Actually, that's not true at all. Directed evolution is explored all the time in the laboratory, and animal breeding produces changes in body form that are greater than the differences between many natural species.
What mechanism prevents (in the words of Wallace) varieties from departing indefinitely from the original type?
Your objection to chance assumes that evolution has a goal, or in the words of Dembski, a specified outcome that it is required to reach. But this is not the case. Evolution is a drunkard's walk, constrained only by the fact that some steps terminate the walk for a particular individual.
In order to argue that a random walk will not produce a branching tree, you have to ignore several things that are observed to happen.
First, genetic change does occur and is passed down to offspring. Second, the process of reproduction creates far more offspring than survive to reproduce. Third, the selection of which offspring survive is not completely random; it is biased. Some traits are statistically better than others at surviving and reproducing. Fourth, populations are occasionally divided by barriers the result in two non-interbreeding populations.
The sequence of change, followed by differential reproductive success, constitutes an algorithm, which combined with barriers that divide populations, produces a branching tree.
You asked me what natural processes required for evolution have yet to be observed through scientific methods. The answer is...chance.
This statement is so silly that I have to assume it is a typo. First of all, chance is not a requirement for evolution. Evolution could occur if genetic change followed a sequence rather than occurring randomly. It is not the source or cause of change that shapes populations; it is the outcome of change that shapes populations. This has, in fact, been demonstrated in the laboratory.
But you know all this, because you have a degree in biology.
“....Actually, that’s not true at all. Directed evolution is explored all the time in the laboratory, and animal breeding produces changes in body form that are greater than the differences between many natural species....”
I never said that there wasn’t an active effort underway to explore evolution in the lab. I know that. What I said was that we’ve tried to reproduce certain aspects of evolution — in the lab — and have not succeeded.
“Evolution” must account for common descent of all life across all time. Considering the complexity of just one single organism, never mind the complexity of the natural — and purposeful — systems in which living thing reside, that’s a pretty tall order for something as small as chance to explain.
Animal breeding is hardly a worthy bit of evidence to throw up to support an endeavor of that magnitude. Now...interestingly...while the ability of intelligent human beings to deliberately breed a cow with sturdier conformity is unworthy to support the “evolution by chance and totally without purpose” argument, it does show that with purpose and design in mind a knowledgeable designer can successfully create variation that serves a goal.
“...Your objection to chance assumes that evolution has a goal, [...] Evolution is a drunkard’s walk, ....”
No, I object to evolution because it is a notion that necessarily assumes no goal, when I believe creation clearly speaks to “goals”. Despite the fact that all of the earth’s living and nonliving systems (including the organisms that live in them) have been clearly organized to function in complex (not chaotic) systems and cycles, evolutionary theorists continue to stubbornly assert that “chance” is responsible for everything and that the way things are today is really...nothing more than a happy set of accidents.
Or, I suppose, to extend your own analogy...The drunkard, despite not being in possession of his faculties and unable to avoid falling off the sidewalk and be hit by a car at any given moment, has still somehow managed to paint a set of beautiful masterpieces, build an amazing series of complex architectural features that are uniquely well-suited in both form and function, and design a vast array of complementary and supplementary systems and networks...all while wearing a blindfold.
It’s the blind watchmaker explanation, recast with a bottle of Thunderbolt. It just doesn’t work.
“First of all, chance is not a requirement for evolution. Evolution could occur if genetic change followed a sequence rather than occurring randomly. ...”
But we’re NOT talking about genetic change following a sequence - that diverts the discussion down a philosophical rabbit trail. Despite your restatement of the 4 mechanisms of change using more technical jargon, you didn’t say anything I hadn’t already covered. Nor does anything there really diminish the role of mutation as the implicit or explicit starting point for evolutionary change.
Mutation remains the first mechanism of evolution - followed by some combination of genetic drift, migration, and natural selection. Mutation, as I have already said...rather patiently...is about chance. Evolution is premised upon chance.
“...But you know all this, because you have a degree in biology. ...”
Oh. Look. A potshot. Again.
"the wonderful progress of the United States, as well as the character of the people, are the results of natural selection" - Darwin, Descent of Man, ch.5. Is the "progress of the United States" a genetic change? It must be if it arose by natural selection, as Darwin says. What about the "character" of the american people? Is that genetic? What are the loci for these genes?
Second, the process of reproduction creates far more offspring than survive to reproduce.
This assertion is nonsensical. Are there far more Norwegians born than can survive to reproduce? Is your pet cat busy producing "far more offspring" than can survive? What about you?