noobie said:
A theory is an explanation which can be supported by a set of observations or data that one may have. It can never be proven true but only disproved. But the only useful theories in science are the ones that can correctly predict natural phenomena. We use the word theory in our lab all the time and 99% of the time it's another way of saying it's our best guess.
It is important at this point to note the difference between evolutionary theory and what you presumably mean by "theory." What you seem to mean is simply a proposed explanation for some occurence or other, an explanation that probably stands a great chance of being reduced to a more accurate explanation. Something along the lines of the ether theory of the Lorentz transformation being reduced to the relativistic theory. In this case, however, it wasn't a theory in the same sense as evolutionary theory that was being reduced. It was only an explanation of a small set of equations. Evolutionary theory, on the other hand, is far more widely encompassing, something more akin to the entire standard model in physics or atomic theory in chemistry.
I'm going to sidetrack briefly to explore how scientific theories come to be discarded. Strictly speaking, I'm not sure that any scientific theory has ever been disproven in the way you seem to think evolutionary theory can be disproven. The ether theory to explain the Lorentz transformation, for instance, wasn't really a theory at all. It was little more than conjecture. The transforms themselves, the set of equations, was the only part of the work that could be considered even part of a theory. The proposed explanation for the transformations was really only a hypothesis, one that was disproven, as hypotheses often are. The theory under which the hypothesis was constructed, however, was simple Newtonian mechanics. The ether hypothesis was constructed in an attempt to reconcile the transformations with a Newtonian universe. So do we want to say that Newtonian mechanics was
disproven? I certainly don't want to say that, especially given that his equations still hold true under almost any circumstances and certainly under any everyday circumstances. I want to say that the theory of Newtonian mechanics was
reduced to relativistic mechanics, rather than disproven.
So what does it mean for a theory to be reduced? The current definition given in the philosophy of science is as follows: Any theory a is said to be reduced to theory b if, and only if, all of the statements of theory a can be stated in terms of theory b. Thus, any statement of Newtonian mechanics can be made using the terms of relativistic mechanics. The reverse is not true, and so we can say that Newtonian mechanics has been reduced to relativistic mechanics. Several hundred years before this, the geometrical physics of Descartes was reduced to Newtonian mechanics. To use an example you would likely be more familiar with, classical thermodynamics has been reduced to statistical mechanics. Nonetheless, you presumably still use quite a bit of classical thermodynamics in your work (we certainly do here at school, where I actually am a chemistry major).
In light of this, we should not speak of the possibility of evolutionary theory being
disproven, but rather of it being
reduced. In fact, in many ways, it already has been. The theory of genetic evolution first formulated after the work of Mendel has since been reduced to a molecular theory involving point mutations, recombinance, and other sources of genetic variation. Even the entire framework of evolutionary theory has been largely reworked from a theory that natural selection operated on the level of the individual to the idea that selection operates primarily on the level of the single gene. Darwin's basic theory, however, that the biodiversity we observe today is the result of descent with modification, tempered by the pressures of natural selection, has never been reduced or eliminated from any evolutionary explanation. Part of the reason for this is the sheer amount of evidence to corroborate Darwin's claim. In fact, there is far more evidence to support his claim than there is to support any claim by any of the physical sciences. The reason for this is that evidence comes from so many different avenues, from paleontology to geology to molecular systematics to pharmaceutical research to behavioral studies to comparative morphology and embryology, with each new piece of evidence supporting every other piece of evidence that Darwin's basic claim regarding descent with modification and natural selection (two observable and non-contentious phenomena) is truly the source of the world's biodiversity.
Could you point me to direct concrete evidence that evolution occur.
Presumably you have no qualms with microevolution, evolved resistance to antibiotics and pesticides and such. The Talk Origins archive is a great source (probably the most popular one here) for information regarding the evidence for macroevolution. They have a page specifically addressing
Observed Speciation Events. No, they can't go back and confirm every single speciation event that ever occured, such as the series connecting humans and chimps by a common ancestor. Neither can the physical sciences go back in time to confirm that every chemical reaction that has ever taken place obeyed the law of entropy.
I would like to add to their list the very obvious examples of domesticated pets and food products, both plant and animal. The species that we cultivate for food or keep as pets today bear little resemblance to their ancestral wild species that existed when humans first began to selectively breed. You might say that intelligent intervention was required and that this disqualifies these as speciation events, but I would argue otherwise. From the point of view of the genomes doing the evolving, human breeding practices are just another environmental pressure that works no differently from ordinary sexual selection, only faster. There is nothing supernatural going on.
Evolution is not an empirical science in the same sense of physics or chemistry where you can come up with the a theory and test those theory over and over. Evolution is more of a historical science because you are looking for clues throughout history to construct an explanation of what may have happened.
That is not at all true. Evolutionary theory has made many testable claims that have turned out to be true. Examples of the behavioral predictions made by sociobiology alone are enormous. More along the lines of what you seem to have in mind, however, are the predictions made that there will be transitional forms at all, something that has been corroborated many times. The Talk Origins Archive also has a page on many of these located
here. There is a large amount of material to go through there. I urge you to read all of it, but if you feel your time is limited, you might want to take a look only at the section on transitional forms in the fossil record, found
here.
This isn't a time lapse video of one species becoming another (a single organism never evolves into a different organism and you should know that, although it is interesting to note that all chordate embryos go through a similar developmental process - humans essentially start out the same as lampreys, then develop into something fish-like before acquiring mammalian features and finally human features), but the page itself explains why this evidence is scientific, empirical evidence that does confirm the testable predictions made by Darwin.
Perhaps. But I'm a byproduct of my education and I don't believe evolutionary biology is in the same league as chemistry or physics.
You are correct. In fact, I would say that it is in a far greater league than chemistry or physics. No theory of chemistry or physics has ever found anywhere near the diversity and breadth of applications that the theory of evolution has.
I suspect it's because my professors didn't want to resort to hand waving complicated explanation that the theory of evolution often entails.
Unfortunately, you are likely correct here as well. Evolutionary biology is a complex field that is difficult to understand properly. Undergrad level courses, apparently even at MIT, don't go over it in near as much detail as it deserves, probably because the sheer amount of information that is disseminated in any biology course, especially in survey courses, precludes going into a great deal of depth regarding any of it, unless the course is specialized to deal with that topic. Also unfortunately, MIT was home to the crackpot that came up with http://mypage.direct.ca/w/writer/hydro.html , the idea that all of the geological and paleontological
evidence for evolution could be explained by appeal to a sieve effect induced by the great flood.
And visit the top science universities in the world, you will see that physical scientists look down on biologists.
That's great to know, but the simply proposition that physical scientists are condescending to life scientists says nothing about the relative scientific value of their respective disciplines. Ask the NSF and other funding agencies where most of their money is going these days and we'll see how much life science is valued relative to physical science.
