The political theory of pluralism holds that power in liberal democracies is distributed among many different groups, whose interests conflict or align in ways that shift over time. It’s partially a descriptive theory, meant to explain how liberal democracies actually work, but also a prescriptive theory, in that most people who believe that pluralism is how things work also believe that pluralism is a good way for things to work.
Pluralists are often accused of ignoring the fact that some groups are consistently more powerful than others – in particular, Marxists believe that Capital is significantly more powerful than all other groups, and that Labor is the only other group powerful enough to challenge it. While not all Leftists are Marxists, most nevertheless believe in some similar “bipolar” model of power (in some specific cases called a “Power Elite” model): Corporations versus the People, the Kyriarchy versus the Oppressed, and so on. Far-right theorists don’t participate much in mainstream political science, but if they did, they would probably criticize pluralism using similar models – Secular Humanism versus Christianity, Jews versus Aryans, the Cathedral versus whoever neoreactionaries think the good guys are, the West versus the Caliphate, the Caliphate versus the West, and so on.