Last month, in the early hours, an act of traumatising racist violence occurred on the campus of Emory University in Atlanta, Georgia. Students woke up to find that someone had written, in chalk, the words “Trump 2016” on various pavements and walls around campus. “I think it was an act of violence,” said one student. “I legitimately feared for my life,” said another; “I thought we were having a KKK rally on campus”. Dozens of students met the university president that day to demand that he take action to repudiate Trump and to find and punish the perpetrators. Writing political statements in chalk is a common practice on American college campuses and, judging from the public reaction to the Emory event, most Americans consider the writing to be an act of normal free speech during the national collective ritual of a presidential election. So how did it come to pass that many Emory students felt victimised and traumatised by innocuous and erasable graffiti?

Emory students are not unique. Many other universities have been rocked by protests this year over what seem like small things to outsiders, such as Halloween costumes, dining hall food and sombreros. This new way of looking at things is spreading rapidly in the UK, too, with growing student demands for bans on words, ideas, speakers and, once again, sombreros. Students on both sides of the Atlantic are demanding that their campuses be turned into “safe spaces” where a subset of ideas and identities will not be challenged. What on earth is going on?

Part of the answer can be found in cultural shifts that have changed the meanings of many words and concepts used on campus, making it hard for people off campus to understand what the protesters are saying. One of us (Haslam) recently published an essay titled “Concept creep: Psychology’s expanding concepts of harm and pathology.” Many concepts are “creeping” – they are being “defined down” so that they are applied promiscuously to milder and less objectionable events.

Take bullying. When research on bullying began in the 1970s, an act had to meet four criteria to count: it had to be an act of aggression directed by one or more children against another child; the act had to be intentional; it had to be part of a repeated pattern; and it had to occur in the context of a power imbalance. But over the following decades, the concept of bullying has expanded in two directions.

It has crept outward or “horizontally” to encompass new forms of bullying, such as among adults in the workplace or via social media. More problematic, though, is the creeping downward or “vertically”so that the bar has been lowered and more minor events now count as bullying. For example, the criteria of intentionality and repetition are often dropped. What matters most is the subjective perception of the victim. If a person believes that he or she has been made to suffer in any way, by a single action, the victim can call it bullying. As the definition of bullying creeps downward for researchers, it also creeps downward in school systems, most of which now enforce strict anti-bullying policies. This may explain why Emory students, raised since elementary school with expansive notions of bullying and subjective notions of victimhood, could perceive the words “Trump 2016” as an act of bullying, intimidation, perhaps even violence, regardless of the intentions of the writer.

A second key concept that has crept downward is trauma. Medicine and psychiatry once reserved that word for physical damage to organs and tissues, such as a traumatic brain injury. But by the 1980s, events that caused extreme terror, such as rape or witnessing atrocities in war, were recognised as causing long-lasting effects known as post-traumatic stress disorder (PTSD).

The original criteria for PTSD required that a traumatic event “would evoke significant symptoms of distress in almost everyone” and would be “outside the range of usual human experience”. But in recent trauma scholarship these stringent criteria are gone; like bullying, trauma is now assessed subjectively. In one recent definition used by a US Government agency, trauma refers to anything that is “experienced by an individual as physically or emotionally harmful or threatening and that has lasting adverse effects on the individual’s functioning and physical, social, emotional, or spiritual well-being.” For Emory students raised within a psychotherapeutic culture that employs this low threshold, we cannot blame them for labelling their reactions to “Trump 2016” as a personal and collective trauma. “We are in pain,” said one of the students.

A third key campus concept that has crept downward is prejudice. As overt prejudice has declined precipitously, the term has crept outward and downward. For example, the concept of “modern racism” was developed to refer to people who may show no overt prejudice, but who endorse policy positions that might be associated with prejudice, such as opposing the use of racial preferences in college admissions. More recently, the concept of “implicit prejudice” has become popular after experiments showed that it takes most people slightly longer to associate pictures of Black people (vs. White people) with good words (vs. bad words).

As with bullying, prejudice is now in the eye of the beholder. If a person feels that a word, facial expression or even a subtle hand movement makes them uncomfortable in a way related to a protected identity, then an act of prejudice has occurred. For Emory students steeped in training about prejudice and inclusion, there is no need to know the intentions of the midnight chalker. The word “Trump” activates associations to racism in their minds. Therefore, anyone who writes his name has committed an act of racism, perhaps even traumatizing racial violence.

Concept creep does not happen to all psychological terms – it happens primarily to those that are useful in what sociologists have called a “culture of victimhood”.

In such cultures there are two main sources of social prestige: being a victim or standing up for victims. But victimhood cultures don’t emerge in the most racist or sexist environments – they tend to emerge in institutions that are already highly egalitarian (such as Emory and Yale) and in which there are authorities (such as deans and college presidents) that can be entreated to step in on the side of the victims. In such settings political potency is increased by amplifying the number of victims and the degree of their victimization. Concept creep serves as a rhetorical weapon of victimhood culture.

Once you understand this campus dynamic, you can more easily understand the many new concepts that have emerged from university campuses in the last few years.

If all of society, including the campus, is rife with bullying and prejudice, and if people are easily traumatised, then it is obviously a good and humane thing to provide members of marginalised groups with safe spaces where nobody will say things that might make them feel more marginalised. Some students want their entire campus to become a safe space, even if that means that non-progressive or non-approved ideas, professors and speakers are banned or denied a platform on the grounds that their words are considered hate speech. Advocates of “no platforming” will sometimes shout down speakers they disapprove of, denying everyone in the audience the chance to listen to a speaker they have come to hear.

The yearning for safety in a dangerous world also explains the growing demands that students make for trigger warnings, which are warnings professors are expected to give about any course readings that might activate memories of trauma in any of the students.

And it’s not only reminders of rape that are triggering; students sometimes demand trigger warnings for novels that portray racism, classism or colonialism. It is everyone’s collective duty to protect vulnerable students from experiencing negative emotions in the classroom. Those who want to lower the bar for definitions of bullying, trauma and prejudice hope that the expansion of these concepts will protect vulnerable people and raise the public’s sensitivity to harm.

Regrettably, the outcomes are likely to be less rosy. Diluting concepts of harm swells the ranks of people who are encouraged to see themselves as harmed, vulnerable and in need of protection, which may cancel out any benefits gained by reducing insensitive behaviour.

As the Canadian philosopher Ian Hacking observed, concepts create identities. Hacking described “looping effects” in which people come to see themselves through the lens of a new concept and define themselves in its terms.

Students who are taught to interpret small or ambiguous experiences on campus, such as seeing “Trump 2016”, as instances of bullying, trauma or prejudice, rather than as the ordinary ferment of differing people with differing views, come to see themselves as aggrieved and fragile victims. Their vulnerability defines them and gives them a moral platform from which to demand protection and safety. At the same time, they typecast their opponents as bullies, traumatisers and aggressors.

This polarised image of vulnerable victims needing protection from vilified perpetrators is hardly a promising basis for a mature and respectful exchange of views on campus. It shuts down free speech and the marketplace of ideas. And it is not even healthy for the students who are the objects of concern.

Of course young people need to be protected from some kinds of harm, but overprotection is harmful, too, for it causes fragility and hinders the development of resilience.

As Nasim Taleb pointed out in his book Antifragile,muscles need resistance to develop, bones need stress and shock to strengthen and the growing immune system needs to be exposed to pathogens in order to function. Similarly, he noted, children are by nature anti-fragile – they get stronger when they learn to recover from setbacks, failures and challenges to their cherished ideas.

A university that tries to protect students from words, ideas, and graffiti that they find unpleasant or even disgusting is doing them no favors. It is setting them up for greater suffering and failure when they leave the university and enter the workplace. Tragically, the very students who most need the strength to face later discrimination are the ones rendered weakest by victimhood culture on campus.

The unrest on university campuses has not just been caused by creeping concepts. Black and Muslim students, in particular, must endure ignorant questions and other indignities that other students rarely face. Diversity is difficult, and more must be done to make all feel welcome on campus. But universities should be careful not encourage victimhood culture, looping effects and greater fragility

One step that might reverse concept creep is to expand notions of diversity to include viewpoint diversity, especially political diversity. Between 1990 and 2010, American university faculties went from leaning left to being almost entirely on the left, especially in the humanities and social sciences. But if students are not exposed to conservative ideas, they are more likely to find them traumatising when they encounter them outside of college.

Ultimately, it is the students themselves who will have to stand up and reject victimhood culture and its creeping concepts. One way to do this is to embrace the term “danger” the way earlier activists reclaimed the term “queer”.

Students at every university should push their student governments to hold a vote on whether the students want a “safe” university that routinely bans speakers, warns students about novels, and punishes students and professors for speech acts, or a “dangerous” university that takes no steps to protect its students from exposure to words, speakers, and ideas (with limited exceptions such as slander or threats of violence).

The debates that would surround such campus votes would help students see that too much safety is, ultimately, more dangerous than anything written in chalk.

Jonathan Haidt is author of The Righteous Mind and professor of business ethics at New York University Stern School of Business. Nick Haslam is professor at the School of Psychological Sciences, Melbourne. To learn more about concept creep, please visit HeterodoxAcademy.org