Everyone is against hate. President Donald Trump appears to his critics as a hatemonger, while Trump’s defenders, rather than claiming the president hates wisely and well, accuse critics and Democrats of being hateful themselves. Yet we are rarely told what is wrong with hating our political foes. Hate is perhaps too emotional and subjective, or too destructive, while politics should be a domain of impersonal reason in which force has no role. Yet in a 1946 essay, “An Eye for an Eye,” the French philosopher Simone de Beauvoir concluded that precisely insofar as hatred is a violent, personal feeling, politics cannot do without it.In early January 1945, the French writer and editor Robert Brasillach was about to go to trial for collaboration with the Nazi occupation. A pioneering film critic and less successful novelist, Brasillach was also a virulent anti-Semite who welcomed the German invasion of France as an opportunity for violence against Jews. In a weekly column of his menacingly titled newspaper Je Suis Partout (I Am Everywhere), Brasillach listed the names, aliases, and last known whereabouts of Jews who had gone into hiding. He was a gleeful advocate of genocide. The outcome of his trial was a foregone conclusion: He would be sentenced to death.Writing her memoirs two decades later, Beauvoir recalled her anger when, a few days before the trial, an acquaintance asked her to sign a petition urging French President Charles de Gaulle to spare Brasillach’s life. She answered that people like Brasillach did not deserve to live; she agreed with her friend Albert Camus who told her, “we have nothing to do with such people, the judges will decide.”Yet something in Beauvoir dissented from Camus’ assertion. She decided to see the trial for herself, going in her capacity as a journalist for her magazine Les Temps Modernes. As the France scholar Alice Kaplan recounts in The Collaborator: The Trial and Execution of Robert Brasillach, the prosecution used homophobic innuendo to suggest that Brasillach was fixated on Nazi images of masculinity and had, as it were, spread his legs for the Germans. Only his crimes against the French state were discussed, not his role in the deaths of thousands of French Jews.Beauvoir was disturbed by the prosecution’s combination of the sordid and officious. She was still more troubled to see Brasillach facing death with dignity. He refused to renounce his actions, to claim he had been misled, or to seek the mercy of the court. His poise left Beauvoir wondering how a morally compromised legal system could punish a man who, at least at the moment of his sentencing, showed a kind of heroism.On her way out of the trial, Beauvoir ran into some Communist friends, and shared with them her discomfort about the course of the proceedings. The French Communist Party had been a leading force in the resistance against Nazi occupation, and it took a hard line against collaborators—in part to cover the party’s own history of implicit collaboration with the Germans between 1939 and 1941, when the Soviet Union and Nazi Germany had been allies. Beauvoir’s Communist friends curtly told her “she should have stayed at home.” She had no business muddying a simple political question with her personal feelings.But Beauvoir could not stop thinking about the trial. “My mind could not unstick itself,” she later wrote. She sensed that there was something amiss not only in how the trial had been conducted, but in the very terms of the debate over Brasillach’s sentence. On the one hand, there was the petition for sparing Brasillach, sponsored by Claude Mauriac, a Catholic writer whom Brasillach had vilified as a “born antifascist.” After the war, Mauriac argued in a series of essays that the Nazi occupation had been a reign of hatred that only “love” (charité) could overcome. Camus responded to Mauriac with a series of critiques, but finally decided to sign the petition, on the grounds that the death penalty is always illegitimate. On the other hand, the Communists saw killing war criminals as a practical question: They were enemies to be eliminated. Both of these alternatives struck Beauvoir as shallow and inadequate. Brasillach’s crimes demanded something more, Beauvoir felt.In February 1946, one year after Brasillach’s execution, her insistent, agitated refusal to forget brought forth the essay “An Eye for an Eye.” Beauvoir defended her decision not to sign the petition in Brasillach’s favor, but elaborated on her uneasiness about his punishment and justified the place of emotions in politics. Writing back to the judges, Mauriac, Camus, and the Communists, she made a striking and strange defense of the death penalty as a weapon of revenge and an expression of hatred.***Beauvoir structures “An Eye for an Eye,” as the story of how she learned to hate. It begins with a portrait of herself and her fellow leftist intellectuals before World War II. Until the summer of 1939, she claimed, she and her friends had not known what hate was. When they considered their political enemies, foreign or domestic, it was with Olympian “contempt.” When they considered criminals, it was with pity informed by the indulgent sociology of vulgar pseudo-Marxism. Such people were victims of an unjust capitalist society, or mentally disturbed, she had reasoned. The violence of murderers and fascists filled her with “horror,” but she could not hate those who committed it. Hatred was just more horrible violence, and she could wish no one dead.In the disastrous summer of June 1940, as the German army stormed through France, Beauvoir began to hate. While some writers, like Camus in his novel The Plague (1947), compared the Nazi occupation of France to a natural disaster, Beauvoir argued that her feelings of hate showed such comparisons were false. “No one hates hail and plague,” she observed, “we only hate people.” Her hate for the Nazis and their French sympathizers was a searing reminder that what was being done in occupied France was being done deliberately by particular people in accordance with their beliefs and characters. To hate the people who did it—rather than merely to lament their actions or regret their being caught up in a social system—was to remember that war, oppression, and genocide are not only political phenomena, but also personal ones.Simone de Beauvoir discovered that hate is a force that clears the way for violence. ‘Suddenly we find ourselves judges and executioners,’ and every time a mob attacks or a court condemns, she wrote, ‘we are complicit.’Hate, Beauvoir asserted, is not a refusal to consider or understand the person hated, or the severance of a connection with them. It is a “relationship that is concrete and interpersonal … like love.” In her 1949 bestseller, The Second Sex, Beauvoir explained that love and hate are “alternatives,” opposing ways of responding to a common situation that arises when two people meet in a “real relation.” Each person sees the other and recognizes that they themselves are being seen by the other. Each will have to choose how to consider the other person, how to relate to them, and how to appear in the other person’s eyes. In so choosing, each is forced to “reveal values and ends in the world.” To love another person is to show what one holds worthy of love—and to hate, therefore, is to show what one holds worthy of hatred. Our feelings about other people are not passing whims that bubble up from nowhere; they express who we are and commit us to action.Beauvoir received her second lesson in hate as the Allies liberated France in 1944. Many who were suspected of having sympathized or collaborated with the Nazis were humiliated, beaten or killed in waves of spontaneous violence. As these died down and order was restored, the French state began organizing trials and executions of its own.Until the killing started, Beauvoir remembered, “hate had been easy.” It had seemed like a feeling one carried inside oneself, a purely personal affair with no consequences. But hate, she discovered, is a relationship that extends outward to the person hated, a force that clears the way for violence. “Suddenly we find ourselves judges and executioners,” and every time a mob attacks or a court condemns, “we are complicit.”***Beauvoir also knew something about complicity. During the Nazi occupation, she had given a kind of implicit sanction to anti-Semitic laws by signing an oath that she was not Jewish, which allowed her to work as a teacher after Jews had been expelled from such positions. After the liberation of France, Beauvoir never apologized for her actions. But she became a pitiless analyst of complicity. The Second Sex, for example, rests on the premise that women accept the submissive, passive roles offered to them in a sexist society—they are not helpless victims, but agents of their own oppression.In “An Eye for an Eye,” Beauvoir declared she was doubly complicit in the violence that followed the liberation. First, the perpetrators of that violence claimed to act in the name of the French people, and Beauvoir did not resist their speaking for her. Second, and more radically, Beauvoir’s feelings of hatred, her having wished death against people like Brasillach during the occupation, were part of a collective emotional and political process that made their executions possible after the war. Feelings and thoughts could be acts of violence, she insisted—and it was precisely because they could be so that Brasillach was himself guilty of murder. “There are words as lethal as gas chambers,” she wrote in her memoirs.This did not mean that Beauvoir was opposed on principle to something like present-day notions of “hate speech” or terrified by the specter of violence in everyday emotions. Her point was that some people should be hated and killed. We must not allow the state, or our neighbors, to enact violence, she urged, unless we are prepared to take up our own share of the responsibility for having allowed it. Beauvoir went still further, in a radical set of political and ethical claims that few philosophers have followed: Not only are we responsible for the violence and death our hate engenders, she claimed, but our hate is the only thing that can make violence and death legitimate. Justice without hate is a farce.The legal system, Beauvoir argued, aims to restore a social order that has been violated. It “punishes without hate in the name of universal principles.” In a trial, the accused is only a kind of case of wrongdoing to which the corresponding rules are applied. It is perhaps necessary, Beauvoir accepted, that criminals be punished through a process guided by abstract norms and technical expertise, given that the alternative is mob violence. But in our hearts, we know that what we want from the judicial process is not the affirmation of abstract principles but revenge. We want the perpetrator to suffer as much as the victim; we want, as Moses knew, an eye for an eye.Revenge is therefore the psychological foundation of justice, the hidden ressentiment behind our principles. Unfortunately, it is also doomed to failure. Beauvoir observes that what we seek in the pursuit of vengeance is to force the perpetrators to recognize their crimes, to make them understand the enormity of what they have done. But every way they could respond to this summons will disappoint. Some wrongdoers, like Eichmann, will appear incapable of understanding, at least in public. Others will plead for mercy, making us feel like perpetrators. And a few, like Brasillach, will go to their deaths with a courage that confounds our hatred. None of these outcomes is satisfactory. But, Beauvoir counters, neither are any of the outcomes of any other human action, which all “imply failure.” Revenge seems impossible but necessary, just as love, the fusion of one free individual with another, is both the most everyday affirmation of ourselves, and the unattainable horizon of desire.If we fail to acknowledge that justice begins in hate and the longing for revenge, Beavoir warns, we will allow it to be turned into a source of moral capital and political legitimacy by those to whom it does not belong. Thus the legal experts at Brasillach’s trial presented his crimes as if they were a matter of treason against the French state. But Brasillach was responsible for the deaths of the specific people whom he named in his paper; his crime was against those individuals, not the state. Such a man must be hated if those whom he wronged are to be remembered and avenged. We must, Beauvoir suggested, psychologically participate in Brasillach’s sentence, we must will his death together to give it an ethical significance that the official judicial proceedings deny it.Hating Brasillach, indeed, appeared to Beauvoir not only as an ethical duty to his victims, but also to Brasillach himself. His crimes were the expression of his life, his values, and character. He had made himself an anti-Semite and Nazi collaborator. As she watched him in the courtroom, Brasillach had struck her as possessing a tragic nobility because he was the only one present to grasp the stakes of what was going on, to understand that not merely a particular action, but an entire life, was being judged.Defending society, in which we are complicit in our daily actions, words, and thoughts, means hating its enemies, not as “abstract symbols,” but as individuals who have freely chosen their own fates. “Professional judges only follow orders,” Beauvoir warns. They are, in a sense, no more capable of an authentic moral understanding than an Eichmann, having disavowed the emotional and ethical foundation of punishment and instead administering sanctions according to the laws and guidelines set forth by the state. We, the public in whose name the judges act, must supply that understanding. We must hate deliberately, accepting our fatal responsibility, while understanding that our hatred will not bring back Brasillach’s victims, or restore justice, or improve the world in any material way. But, Beauvoir insists, hatred is the only way to recognize perpetrators, victims, and observers as free, responsible individuals, whose actions, words, and feelings have moral weight and political consequences.