Is the theory of evolution a fact?

[Biophreak]

Evolution is a fact, its mechanism, that is how and why it happens, is a theory.

You have this backwards. Evolution is a theory to explain the progression towards or away from complexity in an attempt for an organism to me most adapted to its particular environment.

That natural selection occurs is a fact. Natural selection is the proposed mechanism by which evolution is driven.

Richard Dawkins outlines this clearly in his book, "The God Delusion" (a great read!). Natural selection isn't a force so much as it is a result. For natural selection to take place you must have:

1) Replication
2) Heredity
3) Variance
4) Selection forces

In any system, living or otherwise, when these four criteria are present, natural selection WILL occur. Not MIGHT occur, but WILL occur. It is an inevitability, analogous to how on Earth, if you let go of a ball, it WILL fall down.

 

[russ_watters]

You have this backwards.

No, he doesn't have it backwards. Here's another way to look at it: In science, theories are often named after the factual observation they are intended to describe. Some examples:

Newton's theory of gravity is named for the physical phenomena known as "gravity". Its purpose is to describe the functioning of that phenomena. The phenomena of "gravity" is known to exist - it is a fact. That is, indeed, a requirement under the definition of "theory".

Plate techtonic theory is a theory discussing the observed fact that the continents of the world float on plates above the Earth's mantle.

Chaos theory is a theory discussing the phenomena of highly complex (chaotic is almost slang there...) systems.

Evolution is a theory to explain the progression towards or away from complexity in an attempt for an organism to me most adapted to its particular environment.

That's not a very good way to describe it, but what you are trying to describe there is the observed phenomena of evolution.

When Darwin first proposed the theory, it required a logical leap. He saw different, similar birds and concluded that they actually had related ancestors. He didn't have access to the tree of life to know for sure (ie, via dna or fossil record). Now we do have access to that tree (in large part). Now we do know that birds that appear to be related are related via common ancestors. That observed phenomena - that animal species change over time - is called "evolution".

So similar to the way I described it above:

The theory of evolution seeks to explain the observed phenomena of evolution.

 

[Biophreak]

No, he doesn't have it backwards. Here's another way to look at it: In science, theories are often named after the factual observation they are intended to describe. Some examples:

Newton's theory of gravity is named for the physical phenomena known as "gravity". Its purpose is to describe the functioning of that phenomena. The phenomena of "gravity" is known to exist - it is a fact. That is, indeed, a requirement under the definition of "theory".

Plate techtonic theory is a theory discussing the observed fact that the continents of the world float on plates above the Earth's mantle.

Chaos theory is a theory discussing the phenomena of highly complex (chaotic is almost slang there...) systems. That's not a very good way to describe it, but what you are trying to describe there is the observed phenomena of evolution.

When Darwin first proposed the theory, it required a logical leap. He saw different, similar birds and concluded that they actually had related ancestors. He didn't have access to the tree of life to know for sure (ie, via dna or fossil record). Now we do have access to that tree (in large part). Now we do know that birds that appear to be related are related via common ancestors. That observed phenomena - that animal species change over time - is called "evolution".

So similar to the way I described it above:

The theory of evolution seeks to explain the observed phenomena of evolution.

Sorry to say, but you are wrong in several parts of your statement.

First, he DOES have it backwards. Evolution is first and foremost a theory, hence the name "Theory of Evolution", which you will find in any biology textbook. By the scientific definition, a theory is an assertion that is made and backed up by a set of observable phenomena and experiments.

Second, in regards to gravity: You say that "the phenomen[on] of gravity is known to exists- it is a fact". This statement is false. The correct statement would be to say that the phenomenon that objects tend to fall towards a center of mass is a fact. Gravity, as it stands, is not a law or fact. It is still a theory.

Third, in regards to your statement, "but what you are trying to describe there is the observed phenomena of evolution. ": No, I am trying to describe exactly that which i wrote.

Fourth, in regards to "The theory of evolution seeks to explain the observed phenomena of evolution.": You are incorrect in saying this. The theory of evolution, which is proposed to be driven by natural selection, is an extrapolation of the observed phenomenon that accumulating mutations result in new phenotypes. Though this may sound like splitting hairs, there are important differences between the two statements. The reason what you are saying is wrong is that you cannot 'observe evolution'. Evolution can never be observed in a single organism- that is because single organisms do not evolve. Evolution in the correct sense of the word is a change in the genetic material of a POPULATION of organisms from one generation to the next. In order to "observe evolution" one would have to have the capacity to observe the entire population of organisms' genomes. At the time, this is very close to impossible to do since observing an entire population's genetics from one generation to the next is not economically or experimentally feasible.

To be clear, I am not trying to argue the semantics here, but many of the things you wrote are widely held (though inherently false) statements about the true (scientific) definition of words, and it IS important to distinguish between correct and incorrect usages of these words. The way that you and I are explaining things is generally very similar, though for scientific discussions, even the use of a single incorrect notion can make your statement false, i.e your statement about gravity being a fact.

 

[russ_watters]

Turns out there is an entire wiki page on this very subject:

The statement "evolution is both a theory and a fact" is often seen in biological literature...

http://en.wikipedia.org/wiki/Evolution_as_theory_and_fact

They also use my gravity example on that page. I found this via a google of the question that turns up tons of other confirmation of what I said.

 

[Monique]

Turns out there is an entire wiki page on this very subject: http://en.wikipedia.org/wiki/Evolution_as_theory_and_fact

They also use my gravity example on that page. I found this via a google of the question that turns up tons of other confirmation of what I said.

That raises the question, what was there first, that wiki or this thread?

 

[russ_watters]

That raises the question, what was there first, that wiki or this thread?

Dunno, but the seven scholarly references attached to that sentence I quoted all have dates attached to them...

Really, it spider-webs out. The first link is actually to the talkorigins page on this subject, which contains a large excerpt from an article on the subject written by Steven Jay Gould. The title: "Evolution is a Fact and a Theory".

 

[Biophreak]

I actually rather think that the wiki supports my point more so than it supports yours, especially in regards to gravity.