existentialist,
Thanks for your reply.
>> in science,not all "explanations that make accurate predictions and explain all the available evidence",can be experimented on. That was my point in the beginning.Some can and some can't. For example, no one can perfectly prove the Big Bang theory since it's impossinble to do so,otherwise, we would have to go back to the very beginnning of the universe in order to observe the phenomena itself and provide the data in question.
It is true that it is impossible to re-observe events that happened only one time. However, in this case, there is still mountainous evidence that can lead us strongly toward certain conclusions.
The situation is similar to collecting forensic evidence after a murder. It is true that we cannot actually observe the murder happen, although admittedly this would be the most sure way of getting the facts. However, surely you would agree that evidence such as fingerprints, DNA samples, weapons, witness accounts, and so on can converge to give a clear and convincing picture of what happened. Sometimes the picture leaves room for doubts, but sometimes it points to an inescapable conclusion.
The Big Bang was a one-time event that scattered evidence everywhere. I won't go into that evidence here, but in this sense it is like the forensics example I gave above.
Evolution, on the other hand, has a different quality. It is true that the evolution of life to the current state is something that happened in the past, but evolution is an ongoing process, and it is possible for us to directly observe it happen. Creatures with extremely short generation cycles, such as bacteria, are prime candidates for this, and such evolution can directly be observed. (http://www.talkorigins.org/faqs/faq-misconceptions.html#observe)
Evolution also has some of the "one-time event" quality, inasmuch as any given evolutionary branching event occurred only one time. However, because our planet is so superabundantly covered in life, we are literally drowning in biological data, and upon observation, it all points to evolution. Some of the strongest evidence for common descent comes from DNA analysis, which is as close to a smoking gun as we could hope for. Here are a couple articles I wrote on this topic:
http://www.jehovahs-witness.com/6/86797/1.ashx
http://www.jehovahs-witness.com/6/87238/1.ashx
An important aspect of a scientific theory is that if even one piece of data can be found to contradict the predictions of the theory, the theory must be changed or discarded. After 150 years of intensive investigation, evolutionary theory has undergone some fine-tuning, but probably none that would be apparent to the layperson. It is incredibly successful at describing what we actually see around us.
>> establishing the fact of evolution, and proposing a theory--natural selection--to explain the mechanism of evolution.Well,which one is it? A "fact" or a theory? Evolution is a fact, but the mechanics of it are theory?,hhhmmmmmm.....
This is a critical point. The facts overwhelmingly support the idea that biological change occurs over time. This is what is referred to as the fact of evolution. The theory part is, yes, but how, and why? Even before Darwin proposed Natural Selection, scientists were coming to grips with the idea that life changes over time. Others put forward theories to account for how this occurred, but they were unsuccessful (see Lamarckianism in Wikipedia for more). Natural Selection is the primary mechanism by which evolution is thought to occur. This is the "theory" part.
It is possible to test this theory, for example, by creating two identical populations of bacteria (offspring from the same colony), and putting them in different environments and seeing whether genetic divergence occurs, and whether it occurs in concordance with the predictions of Natural Selection. In fact, divergence - actual genetic change - does occur as individuals compete for available resources and the "fitter" are selected.
>> For example, it can't explain what actually came BEFORE the Big Bang. I feel it ahould be either speculation OR "fact," seoerately not both, mixed together.
Science cannot explain what happened before the Big Bang because science relies on observation, and it is not possible to observe - either directly or via evidence - what happened before the birth of the universe. Actually, I see this as a strong point. There are some questions that science cannot answer, and science does not pretend that it can. A similar question is, how did life begin? The available data is quite scanty, so the best we can do is make educated guesses. (Incidentally, the question of life began is *completely* separate from evolution. Evolution explains how existing life changes across generations.)
Cheers,
SNG
