You can, we all know, have too much of a good thing. Even when that thing is goodness itself. Indeed, I would argue, there are few worse ideas than that of natural human goodness. And none that has had more catastrophic consequences. The idea of intrinsic human goodness was given its purest, most extreme and most influential expression (inevitably) by a Frenchman — or at least a French-speaking Swiss — Jean-Jacques Rousseau. 

“The fundamental principle of all morality”, Rousseau wrote, “upon which I have reasoned in all my writings and which I developed with all the clarity of which I am capable, is that man is a being who is naturally good, loving justice and order; that there is no original perversity in the human heart, and that the first movements of nature are always good.”

Rousseau was of course aware — none more so — of all the evil in the world. But that was the fault, he was sure, not of man but of society and its institutions: “man is naturally good”, he insisted, “and it is solely by these institutions that men became wicked”. Rousseau wrote in the decades before the French Revolution, of which he became both inspiration and hero. A century earlier, during the parallel upheaval of the English Civil War, Thomas Hobbes had offered a very different picture of the “natural” human condition. 

Hobbes saw the life of “natural” man as “solitary, poor, nasty, brutish, and short”. So, far from society corrupting man, it was only by his recognition of a “common power to keep them all in awe” that he was rescued from his “natural” state of “war of all against all”.

Of course, neither Rousseau nor Hobbes had ever seen a “natural” or pre-social man nor witnessed him in the “state of nature”. Instead, and however much they draped their radically opposed visions in historical or anthropological dress, they remained mere philosophical abstractions.

All this was pointed out by David Hume with his usual devastating clarity. “Philosophers may”, Hume observes, “extend their reasoning to the supposed state of nature, provided they allow it to be a mere philosophical fiction, which never had, and never could have, any reality.”

Until now. Or rather, until the years 1989-1994, which saw the World Wide Web spring, more or less fully formed, from the head of Sir Tim Berners-Lee. For on the web, as in the state of nature, there are no laws and few frontiers; no policemen or judges, though many self-appointed vigilantes; no kings or presidents but a rough — very rough — equality and few property rights and those hotly disputed. 

Instead, men and women meet as their naked selves, on neutral territory, and stripped of the specifics of culture, language, customs, decency and even, if they choose through encryption and anonymity, faceless and shorn of identity itself. In other words, Berners-Lee, among his many other achievements, has proved Hume wrong, since with the World Wide Web he has translated the “philosophical fiction” of the state of nature into — admittedly virtual — reality.

But virtual reality is surely real enough to show man in his “natural” self. This means in turn that, thanks to the World Wide Web, we can test the rival and contrasting pictures of “natural” man and the state of nature in Hobbes and Rousseau. We can even do it with a measure of numerical precision. 

There are 27 million registered users of Wikipedia. They and their world correspond, I would suggest, to Rousseau’s depiction of frugivorous virtue (he thought that human dentition showed that we were originally pacific fruit-eaters, only becoming warlike carnivores with agriculture and socialisation). It is a goodly number. On the other hand it is dwarfed several times over by the 330 million users of Twitter. This means it is an easy victory for Hobbes, since if there is a better description of the Twitter-sphere than the “war of all against all”, I have yet to find it.

Berners-Lee himself concedes as much with his call for a new Contract for the Web. For the Contract would police his fallen paradise with the Hobbesian correctives to human frailty of laws and regulations, imposed, of all things, by the state. 

What makes the loss of Rousseauian innocence all the more poignant are the local details. CERN (Conseil Européen pour la Recherche Nucléaire), where Berners-Lee carried out the crucial work for the World Wide Web, is based in the commune of Geneva, a few miles from Rousseau’s birthplace. While Berners-Lee himself is a Unitarian Universalist, that is a member of a quasi-church whose Seven Principles, headed by a belief in “the inherent worth and dignity of every person” are a sort of abstract, in tamer language, of Rousseau’s own heady idealism about the “natural” human condition.

Rousseau was franco-swiss and Unitarian Universalism is American. But they have a direct English equivalent in the Quakerism in which I was brought up but soon rejected. It too centres on a doctrine of innate human goodness, though it is (or at least used to be) expressed in more formally religious terms as “that of God in every man”.

Quakerism, despite the tiny number of its adherents, has had a profound impact on English life, from garden cities like Bourneville to prison reformers such as Elizabeth Fry. 

Its tenets remain especially influential in prisoner rehabilitation and both their strength and their drawbacks were conspicuous in the terrorist attack at Fishmongers’ Hall last November. The attack took place at a conference mounted by Learning Together, a programme run by the Institute of Criminology of Cambridge University that seeks to rehabilitate inmates and ex-offenders by bringing them together with students and recent ex-students of the university.

The depravity of jihadi killer Usman Khan surely offers irrefutable evidence against a Rousseauian model of human nature

The fundamental principle of the programme is the authentically Quaker/Rousseauian one that no criminal, however apparently depraved, is beyond redemption. A star exhibit of the success of the approach was the supposedly de-radicalised ex-terrorist, Usman Khan, who had been befriended by student activists on the programme such as  Saskia Jones and Jack Merritt. 

“They did not see him as a former terrorist,” a former police sergeant who had also mentored Khan explained, “but as someone they believed was able to reform.” Their reward was to be stabbed to death as victims of Khan’s carefully plotted rampage. He first exploited their innocence to dupe them into believing in his rehabilitation; then, to signify his contempt for his befrienders, he murdered them first.

It would be hard to find a clearer example of human depravity, to view the matter through our eyes. Or of jihadi rejection of Western values, to see things from his point of view. But, however viewed, Khan’s behaviour surely offers irrefutable empirical evidence against a Rousseauian model of human nature.

Or so you would think. But not if you were Jack Merritt’s father. Instead, in an extraordinary intervention, he denounced prime minister Boris Johnson as the perpetuator “of an agenda of hate” for suggesting — mildly in the circumstances, I would have thought — that terrorists should serve their full sentences. 

And, in a letter to the Guardian, he recited his son’s passionately Rousseauian creed: that the problem was “our society failing those most in need”. The effect was to turn the poor lad into a Rousseauian martyr, stabbed to death by a fanatic while proclaiming, with his last breath, that he “believed in the inherent goodness of humanity”. 

Rousseau went mad. But then believing in impossible things — such as inherent human goodness — tends to do that to people and (I fear) to societies.