a totalitarian and authoritarian regime, Koestler offers an in-depth depiction of a character enduring psychological oppression. The novel investigates the impact of extreme mental fatigue on a character renowned for his logical prowess, who has also withstood various physical tortures. Gletkin describes it as “a matter of constitution,” as Rubashov is deprived of sleep and mental respite, subjected to incessant interrogation and humiliation until he reaches, in a distorted manner, the final endpoint of his rational thinking. This exploration of a human's capacity to operate as a purely logical entity, stripped of comfort and individuality, is a key theme of the novel. It underscores the divide between what Rubashov perceives as the “old guard” and the “Neanderthal” new generation of Communists.

One of the main ideas with which Arthur Koestler grapples in Darkness at Noon is the belief, central to Communist ideology in the USSR, that the individual is unimportant or even nonexistent in comparison to the collective. It is this belief that allows Party officials like Rubashov, Ivanov, and Gletkin to sacrifice individual Party members like Richard, Little Loewy, Arlova, Bogrov, Hare-lip, and Rubashov himself without emotion or regret. While in prison, however, Rubashov begins to question the decisions he made to denounce or expel individual people for the sake of the Party. After he sees his old friend Bogrov dragged past his cell, calling Rubashov’s name, Rubashov finds he can no longer subscribe to the old logic still employed by his former commander, Ivanov, who justifies Bogrov’s execution by claiming that it was necessary to the collective good. There are two distinct forms of morality, Ivanov claims:

“One of them is Christian and humane, declares the individual to be sacrosanct, and asserts that the rules of arithmetic are not to be applied to human units. The other starts from the basic principle that a collective aim justifies all means, and not only allows, but demands, that the individual should in every way be subordinated and sacrificed to the community—which may dispose of it as an experimentation rabbit or a sacrificial lamb. The first conception could be called anti-vivisection morality, the second, vivisection morality.”

Ivanov argues that humanist (“anti-vivisection”) morality is impossible for any ruler to actually uphold, and he finds Rubashov’s newfound concern for the rights of individuals sentimental.

Rubashov also begins to acknowledge his own individuality for the first time, referring to this illogical, deeply personal part of himself as the “silent partner” in his thoughts as the “first-person singular,” or the “grammatical fiction.” As Party members are meant to consider themselves not as individuals but as parts of a collective, Rubashov’s acknowledgment of his individuality and interior world can be considered deeply subversive.

Rubashov’s relationship with his unseen and unnamed neighbor, No. 402, demonstrates the importance of individuality as well; the two prisoners hold opposing political views and relate to one another entirely on individual, human terms. Rubashov and the other prisoners—eventually including Ivanov—are sacrificed for the sake of the preservation of the “Bastion of the Revolution,” the good of the “masses” whom Rubashov believes the Party no longer understands at all, and the creation of a utopian future that will never arrive. By the novel’s end, Rubashov is convinced that not only do the means (the denial of the individual and the pursuit of pure reason) fail to justify the end (supposed social progress), but the means actually affect the end, meaning that unjust methods warp and obscure the goals to which they are applied. Rubashov no longer believes in the Party’s methods, and when he tries to picture its present or future achievements, he sees “nothing but desert and the darkness of night.”

Many of the events of Darkness at Noon—the arrests, imprisonments, trials, and executions—revolve around the fact that the “new guard,” represented primarily by Gletkin, is eliminating the “old guard” represented by Rubashov, Ivanov, Bogrov, and the polite, elderly veteran of twenty years’ imprisonment called Rip Van Winkle. Just as No. 1 (Joseph Stalin) replaced the original leader of the Communist Party (Vladimir Lenin), the new guard are now replacing the older intellectuals and revolutionaries who led the revolution, fought in the Russian Civil War, and brought the USSR into being. The world of the old guard and its dreams of global revolution is vanishing as its members are systematically “liquidated.” Rubashov’s counter-revolutionary neighbor, No. 402, belongs to an old, dying world as well—the pre-revolutionary, monarchist world of Russia under the Czar, where honor was romantically defined as dying bravely for one’s beliefs, and the soldiering life was “jolly good fun.” Rubashov fought to change that world by pledging himself to the “Party of the Plebs,” but now, worn-out and defeated, he finds himself an unwanted citizen of a world being remade by the new breed of Communists he calls the “Gletkins” or the “Neanderthalers”: the younger generation who grew up after the revolution and are, for all their ruthlessness, humorlessness, and blind faith in the Party, the old guard’s “spiritual heirs.” He describes the essential difference between the new and old guard this way:

Ivanov had trailed his past after him to the end; that was what gave everything he said that undertone of frivolous melancholy; that was why Gletkin had called him a cynic. The Gletkins had nothing to erase; they need not deny their past, because they had none. They were born without umbilical cord, without frivolity, without melancholy.

During his interrogation by Gletkin, Rubashov reflects that the charges against him are absurd because the old guard spent all their spiritual energy long ago, during the revolution, the war, and the bouts of imprisonment and torture they all endured and which have left Rubashov and his comrades much too exhausted to act on the traitorous impulses of which they are now being accused. Eventually Rubashov resigns himself to the idea that the only thing left for him and the rest of the old guard to do is to accept that they are being scapegoated and sacrificed by the new guard who have replaced them—and then to “sleep” and wait for history to judge their actions.