Abstract
Among the most important of all constitutional choices that have to be made in democracies is the choice of relationship between the executive and the legislature, in particular presidential versus parliamentary government. Political scientists disagree about which of the alternatives are preferable, but they are in agreement that the choices made by democratic constitutional engineers can have far-reaching effects on how well the democratic system operates. For democratizing countries, these choices are particulraly crucial because the success of the newly founded democratic system depends on it. In addition, if the new democracy does prove to be viable, the initial choices are likely to last for a long time. Seymour Martin Lipset and Stein Rokkan have pointed out that the party system established at the beginning of a country's democratic experience tends to become virtually frozen. This applies even more strongly to the fundamental constitutional structure: drastic constitutional changes like shifts from presidentialism to parliamentarism or vice versa are extremely rare in established democracies. This paper will explain the preference of one political regime upon another.
