Demons is often noted for the range of clashing ideologies present in the novel. As in most of Dostoyevsky's other works, certain characters are descriptive of specific philosophies.
- Nihilism, embodied by Pyotr Verkhovensky, is an anarchist ideology that demands the destruction of the current social order.
- Shigalevism (or "shigalevshchina") is a philosophy specific to the book and particularly to the character Shigalev. Shigalevism demands that ninety percent of society be enslaved to the remaining ten percent. Equality of the herd is to be enforced by police state tactics, state terrorism, and destruction of intellectual, artistic, and cultural life. Like Verkhovensky, Shigalev agrees that for "reason" to spread, one hundred million heads will have to roll. In Marxist interpretations, Shigalev and his fellow conspirators are seen as caricatures, and as "a slander on socialism." Others, including Soviet dissidents Boris Pasternak, Igor Shafarevich, and Alexander Solzhenitsyn, have called Dostoyevsky's description of Shigalevism prophetic, anticipating the tactics used following the October Revolution. Pasternak often used the term "Shigalevism" to refer to Joseph Stalin's Great Purge.
- Slavophilism is a philosophy asserting the paramount importance of the heritage and traditions of the Slavs in Russian culture, particularly in opposition to cultural influences originating in Western Europe. Slavophilism and the related movement known as Pochvennichestvo, which emphasized the unique mission of the Russian Orthodox Church, are given voice in the novel primarily through the character of Ivan Shatov, although Shatov describes that mission as universal rather than merely Russian.
- Tsarism is embodied by the provincial Governor Andrei Antonovich von Lembke, who is a German aristocrat and convert from Lutheranism to the Russian Orthodox Church. Like the government he serves, Count von Lembke is shown to be incapable of dealing with radical extremism.