Either the human mind has a natural bent towards binary oppositions or else it is the instinct of the herd to seek them out, or both. Some are short lived and abandoned, others long lasting and fiercely embraced. They create problems of one kind of another, thanks to that wretched thing called “reality”.
So the doctrine of Heaven and Hell is no sooner promulgated than some wit points out that human beings - real people - are rarely, if ever, paragons of virtue or totally sunk in vice but rather a very ordinary mixture of good and bad. So how are they to be divided when the path branches up to Heaven or down to Hell? Enter the theologians, a new caste of men (and I write men deliberately) brought into being by the advent of written-down religions and only too happy to engage with any problem which would help keep them in employment for a couple of millennia. Even today, the government of my country thinks the vexatious problem of Heaven and Hell important enough to pay decent taxpayer-funded salaries to the experts. One day, take a look online at just how many Christian theologians the universities of Oxford and Cambridge still find room for. They provide excellent board too; and at high table the toast is to the Awkward Squad which keeps them in business.
One potential solution has been around for a very long time: Purgatory is the place where the problem of shades of grey is dealt with before a Final Solution is arrived at. But to the original objector, this is not so much solution as the ever-popular alternative of kicking the can down the road.
The Final Solution usually identified by those words was a rather shorter lived binary - twenty five years, max? - created by Germany’s National Socialists who having divided the world into Aryans and Jews faced a similar problem: some Aryans weren’t quite Aryan (maybe they had a bit of Slav about them) and some Jews were a bit Aryan, like those who had won the Iron Cross in World War One or who had one Aryan parent. The problem clearly needed to be turned over to the experts, in this case biologians and such like who might be able to give decisive answers - by which I mean answers which could be converted into useable bureaucratic forms. Hopefully, the experts could spin a convincing yarn to explain what quantum of Aryan blood in a person was needed to successfully dominate Jewish (or Slavic, though it never quite came to that) blood, and did it matter if it was in the male line or the female line, and so on. Nowadays, people with such scientific tastes have to look elsewhere for employment; maybe in the booming industry of conspiracy theories.
Running the Nazis a close second during more or less the same period were the Communists who had their own rival binary which divided the world into Capitalists and Workers, Bourgeoisie and Proletariat. Unfortunately, this was another case where Two Sizes Fits All clearly did not work, though perhaps it could be made to work. Stalin thought so: you just had to kill a lot of people. He reached that conclusion before Hitler reached his. This was another case where a cadre of experts was brought into being (or elbowed their way forward), the Marxist theoreticians tasked with the Problem of the peasantry and the Problem of the petty bourgeoisie, to name but the two principal ones. The theoreticians flourished in Russia and Germany and later France where the French government funded university departments of philosophy and sociology where these tough problems were traditionally chewed over amidst the smoke of state-owned and life expectancy-reducing Gauloises. I did recently try to re-read some of the solutions they came up with; if you have studied theology, or have a taste for it, you will enjoy these books which move concepts and scholastic distinctions around as if on some chessboard, everything agreeably fact-free. Try Nicos Poulantzas, Classes in Contemporary Capitalism (1975) .
Stalin had to fight an uphill struggle, largely because in 1921-22 Lenin U-turned and pushed through a New Economic Policy to replace the disaster of War Communism. Between1921 and 1928 the NEP brought economic recovery to the new Soviet Union - but at a price. Stalin didn’t like what he saw. Capitalism was making a re-entry through trade if not through industry (which remained in state hands); a class of petty bourgeois self-employed artisans and traders, the NEP-men, emerged who were not only not proletarians but also had the wrong ideas, whose “subjective” consciousness was not and could not be that of a Good Communist. Stalin, with the benefit of theological training, decided to apply the original Marxist binary, Proletarian or Bourgeois, without fudge and do what no one else had ever really dared: criminalise all self-employment and turn all those traders and craft workers into state employees, dependent on the state for their wages, their housing, and their ration coupons. Either you complied or you became a black marketeer - as former NEP-men often did, the ration coupons leaving much to be desired.
In all three cases sketched above, intellectual labour is deployed in the service of practically-oriented politics. The priests sought hegemony over their flocks in the form of compliant behaviour and financial offerings; Heaven and Hell were the carrot and stick. Hitler wanted a Judenfrei world for reasons which may be a bit more obscure. Stalin wanted to run the whole panoptical show and turning everyone into a state employee, a prisoner, or a dead body pretty much achieved that goal. The white-collar theologians, biologians, Marxians have - for the most part - been compliant ancillary help to all such endeavours.
It is easy to add to the list of such binaries …. but don’t get me started. We all wish for certainties and easy allegiances when, really, they are only to be found in mathematics. When we do our sums, at least there a simple binary really does apply. Either we get them right or we get them wrong. We have culture wars because people missed their vocation as accountants.
 And for an alternative approach from the same period, I recommend The Petite Bourgeoisie, edited by Frank Bechhofer and Brian Elliott (1981) and especially the chapter “Artisanal Bakery in France …” by Daniel Bertaux and Isabelle Bertaux-Wiame.
 The peasants and the pen-pushers were also nationalised, though some of them too became black marketeers, the pen-pushers falling into that category when they circulated poems under the counter or just read them to friends. You could lose your life for doing that, as did Osip Mandelstam for the Stalin Epigram of 1933.