Victoria 2 represents the different ideologies people might hold. These include a couple forms each of Conservative, Liberal or Socialist, as well as Fascist.
In general, you might find your country is mostly populated by conservative farmers at the beginning of the game, but as people communicate and learn about new ideas, and as they begin to move to the cities to work in factories, they may start to lean toward socialism.
You, as the player, have some influence over how this all plays out. You can take action to keep your people happy. But sometimes either mass industrialization or general inattention will cause your citizens to become restless, and they may agitate for new social or political reforms. They may even start to rebel!
In parliament, or your legislative branch, these ideologies will form factions, and like-minded philosophies will sometimes cooperate with each other. However, once tensions rise and more is at stake, they will start to bicker and intrigue against each other. All of this has a bearing on what options you have, as President or King.