Errata #2

Well, this is embarassing. I counted the "parliamentary", "presidential" and "neither" countries from Table 0.1 by hand, and forgot to include Saudi Arabia and San Marino* in my "neither list".  I then calculated the parliamentary countries by simple subtraction of the presidential and neither from the total, and arrived at 22. The correct figure is 20. Surely I don't think this changes anything in the argument, but I regret not having used a software so as to avoid such a simple mistake.

* San Marino would be a "neither" because it does not figure in the Database of Political Institutions. Given that the heads of government are chosen by the Council, it would most likely have been classified as parliamentary if they did appear in that database.