Federal Reserve chairman Ben Bernanke's pledge at Jackson Hole last Friday to "promote a stronger economic recovery" through "additional policy accommodation" has drawn criticism from economists, liberal and conservative, who question whether the Fed has the wherewithal to stimulate economic growth. What we actually need is more spending, say the liberals. No, less spending, say the conservatives. But underneath these disagreements lies an unexamined agreement, a common assumption that no mainstream economist or policy-maker ever questions: that the purpose of economic policy is to stimulate growth.

So ubiquitous is the equation of growth with prosperity that few people ever pause to consider it. What does economic growth actually mean? It means more consumption – and consumption of a specific kind: more consumption of goods and services that are exchanged for money. That means that if people stop caring for their own children and instead pay for childcare, the economy grows. The same if people stop cooking for themselves and purchase restaurant takeaways instead.

Economists say this is a good thing. After all, you wouldn't pay for childcare or takeaway food if it weren't of benefit to you, right? So, the more things people are paying for, the more benefits are being had. Besides, it is more efficient for one daycare centre to handle 30 children than for each family to do it themselves. That's why we are all so much richer, happier and less busy than we were a generation ago. Right?

Obviously, it isn't true that the more we buy, the happier we are. Endless growth means endlessly increasing production and endlessly increasing consumption. Social critics have for a long time pointed out the resulting hollowness carried by that thesis. Furthermore, it is becoming increasingly apparent that infinite growth is impossible on a finite planet. Why, then, are liberals and conservatives alike so fervent in their pursuit of growth?

The reason is that our present money system can only function in a growing economy. Money is created as interest-bearing debt: it only comes into being when someone promises to pay back even more of it. Therefore, there is always more debt than there is money. In a growth economy that is not a problem, because new money (and new debt) is constantly lent into existence so that existing debt can be repaid. But when growth slows, good lending opportunities become scarce. Indebtedness rises faster than income, debt service becomes more difficult, bankruptcies and layoffs rise.

Central banks used to have a solution for that. When growth slowed, they would simply buy securities (usually government bonds) on the open market, driving down interest rates. Investors who wouldn't lend into the economy if they could get 8% on a risk-free bond might change their minds if the rate were only 5%, or 2%. Rates that low would stimulate a flood of credit, jumpstarting the economy. Today that tool isn't working, but central banks are still trying it nonetheless. With risk-free interest rates near zero, they continue creating money through the same means as before, now calling it "quantitative easing". The thinking seems to be: "If you have more money than you know what to do with and are afraid to lend it, how about giving you even more money?" It is like giving a miser an extra bag of gold in hopes that he'll start sharing it.

Most commentators interpret Bernanke's remarks as signalling the possibility of a new round of quantitative easing. If so, the results will likely be the same as before – a brief churning of equities and commodities markets, but little leakage of the new money into the real economy. In all fairness, we cannot blame the banks for their reluctance to lend. Why would they lend to maxed-out borrowers in the face of economic stagnation? It would be convenient to blame banker greed; unfortunately, the problem goes much deeper than that.

The problem that we are seemingly unable to countenance is the end of growth. Today's system is predicated on the progressive conversion of nature into products, people into consumers, cultures into markets and time into money. We could perhaps extend that growth for a few more years by fracking, deep-sea oil drilling, deforestation, land grabs from indigenous people and so on, but only at a higher and higher cost to future generations. Sooner or later – hopefully sooner – we will have to transition towards a steady-state or degrowth economy.

Does that sound scary? Today it is: degrowth means recession, with its unemployment, inequality and desperation. But it need not be that way. Unemployment could translate into greater leisure for all. Lower consumption could translate into reclaiming life from money, reskilling, reconnecting, sharing.

Central banks could play a role in this transition. For example, what if quantitative easing were combined with debt forgiveness? The banks get bailout after bailout – what about the rest of us? The Fed could purchase student loans, mortgages or consumer debt and, by fiat, reduce interest rates on those loans to zero, or even reduce principal. That would liberate millions from the debt chase, while freeing up purchasing power for those who are truly underconsuming.

More radically, central banks should be allowed to breach the "zero lower bound" that has rendered monetary policy impotent today. If investors are unwilling to lend even when risk-free return on investment is 0%, why not reduce that to -2%, even -5%? Implemented as a liquidity tax on bank reserves, it would allow credit to circulate in the absence of economic growth, forming the monetary foundation of a steady-state economy where leisure and ecological health grow instead of consumption.

One thing is clear: we are at the end of an era. No one seriously believes that we will grow ourselves out of debt again. There is an alternative. It is time to begin the transition to a steady-state economy.