Generals are often accused of fighting the last war, of confronting every foe through the prism of earlier battles. Political polemicists, no less than military leaders, run the risk of conflating the past and present. Over the past few months, some of our sharpest liberal writers have been warning of a resurgent identity politics, a new political correctness that evokes earlier clashes. Many of these writers have been shaped by the political correctness fights of the 1990s—a tangle of arguments about the literary canon, speech codes, and multiculturalism. Indeed, many of the complaints about the new political correctness foreground ’90s campus conflagrations in which they played some small part—giving their writing a peculiarly antique tinge for arguments that are ostensibly about a twenty-first century perversion of popular culture.

In their description of the new political correctness, these writers point to what they see as a novel and pernicious development: notably, the spread of trigger warnings (advisory labels on syllabi and course outlines alerting students of material that might provoke painful memories) and safe spaces (specially designated locations for rape survivors or LGBT people, for example, to find comfort and community). On an immediate level, the critics raise the question of efficacy. “Trigger warnings aren’t much help in actually overcoming trauma,” Jonathan Chait rightly notes in his essay “Not a Very P.C. Thing to Say,” published earlier this year in New York magazine. “An analysis by the Institute of Medicine has found that the best approach is controlled exposure to it, and experts say avoidance can reinforce suffering.” Safe spaces and the larger trend toward hypersensitivity encourage students to “self-infantilize” and become more “insular,” writes Judith Shulevitz in a piece for The New York Times titled “In College and Hiding From Scary Ideas.

But more pressingly, these writers argue, such insulations amount to a kind of willful ignorance more than a tolerant openness. By Chait’s definition, “Political correctness is a style of politics in which the more radical members of the left attempt to regulate political discourse by defining opposing views as bigoted and illegitimate.” As Shulevitz writes, “People ought to go to college to sharpen their wits and broaden their field of vision. Shield them from unfamiliar ideas, and they’ll never learn the discipline of seeing the world as other people see it.” By this view, political correctness is inherently illiberal, a form of thought control inimical to the open debates that should be promoted by education.

Trigger warnings, as anyone who has witnessed the clueless Hannah Horvath issuing them in her Iowa seminar on the most recent season of “Girls” can attest, are a fair target for criticism. When the reporter Jenny Jarvie, writing for The New Republic, brought widespread attention to their prevalence last year, she also pointed out their excesses. Jarvie quoted a Rutgers student who wanted The Great Gatsby to come with this advisory: “suicide, domestic abuse and graphic violence.” Since all narrative is conflict-driven, it would be hard to imagine a work of fiction that isn’t triggering. And many trigger warnings read like a parody of over-protective skittishness, like the Oberlin document warning that Chinua Achebe’s Things Fall Apart may “trigger readers who have experienced racism, colonialism, religious persecution, violence, suicide and more.” Safe spaces, too, seem like an abandonment of the traditional role of higher education as a passage into maturity. In her description of a safe space for rape survivors at Brown University, Shulevitz calls attention to the childish décor: “cookies, coloring books, bubbles, Play-Doh, calming music, pillows, blankets and a video of frolicking puppies.”

But are trigger warnings and safe spaces really examples of a new form of political correctness? Chait menacingly describes the new P.C. as “the language police.” Critics pose the argument that, through threats of lawsuits and overzealous parental interference, the timidity of the self-infantilized will cast a shadow on academic culture as a whole. Yet surely people who need trigger warnings and safe spaces are less scary than they are scared. If students are “self-infantilized,” how can they also threaten the free speech of the broader campus? And if universities are so quick to surrender to these ostensible threats of retribution, so unwilling to make arguments against veritable babies, then there could hardly be a robust free speech culture on campus to begin with. There is a disjunction in these accounts: The new P.C. proponents are self-evidently ludicrous, and they also wield an outsized power over academic life. (These accounts also fail to show how, exactly, such outlandish ideas so quickly gain a foothold in major institutions full of the most educated members of society.) Perhaps it’s possible to see trigger warnings and safe spaces as less a cause than a symptom of a stifled intellectual culture on university campuses.

But the biggest problem with the jeremiads against the new P.C. is that they treat the so-called politically correct as radical freaks who are outside of mainstream American society—opposing the common sense free-speech position held by wholesome liberals and conservatives. Yet far from outlier ideas, trigger warnings and safe spaces grow out of impulses that are broadly shared. For many decades, the United States has been the home to a thriving vernacular therapeutic culture, where ordinary citizens borrow concepts from psychology and use them as tools of self-improvement, often, in the process, forming distinct political and social identities. In a society where Oprah Winfrey is a guru to millions and self-help books are perennial best-sellers, the adoption of folk therapy is hardly the mark of eccentricity. Moreover, trigger warnings and safe spaces echo the larger jitteriness that has marked American culture for many decades, gaining special salience after September 11, 2001. To understand trigger warnings and safe spaces, we would do well to forget the category of political correctness altogether, and look back at the origins of post-traumatic stress disorder (PTSD).

PTSD: A Cultural History

1597: Some historians point to Hotspur in Shakespeare’s Henry IV, Part 1 as an early example of PTSD. “Why dost thou bend thine eyes upon the earth, / And start so often when thou sit’st alone?” asks Harry’s wife, Lady Percy.

1666: Samuel Pepys witnesses the Great Fire of London and records its troubling aftereffects in his famous diary: “The fears we have of new troubles and violences, and the fear of fire among ourselves, did keep me awake a good while.”

1865: Walt Whitman describes vivid Civil War flashbacks in the poem “The Artilleryman’s Vision”: “There in the room as I wake from sleep this vision presses upon me; / The engagement opens there and then in fantasy unreal, / The skirmishers begin.”

1925: In Mrs. Dalloway, Virginia Woolf creates a famous portrait of shell shock in the character of Septimus Warren Smith: “For now that it was all over, truce signed, and the dead buried, he had, especially in the evening, these sudden thunder-claps of fear. He could not feel.”

1950s: Some survivors of Nazi concentration camps are diagnosed with “Concentration Camp Syndrome.” Elie Wiesel, though not himself a sufferer, told an interviewer, “The question is really not how we survived the war, but how we survived mentally afterwards.”

1999: Author Alice Sebold publishes Lucky, a memoir detailing her rape and related PTSD: “When I was raped I lost my virginity and almost lost my life. I also discarded certain assumptions I had held about how the world worked and about how safe I was.”

2000: After being shot, Josh Lyman (Bradley Whitford) is diagnosed with PTSD on an episode of “The West Wing.” “Well, that doesn’t really sound like something they let you have if you work for the president,” he tells his doctor. “Can we have it be something else?”

2014: The year’s top-grossing film is American Sniper, which tells the story of Navy seal Chris Kyle, who himself had sought treatment for “combat stress” and was murdered in 2013 by an Iraq veteran suffering from PTSD.

That soldiers are emotionally damaged by war has long been known. During the Napoleonic Wars, doctors spoke of “exhaustion.” By the American Civil War, the term of art was “soldier’s heart.” By World War I, this was updated to “shell shock.” The label became “combat fatigue” in World War II. Much of this early analysis was much more moralistic than medical, with traumatized soldiers blamed for their own suffering. Thus pioneering British neurologist Dr. Arthur F. Hurst, who worked with soldiers psychologically scarred by major World War I battles, flatly stated in his 1918 book

Medical Diseases of the War that “A man with a good family history, who has never suffered from any nervous disability, only develops war neuroses, including shell-shock, under exceptional circumstances.”

It was not until the 1960s that the seeds of the concept of PTSD—which took a more sympathetic and humane view of soldierly suffering—were planted. In the late ’60s, anti-war veterans, who had both witnessed and participated in atrocities, became dissatisfied with the psychiatric counseling they received from the government and began to seek a way to deal with their violent memories. In the spirit of the times, these vets formed “rap sessions” to talk amongst themselves. These vets allowed psychiatrists into the sessions but only on the condition that they entered as peers, not as authority figures. Former Marine Jack Smith, who served in Vietnam from 1968 to 1969 and became an active figure in Vietnam Veterans Against the War, recalled, “We were trying to understand what we were feeling about the war . . . [the rap session] was a safe place to talk”—the embryonic safe space, one might call it. Like the consciousness-raising sessions of feminists and the emerging gay rights movement, these meetings were sites of deeper politicization and self-education. And these rap sessions were the places from which the concept of PTSD emerged.

Like American society as a whole, the psychiatrists who treated vets were deeply polarized. Hawkish psychiatrists were adamant that concepts like combat fatigue had no diagnostic value. As a Veterans Affairs psychiatrist told the Los Angeles Times in 1975, there was “no evidence that Vietnam had produced a disproportionate share of people who are maladjusted to society and no evidence that the primary contributor to that maladjustment was military service.” In an essay published in Strangers at Home: Vietnam Veterans Since the War, psychologist Charles R. Figley noted, “In the mid-1970s the mental health profession barely recognized the plight of the emotionally disabled Vietnam veteran.”

More dovish colleagues, spearheaded by the politically engaged psychiatrists Chaim F. Shatan and Robert Jay Lifton—who both did groundbreaking work on the traumatic impact of war—developed a precursor to the concept of PTSD, “catastrophic stress disorder,” as a way of arguing that the traumas of war were not just physical and fleeting, but psychological and long-lasting. Lifton, a prolific Harvard professor, was especially famous for his studies of Nazi medicine and Hiroshima survivors, which argued that “immersion in death” created “prophetic survivors” with “special regenerative insights.” Participating in rap sessions with veterans like Jack Smith, Shatan and Lifton developed the idea of a “post-Vietnam syndrome” and came to see these former soldiers as another group of “prophetic survivors” who could lead the charge in the anti-war campaign.

As historian Ben Shephard noted in A War of Nerves: Soldiers and Psychiatrists in the Twentieth Century, the diagnosis of PTSD did not just bring about a modernization of the vocabulary of post-war melancholy but also the dawn of an era in which a medical label came with political baggage. Anti-war psychiatrists tended to emphasize the consequences of ignoring veterans’ emotional disorders—sometimes with partisan ends. “The post-Vietnam syndrome,” Figley wrote, “became a frightening buzz word among clinicians and journalists, but in fact was a thinly veiled position of opposition to the war: stop the war or more young killers will be released to terrorize the population.”

By 1980, Shatan, Lifton, and their allies in the veterans community were successful in lobbying for the inclusion of PTSD in the third edition of the American Psychiatric Association’s bible, the Diagnostic and Statistical Manual of Mental Disorders (DSM). “The essential feature [of PTSD] is the development of characteristic symptoms following a psychologically traumatic event,” the DSM-III read. Those symptoms involved “re-experiencing the traumatic event; numbing of responsiveness to, or reduced involvement with, the external world; and a variety of autonomic, dysphoric, or cognitive symptoms.” Since then, PTSD has increasingly shaped how both psychiatrists and laypeople understand the aftereffects of trauma. Despite its origins in the anti-Vietnam War movement, PTSD is now a widely accepted psychological diagnosis.

The idea of PTSD was bound to gain a greater foothold in popular consciousness in the twenty-first century as hundreds of thousands of American soldiers saw combat in Iraq, Afghanistan, and elsewhere. There has been an enormous surge in PTSD diagnosis in the military: In 2003 there were 190,000 veterans seeking care for PTSD. By 2014, the number had nearly tripled to 540,000. In the same year, a congressionally mandated study conducted by the Institute of Medicine concluded, “Demands for post-traumatic stress disorder services among service members and veterans are at unprecedented levels and are climbing.”

And as the label has evolved, it’s taken on wide-ranging usage: PTSD is now used to diagnose the aftereffects of traumatic experiences ranging from domestic abuse to war-zone reporting. The label’s evolution isn’t totally discordant with its origins: The concept of PTSD was an organic outgrowth of research Shatan and Lifton did on civilians as well as soldiers. As far back as the DSM-III, PTSD encompassed traumas that could easily take place outside a military context, like surviving an earthquake. Most recently, the latest definition of PTSD in the DSM-5 (they dropped the roman numerals with this revision), expanded the definition to include the response to the trauma of “sexual assault … [and] recurring exposure that could apply to police officers or first responders.” PTSD has been studied in the context of the aftermath of Hurricane Katrina, in the effects on boys when they move to a wealthier neighborhood, and injuries suffered by athletes playing hockey and football. After Ferguson and Baltimore, there has been discussion of PTSD as a possible aftereffect of the riots.

The pervasiveness of this diagnosis has been cultural as much as medical. PTSD has shown up in everything from the comic strip “Doonesbury” to movies like The Hurt Locker and even more popular fare like the Bourne spy thrillers. This summer, moviegoers will meet Max, a dog that suffers PTSD after serving in Afghanistan. A recent memoir by conflict-zone reporter Mac McClelland was titled Irritable Hearts: A PTSD Love Story.

The explosion of trigger warnings and the growth of safe spaces is best understood as a consequence of the expanded social and cultural role that PTSD has assumed in our society. The concept of PTSD rests on the importance of buried memories—memory traces—which can be reignited as flashbacks. PTSD is, in a crucial sense, a theory of memory: It posits that for certain people the memory of a trauma always exists, lying just below the surface of consciousness, ready to be triggered. A theory of this sort will naturally lead to a heightened vigilance. In his path-breaking research, Shatan said we have to confront “the unconsummated grief of soldiers—impacted grief, in which an encapsulated, never-­ending past deprives the present of meaning.” As silly as trigger warnings and safe spaces may seem, they are rooted in genuine, widely accepted science.

In the ’60s, the sociologist Philip Rieff used the phrase “the triumph of the therapeutic” to describe the way psychiatric ideas have become part of the common coin of everyday life. Rieff was dismayed by this trend, seeing the therapeutic as a threat to previous notions of the “sacred”—the transcendental aspirations which have guided human behavior in traditional societies. As he wrote in a 1987 retrospective piece in the journal Salmagundi, “the levelling languages of the therapeutic, against the ladder languages of faith, may yet succeed in eliminating both the dreadful joys of ascending to a higher life and the dreadful self-torments of failing to make those ascents.” In other words, therapy—or, the therapeutic mode—makes us shallower people, satisfied to accept our flaws as lasting conditions.

Many of Rieff’s fellow cultural critics, whether on the left or the right, shared his regrets. The libertarian psychiatrist Thomas Szasz questioned the whole validity of psychiatry as a science and feared that the therapeutic would destroy notions of personal responsibility; the left populist Christopher Lasch, critical of corporate liberalism, was terrified that the therapeutic would be a tool for the managerial class to manipulate the masses; the radical Russell Jacoby saw the therapeutic as a tool for creating social amnesia and foreclosing collective action. These were very different writers, but they instilled a sense among intellectuals of many different stripes that therapeutic culture was vulgar, manipulative, and inhibited progress toward the greater good.

But the intellectual rejection of “the therapeutic” has had little impact on average Americans, who have found in this mode ways not just to grapple with their personal problems but also—as in the case of Vietnam vets—forge political identities. These identities might seem as though they are excessively focused on victimization or identity politics, but association can lead to political empowerment. Participation in self-help has given once marginalized groups a new way to organize and give voice to their complaints and their needs. The “sacred order” that Rieff nostalgically mourned had little use for the desires and dilemmas of ordinary people, who were enjoined to suppress personal problems in order to serve the higher goods of family, nation, or God. In contrast to the stern self-abnegation of these older traditions, therapeutic culture is profoundly democratic, holding out the idea that everyone has a right to minimize personal suffering and make a grasp at happiness.

It’s easy to caricature the vanguard of the so-called politically correct: to paint them as fanatics who are trying to destroy well-established norms of free speech. But they are not caricatures; they are products of history. Most current college students grew up in the shadow of September 11, with the specter of large-scale terrorism always looming and with a steady stream of soldiers returning home to grapple with their demons. It is no wonder that they feel that they, too, deserve security, even in the precarious and flimsy form of trigger warnings and safe spaces.