Is Donald Trump the end of the Enlightenment? Plenty of people think so. “The Trump team has shown contempt for Enlightenment values shared by liberals and conservatives alike,” wrote former senior State department official Suzanne Nossel recently. “The principles that Trump aims to defeat include the bedrock tenets of the Enlightenment and of American democracy.”

The Financial Review’s Andrew Clark devoted a column to discussing whether “Trump’s arrival signals the end of the Enlightenment”.

A piece in Salon claimed Trump’s inauguration “announces the beginning of the end of the Enlightenment itself”.

“Today’s cry of protest … is a rejection of the Enlightenment,” a Boston Globe columnist wrote in a piece in December entitled “The Enlightenment had a good run”.

However, time has been called on the Enlightenment before. That Platonic Ideal of Guardian commentators, George Monbiot, called “The End of the Enlightenment” in 2001 when he juxtaposed the US “victory” in Afghanistan (hmmm) with the loss of basic civil liberties in the US. A New Scientist discussion focused on the end of the Enlightenment at the hands of religious fundamentalism in 2005. The growing attacks on climate science in 2012 moved another writer to declare the end of the Enlightenment (sorry 2012, but you ain’t seen nothin’ yet). Neoliberal cuts to education budgets were the end of the Enlightenment in 2013. The Enlightenment was been a long time dying, and the murderers are manifold; Trump is only the latest.

As the constant cries of its death suggest, it seems everyone loves the Enlightenment, even if they don’t know a whole lot about the eruption of rationalist, anti-religious and reformist thought across the 18th century.

When prime minister, John Howard declared, with his usual casual indifference to Australia’s first peoples, that Australia’s “dominant pattern comprises Judeo-Christian ethics, the progressive spirit of the Enlightenment and the institutions and values of British political culture”. Tony Abbott — who, with his aggressive Catholicism and bloodlust for the culture wars, would surely, had he been born in 18th century France, have been among the most aggressive royal persecutors of the philosophes — complained in 2015 that Islam had failed to undergo a reformation and an enlightenment.

This is profoundly ironic, given both Abbott’s ideology and the fact that he made the statement on Sky News, the most demonstrably anti-Enlightenment form of media in Australia, but also profoundly ignorant; it was only via Islamic scholarship that many of the West’s classical texts survived the medieval period, quite apart from the crucial Arab scientific and mathematical advances that the West benefits from to this day.

But not everyone does love the Enlightenment. The Catholic Church, certainly, still regards the Enlightenment with hostility; given it only “forgave” Galileo in the 1980s, it will probably come around in a century or so. And post-modernists saw it as perniciously offensive, fundamentally linked to capitalism, its assertion of universal values an arrogant, Eurocentric form of cultural imperialism. Some saw in its exultation of reason the ushering in of a new tyranny that stripped humanity of our innate value as living beings and led the way to the Holocaust and other 20th century genocides.

Marxists took a different view. While intellectual history is subordinate in Marxist theory to economics — the ideas of the Enlightenment mere superstructure to the core historical forces at work — and the Enlightenment was understood as a primarily bourgeois phenomenon (indeed, the actions of a revolutionary bourgeoisie) the crucial role of the Enlightenment in the development of Marxist thought was recognised from the outset as providing the tool of rationality that, once employed by bourgeois intellectuals, would now be employed by anti-capitalist forces. The Enlightenment was thus a crucial stage in the development of Marxism itself, even if that tool was to be used against the bourgeoisie.

Well … so what?

The Marxists make a fair point. The Enlightenment was, necessarily, an elite phenomenon; the people being enlightened were wealthy European men, and a few women, but who tended to be outside the existing ruling class of monarchs and aristocrats (England, at this stage, was essentially the same, with a tiny franchise and corrupt electoral system). The label “bourgeois” is perfectly apt. But the issue of structure and superstructure is more fundamental. If the Enlightenment occupies such a central role in our self-conception as modern societies, what was the origin of the Enlightenment and its most powerful ideas of reason and universal rights?

This argument has long been fought over by historians in the context of the causes of the French Revolution — which came hot on the heels of the French Enlightenment — and the key influences on the American revolutionaries and founding fathers. Were these ideas the “mere” product of economic forces? Were they simply the musings of certain Great Men Of History that sprang forth without precedent and took hold? What is the origin of this most crucial component of the Western self-conception?

The Marxist explanation is pretty sound for at least part of the Enlightenment. One important angle is that capitalism made the spread of Enlightenment ideas easier — the seminal intellectual text of the Enlightenment, the Encyclopedie, was funded by subscriptions (although there were few “capitalists” and people of business buying them); the whole venture relied on there being a reading public in France large enough to support the publication of what became a decades-long publishing venture.

There are also clear philosophical links between capitalism and strands of Enlightenment thought. One of the two key 17th-century philosophers who heavily influenced the Enlightenment, John Locke, established the contractarian basis for England’s limited monarchy model after 1688. Locke’s key works had been written before then, but the Glorious Revolution of 1688-89, in which the last Stuart monarch was forced out and replaced by the Dutch invader William of Orange, was a revolution of vested interests — the English landed class — against a monarch threatening to replace the country’s informal constitution with absolutism.

Locke’s justification for private property and the right of a people to remove a monarch if the latter was no longer serving their interests was perfect for post-Stuart England, which would become the economically dominant imperial power of Europe in coming decades. It would be nearly a century later that Adam Smith would provide a still-clearer link between Enlightenment thought and capitalism.

But a regular theme of much of the historiography of the Enlightenment is that there was more than one — there were different national Enlightenments, there was a high/low Enlightenment. Enter historian Jonathan Israel, who has pursued what he argues is the most profound distinction of all, between the moderate and radical Enlightenments. The moderate Enlightenment was that of Locke, and of Voltaire — probably the only Enlightenment “philosopher” most people could name — who was open about his contempt for the great mass of people and who believed only the middle class could be “enlightened”.

Indeed, Voltaire, the great enemy of the clergy, believed religion was necessary in order to keep the masses in line. This “moderate” Enlightenment — the Enlightenment you could safely market to “enlightened despots” like Frederick of Prussia and Catherine the Great — was very much the Enlightenment that Marxists would expect from a rising bourgeoisie, and the Enlightenment of the American Revolution, which produced high-flying rhetoric about all men being created equal while maintaining a system of slavery.

But Israel argues that the truly enduring Enlightenment ideas came from a radical Enlightenment that followed reason and universal rights to their logical conclusions. Why have any social orders — why shouldn’t all have basic rights, including women, including Africans, including native Americans, including slaves, including homosexuals? That was where Denis Diderot, the editor of the Encyclopedie, ended up, along with other key figures of the radical Enlightenment such as Baron d’Holbach and Jean d’Alembert. These were the ideas that emerged during the French Revolution and which were to be the most profoundly influential in the 20th century, not the hierarchical, conservative Enlightenment of Voltaire.

This radical Enlightenment owed much to the other crucial 17th-century thinker, the Dutch philosopher Spinoza, whose ideas about religion, toleration and constitutional government derived from his metaphysics: monism (Spinoza believed there was only one substance, and God was that universal substance; there was no deity in a personal sense, therefore no divine law or sanctified order of things).

The radical Enlightenment didn’t meet with unalloyed success, nor was the French Revolution a kind of fulfilment of the radical philosophe‘s dreams. In fact, the radical philosophes were demonised by the Jacobins during the Terror; Diderot, d’Holbach and d’Alembert had all died by the outbreak of the Revolution but surviving radicals like Tom Paine and Condorcet were in hiding or had been jailed by the Jacobins; one, Cloots, had been executed. Robespierre and the Jacobins particularly despised the radical philosophes not merely for their support for free speech and democracy but because they were seen as enemies of the 18th-century philosopher prized above all by the Jacobins, Rousseau.

Wasn’t Rousseau himself an Enlightenment thinker? He did contribute, significantly, to the Encyclopedie but he fell out with Diderot, as he fell out with pretty much everyone he ever met. His own philosophy was fundamentally anti-Enlightenment: he believed reason was the entire problem for humankind and that we’d all been better off in a blissful pre-civilisation when we hadn’t used reason at all. He was a democrat, but hated the idea of any sort of representative democracy — he believed in an authoritarian democracy in which representatives would be constantly monitored for any deviation from the popular will and any disruptive ideas (like those of Diderot) would be shut down as quickly as possible, not by debate and argument, but by censorship.

Rousseau was also profoundly misogynistic, even by the standards of the 18th century. Women, who “are the sex that ought to obey”, could not be citizens, for Rousseau; instead, their place was in the domestic sphere. Rousseau was a very long way from Diderot and d’Holbach, who argued that the alleged inferiority of women reflected their lack of education and lower legal status in European countries, rather than any biological inferiority.

A loathing of reason, a heavily censored political environment, a hatred of women — which modern political figure does Rousseau remind you of? In an insightful article in The New Yorker last year, writer Pankaj Mishra identified Rousseau’s thinking with Trump and the political climate exploited by him, particularly around the importance of fear, and his resentment of what we now call “elites”.

“… because Rousseau derived his ideas from intimate experiences of fear, confusion, loneliness, and loss, he connected easily with people who felt excluded. Periwigged men in Paris salons, Tocqueville once lamented, were ‘almost totally removed from practical life’ and worked ‘by the light of reason alone’. Rousseau, on the other hand, found a responsive echo among people making the traumatic transition from traditional to modern society — from rural to urban life.”

Similarly, Trump appeals to those making the transition from a traditional industrial economy to a globalised, information-based economy.

The Jacobins loved Rousseau: they, too, saw reason as a corruption of the simple wisdom of the labouring classes — wisdom as interpreted, of course, by the Jacobins and their supporters, the sans-culottes of Paris. The sans-culottes were the workers and smaller businesspeople of Paris, ultra-aggressive and politically radical, who relied on the yellow press and rumour for their news, and who were quick to act on the basis of any conspiracy theory that circulated in the city.

Sound familiar?

Trump’s not the end of the Enlightenment, any more than Rousseau, who bitterly railed against not just the radical but the moderate Enlightenment writers, was. But the rich vein of irrationality and fear Trump exploits has intellectual as well as popular roots. Human rights aren’t the only thing that’s universal: stupidity, ignorance and irrationality can be found around the world and across the ages too — as can their defenders.