Dewan and Shepsle explain Acemoglu & Robinson

This how Dewan and Shepsle (2008:548) explain the Acemoglu & Robinson paper ‘Why Did the West Extend the Franchise?

Dewan, Torun and Kenneth A. Shepsle. 2008. "Recent Economic Perspectives on Political Economy, Part II." British journal of political science 38:543-564.

Imagine a political elite confronting the prospect of social unrest. Somehow, politically disadvantaged groups have managed to overcome collective action obstacles to pose a threat. In principle, the elite could promise policy reform of some sort, for example an improvement in working conditions or housing or the distribution of land. They might well deliver on the promise initially, for to fail to do so would provoke the social unrest they currently fear. But once the conditions of unrest have dissolved, or the obstacles to collective action have re-emerged, it is possible for this elite to renege on its promises. That is to say, if the favourable conditions under which politically disadvantaged groups can mobilize are transitory, then promises from the elite that extend beyond the period in which those conditions are expected to hold are not credible. In order to be credible the promise has to take a more durable form, one difficult for the elite to reverse. Acemoglu and Robinson suggest that franchise extension possesses this greater durability – it is more difficult to reverse than, say, a land reform that can be undone.