Evolution of the the Bacterial Flagellum

[Esquilax]

That's certainly part of it. However, even if some of the proteins they found (for example FlgBCFG), those are homologous to each other! I'm no biologist, but I thought the purpose is to show homologies with precursor proteins, not flagellum proteins. I know all of this does not make ID more plausible, but to just say "It evolved and that's it" is not enough. Interestingly, this is what the authors said in the paper:

Notwithstanding the good scientific reasons for new forays in this direction, the lack of a scientific literature on flagellar evolution (emphasis mine) also has another undesirable consequence — it leaves open the suspicion among members of the public that maybe there is some mystery here, that maybe the ID proponents do have a point. Although all experts in this field agree that there is nothing to these claims, as Wilkins has recently pointed out , in these politically charged times, it is no longer enough to say, for example, that bacterial flagella evolved and that is that. Instead, scientific experts have to engage with a skeptical public.

It's like this: the fossil record is resplendent with examples of transitional creatures. The genetic evidence is incontrovertible. Evolution has been observed to happen in both laboratory conditions and otherwise. It's happening. So, given that we know that it's happening for every other organism on the planet, with a vast array of data to back that theory up, the fact that we may not know the exact mechanics of it with regards to this singular thing yet is not a huge problem for evolutionary biology. It's just an admission that we're not omniscient; saying "it evolved and that's it," would be shortsighted I agree, but saying "it evolved" is the only real conclusion we can come to based on the sheer weight of evidence out there.

Meanwhile, we have intelligent design, which only barely classifies as science. Intelligent design, which has been proven wrong on almost all of its salient points, offers no predictive power, no falsifiability, no way to test the things it claims and moreover, that offers no hypotheses of its own beyond negative arguments against evolution. The entirety of the claims made by the design movement boils down to "this couldn't happen by evolution, and therefore creationism." Real science doesn't work like this. Real science has predictive power such that it can be tested and falsified; all intelligent design is, is chaff to obscure the very real evidence for evolution, nothing more.

Even if we never, ever found a single other possibility for flagellar evolution, that doesn't make intelligent design true. At this point, almost nothing would prove intelligent design true, because by and large the proponents of it aren't interested in proving their own claims, just in proving false the claims of their opponents. Because intelligent design isn't real science, it's what happens when anti-science morons think that putting on a lab coat makes them credible.

We shouldn't stop studying and start assuming, though; that's the purview of ID, after all. But there's absolutely nothing wrong with simply assuming that this one creature isn't the exception to a rule that's been proved right over and over, across large swathes of the earth's biological history.