You're basically doing the same when you name-drop "a Bayesian revival in the sciences".

That's not remotely the same thing -- I wasn't bringing that up as some kind of substantiation for any argument, while Callahan was mentioning the thing about "a priori crystallography" (???) as an argument.

But one point that keeps coming up is that if you look closely, anything that people have so far come up with that purports to be a "methodological rule of science", can be falsified by looking at one scientist or another, doing something that their peers are happy to call perfectly good science, yet violates one part or another of the supposed "methodology".

So? I was arguing about what deserves to be called science, not what happens to be called science. And yes, people practice "ideal science" imperfectly, but that's no evidence against the validity of the ideal, any more than it's a criticism of circles that no one ever uses a perfect one. Furthermore, every time someone points to one of these counterexamples, it happens to be at best a strawman view. Like what you do here:

As an example being impartial certainly isn't required to do good science; you can start out having a hunch and being damn sure your hunch is correct, ...

The claim isn't that you have to be impartial, but that you must adhere to a method that will filter out your partiality. That is, there has to be something that can distinguish your method from groupthink, from decreeing something true merely because you have a gentleman's agreement not to contradict it.