Deuda (in)sostenible

De Eichengreen & Panizza, sobre la sostenibilidad de las deudas públicas de los países del sur de Europa.

"For the debts of Europe’s problem countries to be sustainable, absent restructuring, foreign aid or an unanticipated burst of inflation, their governments will have to run large primary budget surpluses, in many cases in excess of 5% of GDP, for periods as long as ten years. History suggests that such behaviour, while not entirely unknown, is exceptional. Countries that have run such large surpluses for such extended periods have faced exceptional circumstances.
On balance, this analysis does not leave us optimistic that Europe’s crisis countries will be able to run primary budget surpluses as large and persistent as officially projected."

Que quiere decir que, durante 10 años, si no hay reestructuración, inflación, o ayuda exterior, estos países deberán mantener un superávit primario (SP = Ingresos - Gastos - pagos de intereses y amortización de deuda) igual al 5% de PIB. Y que esto -diez años con dicho superávit - es extremadamente improbable.

Aparte de los inevitables ciclos y choques, hay razones políticas y económicas que erosionaría la determinación de la sociedad de mantearen tanto tiempo una austeridad tan intensa (piénsese que España todavía no ha logrado tener superávit primario desde que empezó la crisis):

These are large primary surpluses. There are both political and economic reasons for questioning whether they are plausible. When tax revenues rise, legislators and their constituents apply pressure to spend them. In 2014, Greece enjoyed its first primary surpluses after years of deficits and fiscal austerity; the government immediately came under pressure to disburse a ‘social dividend’ of €525 million to 500,000 low-income households. Budgeting, as is well known, creates a common pool problem, and the larger the surplus, the deeper and more tempting is the pool. Only countries with strong political and budgetary institutions may be able to mitigate this problem (de Haan et al. 2013).
Turning to the economics, a slowdown in global growth, worsening terms of trade, and a recession can all disrupt the efforts of even the most dedicated governments seeking to run large primary surpluses for a decade. Recession depresses tax revenues, and the spending cuts needed to maintain the surplus above the promised threshold may depress activity and revenues still further. The government may prefer to let its automatic fiscal stabilisers operate. Whatever the other merits of that choice, it too will prevent the string of primary surpluses from being maintained.