The current debt crisis is the culmination of a long process of public debt accumulation over the last three decades in developed economies. Why this trend? I do not think it has suddenly become fashionable for governments to go deeper in debt, or that suddenly we came up with policy prescription leading that way more than before.
Marina Azzimonti, Eva de Francisco and Vincenzo Quadrini think it has to do with financial liberalization and globalization. The fact that more financial instruments and opportunities are now available certainly must contribute. There is already considerable evidence that the emergence of new borrowing instruments has increased household borrowing in the US, in particular for unsecured debt (credit cards). What these authors show is that a key component in the endogenous increase in public debt is a concurrent increase in income inequality in a political equilibrium. Public debt is beneficial because allows intertemporal smoothing. But at some point, higher debt leads to interest rates too high for the good of a majority. Interestingly, the model shows that it is not necessary for inequality to increase in all countries for this to happen. Globalization leads to a world-wide market, and local interest rates are largely determined on that market.