The Argument from a Dissenting "Expert" in a Quazi-Related Field

In the discussions on Climate Change and Evolution, I have noticed a common type of argument that, for some reason, has great psychological pull.

Here is an example from ThePoachedEgg:

The article begins, "A world-famous chemist tells the truth: there’s no scientist alive today who understands macroevolution."

Here is an excerpt from the article:

Professor James M. Tour is one of the ten most cited chemists in the world. He is famous for his work on nanocars (pictured left, courtesy of Wikipedia), nanoelectronics, graphene nanostructures, carbon nanovectors in medicine, and green carbon research for enhanced oil recovery and environmentally friendly oil and gas extraction. He is currently a Professor of Chemistry, Professor of Computer Science, and Professor of Mechanical Engineering and Materials Science at Rice University. He has authored or co-authored 489 scientific publications and his name is on 36 patents. Although he does not regard himself as an Intelligent Design theorist, Professor Tour, along with over 700 other scientists, took the courageous step back in 2001 of signing the Discovery Institute’s “A Scientific Dissent from Darwinism”, which read: “We are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged.”
On Professor Tour’s Website, there’s a very revealing article on evolution and creation, in which Tour bluntly states that he does not understand how macroevolution could have happened, from a chemical standpoint (all bold emphases below are mine – VJT):

As well as the article's quote from Dr. Tour:

Although most scientists leave few stones unturned in their quest to discern mechanisms before wholeheartedly accepting them, when it comes to the often gross extrapolations between observations and conclusions on macroevolution, scientists, it seems to me, permit unhealthy leeway. When hearing such extrapolations in the academy, when will we cry out, “The emperor has no clothes!”?

…I simply do not understand, chemically, how macroevolution could have happened. Hence, am I not free to join the ranks of the skeptical and to sign such a statement without reprisals from those that disagree with me? … Does anyone understand the chemical details behind macroevolution? If so, I would like to sit with that person and be taught, so I invite them to meet with me.

The article concludes:

In a more recent talk, entitled, Nanotech and Jesus Christ, given on 1 November 2012 at Georgia Tech, Professor Tour went further, and declared that no scientist that he has spoken to understands macroevolution – and that includes Nobel Prize winners! Here’s what he said when a student in the audience asked him about evolution.

I will now summarize the argument:

1. Dr. Tour is a very successful scientist, respected in his field of chemistry.
2. Dr. Tour claims that he does not understand how macroevolution could take place from the perspective of a chemist.
3. Dr. Tour claims that evolutionary biologists also don't understand how macroevolution could take place.
4. Therefore, it is reasonable to think that macroevolution didn't take place. If Dr. Tour thinks so, then certainly others can be justified in thinking so.

Here is why this argument is useless: If we allow this type of argumentation to be valid, I can simply make the same argument:

1. Dr. Dylan Schwilk is a highly successful scientist, respected in his field of plant evolution and ecology.
2. Dr. Schwilk claims that he DOES understand how macroevolution could take place.
3. Dr. Schwilk claims that evolutionary biologists DO understand how macroevolution could take place.
4. Therefore it is reasonable to think that macroevolution did take place. If Dr. Schwilk thinks so, then certainly others can be justified in thinking so.

Then I could proceed to do the same thing, making the argument with every scientist that does and doesn't support macroevolution--and we would come out with a huge majority in favor of macroevolution (including many on par with Dr. Tour--except with PhD's actually in the field of evolutionary biology).

If ThePoachedEgg's argument against macroevolution is valid, then my argument for macroevolution, using the EXACT SAME reasoning, is more valid. I can give more anecdotes about impressive scientists who do accept macroevolution, understand how macroevolution could happen, and think that other scientists do understand how macroevolution could happen.

Does this mean that dissenting scientists are never right? Obviously not! Dissenting scientists can totally be right--but the thing is, they need to have evidence and arguments that support their position. You can't just accuse an entire field of scientists of "not understanding their field", like ThePoachedEgg does, and expect rational people to believe you.

Dissenting scientists, with solid evidence, win Nobel Prizes. Good evidence and good arguments win in science--not anecdotes from dissenters in separate fields who have epiphanies about the supposed lack of understanding present in the majority of scientists in the actual field being discussed. If evolution isn't supported by the majority of evidence and arguments, collect your Nobel Prize, ThePoachedEgg.