Political science is hard!
There has been some recent blogobuzz about the work of Juan Linz, who argued that presidential systems were more prone to breakdowns than parliamentary ones. Breakdown, of course, meant a military coup.
Problem is, Linz’s arguments aren’t airtight in theory or in practice. They strongly hinge on the idea that the constitution’s problem-solving mechanisms are illegitimate. Perhaps that is true in the United States; perhaps if it is not. If President Obama is forced to choose between breaking the law by omission or breaking it by commission, we might have a test of this proposition.
(Omission is letting the U.S. start to default on payments in the next few weeks; commission is authorizing a Treasury auction in contravention of the debt ceiling. Both are in fact illegal.)
In addition, Linz provides no prediction as to whether a strong presidency would be better or worse for stability. A strong presidency (as in Colombia) avoids some of the problems of legislative-executive conflicts; but it increases the problems of getting stuck with a hard-to-remove problematic executive. (This very problem caused the Honduran coup.) A weak president, on the other hand, lessens the winner-take-all problem. (Scott Mainwaring and Matthew Shugart, currently at Notre Dame and UC-Davis, suggested that two decades ago.)
Jim Robinson and Ragnar Torvik have a more developed model that takes into account the fact that many parliamentary systems outside Latin America switched to presidential ones. I like that paper. Thing is, Robinson-Torvik reduces the choice of system to an epiphenomenon ... and predicts that presidentialism will be preferred in societies that are (a) polarized with respect to preferences for public goods; (b) highly divided ideologically; and (c) have a low government budget. If they are right, then a parliamentary system for such a society might be better in some theoretical sense ... but it is also a Nirvana fantasy.
Empirically, there are some problems with Linz. First, Latin America has no parliamentary regimes. That makes intra-regional comparisons difficult. The parliamentary governments of the West Indies have seen three democratic breakdowns (Grenada, Guyana and Suriname). That is a relatively low rate compared to the mainland, but the islands are different from the mainland are different on a whole host of variables, not least their judicial links with the United Kingdom and the willingness of the United States to intervene.
Second, in Africa, neither system is more likely to survive. That poses a problem for the theory, at least in very poor countries. (Ditto very rich ones, where most of the democratic breakdowns have happened in parliamentary regimes: e.g., interwar Europe.)
Finally, a lot of the results are driven by the surprising fact that island states are less likely to experience democratic breakdown.
There may be a killer paper out there. If there is, I am not aware of it.
In other words, the U.S. has some constitutional problems. They may even cause political failure. But I am not sure that our current crisis of ingovernability is due to presidentialism per se.
Moreover, it would seem to me that a stronger executive would obviate the current crisis. This could not happen in Colombia or Brazil. Perhaps that is what (for better or worse) the current crisis will give us.