What has changed since the time when public debt ratios were stable in the medium term?

We look at the United States, the euro zone and the OECD as a whole. Before the subprime crisis, public debt ratios fluctuated but were stable in the medium term: more restrictive fiscal policies in expansion periods offset the expansionary fiscal policies in periods of recession. Why has this no longer been the case since the subprime crisis? What accounts for the upward drift in public debt ratios? Possible explanations are: The determination to combat the loss of potential growth in the wake of the subprime crisis; Public pressure to reduce the unemployment rate rapidly and by as much as possible; Expansionary monetary policies, which have driven long-term interest rates significantly below growth rates; Central banks’ monetisation of fiscal deficits. Private sector deleveraging. The only “reassuring” explanations are the change in collective preferences, in favour of a more active fight against unemployment, and private sector deleveraging. The other explanations are worrying.