The stylized facts regarding technological progress are staggering. Theory tells us that in its absence, persistent per capita GDP growth is impossible (Solow, 1956). The empirical results are no less eye-opening. Time and again, econometric studies conclude that the majority of the cross-national variation in income levels and growth rates derives from the disparities countries exhibit in their levels and rates of change of technological progress (Caselli, 2005; Easterly, 2001; Solow, 1957). On this latter point, Hall and Jones's (1999) seminal study presents us with some particularly revealing facts:

These theoretical and empirical results implore scholars of economic development to explain why some countries exhibit faster technological progress than others do. Political scientists tend to pay too little attention to the issue, however. It is telling that the discipline's most important book on economic growth in the past twenty-five years or so, Przeworski et al.'s Democracy and Development (2000), barely touches on the issue. To be sure, that work uncovers the important finding that rich democracies exhibit more technological progress than rich dictatorships do. Yet, why that tendency exists went largely unexplained in that book, and it remains so today.

I do not point this out to diminish Przeworksi et al.'s contribution. On the contrary, Democracy and Development is an exemplar of well-considered scholarship, and its influence in the discipline is entirely appropriate. Even so, the uncomfortable truth is that we don't know as much as we should regarding the political underpinnings of technological progress, so we don't know as much as we should about countries’ long-run development paths.