More Than Meets the Eye
Carl Sagan once responded to an evolution skeptic with a response that Sagan obviously had given some thought to. You can listen to the question and Sagan’s summary beginning at the [0:24] mark:
Skeptic: How do you explain the switch from asexual reproduction to sexual reproduction?
Sagan: First off, let me say that, that in no way challenges the validity of biological evolution, whether we’re able or unable to explain the fact that many species, by no means all, reproduce sexually today. The Darwinian concept of evolution and natural selection is profoundly verified, not just by the fossil record, not just by the clear experience of artificial selection, but by the record in the nucleic acids, which is obtained by DNA sequencing, in which we can see the similarities and differences of organisms, and trace their evolutionary past—their history.
Sagan begins by explaining that the failure to explain basic and important productions of evolution cannot challenge the validity of evolution. Philosophers call this theory-protectionism. If basic, important theoretical failures can do no harm, then the theory is not falsifiable.
Next Sagan provides three evidences for evolution: fossils, artificial selection and DNA comparisons. Even if all these evidences were as evolution predicted they would not prove evolution. In that case, Sagan’s claim that evolution is “profoundly verified” by these evidences amounts to the fallacy of affirming the consequent.
But it gets worse. For in all three cases, the evidence is not even what evolution expects, but instead contradicts the evolutionary prediction. The fossils do not form an evolutionary tree, but rather reveal abrupt diversity explosions followed by a winnowing due to extinctions. The expected evolutionary tree is turned upside down.
Likewise artificial selection, and the experience of breeders, reveals that species do not simply extrapolate indefinitely as evolution expects. Breeders can be bring about change, but only so much. Darwin had to say that natural selection had something that artificial selection did not. There is no evidence for that, but for our purposes that is irrelevant. The point is that artificial selection does not provide the evidence Sagan claimed it did.
Finally, like the fossil record, the DNA sequences also do not form an evolutionary tree, but instead contradict it. Evolutionists have to prefilter the sequence data, and perform several other intellectual twists, to force fit the data into a tree.
Sagan claimed such arguments profoundly verify evolution. Instead the evidence reveals a host of problems for evolutionary theory.