If there's one thing we modern citizens of the West like to give thanks for, it's our Enlightenment heritage.

From one generation down to the next, the outline of the story has remained essentially the same: medieval Europeans wallowed for centuries in a dank swamp of backwardness and religious superstition, then the Enlightenment took place and we discovered scientific reason, and since that time our overall history has been one of rational progress, as we continue to unlock the secrets of the material universe and push back the tide of human ignorance.

It's a feel-good narrative, and its proponents have little time for such tiresome qualifications as World War I, the Gulag, the nuclear bomb, the Holocaust — all eloquent testimony to the persistence of Western unreason — or the fact that the European Enlightenment itself was part of a project of colonial expansion that involved slavery, genocide, economic plunder and the subsequent immiseration of entire populations.

Eggs and omelettes, you might say. And, of course, historical causes and effects are always up for debate.

But for anyone who wants to valorise the long and notionally successful march of Enlightenment reason, an uncomfortable truth presents itself in, quite simply, the state of the West today.

Political life under Donald Trump represents a triumph of irrationality, Justin Smith argues. ( Getty Images: Chip Somodevilla )

If the West is 'reasonable', why are things so crazy?

It's hard not to feel that things are just a little bonkers right now.

Democracy — the Enlightenment political project par excellence — has landed us with Brexit, an extreme-right surge across Europe and beyond, and an orange-hued reality TV star in the White House.

Two centuries on from the Industrial Revolution we appear to be cooking ourselves alive, and communications technology has birthed a writhing subculture of trolls and conspiracy theorists who appear more and more mainstream with each passing day.

To be sure, these are not the only fruits of the Enlightenment, which has also given many of us a measure of health, wealth, freedom and security that would have been unimaginable to our pre-modern ancestors.

But the question remains: if Western culture is so deeply and firmly rooted in reason, why do things feel so crazy?

One answer lies in the famous claim that "Enlightenment reverts to mythology".

This is the take-home message of Theodor Adorno and Max Horkheimer, Jewish academics who left their native Germany for America in 1934, and who published their classic Dialectic of Enlightenment in 1944 as the murderous insanities of Nazism were being laid bare.

The book describes a historical tendency of modern political orders to experience outbreaks of what appear to be the opposite of modern political values.

Adorno and Horkheimer believed that any rational order would collapse into irrationality. ( Wikimedia Commons: Jeremy J. Shapiro )

A familiar example would be a kind of patriotic fervour, whereby a proudly secular state develops nationalist rituals, ideologies and dogmas that look like religious phenomena. Critics of this are treated like heretics and blasphemers.

But that's not the only spectacle that Adorno and Horkheimer could have predicted.

Recently, we have seen the key Enlightenment value of free speech used as a cover for pushing theories of white supremacy, sex discrimination, reactionary politics and a number of other positions that are solidly (and ironically) anti-Enlightenment.

The heir to 1960s counterculture

According to Justin Smith, author of the recent book Irrationality: A History of the Dark Side of Reason, rational schemes have long given rise into their polar opposite.

From ancient Greece to contemporary America, the triumph of reason seems forever doomed to be a fragile, local, temporary phenomenon.

But interestingly, he says the tactical deployment of irrationality — of the knockabout, cheerfully iconoclastic kind — seems to have moved from the political left to the right.

"All of my early life, the left had a monopoly on playfulness, they owned the counterculture," Smith says.

"Whereas the right was the prototypical conservative Republican parent-figure, telling you to be home by curfew, imposing rules and so on."

But somewhere along the line, what Smith calls an "epochal shift" took place.

"One of the pivotal moments in this shift came in 2016, during the presidential election campaign, when Trump retweeted a meme that had Pepe the Frog in it," he notes.

"This was the moment when Hillary Clinton came out and said that Pepe the Frog was a symbol of hatred.

"All of these alt-right kids who were trying to get Pepe the Frog out there into the public consciousness, when Hillary said that, they were like, 'Yes!! Hillary mentioned Pepe the Frog! We did it!'"

It was at this point, that Smith realised Clinton had lost whatever edge she might once have possessed: she became the "stern, old schoolmistress".

"This was the moment when the effervescence of the extreme right was exactly, in spirit, the heir to 1960s counterculture," Smith says.

"But unlike the 60s counterculture, these people seized the presidency within a very short time after their rise — and I take the rapidity and the scope of this change to be a direct consequence of the rise of new communications and media technologies."

From dorm rooms to global domination

The corrosive effects of misinformation, conspiracy theories and fake news on social media fit neatly with Adorno and Horkheimer's thesis.

When technology designed to level the field of public discourse is used for anti-democratic ends, it's a textbook example of Enlightenment reverting to its opposite.

And Smith takes this phenomenon very seriously.

"The idea that Mark Zuckerberg, even now, can continue to talk about social media as if it were a resource for bringing people with common interests together — as if it were still part of the Harvard dormitory network — is just obscene," he says.

"It is a total failure to take responsibility."

Has Facebook CEO Mark Zuckerberg fuelled the fire of irrationality in contemporary politics? ( Getty images: Chip Somodevilla )

Smith says governments have failed to fulfil their own responsibility to bring social media companies under control. Until that happens, he doubts the chaos will end.

"We live in a system that is effectively a return to feudalism, in the sense that we have lords who control the most profitable companies with no democratic oversight," Smith says.

"This will have to change, there will have to be openness about how the algorithms work, and serious regulation of the flow of information."

'Machines are not going to help us'

But Smith's perception of social media wasn't always so bleak.

He references the Arab Spring revolutions in 2009, when citizens used Twitter to organise, demonstrate, and share what was happening with international audiences.

"[At this time] we were still able to believe that this was a force for promoting and amplifying democracy," he says.

According to Smith, the Arab Spring protesters believed in a dream that had already been articulated by the philosopher Gottfried Wilhelm Leibniz in the 1670s: that we can "outsource" a certain amount of our rational thinking to machines, and that these machines can, by reasoning for us, aid us in the attainment of world peace and stability.

"This was a dream from Leibniz's first designs for 'reckoning engines' in the 1670s, until the Arab Spring of 2009, which just disintegrated into bloody hell," Smith says.

"And over the 2010s, what we've seen is that Leibniz was definitively wrong: machines are not going to help us.

"Certainly, they're not going to prevent the sort of atrocities we're seeing facilitated by social media around the world right now."

But Smith isn't an absolute pessimist about the future of humanity in our tech-driven world.

He believes new norms and laws will emerge that put "overly effervescent irrational people back in their historically limited social position".

And, until then, at least the memes are fun.