In the Introduction to de Tocqueville's Ancient Regime and the French Revolution ("AR") the writer, Elster, notes:
The "Tocqueville Effect" is that revolutions occur when conditions are improving, not (as Marx sometimes asserted) when they are going from bad to worse.
A related fruitful idea is that of the ineffectiveness of both moderate repression and moderate concessions as responses to social unrest.
Equally important in a more general perspective is the idea of “pluralistic ignorance” - the apparent consensus that arises when few people believe in a given doctrine, but most people believe that most people believe it. (This idea was already present in Democracy in America.)
Finally, one can cite the idea of “second-best” political systems - one evil can offset another, so that if one of them is removed, the overall performance of the system will suffer.