In a Vox blog post (that complements another post on Greece), Jeremy Bulow and Ken Rogoff review the academic discussion on a long-standing question—why sovereigns repay their external debt.
Bulow and Rogoff distinguish between
[t]he ‘reputation approach’ pioneered by Eaton and Gersovitz (1981) which builds on Hellwig (1977);
and the ‘direct punishments’ bargaining-theoretic approach of Bulow and Rogoff (1988b, 1989a) which in turn builds on Cohen and Sachs (1986).
They argue that the latter approach—attributing enforceable rights in foreign country courts to creditors—better explains observed outcomes.
[The] direct punishment/bargaining approach lends itself very naturally to incorporating moral hazard; …
reputation models suggest [counter factually] that the governing law of the debt is irrelevant;
[i]n standard reputation for repayment models, write-downs are decided unilaterally—creditors’ particular concerns do not really matter; …
[t]he interests and welfare of unrelated third parties does not matter in standard reputation models; …
[r]eputational debtors borrow in bad times and re-pay in good times, for purposes of income smoothing; [d]efaults, if they are to take place, occur in good times … In reality, many countries borrow as much as they can whenever they can. … Debt crises occur when countries do badly and creditors decide they want to reduce their loan exposure. To some extent, this issue can be addressed by assuming that income shocks are permanent and not transitory, but it remains difficult to rationalise country borrowing only on the threat of lost consumption smoothing. …
[c]reditor identity doesn’t matter; …
[u]nder … general assumptions, the existence of [the option to put savings abroad] leads to the unravelling of any purely reputational equilibrium.
Bulow and Rogoff add that
[a]nother important issue … is that in practice, sovereign debt renegotiations focus very much on the flow of repayments, and much less on how the stock of debt evolves. This is precisely because all sides realise that any future promises can be renegotiated.