Oh boy. Music theory, as such, has no "rules," and so of course Bach did not invent them. Music theory is a descriptive enterprise, which aims to make sense of music as composed/performed/enacted by humans. (I have a PhD in music theory.)
Bach's chorales were functional music for the Lutheran church, and to the extent that they form any sort of "rules" in music theory, it comes from the fact that they have been used to teach harmony for a long time (since at least the 1940s, as evidenced by this article). The reason for that isn't so much that they're prime examples of Western common-practice harmony, but rather that they have a homogeneous texture that's easy to use in classrooms, because they're easy for one person to play at the piano or for students to sing.
Recent music theory pedagogy has largely been moving away from the reliance on Bach chorales to teach harmony, especially as music theory has taken a broader perspective on what music we should be studying anyway. Studying the Bach chorales is just fine if you want to know about how Bach used harmony, but there's a whole lot of music in the world, and there's no meaningful sense in which Bach's music intrinsically defines a set of rules any more than Mozart's or Clara Schumann's or AC/DC's or Meredith Monk's defines a set of rules.
I'm curious, what is music theory pedagogy moving to?
Although as a PhD you obviously know the subject much better than I do, I'll venture a tentative dissent, mostly because I'm curious what your rebuttal will be.
As an undergrad I took a two-course sequence in music theory, I loved most of it. I still remember nearly everything I learned, and twenty years later I was able to more or less reproduce one of my compositions from memory.
Our professor promised us that at the end of the semester we would compose four-part chorales and sound like Bach. I flat-out didn't believe him, but indeed I was able to compose something I was happy with. Overall, at the end I felt like I to a large extent I understood music -- much more so than I initially believed to be even theoretically possible.
By the end of the second semester, as we got into the twentieth century, the "rules" got broader and broader, and the course seemed to get vaguer and vaguer. Although I love twentieth century music, I stopped enjoying the class: different compositions had less and less in common, and there didn't seem to be any large-scale "theory" to be explained. Every piece had its own theory, and I didn't feel like I "understood" anything at all. Rather than attend class, I'd rather just go to a concert hall.
I certainly agree that there are a tremendous variety of musical traditions, many of which arose in places other than Western Europe. Calling it "music theory" is a disservice, when what's being explained is the theory of a single one of these traditions. Nevertheless, I'd rather study one of them in depth than take a broad survey.
I'm not sure what your dissent is, so I'm not sure how to respond to it. I think you're saying that you had a good experience in your music theory classes, which used Bach chorales, and you wouldn't want to discard that experience in favor of a shallower, broader curriculum.
If so: that's not really what I'm saying at all! Even in courses that focus primarily on, say, Western common-practice harmony (as many basic undergrad theory courses do), you're likely to find a much broader variety of music being taught than just the Bach chorales. That's partly because the field as a whole has been moving away from strict adherence to the traditional canon, but also more basically it's just good pedagogy. That is: most music that students play isn't going to be four-part homophony, and so learning to do harmonic analysis of string quintets or saxophone quartets or lead sheets provides a much stronger grounding about how harmony works in real music -- even if you circumscribe harmony quite strictly as "harmony as deployed in Western common-practice music betwen 1700 and 1850."
Disclaimer: I left the field and have been employed full-time as a software developer for more than 5 years, and pedagogy isn't an area of the field I follow closely. A good recent example is the open-access textbook Open Music Theory (https://viva.pressbooks.pub/openmusictheory/); perusing the examples there I think will be a good demonstration of the breadth of both styles and composers that's pretty representative of current pedagogy, even without radically altering the aims of the undergraduate music theory curriculum (which is also happening).
It seems I perhaps misunderstood you and was dissenting against a strawman! Certainly, your second sentence accurately characterizes my point of view.
I remember that our textbook (Kostka and Payne's Total Harmony) had a lot of examples other than Bach chorales, and if I recall correctly the homework exercises did too. The composition exercise I remembered 20 years later was something vaguely similar to a Bach invention. That said, chorales were used quite heavily -- perhaps because they were the simplest interesting examples that illustrated the theory.
My professor wrote out music at the chalkboard during class; he even had a special chalk holder that held ten pieces of chalk, to produce a grand staff. I suspect that other types of music might be less well suited to chalkboard lectures, but that seems to be a trend in academia anyway. I'm a math professor, and we seem to be among the few holdouts in that regard.
Anyway, thanks for the textbook link, I will have a look!
The thing is, all those traditions blend together. You can't say much about the last century of music without talking about jazz, rap, breakbeats, et cetera, and formal western education has just barely figured out those exist. You can go deep in what's taught in formal Western theory education, but you'll miss out on a lot, and you won't be able to make sense of most music.
The longer ago it was, the more the rules of an era of music get codified. You can run the four-part chorale rules like an algorithm.
But it's not just that - prior to Beethoven, composers were seen as not having some internal genius, but were praised by their ability to channel some kind of divine source of music - this view makes music pretty homogeneous for any era. I see a similar (arguably more extreme) outlook in many subgenres of EDM, the music isn't for stroking the producers ego but serves a purpose, the best can make something engaging in a hyperspecific style.
Coming from the increasing individuality in romantic era, 20th century explicitly tried to break those rules and one group explored ideas from folk music (Bartok, Stravinsky, Debussy) and another tried to form new ones from first principles (Schoenberg). In my opinion the latter group mostly failed - maybe they assumed rules come before music, instead of rules being written afterwards to describe music?
I think the "music theory" that will come to define our current era is the same kind of post-modernism that defined literature and art - bands that use different genres like people used to use different instruments, music that explores how rules relate to finished product (Serialism), how fundamentally different recorded music is compared to live performances, sampling, or the exploring artifacts of recording/production/codecs (Alvin Luciers I am sitting in a room/Steve Reichs tape loops/Paul Lanskys Idle Chatter, respectively).
What these all have in common is stepping outside of working in a singular "music theory" and instead working with "music theories". I like this, but not everyone does - this way of thinking about music can become detached from the actual musical experience leading to something like Punk, which then gets quickly subsumed by the thing it was rebelling against.
As another former music student turned engineer I think the breakdown comes from the misinterpretation of "rule" which could better be called "practice" or "style."
My barely-above-pedestrian take is that music theory is an analytical exercise that tries to separate order and patterns from the spontaneous discovery of what "sounds good" in a piece so that the practice can be reapplied to another. The rules of theory aren't really rules, they're a taxonomy of practices exercised by composers and musicians that came before us. And what works changes with the taste of audiences.
A great example to me is parallel octaves, fourths, and fifths. You would be hard pressed to find popular music composed in the 20th century that didn't make liberal use of those, and the technique for writing and playing them is so commonplace it makes no sense to call it a "rule" to avoid them.
That's really interesting. I believe that's the hallmark of a mature field, where it starts bumping up against the limits of understanding in an almost fractal way.
People who have lived the field for long enough can ignore all the curlicues and find a beating heart. Anyone coming in fresh is hammered with detail after detail.
I've noticed something similar with the game I play, Dota 2. It's obv not as rich or beautiful as music, but it's been around for a few decades already, and skill is percolating through the community in a beautiful way. Years and years of muscle memory means people can forget about all the minutae and practicalities and just play.
And if anyone has time for a longer explanation, Adam Neely did a great video about "music theory" - sorry, I mean "the harmonic style of 18th century European musicians". It's worth watching. https://youtu.be/Kr3quGh7pJA
Academic music theory is descriptive. But it's a bit like Latin. You don't learn Latin to speak it, you learn it to understand the foundations of other related languages. It makes it easier to learn them because you have a ready made meta-template for grammar and vocabulary.
Informal music theory is absolutely prescriptive. You cannot write music in a recognisable genre without following the rules of that genre for instrumentation, production, use of rhythm, harmonic colour, melodic form (and sometimes specific melodic cliches), vocal/instrumental stylings, arrangement choices, and decorations.
All of those are invariants for genre. Some of the options cover a wide space of potential choices, but anything outside a genre boundary is very obvious and most people can hear it instantly.
Of course these rules are rarely written down, and most musicians pick them up by ear.
The only difference with Bach etc is that attempts were made to write down the rules. These became Music Theory™.
But in fact the rules don't come close to describing what Bach etc were doing, so they're mostly a poor and misleading attempt. Recently people like Gjerdingen have been expanding on traditional academic theory by going back to the original historical sources - not just the music itself - and examining what and how composers of that period were taught. And sometimes why.
Meanwhile naive statistical analysis is pointless and even stupid. Baroque music is tightly structured and all the elements interlock. So saying "The bass moves by step 50% of the time" is a non-fact.
So - yes it does. But the problem is knowing why at that particular point in that particular piece. And statistical analysis won't tell you that.
I find it interesting that all of your examples to help define the broadness of musical theory as you see it are all, themselves, descended from western musical thought. That might speak to the point being made in a different way than any of us consider it.
Fair point; that's partly my own bias (I know basically nothing about non-Western musics), and partly because of the article I'm responding to ("Bach doesn't tell us anything about gamelan music" isn't an interesting observation).
But also: the majority of academic music theory at the moment does focus broadly on the Western tradition. That's changing, I think, but a quick scan of recent articles in Music Theory Online (https://www.mtosmt.org/issues/issues.php) reveals quite a broad spectrum of music, most (not all!) of it is from the Western tradition.
>Fair point; that's partly my own bias (I know basically nothing about non-Western musics)
Well, let's expand this: how many do in the area HN has the majority of its readers (I presume US and, maybe, Europe)?
I happen to know about a couple of non-western music traditions (because of my geography).
But it's not like those are mainstream or even merely somewhat popular outside of the areas where they are a tradition. It's not like the Austrians listen to ragas, or the Chileans to balkan polyphonic choirs (some might, but then again if we look enough, some would also listen to noisecore or renaissance lute tunes).
I think a trend in contemporary theory is the understanding that western music study is a like a philosophy for how it's been taught and understood for a few centuries. There are a lot of composers that have outright rejected the practice to bring in influences and learn from other cultures in the last half of the 20th century, and more recently schools will teach students some pedagogy from other cultures or perform works from non-western composers as a means of exposure.
The kind of downside is that until the late 20th century, music education (including theory) was basically a master/apprentice relationship and even today we have a lot of that tradition baked into the formal study.
That's a little pedantic. Well music theory in the abstract and academic or niche sense have "no rules", music theory as practiced, has rules, even in pop and rock.
(Otherwise it wouldn't be a "theory" - just descriptions of disjoint practices).
Keys and scales are already "rules". How a triad chord is formed is another rule. Major/minor/modes. Diatonic chords are a rule. Modulations the huge majority of the time follow certain rules. And so on.
Rules might be violated for effect or there might be different spins on them (e.g. blues scales and progressions vs classical music), but there's a foundation of rules that do exist.
It seems like we focus on some exceptions, to be seen as "broad minded" and miss the forest for the trees, the forest being that the majority of music consumed, charting, etc, does follow some rules, and they do come from traditional music theory (with some spins, like different progressions or scales being more common after the blues, some things being more or less common, etc.).
And yes, there are ethnic music traditions with different rules, but as long as we're talking about Europe/North America, the dominant popular music of Central and Latin America, and the majority of the pop/ballad/etc. business globally, there's a foundational ruleset.
Practically, 95% percent of the western population still only (or predominantly) listens to the same kind of music, based on "common practice" harmony - just with the blues and such spices on them on top.
At the furthest from they, they might listen to something like atonal hip hop (though even hip hop tunes had long used samples from earlier pop/rock/jazz/funk tunes) or conventional scales and harmony, usually simplified for the genre.
Man with PhD in subject is pedantic about that subject on Hacker News, film at 11. ;)
There are, of course, stylistic norms, and a lot of those norms are shared across lots of kinds of Western music. The thing I'm pushing back against is a misconception I see a lot that people who teach music theory are arbiters of quality in music, and that music that doesn't "follow Bach's rules" is somehow less good than music that does. (That misconception is probably well deserved, because that is how music theory was presented for a long time. I think that has changed, though, and that you'd be hard-pressed to find someone in the field that holds that position these days.)
Saying music theory has no rules and is purely descriptive, is like saying grammar has no rules and is purely descriptive. These days grammarians have sensibly decided to be descriptive only, but there have been a hell of a lot of prescriptive grammar books over the years.
Well, most popular music follows a few styles. That's not just "popular" as in "top 10". It's popular as in "top 10000".
So, if you want to write music in those styles (say, be a rock band, or a country songwriter, or a German schlager composer, or a fusion jazz player, or a funk-meister), and if you want people to enjoy it and/or buy it, you try to follow those styles too.
That's precisely the point he was making. If you want to understand music and make good music it's important to understand these stylistic conventions. If you deeply understand them you can understand the situations in which they do and don't apply and figure out ways to achieve the result you want.
Bach didn't invent the rules of the contrapuntal Baroque style any more than he invented the "rules of music theory". Which is what the actual FA is saying. However, Bach is a particularly good example of this style and so for a long time people used to study chorale harmonizations in particular and even in my music study I was taught chorale harmonization in the style of Bach. When you're taught this you are taught lots of rules (eg "avoid parallel 5ths") which help to achieve pleasing counterpoint but of course when you look in the Bach chorale canon you can find instances where he violates all of these rules.
>Bach didn't invent the rules of the contrapuntal Baroque style any more than he invented the "rules of music theory". Which is what the actual FA is saying.
I know that, and I agree with the actual FA.
Just not with the comment that there are no "rules of music", which even if pedantically true (obviously, there are microtonal and different harmonic ethnical traditions, there are western niches like noisecore or musique concrete, there is contemporary classical and atonal music, and so on), it falls flat when it comes to the huge majority of music as the audience knows it, and especially western audiences (which the article is addressed at).
Heck, not just in the west but also in Europe, Latin and Central America, Japan, Korea, Chinese pop, etc. follows the same set of foundational rules (12 note scales, major and minor keys plus a dozen variations, modes, triads, and so on). Heck, even A4=440 has been pretty much standard for decades...
> Music theory is a descriptive enterprise, which aims to make sense of music as composed/performed/enacted by humans.
That seems a rather rigid stance. Those same composers may have studied theory, incorporated its elements, and invented new variations that gained adoption which then become theory, right? It feels a bit like language in that sense.
What I mean when I say that music theory is a descriptive enterprise is quite literal: the research that professional music theorists do is designing theories to describe music we see and hear in the real world. So yes, composers (now and in the past) do learn music theory, and do write music with stylistic norms in mind, as well as adding their own spin on things. That work, in my reading, is not music theory, it's composition! The act of "inventing music theory" is something done by music theorists (writ large), not by people writing music.
To use your analogy: composers are inventing music in the same way that normal speakers invent language. I don't think I'd describe new variations on language as "inventing linguistics," though, as linguistics is the in-depth study of language (and as such, "inventing linguistics" is something done by linguists, not by language speakers). But language is not linguistics, in the same way that music is not music theory.
>The act of "inventing music theory" is something done by music theorists (writ large), not by people writing music.
Well, that's a contradiction with: "the research that professional music theorists do is designing theories to describe music we see and hear in the real world".
Given the later, it's actually "people writing music" who create new music theory. Music theorists merely takes notes and write it down (formalize it, descriptively).
>I don't think I'd describe new variations on language as "inventing linguistics," though, as linguistics is the in-depth study of language (and as such, "inventing linguistics" is something done by linguists, not by language speakers).
Well, linguistics is not inventing, but describing what language speakers do in a formal language. We could say they "invent linguistics", but that would be like saying a secretary "invents the typed note" someone dictates to them.
So music theorists might "invent music theory for X", but composers invented X (e.g. modal interchange).
Since this article focuses in on Bach chorales, here's a project I headed up in 2020 during the first months of covid to record (remotely; each person recorded their part individually, then sent it in) all the chorales from Bach's St. Matthew Passion, with some of the greatest Bach singers and players in North America, along with a brief talk before each chorale. Also, we obtained an acoustical model of Bach's church (the Thomaskirche in Leipzig) from its creator, and rendered the sound into that space, with each musician placed approximately where Bach would have had them.
Bach was considered in his lifetime to be a rather old-fashioned composer, not one that invented new theories. Still a respected composer, of course, and quite productive.
That was a time when many people wrote about music theory in one way or another: Corelli, Rameau, Telemann, Quantz, Handel, etc. My understanding is that they mostly tried to explain the existing tradition of baroque music, more than invent new theory. After Bach died, musical tastes changed, and music developed into a different direction.
I'd argue baroque music, and particularly Bach's work wasn't merely a tradition and an affect of taste and fashion, it was discovered, and it is still being discovered though statistical and other analysis techniques used on his work today. Bach's work is all about expressions of implied symmetries and forms, and one of the most interesting aspects of it is that you can essentially extend his pieces by writing consistent theorems in them. It's not just harmony it's iterating the rules within the pieces.
Take this example of Alan Mearn's interpretation of BWV 1007, this isn't mere ornamentation, he has filled out an entire exposition of implied counterpoint, where the alberti bass evolves into a completely new voice: https://www.youtube.com/watch?v=wp98MRKrs2U I'm biased because I think Mearns' new Bach album is the most important interpretation since Gould's Goldberg Variations, and I'm working my way through his sheet music edition, but this idea that Bach's work was an artifact of a time whose importance is diminished by progress is farcical. It's a foundation without which there would be nothing approaching what we know today.
This is how I understand it too - though "the rules of counterpoint" as they are taught today were really codified after Bach (who was already ~50 years out of date!). Typically (not always!) the "rules" of a style of music are malleable and flexible and argued over while the music is still relevant and codified into unchangeable standards after they have fallen out of fashion. Blues is a good modern example. Dubstep and the 100 related genres and vaporwave and it's 100 related genres, are counter-examples, instead slightly changing the rules becomes a new subgenre, which I feel is the same effect but manifesting itself differently.
Bach himself "breaks" at least one rule in every piece, and I can think of one rule that was really due to technological limitations of the time - not modulating to more than 2 keys away, because they didn't have 12-TET and going more than a few keys away sounded more and more dissonant - keyboard instruments were tuned to a specific key.
The story I'm trying to tell is people arguing about the rules of music is no different than how composers/producers/song writers about music today with modern genres, and when some genre dies, the old guard tries to keep it "pure" by zeroing on a set of commonly used stylistic techniques and calling it "the rules" which makes the music more bland and uninteresting by smoothing out the rough edges.
I was taught counterpoint by one of Shostakovichs last students, and my opinion on rules is greatly influenced by him - it's good to learn the rules, even though they aren't really rules, and all the greatest music from that time was written decades before the rules were even codified.
The question is not so much about polyphonic versus homophonic it’s about whether concert goers 300 years ago listened to Vivaldi after they listened to Bach and said “finally, a breath of fresh air!”
I think people get this slightly wrong - he was more regarded as a performer and improvisor, and the pieces published during his lifetime were mostly keyboard/organ pieces that were considered educational. He was a pretty obscure composer but (mostly) well regarded by those in the know, if a bit too intricate for some. After he died he wasn't immediately very influential, instead he was considered very old fashioned.
From Wikipedia:
https://en.wikipedia.org/wiki/Reception_of_Johann_Sebastian_...
After his death, Bach's reputation as a composer at first declined: his work was regarded as old-fashioned compared to the emerging galant style.[a] Initially, he was remembered more as a virtuoso player of the organ and as a teacher. The bulk of the music that had been printed during the composer's lifetime, at least the part that was remembered, was for the organ and the harpsichord. Thus, his reputation as a composer was initially mostly limited to his keyboard music, and that even fairly limited to its value in music education.
I think this is common knowledge and can be found in a lot of music history books. He was essentially the culmination of a contrapuntal tradition, after which people started writing more homophonic music.
When I was a senior, I took the basic Music class, pass-fail, just in the hope that I'd finally learn something about classical music (spoiler: I did it on my own, well after college).
Surprise, surprise: I had an African-American woman teacher, and she exposed us to a lot of blues & gospel music & jazz, as well as classical. We actually had Thomas Dorsey (Take My Hand, Precious Lord) and Furry Lewis visit the class. How many times are you going to luck into something like that?
Since I spent lunch time at the library rather than go home, I also checked out jazz records and listened to them, like Monk, Miles, and Trane. What was supposed to be a primer in classical music instead turned into a lifetime passion for American roots music.
This is no disrespect to either Bach chorales, or whatever is the opposite.
Just like everyone else, I love baiting questions designed to provoke engagement..
I heard a small child playing giant wind chimes (?) at the park today. She had fully-formed musical taste, as far as I could tell, and sounded really good. It helped that the instrument was easy to make good tone with, but all the pieces were there. Tension, release, playing around the root note, rhythm.
Pentatonically tuned?
I enjoy showing people that "can't play" that just using the black notes on a piano can be pretty enlightening.
A sense of rhythm, sometimes however....
I feel like like the term "theory" is somewhat subjective with regards to how it is being used for music. In science a theory is "a well-substantiated explanation of an aspect of the natural world that can incorporate laws, hypotheses and facts". From the discussion I would interpret theory as a set of rules used to achieve some musical effect. It is much squishier because there is likely a large set of music rules that can achieve similar results. In science that is also true but usually the simplest set of rules are chosen that satisfy the conditions. Seems like the scientific approach would be rather limiting for music - making it rather tedious and boring instead of inventive and interesting.
A lot of the early music theory comes from discovering resonating overtones before having the full physics & mathematical model to describe it exactly scientifically. The opening chapters of Theory of Harmony by Arnold Schoenberg are a very interesting read from that perspective.
In a way its the same question as for math. Do mathematicians invent new mathematical theories or do they discover structures and concepts that exist in the idea world outside of our physical reality?
The statistical study of Bach's works seems interesting. That said, I'm not convinced that any of the cited works (McHose, Hanson...) suggest that Bach invented the rules of music theory, they just use him as an prime example for baroque counterpoint. I'm sure those authors are quite familiar with Bach's immediate predecessors like Buxtehude, who had a fairly similar style.
I heard a delightful story about a student who submitted as his own composition a chorale harmonization by Bach that he'd found in an obscure place. He was surprised to receive a failing grade from the professor. When he went to ask why, the professor simply said that it was too good and he couldn't possibly have composed it.
Meh. I think that's sort of overstating things. Pythagorean tuning is an iterated, circle of fifths construction of a scale. And as such it... frankly kinda sucks rocks at explaining triad-based harmony. The numbers don't work out. You can get something that kinda sounds like a chord, but not really. And so two millenia of Pythagorean music really didn't get into triadic harmony at all, because the language that it had with which to express those notes didn't permit them.
It wasn't until vocal music in the early enlightenment essentially happened upon major/minor chords and built modalities around them (largely by accident, because they sound good!) that people went back to the drawing board to build a mathematical description of the scale based on integer ratios instead. And from there, it was a quick jump to the equitempered scale we know today, which (unlike the pythagorean scale) actually is a very good approximation to the "real" chords people were singing.
And the first composer to really put all those new tools together into a coherent theory behind how to compose music was... J. S. Bach. He didn't "invent" all that stuff, but his works were the first ones we can look at and recognize what we now call "modern" exploitations of tuning and tonality. Anyone earlier was missing big pieces. Anyone later was only adding something new here or there.
JSB is a genuine discontinuity, and it's worthwhile to celebrate that.
Not only is it a resounding no, there is ongoing research to find the roots of this cliche.
I can't seem to find the article, but it traces it back to this chemical engineer who did a statistical analysis of the bass lines and cadencial formulae in Bach's chorales.
I've even seen some scans of his analyses, it's wild stuff. Maybe it's on libgen? I can't remember but you can probably do a search for it...
Edit: added a link to the article
Edit2: nope, never mind, that wasn't it. But if I find it I'll add the URL later...
We don't know. From what I've read, we know a little bit about early theory, but don't know precisely what scales and intervals they were talking about.
We know quite a lot about Greek music theory (Thomas Mathiesen's Apollo's Lyre: Greek Music and Music Theory in Antiquity in the Middle Ages is the go-to source here: https://archive.org/details/mathiesen-1999-apollos-lyre/page...). Of course we don't have recordings, but we do have a solid understanding of the theory, and some very good guesses as to the scales and intervals.
Perhaps, but this is true of all subjects: Sports, economics, politics, most hobbies, &c.
On the one hand, this shows the arrogance of the techie: A belief that since we're rather clever in one application of intelligence, we must be clever at all of them, as if intelligence is the ultimate fungible skill.
Intelligence is remarkably handy, and it is a lever: It takes whatever we know and multiplies its value. But it can't do much about fields in which we have little experience. It's simply not possible to have expertise in many fields without actual experience and study in those fields.
But we can't resist assuming that whatever people are talking about, we can derive everything of interest from first principles and not from absorbing a body of knowledge that others have assembled over decades or even centuries.
But let's not demonize ourselves over it. This is a social forum, a kind of digital saloon. And if we visit real-world saloons, we will find armchair political scientists, armchair coaches for every popular sport, armchair police detectives and so forth.
It seems we're just like everyone else, we're just better at sounding articulate when we pontificate upon subjects with which we have little practical experience.
And to add to that: there are plenty of HN'ers who do have a pretty solid grounding in music / music theory. (I'm not one of those, but I'm patiently working my way forward in this super interesting field.)
Bach's chorales were functional music for the Lutheran church, and to the extent that they form any sort of "rules" in music theory, it comes from the fact that they have been used to teach harmony for a long time (since at least the 1940s, as evidenced by this article). The reason for that isn't so much that they're prime examples of Western common-practice harmony, but rather that they have a homogeneous texture that's easy to use in classrooms, because they're easy for one person to play at the piano or for students to sing.
Recent music theory pedagogy has largely been moving away from the reliance on Bach chorales to teach harmony, especially as music theory has taken a broader perspective on what music we should be studying anyway. Studying the Bach chorales is just fine if you want to know about how Bach used harmony, but there's a whole lot of music in the world, and there's no meaningful sense in which Bach's music intrinsically defines a set of rules any more than Mozart's or Clara Schumann's or AC/DC's or Meredith Monk's defines a set of rules.