Like I knew of the concept but it never fully made sense to me. Like I always tried to understand the kind of thought processes that was entailed by labeling someone's thoughts as such, but it always eluded me.
I think I finally get it though and now I realize I see it a TON on reddit. It's the primacy of theory over reality. Like it is when you take a theoretical schema, which may be correct, and over apply it to data to the point that you disregard data that may contravene the theoretical framework. This results in a static view of the world in which everything must be reduced to static frames. Like the idea of transitional fossils that creationists used to harp on back in the day. All fossils are transitional because all organisms are part if a constantly changing and evolving population. So I guess in a way it's kind of like cargo cult empiricism.
I dunno just some rambling thoughts, bored at work.
Assuming vulgar empiricism means what I think it means, it's a really important thing in understanding how science in general works. Many people think that science and empiricism are the same thing (and will look at you like you have three heads if you say otherwise), but empiricism is much, much older than what we would recognize as science.
Aristotle was very much an empiricist, and scholars during the middle ages were completely infatuated with him and his empirical approach. They also made very little progress in advancing their understanding of the world, falling behind advances in the Islamic world. Because the concept of constant progress in understanding the world, which we take for granted today, isn't inherently tied to empiricism. To these scholars, knowledge came from observing the world, and Aristotle observed the world really good, so... that's it. It's done. There's no process of reexamination, refinement, or testing of concepts, the ideas that a person would arrive at simply by looking are correct, final, and complete. Maybe you could find an animal that Aristotle never encountered, but if Aristotle dissected a frog and wrote down "this is how frogs work" then you straight up just don't need to study frogs anymore. Because if you dissect a frog you'll just see the same thing he did and arrive at the same conclusions. So now all that's left is to read Aristotle.
The process of testing and refinement of ideas really became part of the process around the time of Copernicus, and was influenced in a large part by the development of the telescope. The telescope made people more aware of the limitations of our senses and the possibility of refining our instruments to detect things that previous scholars had missed, and those new observations could lead you to arrive at ideas that contradicted those previous scholars. People were reluctant to move away from the geocentric model, but better instruments and data meant that they had to make the model more and more complex to try to make it line up with the observations. It's worth noting that geocentric models still worked in that they could tell you where things would be at a given time, but they required all sorts of assumptions that didn't really make any sense, and were much more complex than the heliocentric model. So the victory of heliocentrism wasn't actually a matter of, empirically, the data shows that this model is right and that one is wrong, but rather, it won because it was simpler and made more theoretical sense. That marked a major shift in Western philosophy away from vulgar empiricism and towards something that we could actually call science, including a more theoretical element and the assumptions that we now take for granted.