Why do we say "evolutionary theory" instead of "evolutionary hypothesis"?

Question

I have always been taught that a hypothesis must be tested in order to make sure that it is 100% accurate before it becomes a theory. As far as I know, no experiments have been done to prove evolution. Also, why do we call it the "big bang theory" if it's never been recreated and studied? Can anyone shed some light on this subject for me?

"I suspect that you have in fact been manipulated by Fundamentalist Christians into believing all sorts of nonsense intended to support creationism."

I was not trying to question the validity of evolution, I was just trying to understand the terminology used with science.

I'll agree with all of you that say I've been taught wrong; the only science class that I had an intelligent teacher in was physics.

Answer 1

Laura ... a lot of excellent answers already. Read them carefully.

I can only reinforce gently that if you've "always been taught" that a hypothesis cannot be called a theory until it is 100% accurate ... then you need to undo that learning ... or you will never understand science. Somebody has taught you wrong.

A hypothesis is a proposed explanation for something ... an explanation that has not been tested at all.

Once it has undergone some testing to *falsify* that hypothesis, if it survives that testing, then we start to call it a theory.

We also begin to look for evidence to support that theory ... but we always call it *evidence*, never "proof". This is because you can never prove a theory, only *disprove* it, falsify it.

Evidence can come either in the form of an *experiment* or an *observation*. It is generally impossible to do experiments on the very large (e.g. the sun), or the very distant (like stars), or the very old (like evolution), but that does not mean we can know nothing about these things ... instead of experiments we do *observations*. (That said, we HAVE done experiments to verify short-term evolution in the laboratory, and have even seen species branch into new species in the laboratory.)

So a theory is just a hypothesis with a lot of evidence. The more evidence (and the more tests it passes), the stronger the theory.

NO theory in science is EVER considered 100% accurate or proven. You prove things in mathematics ... you don't prove things in science.

So evolution falls in the category of a theory with a lot of evidence ... a LOT of evidence. Evidence from fossils, genetics, DNA, vestigial structures, homologies, embryology, bacteriology, virology, biogeography, etc. It has passed tests such as that presented by the discovery of DNA ... had different organisms (e.g. plants and animals, or reptiles and mammals) had a different system for genetics, evolution would have failed an important test. Evolution predicted that they would all have the same genetic basis ... and they did.

Similarly, the Big Bang falls squarely in the category of theory. It was originally just a hypothesis to explain the discovery that the universe was expanding. But it made predictions such as the existence of background radiation in the universe, and specific proportions of light elements in stars, that the distributions and formation of galaxies. And it passed all these tests, that would have *falsified* the Big Bang had it failed.

So evolution and the Big Bang have long graduated past the "hypothesis" phase and are squarely in the "theory" phase ... and evolution is currently considered one of the strongest, most tested theories in the history of science.

Answer 2

I think the problem you are having is understanding the word theory as science uses it. The word theory means, basically, 'explanation'.
The theory of evolution explains the fact of evolution. And yes, as far as science is concerned, evolution is as much a fact as gravity.
It has been observed in real time as well as traced through the fossil record and through DNA comparisons.

A theory does not become a fact or a law. A hypothesis does not become a theory. A lot of people have this misunderstanding of the scientific method.

Lots of experiments have been done on evolution, and lots of observations have been made. Jonathon Wiener's book "The Beak of the Finch" is a good study, as is "At the Water's Edge".
There are many many more.
www.talkorigins.org is a good place to start. The FAQ will answer some of these basic questions.

Answer 3

No theory is 100% certain.  Newton's Laws of Motion were a very scientific theory.  They are wrong, which is to say that they are not 100% accurate.  However, they are a very close approximation under conditions of speeds much smaller than the speed of light, masses considerably smaller than stars, etc.  The approximation is so good that you can't tell the difference under most circumstances of interest, so almost all calculations of orbits of space probes and so forth use Newton's equations even though they are incomplete.

Einstein's theory of General Relativity is similarly a theory, despite our inability to completely test it.

In science, "theory" is a term of art which means something quite different from common usage.  Most people use "theory" and "hypothesis" almost interchangeably.  In science, a "theory" is a model which attempts to explain the currently available data and, because it is a model, makes predictions about what will be found in the future.  You do not have to recreate something to derive valid scientific information about it, any more than you need to kill someone all over again to prove a theory about a murder weapon.

Evolution is a valid scientific theory because it predicts the kind of things we find.  For instance, the age of various fossils predict that we will find an intermediate form in rocks of intermediate age.  Paleontologists see where there are sedimentary rocks of that age, go where they are, and voila! they find an intermediate form of the organism of interest.  Evolution also predicts that you will NOT find many things, like fossils of rabbits in Precambrian rocks.  Pull a rabbit fossil out of the Burgess shale, you'll disprove a lot of evolutionary models.

The Big Bang is a valid theory because it predicts the observations we make:  the universe expands, and the early (far away) universe looks very different from today's.  The eerie uniformity of the universe led others to hypothesize that it had grown from a very small, very consistent space in the first sub-nanoseconds of its existence, and from this they predicted that the fossil remnants of quantum density fluctuations in that unimaginably hot early universe would be detectable today as small variations in the temperature of the Cosmic Background Radiation (CBR).  Variations matching those predictions were found, and confirmed by later tests.  Google "Wilson Microwave Anisotropy Probe" for more on this.

It's the piles of confirming data which makes it very hard to come up with a theory which is more consistent with observations than the Big Bang and evolution.  Even if you are religious, you should think twice about it:  if the one you worship didn't make the universe, this earth and even you this way, why'd they go to such enormous lengths to make it look like they did?  Worse, if you really think they did, is a pathological liar worth your devotion anyway?

Answer 4

>>>>I have always been taught that a hypothesis must be tested
>>>> in order to make sure that it is 100% accurate before it
>>>> becomes a theory.

Sorry, you were taught wrong. Everything in science must be open to falsification, and hence less than 100% certain. Once something becomes 100% certain it ceases to be scientific. Everything has varying degrees of certainty but that certainty never reaches unity.

>>>As far as I know, no experiments have been done to prove
>>> evolution.

Firtsly you need to understand that science experiments are NEVER done to prove anything. NEVER. EVER. UNDER ANY CIRCUMSTANCES.

It is very important that you understand that. A scientific experiement seeks to DISPROVE an hypothesis, never to prove it. If an experiemnt fails to disprove an hypothesis then the hypothesis is strengthened. That is it. It is never proved.

There have been countless experiements done that have attempted to falsify evolution, an none have done so. Because of that evolution is as strongly proven as anything in science. There is far more scientific "proof" of evolution than of gravity or of the heliocentric solar system.

>>>>>Also, why do we call it the "big bang theory" if it's never
>>>>> been recreated and studied?

Because it has been subjected to numerous attempts at falsification and none of them have succeeded.

>>>>>Can anyone shed some light on this subject for me?

Any scientist could. Your confusion stems entirely from misunderstandoing what science is and how it works. I suspect that you have in fact been manipulated by Fundamentalist Christians into believing all sorts of nonsense intended to supprt creationism. Hence your belief that a scientific hypothesis has to be 100% accurate when in fact anyhting that is 100% accurate can not eb scientific, by defintion. And your belief that scientific experiments seek to prove when in fact they seek to do exactly the oposite: they seek to falsify.

Answer 5

That 100% accurate is a fallacy. Gravity and electromagnetism exceed 99%, but would fail by your criterion. Recreation in the laboratory isn't a standard either. A hypothesis makes predictions. If sufficient predictions are confirmed in nature or the laboratory, then the hypothesis is called a theory. If you can do it, great, but if you can't, there are other ways to test the hypothesis. Relativity was confirmed by observiving starlight that bent around the Sun during an eclipse.

Answer 6

The ever expanding universe is one of the facts supporting the big bang theory. Look around you, read a little more and further your education. To many answers here dealt with your questions as they are; the baseless speculations a a child.

Answer 7

100% accurate would make it a fact. A hypothesis is an idea. It becomes a theory when there enough evidence to make very likely.

Answer 8

a lot of data supports it. nothing can ever be proved 100%, but a hypothesis becomes a theory when it is well-tested. look into the studies of the galapagos finches for just one example out of hundreds. it's perhaps the most famous.

Answer 9

It is a theory because there is a lot of scientific evidence that supports it. Many experiments have been performed with results consistent with the theory of evolution.

Best wishes.

Answer 10

I think it's because the word "theory" is just simpler to say than the word "hypothesis."
It's really just an argument of semantics - neither word denotes a proven or verifiable fact or scientific law.

Some theories are simply excepted based, not on experimentation, but on the presence of evidence and the absence of any scientific facts or phenomenon which dispute them.

If there is a religious overtone to your question, I refer you to a quote from Albert Einstein:

"Science without religion is lame, religion without science is blind."