"Evolution" is defined as a change in allele frequencies in populations over time.
Let me try again to show you why this definition of [Darwinian] evolution is utterly inadequate.
Suppose your wife gives birth to a baby boy with blue eyes.
You have just increased the frequency of the recessive gene for blue eyes in the population.
You have also increased the Y chromosome genes.
But no evolution occurred, except by your definition.
Or let us say folks feel the world is dangerous and start breeding pit-bulls. While celebrities want toy dogs so other breeders start breeding miniature dogs. This is not evolution, except by your def.
Or suppose a plant with green leaves suddenly has a mutation for variegated leaves. That would be evolution by your def, and nobody else's. Certainly no scientist would claim they have observed/proven [Darwin's Theory of] evolution, since we have had mutations forever.
Creationists claim that from the Ark, 2 of each land animal gave rise to all other land animals today, through mutation, genetic drift, etc. Even Darwin's finches arose from isolation in the 4400 years since the flood.
The Theory of Evolution is supposed to include something like the following ...
... a process of continuous change from a lower, simpler, or worse to a higher, more complex, or better state ... a theory that the various types of animals and plants have their origin in other preexisting types and that the distinguishable differences are due to modifications in successive generations...
http://www.merriam-webster.com/dictionary/evolution
By your current definition, nobody would be disagreeing on the topic of evolution, since you have left out all the controversial bits concerning origins.
Darwin observed micro-evolution and postulated macro-evolution, from one ancestor.
Time to define terms and clarify the thinking here.
When people talk about "evolution" in the context of "evolution vs. creation" what they mean is common descent by means of natural selection acting on variations. That is what I mean when I say "evolution."
But when pressed for evidence of common descent, the evolutionist starts talking about natural selection. In other words, the evolutionist is talking about the mechanism, not what actually happened.
No creationist I know disagrees with natural selection. The disagreement is on whether all life biologically descended from a common ancestor.
So next, the evolutionist starts talking about the fossil record, claiming it provides evidence for evolution. The creationist points out that it doesn't, and usually the debate either ends or starts over at the beginning.
So guys,
Let's indeed clarify the terms, shall we.
Evolution - gradual change over time
Biological evolution - gradual change of life forms over time
The concise and more specific definition that is generally accepted in science, is the one Jose gave earlier, which takes into account our understanding of genetics. This knowledge wasn't available during Darwin's day, and yet biological evolution was still perceived. What a world.
The issue that you have (which you seem to think is somehow controversial) is about Common Descent. Now you are perfectly at liberty to declare the involvement of one deity or another in natural processes, but please have the decency to admit that you're just acting upon pure faith and not scientific curiosity, because otherwise, you'd find nothing wrong with common descent and the tree of life.
Since you seem to take issue with the term itself, let's for the purpose of this discussion rename evilution and just call it "descent with modification" or DM for short.
1) DM is real, we know that, not because of fossils, but rather because of real-time observation of all procreation at work. We can see the differences between members of the same "kind", we can see how characteristics and traits are being passed on to the next generation. We can even manipulate them by selective breeding of more suitable crops, domestication of animals and the harnessing of micro-organisms for industrial catalysis.
2) The brilliance of Darwin - The man didn't get everything right, he was, in fact, quite very far from understanding DM. But the riddle he was able to solve (and BTW he wasn't the only person at the time looking into it, just the one credited for publishing his work at the right time) was the question of what drives DM. Firstly it is the principle of natural selection (which you agree with) and the principle of speciation through population isolation (which I hope you agree with)
3) By categorizing the living beings that we see today, we notice the similarities and use those to assign taxonomic hierarchies based on the traits of the various "kinds". We can confirm these hierarchies by comparing the genetic code of these "kinds". BTW this work began long before Darwin, and even without his publications, there already was great puzzlement because of the obvious similarities between us and apes
4) The qualities of DM coupled with our ever increasing understanding of biodiversity permit only one conclusion: rewind a nested hierarchy and you have -
A COMMON ANCESTOR. oh the horror!
And here is the big question, how can we be so sure?
Well, insert fossil evidence. The hypothesis of common descent would require there to have existed in the past, species that line up the DM of every extant species and converge the lineages - aka the tree of life!
5) So what do we find? As we all know the rarity of fossilization prevents us from gaining the complete picture. So far, nonetheless, all fossil evidence fits nicely into the tree and there has been no finding to suggest that the model would be inaccurate. Furthermore, the overwhelming similarities of the cellular mechanisms, metabolisms, genetic "semantics" etc cross-validate that all life on our planet has a single origin.
Now, this is the opportunity for you, my fellow creationists, to come up with evidence of your own, that would not only neatly explain all the known life forms, past and present, but would also demonstrate conclusively that common origin cannot be true.
Until you do, just give us all a break and accept the scientific consensus!
Cheers
PS: "whether all life biologically descended from a common ancestor"
Strictly speaking, this is irrelevant to DM and common descent, as the theory would easily allow for multiple, parallel, trees of life to exist. Moreover, when we go down to single-celled organisms the tree becomes more of a "shrubbery" anyway.
Unfortunately for you, the genetics of very much nearly all organisms alive today is absolutely identical, which does not conclusively prove but renders a SINGLE common origin the likeliest explanation
