“二加二等于五”（即2 + 2 = 5）有时被简洁生动地用于代表一种不合逻辑的阐述，特别是用于代替与逻辑理论相悖的理论阐述。它最先广为人知出于英国著名作家乔治·奥威尔的反乌托邦名著《一九八四》（第一部第七章）中。「二加二等于五」同一般人们所认知的「二加二等于四」形成强烈的真伪对比。小说中的男主角温斯顿·史密斯担心「到最后，党可以宣布，二加二等于五，你就不得不相信它」。他认为，当人人都相信这个谎言就是真理时，它是否最终会变成真理？温斯顿最后写道：「所谓自由就是可以说二加二等于四的自由。承认这一点，其他一切就迎刃而解。」

The phrase "two plus two equals five" ("2 + 2 = 5") is a slogan used in many different forms of media; more specifically in George Orwell's Nineteen Eighty-Four as an example of an obviously false dogma one may be required to believe, similar to other obviously false slogans by the Party in the novel. It is contrasted with the phrase "two plus two makes four," the obvious—but politically inexpedient—truth. Orwell's protagonist, Winston Smith, uses the phrase to wonder if the State might declare "two plus two equals five" as a fact; he ponders whether, if everybody believes it, does that make it true? The Inner Party interrogator of thought-criminals, O'Brien, says of the mathematically false statement that control over physical reality is unimportant; so long as one controls one's own pe****tions to what the Party wills, then any corporeal act is possible, in accordance with the principles of doublethink ("Sometimes they are five. Sometimes they are three. Sometimes they are all of them at once").