Adam Przeworski, Michael Alvarez, Jose Antonio Cheibub, and Fernando Limongi. “What Makes Democracies Endure?” Journal of Democracy 7 (January 1996), 39-55.
If a country, any randomly selected country, is to have a democratic regime next year, what conditions should be present in that country and around the world this year? The answer is: democracy, affluence, growth with moderate inflation, declining inequality, a favorable international climate, and parliamentary institutions.
The survival of democracies does depend on their institutional systems. Parliamentary regimes last longer than presidential ones. Majority-producing electoral institutions are conducive to the survival of presidential systems; presidential systems facing legislative deadlock are particularly brittle. Both systems are vulnerable to bad economic performance, but presidential democracies are less likely to survive even when the economy grows than are parliamentary systems when the economy declines. Evidence indicate that parliamentary democracy survives longer and under a broader spectrum of conditions than presidential democracy.
There is no evidence that democracies are "consolidated" over time or that at any level of development the mere passage of time makes the demise of democracies less likely. The drop in hazard rates observed over time (uncorrected for the level of development) could just be the result of countries developing economically.
