“I simply do not have the time or energy to read a historical document.”
That’s a shame, because it gives great insight into the nature of the theory. It wasn’t until I read Origin that I began to realize just how circular the reasoning was by which Darwin supported his assertions. The theory has been refined, but it is still dependent on most of those assertions, so it’s good to examine his reasoning if you want to critically examine modern evolutionary theory.
“The problem of trying to define species is that nature did not produce distinct groups of organisms that could be neatly categorized into different species. That isn’t a problem of definition, it’s the essence of biology.”
This is essentially just repeating a tenet of evolution as fact. It’s an assumption that’s absolutely essential to evolution, so I’m not surprised that it’s usually taken as a given.
Ask yourself, though, how is that scientifically established? What experiment demonstrates that there are not distinct groups of organisms? Darwin inferred this from observation, but didn’t establish it himself, and even admitted in Origin that, if it were found not to be true, it would be very damaging to his theory.
“Speciation is not an event, but a continuously on-going process.”
Yes, of course, that’s a crucial point of the theory. However, by “speciation event” I’m talking in the context of a rapid or significant instance of the process that can be cited as dramatic evidence for the theory. If you are going to cite something as insignificant as a wild bovine becoming a domestic bovine as evidence for evolution, then you’re not providing any evidence for the more radical assertions of the theory, just the parts that everyone agrees on.
“Clearly, humans and finger monkeys are separate species, but if one could go far enough back in time, observing specimens every few generations, one would see the two species eventually converge until they appear to be the same.”
That’s a nice story, but we cannot go back in time, and nobody ever has seen such a thing, so it’s really just a fantasy. Finding a chain of skeletal remains that you can arrange in order of similarity, from monkey-like to man-like, does not establish that such a progression actually occurred as evolution predicts. Similarly, arranging genomes by similarity doesn’t establish that the similarity is due to common ancestry.
“I should also add that no one is trying to “find evidence for Darwin’s ideas.””
Well, in practice, his ideas are simply assumed to be correct, and any evidence that is found is interpreted as if those ideas were correct. So, any new or existing evidence is never critically examined to determine whether it might contraindicate the theory, but instead it is interpreted in the manner which best supports the theory. So, the result is that scientists are fitting the evidence to the theory, even if they are not consciously trying to do so. It’s simply the result of their assuming the theory to be true and hardly ever bothering to consider possible alternatives to it.
“If you take into account cross-breeding forced by humans, then the already blurry idea of species becomes even more muddy.”
Which I would cite as evidence that the idea is faulty, and should be refined in light of our experience.
“When a population is split, the longer the two parts of the original population are separated, the more different they become. At some point, they become different enough to warrant being called different species.”
At what point? This is another of the flaws of the theory. The groupings must be indistinct enough to allow for the idea of macroevolution to be tenable, yet, we observe distinct groups in nature that must be accounted for. So, there is this nebulous, undefined event where an organism undergoing gradual changes suddenly is not able to breed with its closely related organisms. Breeding is not a gradual event, it is a fairly yes/no affair, so the species cannot gradually lose the ability to interbreed.
At some point, they can interbreed, and then, they cannot. This is a “speciation event”, that really hasn’t been documented or explained by scientists. The mechanics of such an event, for sexually reproducing organisms at least, are a logistical nightmare. If a mutation causes the final change, then the first offspring of the new species is not sexually compatible with at least some of the members of the parents species. Since we don’t know exactly how the incompatibilities work, we can’t be sure that the offspring would be compatible with ANY of the parent species. If that were the case, it would simply be a dead end, an effectively sterile mutant.
Even partial sexual incompatibility is a fundamental disadvantage that isn’t taken into account in the evolutionary calculus. A beneficial adaptation that resulted in this kind of speciation would have to be advantageous enough to overcome a fundamental handicap to the essential process of the organism’s survival. Yet, that hurdle never seems to be addressed. Scientists simply pretend it isn’t there.
“These are both evolutionary processes.”
I feel like we’re talking in circles. Have you ever discussed evolution with a critic before? Nobody disputes natural selection, artificial selection, or changes resulting from recombination, or even parasitizing genes from other organisms. When critics speak of something not being evidence of evolution, we’re not speaking of them not being evidence of those processes. We are speaking of them not being evidence for what is sometimes called “macroevolution”, the part of the theory that says all organisms share common ancestry, and all species, no matter how distinct, have arisen from the gradual changes produced by the processes.
So, a wild animal changing as it is domesticated, by well understood and accepted processes, isn’t evidence for macroevolution, which is what is in dispute. Many domesticated animals and plants can still revert back to forms similar or identical to their wild progenitors, demonstrating the relatively minor variations we are introducing by these processes. The variations we introduce can seem dramatic, because we can essentially accelerate the selection process, but we’re not similarly accelerating the proposed processes necessary for macroevolution, such as mutation, so we will never see, say, a cat bred into a non-cat. It simply can’t happen by those processes.
“The fact that two ape chromosomes fused at some point to become one human chromosome isn’t such a big deal, really. The genes are all there in either case, and our genomes are nearly identical.”
We have no real definite knowledge of how much difference in the genome can exist and still allow interbreeding, so the only real test is to try it. We have many similarities in our genomes to gorillas as well as chimps, yet they can’t interbreed with each other, and I doubt either could interbreed with us. Until someone tries it, I guess it will be an open question though. I wouldn’t hold out much hope for a humanzee though :)
Okay, let's just stop right here. When you have to copy/paste or paraphrase the same old anti-science nonsense that's already infesting the web in multitudes of anti-science "creationist" sites, that tells me that you have *no* education in science or the scientific method. It also sends me the message that you have no desire to learn any real science. Claiming that you've read On the Origin of Species and "realized" just how circular Darwin's reasoning was--a meme that is widely propagated on anti-science "creationist" websites--does nothing to convince me that you know *anything* about the theory, either as it was originally proposed by Darwin, or in its current form. If you are going to assert supposedly circular reasoning, can you explain how/why the reasoning is allegedly circular? Hint: science is a cyclical/iterative process; to someone who is clueless, I suppose cyclical could appear circular. But it's not.
Here is an example of circular reasoning:
The Bible is infallible.
Why is it infallible?
Because it is the word of God.
How do you know it is the word of God?
Because it says so in the Bible, and the Bible is infallible.
Notice how there is NO exterior corroboration of any of the assertions.
I will say one more thing about theory. Theory is an explanation of a physical process that is formulated (and refined) on the basis of extensive observation and testing. The physical process--in this case, evolution--does not change because someone made a theory to describe it. Gravity doesn't exist because of gravitational theory. The electromagnetic spectrum doesn't exist because someone formulated the theory of electromagnetism. And evolution did not spring into existence just because Darwin proposed an explanation for it.
Bonus question: what were some of the other theories of evolution, and how did they fail to withstand experimental testing? (For a double bonus, answer that based on real science, and not on what you read at Answers in Genesis.)