This post in the series focuses on the “remain” part rather than the “become” part. Juan Linz has famously argued that presidential democracies don’t work, with the exception of the US. To simplify things a bit, in a presidential democracy – where you have of course also a parliament – the executive power is elected directly by popular vote. People elect a president and this president selects her government. The people also elect members of parliament in separate elections. In a parliamentary democracy the executive isn’t elected directly by the people. The people elect only the members of parliament. The political party (or parties) that manage to get a majority of elected members of parliament then form a government (often after coalition negotiations between parties when there isn’t one party that has managed to acquire a majority of representatives in parliament).
One of the causes of the breakdown of presidential systems is the opposition between legislature and executive: both the president and the majority in the legislature have democratic legitimacy since they are both directly elected. That’s not a problem when both are of the same political family, but when they are not, it’s a recipe for stalemate at best and breakdown at worst.
Under such circumstances, who has the stronger claim to speak on behalf of the people: the president or the legislative majority that opposes his policies? Since both derive their power from the votes of the people in a free competition among well-defined alternatives, a conflict is always possible and at times may erupt dramatically. Theme is no democratic principle on the basis of which it can be resolved, and the mechanisms the constitution might provide are likely to prove too complicated and aridly legalistic to be of much force in the eyes of the electorate. It is therefore no accident that in some such situations in the past, the armed forces were often tempted to intervene as a mediating power. (source)
On the other hand, parliamentary systems seem to be less stable in countries plagued by bitter ethnic conflict, as is the case in many African countries.
More posts in this series are here.