In its broadest sense, the phrase “there’s no magic money tree” is just a variation on “money doesn’t grow on trees”, a thing you say to children to indicate that wealth comes not from the beneficence of a magical universe, but from hard graft in a corporeal reality. The pedantic child might point to the discrepant amounts of work required to yield a given amount of money, and say that its value is a social construction.

Over time, that loose, rather weak-minded meaning has ceded to a specific economic critique; Jeremy Corbyn – along with anyone who challenges the prevailing fiscal narrative – is dangerous and wrong, since he wants to print money. Money cannot be created from nowhere, because there’s no magic money tree. End of.

The flaw in that argument is that all money is created from nowhere. In normal circumstances, it is created from nowhere as credit, by private banks, and lent to us, usually (85% of the time) in the form of a mortgage on an existing residential property. Decades of credit extension have perverted the housing market to turn a mortgage into a lifetime’s bonded servitude. The economists Jordá, Schularick and Taylor argued convincingly last year that the causes of this economic crisis, the next and the one before are all, fundamentally, the extension of credit and its impact on house prices. So the magic money tree isn’t gushing cash in a socially responsible fashion (if it were used responsibly, it wouldn’t be magic) but the idea that we have a centrally planned, carefully stewarded monetary policy, with finite creation and demonstrable long-term aims, which some loonie leftie wants to come along and unravel, is simply wrong.

In abnormal circumstances, such as the ones we’ve lived through since the financial crisis, central banks are also magic money trees. In the bizarre construction of current economic orthodoxy, you’re not allowed to say so, even though the Bank of England has created £375bn in quantitative easing (QE); the Federal Reserve bought $1.25tn worth of mortgage-backed securities in its first round of QE; the European Central Bank had as a core principle that it couldn’t create money until, suddenly, in awesome amounts, it could; the Bank of Korea has a stimulus package, as does the People’s Bank of China; and Japan started it. Central banks typically justify money creation on the basis that it’s temporary, it’s unfortunate, it’s driven by the crisis and it will ultimately get back to normal.

None of that alters the fact that no bank had that money in savings. I recently said out loud, “we do have a magic money tree, it’s called the Bank of England” in a Newsnight debate with a former adviser to Blair, John McTernan. He made a face like a politician accidentally talking to a member of the public but what the camera didn’t catch was Evan Davis, who stuck his tongue out, like a cat taking a pill. It was days ago, and people are still tweeting me pictures of the Zimbabwean dollar and the Weimar Republic, saying “is this what you want? IS IT?”

Quantitative easing is bizarrely unapproachable, even though it’s happening right across the world and its unwinding will dominate the economic picture for years to come; one is allowed to reference QE, so long as one maintains at all times a technocratic tone, to indicate that one understands and approves of it as nothing more than a lever to create stability. It was the best idea ever, until you suggest something similar could be done for a social purpose, and then it’s the most perilous idea ever. To interrogate why the benefit must always go to the existing asset-holding class, why human ingenuity can’t devise anything more productive and equitable, is to reveal the shaming depth of your incomprehension. It’s not that you don’t understand money; it’s that you don’t understand the exigencies of the debate, which are that you sign up to a number of false principles before you start.

It turned out that the “no money tree” brigade meant: “If you create money infinitely, that will cause inflation” That is a really curious argument against Corbyn’s people’s QE, like going up to someone eating a banana and saying: “If you eat limitless bananas, you will give yourself potassium poisoning.” There’s a secondary argument about the independence of central banks from governments, which is actually rather an elegant example of our dishevelled politics: if the government issues no directive to the Bank of England, and all the gains of QE go to the wealthiest, that’s “independent”. If the government had said, invest this in, say, the green economy, that would have been independence lost. It has become normal to see upwards redistribution as a law of the physical universe, and anything else as the interference of a heavy-handed state.

None of this is to say that people’s QE is straightforward and unproblematic; Corbyn is talking about spending on infrastructure (housing, broadband), whereas that phrase as it was coined described helicopter money, or overt money financing, literally getting money into the economy by randomly giving it to people. They’re two discrete propositions – overt money financing and green and social investment – and rolling them into one doesn’t do much to promote understanding on this terrain.

However, the real barrier to debate is, as with so much in the realm of debt and austerity, that it’s conducted in bad faith, with infantilising aphorisms, aimed not at deepening understanding but at shooing away public interest with unavoidable economic realities. As a tactic, this has reached the end of its plausibility.