[top] -- [home]There's nothing here about Dr. Senapathy's theory. This is just heat about the definitions and proper use of the words "theory" and "fact."
You don't have to read all of this. Just promise never to say "evolution is a fact" and we'll get along fine.
To save time, just skip down to at the The Mark Barton Digest.
From Moshira Hassan: I personally strongly believe in the concept of evolution. I tend to consider it a fact. Nevertheless you can't PROVE it, we were not around to see things happen. We can deduct the model of evolution from what we see at present. But then again, who is to prove the actualistic approach? In fact you can rarely prove models, only falsify them. This means that the evolutionary theory is actually an evolutionary hypothesis. A models is good/valid as long as it explains a certain phenomenon.
From Karl Altenburg: What part of the fact of evolution can not be proven? That life forms are descendant from other life forms? That offspring may be different from their parents? That life on Earth shares a common, ancient ancestor?
There are many aspects of evolution that we can observe and can record. It is easy to explore the process of differential selection on different breeds of pets, flowers, cows, etc. We can easily observe mutant offspring, especially in populations of fruit flies (for example).
JM: All of those things are micro-evolution and can be observed. They occur over relatively short periods of time.
Karl: And though it is a little harder to observe, we can look at all known life on Earth and find compelling evidence for our shared ancestry (RNA for example).
Evolution is not something that only happened in the past. Evolution is taking place right now, right in front of you (or inside of you). Evolution is a fact. Proposals for its operating mechanisms may be considered theories or hypotheses.
(Do physicists consider gravity a theory or is it a fact? Is there a theory of the mechanism of the process of gravitation?)
From Mark Barton: Excuse a lurker physicist butting in. It is certainly a fact that everyday objects fall in the general direction of the earth. Whether you call this observation "gravity" or not is a matter of taste. I personally wouldn't if speaking carefully.
In the context of Newtonian mechanics we have a "theory of gravity," whereby objects with mass exert a Newtonian force on other objects with mass. (You have probably come to think it obvious that the earth attracts falling objects, but Newton's contemporaries were only just getting rid of the idea that it was the center of the universe attracting them, and that the earth was simply in the way. Can I convey the cleverness of this by saying that we rank Newton up there with Darwin?) Masses being attracted to other masses is "gravity" as a physicist understands it, and any specific proposal along these lines is a "theory of gravity".
There is no mechanism implied in Newtonian gravitation -- it is just a "spooky action at a distance" to quote Einstein. The information content of the theory is solely in the formula F=GMm/r^2.
In physics parlance, what makes it a theory is that it takes a small number of ideas (the gravity formula plus Newton's laws of mechanics) and explains in detail a lot of phenomena (orbiting of the planets around the sun, orbiting of the moons round the planets, various lab measurements, etc.). It was a successful theory because for a long time it did this correctly -- it predicted many things which were observed but avoided making wrong predictions.
However by the end of the 19th century there was a question mark hanging over it. It was not clear whether it could successfully explain the orbit of Mercury. The long axis of Mercury's orbit precesses about 5000 seconds of arc per century, whereas a naive application of Newtonian gravity suggests zero. In fact corrections (e.g., for the fact that the sun is not exactly spherical) had been found to explain all but 43 seconds of arc per century, but the observations were sufficiently precise that this was an unacceptable discrepancy.
In the event it was overturned and replaced by a new "theory of gravitation," this time based in Einstein's "theory of relativity." In relativity one avoids talking in terms of forces -- gravity is a curvature of space-time. Lumps of matter bend the space around them and a freely falling object takes the straightest path it can in the bent space-time.
It's not clear whether you would call this a mechanism or not. The theory of gravity has been engulfed by a theory of space and time so we now have a "mechanism" for gravity, at the expense of needing a "mechanism" for space and time, whatever that might mean. The information content is now in certain formulae describing the effect of matter on space-time and of space-time on matter.
However we have a more compact set of fundamental principles than before and can make correct predictions about more things than before, so we are justified in calling it progress. It currently makes no incorrect predictions that we know of. We specifically suspect it would break down if the temperature approached 10^32 K, but this could only have happened ridiculously early during the Big Bang.
Having had our fingers burnt over Newton's theory of gravity, physicists are not in the habit of using the word "fact" particularly often, except in circumlocutions like "because of the fact that...". In fact I cringe when I see exchanges like the one above, even though, like one author quoted [above], I haven't the slightest problem with the evidence.
I feel particularly uncomfortable when I see people contrasting theory and fact, e.g. (from above),
Karl wrote: "Evolution is a fact. Proposals for its operating mechanisms may be considered theories or hypotheses."
The creationists are perfectly right. Biologists (assuming Karl Altenburg is a biologist) are using "theory" to mean something less well-tested than a "fact." Evolution (which in context seems to mean the fact that all life fits into the same family tree) is no less a theory (in the sense that we leap to defend) than natural selection. From the defining principle we make predictions about what fossils we might find and about what similarities we might expect between living things. We see these things, lots of them, and not contradictory things, so it's a very well tested theory and, if you are insensitive to hubris, also a fact. But I'll never be comfortable using that word in an argument with a creationist. The point at issue is whether evolution is a well enough tested theory to deserve that label (I think so), and to bandy the F-word around begs the question and is rude.
From Steve La Bonne: No, you're missing the point. The statement "Evolution is a fact" simply means "the genetic structures of populations change over time"; as opposed to pre-evolutionary thinking about species, which considered them to be stable, unchanging essences. It is quite simply a fact that evolution, in this very basic sense, does occur. There is no question-begging or rudeness about it, and in no sense is it theoretical -- it is an observation about living things.
From Greg (gskas1@cc.monash.edu.au): Using this definition of "evolution" as outlined above, does tend to make one lean toward calling it a fact, but I disagree that this explanation is what people really mean when they discuss evolution.
Take for example, the so-called "zoo" hypothesis that states that evolution as proclaimed does not in fact occur, but rather the new species are simply placed on earth, by aliens, who then kill off the species that is being replaced. This theory explains the fossil record much better than the traditional Darwinian theory, (no need for messy "missing links," that refuse to be found), and works well with the DNA, evidence (obviously it would be easier to construct the new creatures out of the older ones blueprints).
Although farfetched, this theory, in fitting the evidence, illustrates that evolution is not a "proven" fact. If it was, then we would be easily able to point to a scientifically verified case of evolution, and say. "Here it is."
Mind you, I do not regard evolution below the species level as proof, as this is not what is under debate, but rather evolution above the species level.
For "proof" of any theory, the supporters need to satisfy exactly the same requirements as those required of those claiming paranormal powers. Proof needs to be unambiguous, and not up for reinterpretation after the event. Statistical significance, or likelihood is not a part of the equation.
So clearly, to prove that evolution can occur, there needs to be a scientifically verified, and indisputable example of evolution above the species level, something which has not occurred (and most likely will not happen, until scientists quit their squabbling over what it means to be a "species").
The most likely theory does not become "fact," just because a better one has not been thought of yet.
From Ron Nadel: The fossil record is one of the reasons that evolution of life on earth is considered to be a fact. It is only the mechanism for that evolution, natural selection, that remains in the realm of theory at this time. It is not rude to come to these conclusions. Perhaps some people are put off by strong statements or assertions, since facts don't leave a lot of room for people's opinions.
From Bob Morse: That's a self-contradiction, and you need to choose: Are you saying that the doctrine of evolution is a "fact" or a "conclusion"? Or are you saying that there is no difference between "facts" and "conclusions"? (If I conclude, for whatever reason/s, that leprechauns exist, is my conclusion a "fact") Or is your qualifying phrase "considered to be ..." more pointed than rhetorical? (Any belief, including a belief in leprechauns, may be "considered to be a fact" by the people who believe it, but that doesn't make it a true, objective "fact.")
What the fossil record reveals is that certain INDIVIDUAL organisms lived and died at certain particular times. That's all. It does NOT reveal -- and CANNOT reveal, conclusively -- that particular other organisms did NOT live and die at the same time. And it certainly does NOT reveal WHY the preserved individual organisms lived and died when they did. Even logical inferences derived from probabilistic assessments are, in fact, only inferences.
The statement that "evolution is a fact" has become an undisputed cultural truism for many, but anyone outside that culture will not be so charitable as to accept the statement at face value. A declaration from evolution's proponents that, in effect, "I don't care what you say, it's a fact anyway," is no more than a spineless retreat, since it quintessentially begs the question and throws up a wall that precludes any further discussion. Moreover, it puts the smell of blood in the water and thereby encourages the opposition.
Please note that I'm not taking sides here -- just trying to clarify the Rules of Engagement.
On reflection, I suppose I could have saved a lot of time and bandwidth if I'd just framed my original post like this:
Evolution is a fact.Ain't that what we're arguing about?
From Craig Duncan: I see the word "theory" used here in a pejorative sense, as though it were some kind of offbeat speculation. Actually a theory is a TOOL which scientists use for organizing and understanding their observations and which they also use for planning new experiments. In this sense, the theory of evolution is the most powerful tool which we have for understanding biology. Virtually every time we ask the question "why" in biology, the answer is based in the theory of evolution.
But, when I call the theory of evolution a tool, that does not mean that it is merely a convenience, a sort of catch-all for our observations. The basic axiom of all science, dating back to the Ancient Greeks, is the idea of a NATURAL LAW. Scientists believe that when they discover a logical structure of ideas which explains and predicts events in the real world, that they then have discovered something fundamental about nature- a natural law. The structure of ideas can change... theories are revised, sometimes radically. But the fundamental, underlying process does not change. This fundamental process cannot be called a "fact." Facts are things which can be directly observed. The fundamental process can only be INFERRED from factual observations.
So, we have 3 components here. Factual observations from fossils, DNA sequences, morphology, etc. are first. The theoretical framework dating from Darwin, which had been modified and expanded by others is second. Finally, there is the natural law of evolution. The first is a body of observations which is constantly being expanded. The second is a frame-work of ideas, based on a central premise, which is still growing today. The last is a basic underlying feature of nature, something which cannot be expressed in words, but which we try to grasp with the theoretical component.
So, when creationists question, we can answer that evolution is a natural law, described by a detailed and successful theory, which is supported by a vast matrix of factual observations from many different disciplines. Evolution is real.
From Steve La Bonne: OF COURSE there is no difference [between a "fact" and a "conclusion"]! A fact is the conclusion that one reaches after considering overwhelmingly strong evidence. What else could it possibly be? An empirical (scientific or otherwise) statement can never be a logically necessary truth like a mathematical theorem.
From Bob Morse: Any and all such inferences are merely interpretation and speculation no matter how much evidence may support them, and no matter what proportion of the esteemed scientific community may accept them--or declare them "facts."
From Steve La Bonne: I think [Bob Morse] suffers from a very basic confusion as to what "knowledge" is. ALL non-mathematical knowledge -- including your knowledge that there is a Usenet newsgroup called "sci.bio.evolution" and that you can post to it using certain procedures -- is precisely a set of inferences based on evidence. If the evidence is overwhelmingly strong -- as is the case with evolution -- then there is little or no "speculation" involved. If you still wish to doubt in the face of overwhelming evidence, you're logically entitled to do so -- but you are then committed to the full Cartesian skeptical program, which reduces to solipsism-of-the-current-moment. Not a position that can be taken seriously by serious people, I'm afraid.
If you have a different definition of "knowledge," one which somehow avoids any "inferences" or "conclusions," I should like very much to see it. (Again, make sure you're not confusing knowledge of empirical facts with proof of mathematical propositions.) But I think such a discussion is more appropriate for a philosophy group.
From Bob Morse: Yes, of course. And I apologize to everyone for being so provocatively casual in my choice of words. Didn't mean to stir up such an epistemological fuss.
I agree that the validity of any knowledge can be assessed only on a "continuum of certainty." My objection to the original post (which insisted that evolution is a "fact") is that the term "fact" implies a 98-100 score on a 0-100 scale of certainty, and I frankly don't believe it deserves a score in that range. I just don't see evolution as an equivalent certainty to, say, my sense that the sun will rise again tomorrow (to which I'd assign a 99). For that matter, I'd say that the notion of a fossil being a true representation of a past life is a significantly greater certainty than whatever conclusions may be drawn from the fossil record.
Even if most reasonable, knowledgeable observers believe that evolution is 90-95% likely to be true, that missing 5-10% soundly invalidates any claim to "facthood." It's sort of like the "reasonable doubt" criterion that will soon face OJ's jurors.
>Saying "evolution is a fact" is in effect saying "the theory of
>evolution is almost certainly the correct inference to draw from
>the evidence."
Not quite. Delete the qualifying "almost" and I'll agree, and the smug omission of the "almost" is what ticked me off in the first place. And one more thing: Saying "evolution is a fact" to someone who disagrees with you is in effect saying, "Shut up, I don't want to talk with you anymore." (Well, maybe that WAS the point, after all, but I don't like rudeness.)
JM: Physicist Mark Barton makes some excellent points in this post about the usage of the word "fact" as it relates to "evolution." There may be an early implication here that Dr. Senapathy is a creationist, but that is not so.
From Mark Barton: Indeed, in any context other than talking some sense into a creationist, I too would consider [evolution] a fact (in a certain sense). But the only plausible context for using the aphorism about evolution being a fact is in debate with creationists!
Notice that there are three different senses of "fact" in use.
One response to this is to point out that in this context, "theory" means a big logically organized explanation, and has no implication of speculation. This is true, and ought to settle the issue, except that it has the rhetorical firepower of a wet tea bag.
I actually rather like Ron's form of words above, "[Evolution] is considered to be a fact." That makes it adequately clear that "fact" is being used in sense two and that scientists consider evolution to be proven beyond reasonable doubt, while allowing the possibility of a civilized debate in which further evidence for evolution can be presented.
However much as the situation needs to be put across strongly I still object to "Evolution is a fact" because it permits misinterpretation in either sense one or three. Sense one is question begging and rude, and leaves no scope for continuing discussion. In sense three it's just plain wrong, unless you make the assumption (which is question begging to creationists) that macroevolution is that same as microevolution. In fact from the quotes I've collected in the appendix below, the probability of it being understood in sense two is vanishingly small, even in the evolution camp.
In fact the overwhelming majority of people (who bothered to post in this thread) seem to hear this remark in sense three, whereas it can only have its intended impact if received in sense two. Some hear it as a manifestly false statement involving macroevolution, and some hear it as a manifestly true statement involving microevolution. Of course creationists are a different audience, but we already know they have problems with the idea of "proven beyond reasonable doubt," so I wouldn't get your hopes up for sense two.
Mark Barton's comments appear here in bold.
From: Moshira Hassan, mhassan@geomar.de >I personally strongly believe in the concept of evolution. I tend to >consider it a fact. Nevertheless you can't PROVE it, we were not around >to see things happen. We can deduct the model of evolution from what we >see at present. But then again, who is to prove the actualistic approach? >In fact you can rarely prove models, only falsify them. This means that >the evolutionary theory is actually an evolutionary hypothesis. A models >is good/valid as long as it explains a certain phenomenon. >Now, I say it is a hypothesis and not a fact. It is an extremely probable >hypothesis/model/concept...It is important to me to note that; and I don't >believe scientists loose credibility if they don't consider evolution a >fact. "That is just the way it is"; propagating dogmas or paradigms is >what makes scientists lose in credibility. Apparently a sense three-er.
From: Karl Altenburg, altenbur@plains.NoDak.edu >What part of the fact of evolution can not be proven? >That life forms are descendant from other life forms? >That offspring may be different from their parents? >That life on Earth shares a common, ancient ancestor? > >There are many aspects of evolution that we can observe and can record. >It is easy to explore the process of differential selection on different >breeds of pets, flowers, cows, etc. We can easily observe mutant >offspring, especially in populations of fruit flies (for example). >And though it is a little harder to observe, we can look at all known >life on Earth and find compelling evidence for our shared ancestry >(RNA for example). >: Species were not created as definite species but evolved from (common) >: ancestors - as you pointed out, this is generally accepted as a fact >: (see, I even use evolutionary hypothesis as a fact :) ) >Evolution is a fact. >: You cannot use this definition though, when dealing with fossil >: organisms - obviously. So here species are defined morphologically. >Evolution is not something that only happened in the past. Evolution is >taking place right now, right in front of you (or inside of you). Sense one, perhaps?
From: Jeffrey Mattox, >>Evolution is a fact. >No, you even said "compelling evidence." That does not make it a fact. >If it were a fact as you suggest, there would not be nearly so much >controversy about Darwin's theory. >>Evolution is a fact. .... >You are repeating yourself, but doing so does not make it any more true. Sense three, I reckon.
From: Robert B. Hole, rbh2@Ra.MsState.Edu >Actually, evolution is defined as "change over time in a lineage." You >can quibble whether it's genetic or morphological or some other change, >but it's still change. It says nothing about a direction or >anything else. And evolution is a fact. There is a change over >time in >all lineages that have been examined (here's a simple one: you're not >identical to your parents), therefore, evolution occurs. >This IS similar to gravity, when gravity is defined (as I think it can >be >defined) as "attraction among masses." It exists. What is called the >"theory of gravity" is, like the "theory of evolution" a theory to >explain the HOW it works, not THAT it works. Sense three, with the assumption that micro-evolution and macro-evolution are the same thing, which makes it true, but is question-begging in the context of a discussion with creationists.
From: Steve Pridgeon, uq462@freenet.victoria.bc.ca >>defined) as "attraction among masses." It exists. What is called the >>"theory of gravity" is, like the "theory of evolution" a theory to >>explain the HOW it works, not THAT it works. >It may be a little easier to understand if you give the theory its >full title of "The Theory of Evolution by Natural Selection". >Evolution and natural selection are both observable phenomena; the >theory is that one is the result of the other. Hard to say, but I think sense three as far as "facts" are concerned.
From: Bob Morse, morse@inxpress.net >That's a self-contradiction, and you need to choose: Are you saying that >the doctrine of evolution is a "fact" or a "conclusion"? Or are you saying >that there is no difference between "facts" and "conclusions"? (If I >conclude, for whatever reason/s, that leprechauns exist, is my conclusion a >"fact"?) Or is your qualifying phrase "considered to be ..." more pointed >than rhetorical? (Any belief, including a belief in leprechauns, may be >"considered to be a fact" by the people who believe it, but that doesn't >make it a true, objective "fact.") Grabs sense three for himself, but can imagine others using sense one.
From: gskas1 >Take for example, the so-called "zoo" hypothesis that states that evolution as >proclaimed does not in fact occur, but rather the new species are simply >placed on earth, by aliens, who then kill off the species that is being >replaced. This theory explains the fossil record much better than the >traditional Darwinian theory, (no need for messy "missing links", that refuse >to be found), and works well with the DNA, evidence (obviously it would be >easier to construct the new creatures out of the older ones blueprints). >Although farfetched, this theory, in fitting the evidence, illustrates that >evolution is not a "proven" fact. If it was, then we would be easily able to >point to a scientifically verified case of evolution, and say. "Here it is" Definitely sense three, no?
From: Wesley R. Elsberry, welsberr@orca.tamu.edu >Fortunately, then, the status of evolution as a fact is not dependent in >any sense upon the fossil record. We observe evolution occurring today, >and the observations are not inferences. Sense three, but with the trendy definition of evolution.
From: S. La Bonne, labonnes@csc.albany.edu >Hold it there; that's where your confusion is. You can't PROVE >anything outside the domain of mathematics. Proof is an inappropriate >concept, and demand, in talking about science. The standard for >scientific facts is much like that for criminal conviction in the >Anglo-American legal system: a fact is something known beyond a >reasonable doubt. By this standard, it is clearly a fact that >biological evolution has occurred and continues to occur. Hope this >helps! At long last, a sense two! He must be lonely. Except that he later says: >No, you're missing the point. The statement "Evolution is a fact" >simply means "the genetic structures of populations change over >time"; as opposed to pre-evolutionary thinking about species, which >considered them to be stable, unchanging essences. It is quite simply >a fact that evolution, in this very basic sense, does occur. There >is no question-begging or rudeness about it, and in no sense is it >theoretical- it is an observation about living things. ... which would be sense three. (Different context, sort of, so I don't mean to pillory poor Steve.) It is still question begging though.
From: Ron Nadel, NADEL@litc.lockheed.com: >The fossil record is one of the reasons that evolution of life on >earth is considered to be a fact. It is only the mechanism for >that evolution, natural selection, that remains in the realm of >theory at this time. It is not rude to come to these conclusions. >Perhaps some people are put off by strong statements or assertions, >since facts don't leave a lot of room for people's opinions. Sense two, maybe.