I write on the principles of centrism at the Gruntled Center whenever I think of one.
Sociology as a discipline celebrates social movements. We look for the conditions under which people can be roused to activism for social change.
Yet in a centrist social theory, in a well-functioning society there would be no need for social movements. The daily action of incremental improvement - meliorism - would gradually mitigate social problems and improve social life. Social life will never be perfect, but the meliorist ideal does believe in gradual improvement.
Meliorism reduces social friction. Social movements are like earthquakes, which happen when unresolved friction builds up.
The proponents of social movements like the conflict, as well as the social progress. Centrists, by contrast, see conflict as a danger and a social failure. We try to engineer a society with gradual progress that removes the need for social movements.