"I don't care who writes a nation's laws – or crafts its treatises – if I can write its economics textbooks," said Paul Samuelson. The Nobel prizewinner grasped that what was true of gadgets was also true for economies: he who produces the instruction manual defines how the object will be used, and to what ends.

Samuelson's axiom held good until the collapse of Lehman Brothers, which triggered both an economic crisis and a crisis in economics. In the six years since, the reputations of those high priests of capitalism, academic economists, have taken a battering.

The Queen herself asked why hardly any of them saw the crash coming, while the Bank of England's Andy Haldane has noted how it rendered his colleagues' enchantingly neat models as good as useless: "The economy in crisis behaved more like slime descending a warehouse wall than Newton's pendulum." And this week, economics students from Kolkata to Manchester have gone on the warpath demanding radical changes in what they're taught.

In a manifesto signed by 42 university economics associations from 19 countries, the students decry a "dramatic narrowing of the curriculum" that presents the economy "in a vacuum". The result is that the generation next in line to run our economy, from Whitehall departments or corporate corner-offices, discuss policy without touching on "broader social impacts and moral implications of economic decisions".

The problem is summed up by one of the manifesto's coordinators, Faheem Rokadiya, at the University of Glasgow: "Whenever I sit an economics exam, I have to turn myself into a robot." But he and his fellow reformers aren't seeking to skimp on algebra, or calling for a bonfire of the works of the Chicago school. They simply object to the notion that there is one true way to do economics, especially after that apparently scientific method has been found so badly wanting.

In their battle to open up economics, Rokadiya et al have one hell of a fight on their hands, for the same reason that it has proved so hard to democratise so many aspects of the post-crash order: the forces of conservatism are just too powerful. To see how fiercely the academics fight back, take a look at the University of Manchester.

Since last autumn, members of the university's Post-Crash Economics Society have been campaigning for reform of their narrow syllabus. They've put on their own lectures from non-mainstream, heterodox economists, even organising evening classes on bubbles, panics and crashes. You might think academics would be delighted to see such undergraduate engagement, or that economists would be swift to respond to the market.

Not a bit of it. Manchester's economics faculty recently announced that it wouldn't renew the contract of the temporary lecturer of the bubbles course, and that students who wanted to learn about the crash would have to go to the business school.

The most significant economics event of our lifetime isn't being taught in any depth at one of the largest economics faculties in the country. So what exactly is a Russell Group university teaching our future economists? Last month the Post-Crash members published a report on the deficiencies of the teaching they receive. It is thorough and thoughtful, and reports: "Tutorials consist of copying problem sets off the board rather than discussing economic ideas, and 18 out of 48 modules have 50% or more marks given by multiple choice." Students point out that they are trained to digest economic theory and regurgitate it in exams, but never to question the assumptions that underpin it. This isn't an education: it's a nine-grand lobotomy.

The Manchester example is part of a much broader trend in which non-mainstream economists have been evicted from economics faculties and now hole up in geography departments or business schools. "Intellectual talibanisation" is how one renowned economist describes it in private. This isn't just bad for academia: the logical extension of the argument that you can only study economics in one way is that you can only run the economy in one way.

Mainstream economics still has debates, but they tend to be technical in nature. The Nobel prizewinner Paul Krugman has pointed to the recent work of Thomas Piketty as proof that mainstream economics is plenty wide-ranging enough. Yet when Piketty visited the Guardian last week, he complained that economists generate "sophisticated models with very little or no empirical basis … there's a lot of ideology and self-interest".

Like so many other parts of the post-crash order, mainstream economists are liberal in theory but can be authoritarian in practice. The reason for that is brilliantly summed up by that non-economist Upton Sinclair: "It is difficult to get a man to understand something when his salary depends on his not understanding it."