After attacks such as Nice, we demand answers [1]. A requirement to understand is necessary both to protect ourselves in the future and to deal with the consequences of horror. What was the motivation? Are there links to other individuals? How did the killer arrive at the decision to kill?

That desire to understand is hardly a new phenomenon, although modern media have made it more pervasive. Joseph Conrad, in the complex character of Verloc – the anarchist bomber, double agent and provocateur of the The Secret Agent – was an early explorer of this territory [2].

White people who buy guns to shoot up cinemas and schools are put into one category: “lone wolves” [3]. And inevitably the focus is on psychological and social problems. Individuals from a Muslim background are instantly placed in another category: “terrorists”. But when it comes to attacks such as those in Nice and Orlando [4], the distinction is increasingly unclear.

If those two attacks – as seems very possible – were as much about the inadequacies of the attackers as about Islamic State; if Isis, or simply the fact of the attention given to such mass killings claimed by Isis, is no more than a nudge that legitimises, in the perpetrator’s mind, mass killing – then perhaps there is no meaningful distinction.

Part of the problem is that we have come to expect to see in these attacks, especially jihadi-inspired events, certain attributes. But like the proverbial generals always fighting the last war, there is a time lag in our understanding of the patterns of violence.

There is the inevitable search for evidence that these are thoroughly organised murders – leaving behind an email trail, evidence of contact and warnings of intent on social media. There is an expectation of a familiar path to radicalisation or membership of a group. It should have a coherent justification.

This is the model of 9/11 and al-Qaida: violence marked by a certain fastidiousness of purpose, and long in the planning. That path was understood: individuals were recruited, travelled to training camps in foreign warzones and drawn into plans that were sometimes years in the making. The new kind of outrage, though, appears very different.

What matters is the fact of the act alone and its power to frighten, divide and destabilise
A key innovation of Isis has been to reverse the polarity of responsibility: encouraging acts of violence that it accepts as bloody tributes thrown at its feet. That has best been summed up in statements by Isis spokesmen such as Abu Muhammad al-Adnani [5], who in 2014 encouraged ad hoc attacks using whatever tools are easily available [6], including vehicles.

And while Isis is organised in places where it is strong, and is capable of setting up cells outside its own territory, it has also recognised that all it needs to do to widen its impact is to provide a lethal context for attacks [7] – a convenient peg for the angry and alienated.

The crucial point that many have missed is that it does not actually matter to Isis whether there is any real connection: whether the new “soldiers” it claims after the fact are more disturbed than ideological. What matters is the fact of the act alone and its power to frighten, divide and destabilise – and that the attack is understood to be inspired by Isis.

The problem for western governments and security forces is that even if that is actually understood, it is hard to convey to a frightened population for whom such subtleties are meaningless. It is also a risky argument. To say that “radicalisation” can be so instantaneous plays into the hands of individuals such as Donald Trump who would present all Muslims as a risk [8]. Then there is the practical issue of what this means for law enforcement if what we are talking about is an individualistic and post-ideological attraction to violence looking for a model to copy, then that is close to impossible to counter.

If there is a parallel that should serve as a warning – and I make the comparison extremely carefully and with many caveats – it is to be found in some of the incidents that have occurred during the so-called “knife intifada” [9] in the occupied territories. There, smarter Israeli security officials, if not the political cadre, were quick to recognise that one category of those involved in attacks were those with personal problems for whom the act of violence, emulating others, gave a retroactive meaning to their deaths. Again, a common feature in many incidents was a lack of any warnings and few if any connections to groups that might afterwards have praised the attacks.

What this means is that there will have to be a fundamental rethinking of how we seek to describe such events. It is an issue that has become all the more urgent as the French interior minister, Bernard Cazeneuve, said today that no links have been established yet between the attacker and Isis [10].

But what if, in this context, that idea of radicalisation is essentially meaningless and what we mean is something more vague, akin to an emotional response? Where an unstable individual – perhaps already prone to grandiose, deadly and narcissistic thoughts – borrows the forms and ideas of a certain kind of mass killing because they are familiar?

And the tragic reality – and the twisted genius of Isis’s pitch – is that it does not matter. They have supplied permission, mediated both via their own outlets and conventional media and through the acts they claim.

And what that implies is that the already false distinction between the disturbed “lone wolf” individual and organised “terror” as we have understood it, has broken down. Our tools for understanding motive have failed.

Returning to Conrad, all we really have left is the name-tag tied to Stevie – the young man with learning disabilities Verloc sends to deliver his explosives and who dies in the act. A violence whose shape increasingly appears unknowable.

Peter Beaumont