"I show that the lower orders ****often join****, and have good reason to join, the conservative cause: in fending off a democratic movement from below, conservatism gives them a taste of lordly power they otherwise would not enjoy."
****often join**
In other words, they often do NOT join. Hence no explanation focusing only on one phenomenon is of any interest. An explanation is needed for _both_ phenomena.
Also: That X occurs often does not in itself establish that X exists. That is, we may well have a series of historical events each of which requires _separate_ explanation, and the attempt to see them as a coherent category, all falling under the same explanation, is chasing an illusion.
Carrol