When I listened to Greta Thunberg’s recent speech at the UN, I was struck by the immediacy of her dystopian vision (‘entire eco-systems are collapsing’), her disgust for those who deny its truth (her ‘I dare you’ refrain) and the absolute moral imperative, in her eyes, for drastic economic action. While this speech has sparked considerable public discussion, an important point has been missed. If we put climate change to one side for a moment, it is clear that Greta’s message, in broad outline, is nothing new. If the lyrics have changed, the tune is all too familiar.

Previous generations have heard, from similarly-impassioned witnesses, about the imminent collapse of civilisation, an expert consensus supporting this view and the requirement for revolutionary action if salvation is to be achieved.  Marxists come to mind in this regard, as do the Club of Rome environmentalists who predicted near-term natural resource exhaustion in the 1970s. Even the largely now forgotten Prohibition movement from the early twentieth century sang a similar refrain. Each of these movements appealed to deep-seated insecurities and beliefs.  Each triggered broad political and social movements which spread like wildfire, capturing the elites of their time. But each had a limited shelf-life. After their time in the sun, they largely disappeared from the scene, reverting to the relative obscurity from which they came.

By the way, I am not questioning the legitimacy of climate change as a focus for scientific study, policy attention and reasoned community debate. As a political community, it is entirely appropriate that we consider, calmly and soberly, hypothesised risks, the merits and drawbacks or possible responses. This rational, necessarily prosaic perspective would be rejected by Thunberg and many others.  For them, climate change is literally life and death, an unfolding dystopic vision which obliterates all other concerns.

But why does climate change evoke such a reaction? What explains this issue’s potent psychological and emotional appeal? Let’s look at parallels with the other, similarly transformative movements mentioned before. Three things stand out. They reduce our world, in all its complexity and unknowability, to a single, defining conflict. They appeal to scientific or expert authority; the only source of revealed truth which, for atheists and agnostics, can command uncritical acceptance. They hold out a simple, neat and morally-satisfying solution; a bridge to an idealised world where harmony is once again achieved, for all time.

At the heart of each vision is a defining conflict that explains all, a feature they borrow from religious and traditional tribal belief systems. For Marx, it is between capital and labour. Prohibitionists fetishised the demon drink, which they saw as undermining personal morality. And for the Club of Rome, the tension was between capitalism (economic growth) and the natural world.

This reductionist, binary way of seeing the world has always been highly seductive. It simplifies the complex, fragmented reality we experience, offering the key to deeper understanding. It can be manipulated to explain the past and foretell the future. And it typically has a distinct moral dimension, pitting villain against victim. It is suggestive of how children perceive things, but perhaps we never grow out of the temptation to think this way. In largely secular societies, these binary world views are more likely to be given scientific than spiritual expression.  Both Marxism and radical environmental programs style themselves as scientific. Of course, most science takes place in obscurity, behind the laboratory door.  Scientific ideas are complex and couched in technical language. For a science to break through, it must be presented to the public in an easily comprehended form, without qualification or caveat, and appeal to deep-seated fears and aspirations.

History shows that elites adopt the novel scientific idea first, but then disseminate it more widely. This process, I should stress, is not a rational one, involving patient explanation and debate. It is more akin to the spreading of wildfire or the adoption of a new fashion. One day, the dystopian vision is a minority one, the next it is an unquestioned orthodoxy.

The third element these movements must offer is a single, simple morally-satisfying solution. A promise of salvation. A way to banish, for all time, the existential conflicts they invoke. For Marx, of course, communism was the only answer. For Prohibitionists, alcohol had to go. For the Club of Rome, an end to economic growth. For climate zealots (as opposed to rationalists), it is a zero-emission world. For the true believers, no other policy response can be tolerated, even from those (especially from those) who, in other respects, share their world view.

Marxists despised unionists who pragmatically accepted capitalism, but worked to ameliorate its adverse effects.  Lenin famously dismissed Australian trade unions as bourgeois for this reason.  Equally, climate change purists cannot abide Bjorn Lomborg, a man who accepts their scientific vision, because he wants to minimise the costs of mitigation (with support for research and development rather than emissions austerity).

When universal visions offer these three things (a highly evocative defining conflict, the sanction of science and a neat, morally-satisfying resolution) they have proven to be irresistible. Each element both buttresses and is in turn reinforced by the other. The result is a tightly-held, passionately-believed world view which is impervious to external criticism. A perspective which, for its adherents, only fools and the morally-corrupt would dare to question.

It is easy to see how this dynamic does harm. Society is divided into incompatible factions: the true believers and the rejectionists, who in their way are just as irrational. Those who, by temperament or from experience, would prefer to remain free of both camps, are forced to choose sides. In these circumstances, rational debate is replaced by name-calling and insults. Pragmatism becomes a dirty world. Persuasion gives way to intimidation and peer pressure. History shows that popular obsessions pass. The bubble eventually bursts. But great harm can be done in the meantime.

Greta Thunberg is nothing if not sincere. At the UN, she spoke with the zeal of someone who has unlocked the key to everything. The single, eternal truth which trumps all others. One day she will realise that the world and humanity are more complex than this. Like so many of us, she may regard her dystopic fantasies as a youthful rite of passage. Looking back, I am sure, her teenage exuberance will be forgiven. But what will be the excuse of those who egged her on?