What happened to Trump was a shock but not a surprise - and that should worry us

It showed that, despite all the resources and protections available to law enforcement, little can be done to prevent a determined individual from threatening the life of the frontrunner in the current US presidential campaign. We may think political trends are relatively stable - but Sunday morning's events show us that things may at any point be upended in sudden and unpredictable ways.

Yet, in another sense, the attempted assassination should not have been a surprise. US political rhetoric, beliefs and acts have been marked by increasing extremism in recent years.

This coarse and divisive political rhetoric cannot be dismissed as "mere words." The political interests of individuals are shaped by their beliefs, and their beliefs are shaped by political rhetoric - not least that of leaders.

In short, where rhetoric becomes more extreme, beliefs become more extreme, and so political acts just as surely follow in the direction of what was once unimaginable.

Consider the rhetoric of Trump and Biden themselves: Trump's longstanding denunciations of groups spanning immigrants, elites, and the "deep state" have escalated in their intensity. They emerged from an "America First" narrative which pitted everyday Americans as victims of a conspiracy of globalist elites who sold them out to foreign interests.

In the context of Trump's criminal indictments, he has gone further, condemning the Biden administration for orchestrating his prosecutions, offering himself to his supporters as a source of their "retribution" and warning of a "bloodbath" should he lose in November.

However, Biden's rhetoric has been increasingly strident as well. Indeed, the logic of American campaigning places a premium less on persuading undecided voters than on mobilizing an angry base. In this light, the Biden campaign has not been immune from the temptation to rhetorical excess, painting Trump as a threat to American democracy.

Prior to the 2022 midterm elections, Biden cast "MAGA Republicans" as representing "an extremism that threatens the very foundations of our republic". In a February 2024 fundraiser, Biden remarked: "There is one existential threat: it's Donald Trump."

To be sure, Trump has promised to be a "dictator for one day" - and so one cannot equate the claims of each side. However, the chasm has nevertheless been widening.

The US has been here before. One common reaction in the US was that it "felt like the 1960s," or a return to a decade marked by the assassination of a president (in John F. Kennedy), a Democratic presidential frontrunner (in Robert R. Kennedy) and a transformative civil rights leader (in Martin Luther King).

It felt like a return to a time marked by political extremism on the right and the left - whether in the form of the John Birch Society on the right or the Weather Underground on the left. In that sense, the attempt on Trump's life was a reminder that American politics has often been plagued by tendencies to radicalism, reaction and threats of violence.

Political violence, attacks and attempted assassinations have manifested themselves as well in recent years. The January 6, 2021, attacks on the US Capitol - in the context of wider attempts at intimidating poll-watchers and election workers, as well as Trump-inspired calls to "Hang Mike Pence" - are perhaps the most obvious examples.

However, the trend to violence would both precede and follow the events of that day. In June 2017, a left wing radical shot six people during a congressional baseball practice in Virgina, including US House Majority Whip Steve Scalise. In June 2022, in response to a leak of the Supreme Court's Dobb's decision overturning Roe vs. Wade, an opponent of the ruling (and recent gun cases) travelled to to the home of associate Supreme Court Justice Brett Kavanaugh, planning to assassinate the justice and commit suicide - only to abandon the plan outside Kavanaugh's home.

In October 2022, a right wing radical broke into the home of House Speaker Nancy Pelosi while the Speaker was in Washington. However, her husband, Paul Pelosi, was home, and the assailant would fracture his skull with a hammer in a brutal attack.

Against a backdrop of political rhetoric, violent acts like these should not be surprising. Nor are they out of tune with moments of polarization and radicalism in American history.

As the historian of US politics Richard Hofstadter noted in his work The Paranoid Style in American Politics: "American politics has often been an arena for angry minds."

To be sure, in the current context, one might argue that the more extreme rhetoric has come from the right.

Nevertheless, incentives to more extreme rhetoric have been taken up on each side. In this light, the attempted assassination of Donald Trump was a shock - but it should not be a surprise.