to saying that reproductive success can be EXPLAINED by certain traits.

Now you have to decide which side (left or right) fitness lies. If it's on the left side, it must stay there, and vice versa.

Consider : - Dudes with big swords win more battles.

Now let's say we want to define a concept "battle fitness". The concept is our own invention so we're free to define it any way we like.

1). We might decide that the sword, or other weaponry, CONSTITUTES fitness (fitness on left side). In this case, we can say:-

1a). Their fitness causes their success/They are successful because they are fit
1b). Their fitness explains their success/Their success is explained by their fitness

We cannot say:-

1c). Their swords cause their fitness/They are fit because of their swords
1d). Their swords explain their fitness/ Their fitness is explained by their swords


2). We might alternatively decide that fitness is constituted by winning battles. (fitness on right side). In this case, we can say:-

2a). Their swords cause their fitness/They are fit because of their swords
2b). Their swords explain their success/Their success is explained by their swords

We cannot say:-

2c). Their fitness causes their success/They are successful because they are fit
2d). Their fitness explains their success/Their success is explained by their fitness

(Whether you decide to treat your "fitness" individually or statistically based on groups of organisms is completely irrelevant to the causal structure. A shot to the heart causes cardiac arrest - and everyone who gets shot in the heart suffers cardiac arrest (say). Smoking causes lung cancer - but not everyone who smokes gets lung cancer. )

It's taken me ages, but I think I've finally figured out where all this confusion arises from . And I'm not the only one who's noticed, by the way, but it seems that anyone outside biology who attempts to point these things out is routinely dismissed as an "idiot" who knows nothing about science. This whole brouhaha is purely conceptual; it has nothing to do with empirical matters.

I'm preparing a thread on the "selection of" and "selection for" distinction which suffers from PRECISELY the same malaise.

The scientists hate when the Creationists say "It's JUST a theory". Well, science fans are likely to tell me "It's JUST semantics " .

It's not JUST semantics. The distinction is critical. It's the difference between a causal and a non-causal relationship. It's the difference between nicotine causing lung cancer and nicotine being correlated with lung cancer, which is a very different scenario. Ashtrays are correlated with lung cancer too.

The danger with defining fitness as "the ABILITY to (roughly) disseminate genes", as other posters have done earlier in the thread, and many other people do, is - on which side of our causal diagram does this "ability" lie, left or right? Does the ability lie in the sworded warrior? (left) Or in battle success? (right).

It's not structurally problematic as long as we're meticulous, but it's a recipe for anarchy among the meticulously-challenged. Equivocation between the two IS rampant, everyone and their pre-Cambrian rabbit is doing it!


Nas, for future reference, I respectfully request you to state here and now which side of the causal diagram your "fitness" lies. I want it carved in stone, so to speak, so that I can refer you back to it later if necessary, And hopefully get a handle on this mess!

Thanks

(P.S. I almost wrote "... winning battles successfully" )
(Edited by CoIin)
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CoIin
CoIin: And so, harken up everybody , if current biological orthodoxy is indeed to define fitness in terms of reproductive success, and you adopt this position, then you are allowed to say:-


3a). Traits cause fitness/Organisms are more or less fit because of their traits
3b). Traits explain reproductive success/Reproductive success is explained by traits

But you must NEVER catch yourself saying:-

3c). Fitness causes reproductive success/Organisms are reproductively successful because they are fit
3d). Fitness explains reproductive success/Reproductive success is explained by fitness


In other words, don't EVER let me hear you say "These dang rabbits have lots of kids because they're fit."

How clear can a fellah be

Watch yer tongues now, boys and girls
(Edited by CoIin)
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CoIin
(Post deleted by CoIin 10 years ago)
nasdaquero
nasdaquero: I don't really know what "current biological orthodoxy" means. But if pressed I'd say that I would agree with 3 a and 3 b. But once again, this would be qualified by "in a certain place, at a certain time." As for "moving goalposts"--well, just because you interject "watch for pre-Cambrian rabbits" doesn't obviate the example. Evolution is descent with modification: as far as all the evidence suggests, life has evolved from simpler, less organized forms. All life present and past has a common ancestor. Everything is based on DNA, and we see no evidence of spontaneous creation of life today or in the past. As for natural selection, again, all the evidence suggests that it is the primary "motor" for adaptation of individuals to their enviroment. On the other hand, DIVERSITY is explained by speciation, which mostly takes place through vicariance (there's debate as to the degree of physical separation needed for new species to form, but there's no doubt that that separation is a prerequisite.). Punctuated equalibria explained the patterns found in the fossil record, but the idea of allopatric speciation predated Gould et al. It's important to realize that biologists for the most part are very aware (more aware than non biologist philosophers) of the limits of their own knowledge. They also know that the labels they use have practical benefit, but don't describe the totality of what they observe, nor does any given definition cover all life forms. You see this in the literature devoted to explaining what a species is.
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CoIin
CoIin: Hi again

Funny you mentioned Gould. Here are a couple of his quotes I just stumbled across apparently related to what I was hinting at above, namely that the so-called neo-Darwinian synthesis is so fluid and diverse that's it's hard to see what might ever constitute a falsification.

It seems more like an encyclopedia than anything else. Any particular entry is (we would hope) subject to revision, but how would one ever refute the entire Encyclopedia Britannica?



1. Stephen Jay Gould has complained that vagueness in the definition of the neo-Darwinian synthesis "imposes a great frustration upon anyone who would characterize the modern synthesis in order to criticize it."

2. The modern synthesis has sometimes been so broadly construed, usually by defenders who wish to see it as fully adequate to meet and encompass current critiques, that it loses all meaning by including everything..... Stebbins and Ayala [two eminent defenders] have tried to win an argument by redefinition. The essence of the modern synthesis must be its Darwinian core.
(Edited by CoIin)
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nasdaquero
nasdaquero: Well, the "new" or modern synthesis was completed by 1947. A lot has gone on since then, both theoretically and in terms of our acquisition of knowledge. The contribution of Gould was to focus on the fact that fossils seemed to show that relatively rapid evolutionary change after a period of stasis was possible and in fact probably the rule for most lineages, contrary to the modern synthesis which viewed evolution of species as slow and gradual. This is consistent with what we can observe in nature, and advances in genetics help explain this rapid change. So if you want to look at it one way, Gould's focus helped to "falsify" the idea that gradual change across populations was the most common mode of change, and put the emphasis on vicariance (often of peripheral poplulations) as a prerequisite for speciation, and speciation as the key to biological diversity. Regarding falsification, if someone were to demonstrate that acquired characteristics could be passed on genetically, then Lamarck would be resurgent. This has not been demonstrated, so Dawrwinian natural selection is still the ruling theory of adaptation.
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gretle56
gretle56: Biological fitness apposed to psychological fitness? Or Spiritual fitness?
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nasdaquero
nasdaquero: Different realms of inquiry
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gretle56
gretle56: exactly my point
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CoIin
CoIin: A book recommendation - "Evidence and Evolution : The Logic Behind the Science" by Elliott Sober

I'm sure we've all read those run-of-the-mill Evolution vs Creationism treatments where we're presented with a pile of evidence purportedly supporting one position and another pile purportedly supporting the other. The peroration invariably reads something like "... clearly the evidence favors an evolutionary account ...", which for all I know may well be true, but unsatisfying insofar as we're left to "intuit" the conclusion; no attempt is made at a quantitative comparison. Any claim to the effect "It's obvious and that's that" should be treated with caution, I think.

Philosopher of science, Elliott Sober, demands more of his readers. The going isn't easy, and by the time you're finished you'll be seasick from undulatory lashings of statistics and probabilities, but you'll at least be familiar with contemporary theories of evidential confirmation; Bayesianism in particular. Various biological theories are tested against one another, and also against Creationist theories wherever possible. This is often difficult since we lack any information regarding the motives of this putative Creator (did she want to create perfect creatures? Less than perfect creatures? etc).

Yes, boys and girls, you'll be able to deploy more than just the effete "We have evidence!" (and that's that!)

Much of what's contained in the book helps to clarify topics covered earlier in this thread. Of interest to you Nasdaquero, perhaps, will be Sober's comments regarding the testability of current evolutionary theory, an issue we have delved into ourselves to some extent above.

People tend to speak, rather naively I think (see Dawkins), as if evolutionary theory is the kind of beast that can be confirmed or disconfirmed AS A WHOLE, as if one scrawny pre-Cambrian rabbit could bring the entire edifice toppling to the ground.

Now, I'm not denying the testability/falsifiability of evolutionary theory; but confirmation or disconfirmation, if it happens at all, happens at a lower level, at the level of the components rather than the entire assemblage. I think the analogy I made to an encyclopedia earlier is quite apposite; we might expect individual entries to be modified over time, but it's surely chimerical to suppose that the entire Encyclopedia Britannica might be "falsified" in one fell swoop.

As the clearheaded Sober says: "Creationists often talk of 'testing evolutionary theory', and biologists sometimes talk this way as well. The context of their remarks sometimes reveals which specific proposition the authors have in mind, but often this is not the case. It is important to recognize that the phrase 'evolutionary theory' is too vague when the subject of testing is broached. There are a number of propositions that evolutionary biologists take seriously. The first step should be to specify which of these is to be the focus."
(Edited by CoIin)
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CoIin
CoIin: Testability

One must be wary with regards claims about the "testability" of a hypothesis. The biologist will sometimes be heard to exclaim with some braggadocio that selection is a "testable empirical hypothesis". And for all I know it might well be. I'd just recommend caution and an examination of your definitions lest we end up testing language rather than nature.

If you're running computer simulations on natural selection, for example, and find that the fittest prevail each time, or almost every time, be careful what conclusions you draw.

The hypothesis "all bachelors are unmarried" is also testable. Go out there and conduct interviews if you like. I doubt you'll be disappointed. The point is, however, that certain hypotheses do not NEED to be tested. The result is a foregone conclusion. What you are "confirming", in this instance at least, is a truth of language, not a truth of the world.
(Edited by CoIin)
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CoIin
CoIin: I'm in the middle of reading a superb book entitled "Keywords in Evolutionary Biology" edited by Evelyn Fox Keller and Elisabeth A. Lloyd.

The book consists of an A-Z explication of terms commonly used in evolutionary biology. The editors and contributors laudably admit that the meanings and usages of many of these terms are implausibly confused, varying both diachronically and synchronically, and often utilized in quite incongruous ways by different writers. The collection of essays which constitute the book aims -- equally commendably -- at bringing a measure of clarification to the lexical imbroglio. Contributions are made by historians, philosophers, and biologists, including such luminaries as Stephen Jay Gould, Richard Dawkins, Elliott Sober. and Michael Ruse.

My beady eyes were naturally attracted to the three essays on "Fitness" contained within. The first by Diane Paul traces the historical evolution of the term from its initial coinage to the present day, illustrating the metamorphosis in meaning from that which is INDICATED by reproductive success to reproductive success itself. The symtom of the condition becomes the condition simpliciter.

Vindication!

I offered an analogy of my own earlier in the thread with the concept of "Intelligence" and I.Q. test scores. What I take to be our standard present-day notion of intelligence corresponds exactly with the original (Darwin, Spencer, et al) meaning of fitness: a high I.Q. test score gives us a good indication of intelligence, but is not IDENTIFIED with intelligence, after all, it's quite conceivable that an intelligent person could deliberately perform badly on the test, for example - a low score is not the same thing as being unintelligent. Likewise with fitness : under the original definition, reproductive success gives us a good indication of fitness, but is not identified with fitness.

In the early-mid 20th century, Ms Paul meticulously chronicles, the meaning of fitness mutated, as these things often do, to become nothing more than reproductive success itself. This would be exactly analogous to us altering the meaning of intelligent to become "the quality possessed by those who perform well in I.Q. tests" - get a high score and you're smart; get a low score and you're not. And that's that!

Now, there are no free lunches, of course. This transformation of meaning comes at the cost of confronting the dreaded spectre of tautology. If fitness JUST IS the quality of reproducing successfully then the fittest CANNOT FAIL to "survive"; "survival of the fittest" transforms from an empirical, testable, and therefore falsifiable, scientific hypothesis about how the world works into a purely definitional truth of the type "all bachelors are unmarried men".

(Compare with "All smart people score well in I.Q. tests" - Empirical or definitional? Falsifiable or unfalsifiable? )

I leave you now in the capable hands of Diane Paul...

"The development of population genetics in the 1920s and 1930s undermined the colloquial usage of fitness in evolutionary biology. In the work of J. B. S. Haldane, Sewall Wright, and R. A. Fisher, the gene was identified as the target of selection and selection itself was redefined as a change in gene frequencies. THE MEASURE OF FITNESS BECAME SUCCESS IN PRODUCING OFFSPRING, IRRESPECTIVE OF THE CAUSES OF THAT SUCCESS. MOREOVER, WHAT BEGAN AS AN INDICATOR OF FITNESS SOON CAME TO DEFINE ITS MEANING. Haldane gave this new concept the (somewhat improbable) tag "Darwinian fitness" in his book The Causes of Evolution (1932)." [my caps]

[...]

"In attempting to solve one problem, however, they had created another. If fitness is defined as success in surviving and reproducing, the statement that the fittest survive is apparently emptied of content. Thus was born the famous "tautology problem" which has bedeviled the field ever since."


Read it all here:- (pp. 112-114)

http://books.google.com.tw/books?id=Hvm7sCuyRV4C&pg=PA112&lpg=PA112&dq=Diane+Paul+Fitness:+Historical+Perspectives&source=bl&ots=z-uQwkXree&sig=WBoTvSC29zQUsyJsVEcNr5eXFOo&hl=zh-TW&sa=X&ei=kQ7oU-_iBcSD8gW69oDwDg&ved=0CCAQ6AEwAA#v=onepage&q=Diane%20Paul%20Fitness%3A%20Historical%20Perspectives&f=false
9 years ago Report
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