OK, very roughly, I think what has happened is that as the repercussions of the French Revolution spread across Europe the old upper class, the ancien régime, gradually lost power to the middle class and those rising up out of the middle class: leaders in business, the arts, the professions and so on. True, after Napoleon was defeated there was an international effort to turn the clock back at the Congress of Vienna, but it was finally unsuccessful. It is my belief that, in most cases, revolutions do away with the old upper class and set the stage for a new upper class. In Russia the tsar and his administration were replaced by the commissars and rulers like Stalin were even more violent and authoritarian than the old tsars. In Western Europe a much more benign state of affairs came to pass where the old aristocracy was replaced by a ruling class, many of whom came to power through democratic elections.
In music what we see (or, rather, hear) is that the crisp classical genres are expanded and transformed into vehicles for the new Romanticism which was really about the exploration and exaltation of ordinary people--the middle class--who were encouraged to delve inside and experience the Romantic trance (that I talked about in this post). At first it was just experienced by small groups in salon concerts, but music became a vehicle for expressing the emotions and aspirations of large groups of people, who listened in the public concert halls built all over Europe. Here is a post where I talk about that.
This is all very well and resulted in a lot of great music that is still quite central to the classical repertoire. But this situation was not entirely satisfactory to the new ruling class. They have a need to shape and monitor the tastes and values of the people they rule, for their own convenience. For one thing it helps to get re-elected and for another, it makes the populace more predictable. Therefore, towards the end of the 19th century we see the development of a host of different kinds of social controls. These include the State Socialism began by Bismarck in Germany in 1883 to appease the working class so they would stop agitating for outright socialism and the philosophy of education of John Dewey that appeared to make education simply better and more effective but that in reality in arguing that school is a social institution through which social reform can and should take place, handed the ruling class the perfect instrument to control public opinion by controlling how students are taught (and what they are taught, of course).
These two channels, the welfare state and the public school system allow the ruling class to control the populace as a whole in two fundamental ways: first of all, if a significant proportion of the public is receiving regular payments from the government, they will be far more compliant than if they were truly independent of the state. Second, the kinds of ideas and values held by most people will be instilled in them through the school system. Mind you, at the level of higher education, the older enlightenment values of truth and independent thought were, for a long time, still the norm.
But as the 20th century progressed, things seem to have gotten out of hand: governments came more and more to rely on methods that were essentially derived from the political ideas of Karl Marx. But we have to be careful here, because Marx's theories are far-reaching and complex. The important aspect for this argument is that they provide ideal tools by which political leaders can manipulate the public for their own benefit. Perhaps the most evident is the practice of singling out a particular group who are then blamed for the ills of the rest. This group might be rich people or others seen as "oppressors". We see this phenomenon again and again in social protests. It is not enough to point out a social failing, someone must be found to blame for it as that is far more effective politically.
Unfortunately all this seems to have metastasized. Progressivism, instead of just being a political convenience, has become like a tiger, preying on the fabric of civilization itself. Higher education, that used to be free of the crude manipulations found in the public schools, has fallen prey to them in an even more virulent form and now there is scarcely a single social or political progressive idea that is not enforced with brutal strictness in colleges and universities. Forget about the independent scholar, pursuing his researches free of political influence. Last week he was fired.
In music some odd things happened as well. There has always been a bifurcation in music between song and dance and the styles associated with them. I talked about how this was present early in the history of Western music in this post. But in the 20th century this division between popular music and concert or classical music became a vast gulf. At this point, it seems as if the classical side is in danger of disappearing entirely! From the point of view of this blog, and aesthetic quality, that would be a Bad Thing.
The apotheosis of popular music came about because of a number of factors. As societies became more democratic and distinct classes in society (apart from the ruling elite) became more and more ambiguous, the tastes of not only the middle class, but the working class, became the norm in society. The rough energy of rock and roll is perhaps the most striking example. The Beatles, working class boys from Manchester, influenced by American popular music, became the most famous people in the world due to their skill at writing and performing energetic and appealing music--appealing to lower and middle class tastes, that is!
At the other end of the spectrum, the intellectual side of music developed to an extreme in the avant-garde complexities of Milton Babbitt and Pierre Boulez, but this music did not appeal to the large audiences that pop music did.
What seems to be happening now is that composers like Philip Glass and Steve Reich have, more or less, succeeded in reuniting the two streams of music. And in pop music, the trend is towards it becoming, not a vehicle of protest, but a vehicle for the progressive nostrums that are constantly drummed into the students at public schools and universities alike. Pop music now, when it is not simply a vehicle for narcissism or materialism, is all about reinforcing the progressive agenda: feminism, climate change, Occupy Wall Street, and so on. George Harrison wrote a song about excessively high taxes--I expect some pop star now to write one about raising the minimum wage!
So there is my, extremely simplified, view on the social and musical history of the last two hundred years. Please correct me where necessary!
And let's have an envoi. This is The Desert Music by Steve Reich on poetry by William Carlos Williams: