From Charles Eisenstein, writing in The Guardian:
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.