In "The Miracle Workers" Jack Vance plays with an odd philosophical experiment: a society where "magic" is rational, deductive, and logical (but not scientific) and what we know as science is seen as superstition. Some fantasy writers have attempted that, especially as a way to justify why in their worlds there doesn't seem to be any scientific progress, but I believe Vance is the only one who managed to pull it off. "Superstition" here doesn't just mean "we don't know how it works." The jinxmen (the "wizards") know perfectly well what empiricism (science) means and what they mean when they say that empiricism is superstition.
In the preface of "Jack Vance's Treasury," Vance mentions that The Miracle Workers was sent to Astounding because "John Campbell, the editor, had a predilection for unusual ideas." And unusual it was. The jinxmen, with their hoodoo and mental magic, are, indeed, the "rational" ones in the story. When they say that their "magic" is deductive and rational, Vance isn't joking (well, at least, he is doing more than that,) or merely saying "here magic is science, because reasons." He has built a whole justification for that.
The jinxmen know the laws behind their magic, how it works, and why. They may not know the ultimate cause, but who cares really? They are not "superstitious" because they know when their magic is not going to work and why. The process has a deductive logic to it, whereas science is... just playing around until some "effect" is discovered.
But the limits of jinxmanship are what sets the story in motion; it's the appearance of an enemy they are unable to influence. But unlike other stories where this would have been used as an excuse to present the magic-users as mired in superstition, trying to work their useless magic again and again until the Science Man appears, here the jinxmen (from the start) admit that their Art isn't going to work with those aliens. And if they are reluctant to explain so is because the source of their Art —and, therefore, their power and status— depends (partially) on people believing in it (it's not simple placebo, though.) Their power is described as such:
"What happens when I hoodoo a man? First I must enter into his mind telepathically. There are three operational levels: the conscious, the unconscious, the cellular. The most effective jinxing is done if all three levels are influenced. I feel into my victim, I learn as much as possible, supplementing my previous knowledge of him, which is part of my stock in trade."
The jinxmen deal in irreducible qualities, emotions like fear, hate, rage, pain or bravery, which is why they describe their trade as "logical," because to a considerable degree it is. If the foundations are known, there is no need for "empirical speculation" like "from where do the demons come?"
Everything can be deduced from first principles. But what happens when you are trying to hoodoo a race of aliens with a collective mind which may not even have words for those feelings (or those feelings in the first place.) You cannot empathize with them, and at no level (conscious, unconscious, or cellular.)
From their point of view, science is some bumbling baboon playing with things he doesn't understand. Scientists, therefore, become "mystics," people who don't have answers but search for them anyway, who toy in their laboratories, mixing this with that, trying to see if something happens. That "empiricism," however, is what in the end (even if through sheer luck) ends up saving the humans.
"Undoubtedly the ancient were barbarians. They uses symbols to control entities they were unable to understand. We are methodical and rational; why can't we systematize and comprehend the ancient miracles?"
By "symbols," I presume, he means mathematics and scientific notation, and by entities, he means the laws of nature. That may seem like a preposterous way to define science, but compared to jinxmanship, the charge is not unfounded. Who understands gravity or quantum physics? We can control and manipulate physical phenomena, of course, but our "understanding" of them is unlike our immediate, irreducible, and unavoidable understanding of our own feelings. It makes sense that a society based on such magical performances would have problems understanding (or caring) about "Science." Hence, hoodoo is rational and logic, empiricists are miracle-workers and mystics who toy with strange mathematical entities and write down bizarre arcane formulas.
In the previous post, Nathan Housley says that he feels the story shrieks of message fiction. I can see how that may seem to be the case, but I don't think it is. The setting is purely speculative, and "progress" doesn't appear as the inevitable march of history against superstition (empiricism here IS superstition), but as a fortuitous stroke of luck against an enemy they can't understand.
From what I know of him, Vance seems to have had a distaste for intellectual blowhards, obscurantism, and certain brands of organized religion or theology (he pokes fun at lying priests and religious manipulators on many occasions.) However, I don't think this is a message/ideological work to attack such things because I believe the goal of this story was to play with an idea, something to which he was going to return again and again with his "magic system" in the Dying Earth setting, which apparently is some sort of highly advanced mathematics that works in many dimensions and levels at the same time or somesuch. I have noticed that Vance usually tries to "explain" the supernatural in his stories, how it works or how it may work assuming it was real.
That seems like a great feat of speculative fiction to me, to think "let's assume supernatural powers are real" and then work out a Universe whose laws would allow it, and then see what happens. This short story is an example of that, and he pretty much says that its Afterword (which appears in Jack Vance's Treasury.)
"Strange things happen. Almost everyone has had some sort of brush with the paranomal, even the most resistant and skeptical of persons. [...] In olden times angels and demons were held responsible; to date no one has produced a more reasonable explanation. Phenomena such as telepathy and poltergeist may well be manifestations of different and distinct principles; there may be two, three, four or more such realms of knowledge, each at least as rich and intricate as physics or astronomy. There is little systematic study. Conventional scientists shy away from the field because they are, in fact, conventional; because they fear to compromise their careers; because the subject is difficult to get a grip on; because scientists are as susceptible to awe and eeriness as anyone else. So: the mysteries persist; the lore acccumulates, and we know for sure no more than our remote ancestors, if as much... 'The Miracle Workers' [has a] definite psionic orientation, and [makes] at least a superficial inquiry into certain aspects and implications of telekinesis and demon-possession. I can't pretend to offer enlightenment; there isn't any to be had. The [story], in any event, [was] not conceived as [as] argumentative [vehicle], but simply [reflects] my own fascination with the vast and wonderful reaches of the unknow."
Jack Vance 1970.
[I have no idea why there are so many [ ] there]
I'll be honest, that text came a bit as a surprise to me even if I had sometimes suspected it as much. Vance's fascination with these subjects snf his constant attempts to mix science with "magical" elements always seemed too... methodical to me, always going to the extremes of building weird but detailed explanations and philosophical points to justify why such phenomena may occur or how they may work.