Evolution is evident today in how bacteria evolve to resist antibiotics.That bacteria are capable of developing resistance to antibiotics is completely non-controversial, as is the fact, for example, that Americans are on average six inches taller than they were 100 years ago.
These are indeed examples of "evolution," if by that term we mean simply a change over time in the characteristics of a species. And while such changes are evident in their physiological or morphological manifestations, it is also well-documented that they can correspond to changes in the genotype. Of course, environmental factors play a role--and perhaps, at least in the case of human height, a larger role than genetics in the observed changes. Nonetheless, changes in the genetic make-up of a population or entire species have been documented. The generally accepted term for this phenomenon is "microevolution." Again, this sort of change within a species is completely non-controversial.
What IS controversial is whether the same mechanism appealed to in order to explain change within a species (that mechanism being natural selection acting upon gene mutations) can be extrapolated to explain how not only new species but also new families, orders, classes, and phyla came to be. The term given to this larger, hypothetical idea is macroevolution. And the evidence overwhelmingly refutes the idea that macroevolution occurs or has occurred in life's history.
It should be quite obvious that change within a species, for which there is evidence, is an entirely different kettle of fish than all-life-descended-from-a-single-common-ancestor. That's why scientists (and others) actually interested in discovering truth about the origin of life's diversity differentiate between microevolution and macroevolution. If you hear (or read) someone arguing for Darwinian evolution who fails to make this obvious distinction, you can be sure that he or she is being disingenuous (deliberately ignoring the problem), or fallacious (guilty of a critical error in thinking), or both.
Specifically, the informal fallacy generally involved here (as in the argument put forth in the comment left on my blog) is the fallacy known as "equivocation." This is where one changes the meaning of (equivocates on) one of the terms between the argument's premises and conclusion. Here's what the Darwinist argument looks like...
Premise 1: The development by bacteria of resistance to antibiotics is an example of evolution.I hope this is obviously fallacious to you. And the most significant problem with it is that the meaning of the term "evolution" in premise 1, where it refers to microevolution, is significantly different than the meaning of the same term in the conclusion, where it stands for macroevolution.
Premise 2: Such development has been documented.
Conclusion: Therefore, the evolution of all life from a single common ancestor has been proven.
The bottom line is that evidence for microevolution cannot be used in support of the theory of macroevolution. Don't let your neighborhood Darwinist get away with such a poor argument.
In the next post, I'll discuss some of the evidence regarding the limitations of microevolution. In the meantime, here's an example from Hank the Cowdog of equivocation (for my oh-so-sophisticated reader and friend, av8torBob*)...
Drover: Hank, how long's a centipede?
Hank: One foot.
Drover: Isn't that a miracle? All those legs and only one foot!
* I just checked Bob's blog, and his most recent post is on the same subject! Check it out here.